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1

Rhizoctonia solani AG groups in northeast India  

Microsoft Academic Search

Rhizoctonia solani isolates collected from different crops in northeast India belonged to anastomosis group AG 2-2 IIIB (Canavalia ensiformis, Sechium edule, Glycine max and Dolichos lablab). AG 1-1A was detected on Zea mays, Rhizoctonia solani on Sechium edule and AG 4HG-II on a weed, Galinsoga parviflora, which are new records from India.

P. Baiswar; D. D. Rosa; S. Chandra; S. V. Ngachan

2010-01-01

2

Rhizoctonia seedling disease on sugar beet  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia seedling damping-off can cause losses in sugar beet as well as providing inoculum for later root rot. The disease is caused by Rhizoctonia solani. The pathogen has several subgroups, anastomosis groups (AG), of which AG-4 has historically been associated with damping-off, while AG-2-2 is...

3

RHIZOCTONIA SEEDLING DAMPING OFF IN SUGAR BEETS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Diseases caused by Rhizoctonia solani n sugar beets include post-emergence damping off of seedlings, and crown and root rot of mature plants. Sugar beet varieties show varying degree of susceptibility to R. solani. Project goals include development of a reliable method to screen for Rhizoctonia se...

4

Rhizoctonia web blight in: compendium of azalea and rhodendron diseases  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia web blight, caused by several Rhizoctonia spp., is an important disease of evergreen azaleas and other ornamental plants in nurseries. The primary pathogens causing web blight are binucleate Rhizoctonia anastomosis groups (AG) (= Ceratobasidium D.P. Rogers, teleomorph). In southern AL an...

5

Adaptation of Rhizoctonia Solani Kuehn to Fungicides.  

National Technical Information Service (NTIS)

Eight transfers on media containing boric acid led to a 1.5-two-fold increased resistance to boric acid in Rhizoctonia solani. Evidently the main mechanism of increase in resistance is cytoplasmic adaptation. The increased resistance is not fixed in the p...

Y. T. Dyakov

1968-01-01

6

Rhizoctonia solani AG groups in northeast India  

Microsoft Academic Search

Rhizoctoniasolaniisolates collectedfromdifferentcropsinnortheastIndiabelongedtoanastomosisgroupAG 2-2 IIIB (Canavalia ensiformis, Sechium edule, Glycine max and Dolichos lablab). AG 1-1A was detected on Zea mays, Rhizoctonia solani on Sechium edule and AG 4HG-II on a weed, Galinsoga parviflora, which are new records from India.

P. Baiswar; D. D. Rosa; S. Chandra; S. V. Ngachan

2010-01-01

7

CHARACTERIZATION OF RHIZOCTONIA SOLANI ISOLATES FROM RICE IN ARKANSAS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani causes sheath blight, one of the most serious diseases of rice. Over 200 isolates of Rhizoctonia-like fungi were obtained from infected rice samples in Arkansas, of which, 103 isolates were identified as R. solani using rDNA-ITS marker. The remaining isolates were either R. sativ...

8

DOUBLE-STRANDED RNA-MEDIATED HYPOVIRULENCE OF RHIZOCTONIA SOLANI  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani is a soilborne fungal plant pathogen responsible for economic losses of crops worldwide. Isolates of Rhizoctonia (anastomosis group 3) cause a disease commonly known as black scurf, stem and stolon canker of potato. We observed that some isolates of the pathogen lose their ability...

9

Evaluation of strategies for the control of canola and lupin seedling diseases caused by Rhizoctonia anastomosis groups  

Technology Transfer Automated Retrieval System (TEKTRAN)

Several methods with potential for the management of Rhizoctonia diseases of canola and lupin including several methods with potential for the management of Rhizoctonia plant resistance, fungicide seed treatment and biological control using binucleate Rhizoctonia anastomosis groups (AGs) were evalua...

10

Optimized protein extraction methods for proteomic analysis of Rhizoctonia solani  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani (Teleomorph: Thanatephorus cucumeris) is a basidiomycetous fungus which includes important plant pathogens, saprophytes and mycorrhizae. R. solani displays several hyphal anastomosis groups (AGs) with distinct host plant specializations. In order to facilitate studies on its biol...

11

Virulence, distribution and diversity of Rhizoctonia solani from sugar beet in Idaho and Oregon  

Microsoft Academic Search

Rhizoctonia root rot causes serious losses on sugar beet worldwide. In order to help explain why Rhizoctonia root rot management practices have not performed well in some areas of the Intermountain West (IMW), a survey was conducted. In the IMW from 2004 to 2006, 94 Rhizoctonia solani field isolates were collected from sugar beet roots. These field isolates were compared

Carl A. Strausbaugh; Imad A. Eujayl; Leonard W. Panella; Linda E. Hanson

2011-01-01

12

Plant Spacing Effects on Microclimate and Rhizoctonia Web Blight Development in Container-grown Azalea  

Microsoft Academic Search

Rhizoctonia web blight, caused by Rhizoctonia solani and binucleate Rhizoctonia spp., is an annual problem in compact cultivars of container-grown azalea (Rhododendron spp.) in the Gulf Coast states. Increasing the space between plants is commonly recom- mended for suppression of the disease, but experimental evidence for the effectiveness of this cultural practice in container-grown azalea is lacking. During the summers

Warren E. Copes

2005-01-01

13

Sugar Beet Resistance to Rhizoctonia Root and Crown Rot: Where does it fit in?  

Technology Transfer Automated Retrieval System (TEKTRAN)

In sugar beet (Beta vulgaris L.), Rhizoctonia root- or crown-rot is caused by Rhizoctonia solani (AG-2-2). Seedling damping-off in sugar beet is caused by R. solani of both anastomosis groups, AG-2-2 and AG-4. Rhizoctonia solani subgroup AG-2-2 IV had been considered to be the primary cause of Rhi...

14

Biogenesis of pipecolic acid in Rhizoctonia leguminicola  

SciTech Connect

This laboratory has long been interested in the biogenesis and biological properties of two indolizidine alkaloids, slaframine and swainsonine that are produced by the fungal parasite Rhizoctonia Leguminicola. Slaframine, (1S,6S,8aS-1 acetoxy-6-aminooctahydroindolizine) is a parasympathetic secretagogue, and swainsonine (1S,2R,8R,8aR-1,2,8-trihydroxyoctahydroindolizine) is a potent {alpha}-mannosidase inhibitor. This thesis concerns the initial steps of the biosynthesis of these alkaloids from lysine, via the common intermediate pipecolic acid, in whole cells and cell free enzyme systems of R. leguminicola. In confirmation of earlier work performed in this laboratory, L-lysine was used preferentially for pipecolate biosynthesis in R. Leguminicola. This pathway was supported by the finding that cell free extracts of R. leguminicola consistently converted L-(U-{sup 14}C)-lysine to three labelled metabolites: saccharopine, peak II, and pipecolic acid. Peak II was subsequently identified by appropriate proton NMR studies to be {delta}{sup 1}-piperideine-6-carboxylate, and the following pathway of pipecolic acid formation was postulated: L-lysine {yields} saccharopine {yields} {delta}{sup 1}-piperideine-6-carboxylate {yields} pipecolate. This pathway was confirmed by demonstration of each enzymatic step in vitro from purified radiolabeled substrates.

Wickwire, B.M.

1989-01-01

15

SEEDLING RESISTANCE TO RHIZOCTONIA SOLANI IN SUGAR BEET  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani in sugar beet (Beta vulgaris L.) causes damping'off at the seedling stage and crown and root rot in the adult plant. Managing damping-off by azoxystrobin fungicides is promising but genetic resistance is being sought. Phenotypic and microscopic analysis of disease progress pattern...

16

Bodemweerbaarheid tegen Rhizoctonia solani AG 2-1 in bloemkool  

Microsoft Academic Search

Rhizoctonia solani is een algemeen voorkomende bodemschimmel die bij diverse gewassen schade veroorzaakt. Dit pathogeen is moeilijk te bestrijden vanwege zijn goede overleving in de bodem. Bovendien kunnen geringe hoeveelheden van het pathogeen onder gunstige omstandigheden het gewas reeds ernstige schade toebrengen. De mate van schade is slecht te voorspellen. Het is gebleken dat onder bepaalde omstandigheden een hoge bodemweerbaarheid

J. Postma; M. T. Schilder

2005-01-01

17

Fungicidal activity of some plant extracts against rhizoctonia  

Microsoft Academic Search

The leaf extracts of Piper guinensis, Ocimum sanctum, O. gratissimum and Cymbopogon citratus were effective in reducing the radial growth of Rhizoctonia solani in vitro and in checking the spread of the disease caused by the pathogen in the field. P. guinensis was the best in checking the spread of the pathogen both in vitro and in vivo. This was

A. C. Amadioha

2001-01-01

18

Rhizoctonia seedling damping-off in sugar beet in Michigan  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani is an important seedling pathogen of sugar beet, causing damping-off following seedling emergence. Anastomosis group (AG)-4 has been the primary seedling pathogen reported on sugar beet, however, recent screening has found high incidence of infection by AG-2-2. Isolations of R. so...

19

Soil suppressiveness to Rhizoctonia solani and microbial diversity.  

PubMed

Rhizoctonia solani anastomosis group 2-2IIIB causes damping-off, black root rot and crown rot in sugar beet (Beta vulgaris). Based on experiences of growers and field experiments, soils can become suppressive to R. solani. The fungus may be present in the soil, but the plant does not show symptoms. Understanding the mechanisms causing soil suppressiveness to R. solani is essential for the development of environmentally friendly control strategies of rhizoctonia root rot in sugar beet. A bioassay that discriminates soils in their level of disease suppressiveness was developed. Results of bioassays were in accordance with field observations. Preliminary results indicate an active role of microbial communities. Our research is focused on the disentanglement of biological mechanisms causing soil suppressiveness to R. solani in sugar beet. Therefore, we are handling a multidisciplinary approach through experimental fields, bioassays, several in vitro techniques and molecular techniques (PCR-DGGE). PMID:16637155

Bakker, Y; Van Loon, F M J; Schneider, J H M

2005-01-01

20

Biotrophic mycoparasitism by Verticillium biguttatum on Rhizoctonia solani  

Microsoft Academic Search

Verticillium biguttatum cannot utilise cellulose or nitrate-nitrogen and it requires biotin for growth, yet it grew and sporulated abundantly onRhizoctonia solani on cellulose, obtaining at least organic carbon, nitrogen and biotin fromR. solani. Videomicroscopy of inter-hyphal interactions on films of water agar showed thatV. biguttatum behaved as a biotrophic mycoparasite. From germinating spores, it penetrated the hyphae ofR. solani and

P. H. J. F. Van Den Boogert; J. W. Deacon

1994-01-01

21

Timing and Methodology of Application of Azoxystrobin to Control Rhizoctonia Solani in Sugarbeet  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani AG 2-2 is the causal agent of Rhizoctonia root and crown rot of sugar beet (Beta vulgaris) in North Dakota and Minnesota. This disease is a major limiting factor to sugar beet production. Management strategies currently include using partially resistant cultivars and fungicides. ...

22

Rhizoctonia root rot resistance of Beta PIs from the USDA-ARS NPGS, 2006.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thirty Plant Introductions (PIs) from the USDA-ARS National Plant Germplasm System were evaluated for resistance to Rhizoctonia root rot. Materials were planted at the Crops Research Lab-Fort Collins Research Farm in CO and inoculated with dry, ground, barley-grain inoculum of Rhizoctonia solani is...

23

STUDIES ON ISOLATES OF RHIZOCTONIA SOLANI FROM ARKANSAS FOR MANAGEMENT OF RICE SHEATH  

Technology Transfer Automated Retrieval System (TEKTRAN)

The quantitative nature of the resistance to rice sheath blight caused by Rhizoctonia solani has made screening for resistance difficult. Studying field isolates may facilitate resistance screening. Among 200 Rhizoctonia-like fungi obtained from infected rice and two grass species from 19 counties...

24

RHIZOCTONIA ROOT ROT RISISTANCE OF BETA PIS FROM THE USDA-ARS NPGS, 2001  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thirty Plant Introductions (PIs) from the USDA-ARS National Plant Germplasm System were evaluated for resistance to Rhizoctonia root rot. Materials were planted at the Crops Research Lab-Fort Collins Research Farm in CO and inoculated with dry, ground, barley-grain inoculum of Rhizoctonia solani i...

25

SIMPLE AROMATIC ACIDS AND THEIR SALTS IN CONTROLLING THE GROWTH OF RHIZOCTONIA SOLANI UNDER LABORATORY CONDITIONS  

Microsoft Academic Search

Rhizoctonia solani is a fungus pathogenic in many economically important plants. Ten aromatic acids were examined for activity against Rhizoctonia solani using poisoned food technique. All the acids were inhibitory to R. solani. Three of the acids, at concentrations around 0.015% (g\\/ml), completely inhibited the growth of the fungus. Efforts were made to enhance the solubility of chosen aromatic acids

D. T. U Abeytunga; W. A. Jayasundara

26

Characterization of Rhizoctonia isolates associated with damping-off and crown rot of rooibos seedlings  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia species were reported to be an important component of the complex involved in damping-off of rooibos (Aspalathus linearis) seedlings and cause severe crown rot of seedlings in nurseries. However, no information is available on the anastomosis groups (AGs) of Rhizoctonia associated with d...

27

Pathogenicity of three isolates of Rhizoctonia sp. from wheat and peanut on hard red winter wheat  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia-induced root diseases can significantly affect wheat and peanut production where these two field crops are grown in rotation. Hence, this study characterized two isolates of Rhizoctonia spp. from wheat [R. cerealis (RC) and R. solani (RSW)] and one from peanut [R. solani (RSP) ] for cul...

28

Effect of flutriafol on saprophytic survival and growth of Rhizoctonia solani (AG8)  

Microsoft Academic Search

The effect of flutriafol (a sterol-inhibiting triazole fungicide) on saprophytic survival and growth of Rhizoctonia solani (AG-8, causal agent of rhizoctonia root rot of wheat) in vitro and in soil was investigated with agar plate tests, a soilsandwich experiment and soil bioassays. At a concentration of 25\\u000a ?g\\/mL agar, flutriafol reduced the growth of R. solani in vitro, but at

P. J. Cotterill

1993-01-01

29

Differential expression of Phaseolus vulgaris genes induced during the interaction with Rhizoctonia solani  

Microsoft Academic Search

Common bean (Phaseolus vulgaris L.) is the most important grain legume for direct human consumption; however, bean production is affected by several diseases\\u000a such as Rhizoctonia root rot. Few bean cultivars have been identified that effectively resist the attack of this fungus. Herein,\\u000a we used the P. vulgaris Pv-2094 landrace, which is less susceptible to Rhizoctonia root rot, for the

M. L. Guerrero-González; M. Rodríguez-Kessler; R. Rodríguez-Guerra; M. González-Chavira; J. Simpson; F. Sanchez; J. F. Jiménez-Bremont

2011-01-01

30

Use of guazatine and flutriafol for the control of take-all and Rhizoctonia root rot of wheat  

Microsoft Academic Search

A series of experiments with artificially inoculated soil was undertaken to test the efficacy of the fungicide guazatine against\\u000a take-all and Rhizoctonia root rot of wheat (caused by Gaeumannomyces graminis var. tritici and Rhizoctonia solani, respectively) and to develop a chemical control technique against Rhizoctonia root rot. Guazatine was ineffective as a soil-applied\\u000a fungicide against both diseases but, as a

P. J. Cotterill; D. J. Ballinger

1989-01-01

31

Differentiation of Rhizoctonia AGD Isolates from Turfgrass into Subgroups I and II Based on rDNA and RAPD Analyses  

Microsoft Academic Search

Binucleate Rhizoctonia anastomosis group (AG) D is the cause of rhizoctonia-patch and elephant-footprint diseases of zoysiagrass, and winter-patch disease of bentgrass. Rhizoctonia AG-D is also known as the causal pathogen of other diseases such as sharp-eye-spot of cereals, foot-rot of cereals and winter-stem-rot of mat rush. Isolates of AG-D have been divided into the two subgroups AG-D (I) and AG-D

Takeshi Toda; Mitsuro Hyakumachi; Haruhisa Suga; Koji Kageyama; Akemi Tanaka; Toshikazu Tani

1999-01-01

32

The influence of soil moisture and Rhizoctonia solani anastomosis and intraspecific group on the incidence of damping-off and the incidence and severity of Rhizoctonia crown and root rot in sugar beet  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia crown and root rot (Rhizoctonia solani) reduces plant stands, sugar quality and yield in sugar beet. To evaluate the influence of R. solani anastomosis (AG) and intraspecific groups and soil moisture on disease incidence and severity, a field trial was established in Ridgetown, Ontario, ...

33

Microscopic observations on the interaction of the mycoparasite Verticillium biguttatum with Rhizoctonia solani and other soil-borne fungi  

Microsoft Academic Search

The mycoparasitic interactions of Verticillium biguttatum with Rhizoctonia solani and with a variety of other soil-borne fungi were investigated in dual cultures. V. biguttatum interacted with various soil fungi by appressed growth along the host hyphae and infrequent penetrations. Intracellular growth and subsequent sporulation, however, only occurred with R. solani, a few binucleate Rhizoctonia and Ceratobasidium spp., and Sclerotinia sclerotiorum.

P. H. J. F. van den Boogert; H. Reinartz; K. A. Sjollema; M. Veenhuis

1989-01-01

34

Laccase-mediated detoxification of phenolic compounds. [Rhizoctonia praticola  

SciTech Connect

The ability of a polyphenoloxidase, the laccase of the fungus Rhizoctonia praticola, to detoxify phenolic pollutants was examined. The growth of the fungus could be inhibited by phenolic compounds, and the effective concentration was dependent on the substituents of the phenol. A toxic amount of a phenolic compound was added to a fungal growth medium in the presence or absence of a naturally occurring phenol, and half of the replicates also received laccase. The medium was then inoculated with R. praticola, and the levels of phenols in the medium were monitored by high-performance liquid chromatography analysis. The addition of the laccase reversed the inhibitory effect of 2,6-xylenol, 4-chloro-2-methylphenol, and p-cresol. Other compounds, e.g., o-cresol and 2,4-dichlorophenol, were detoxified only when laccase was used in conjunction with a natural phenol such as syringic acid. The toxicity of p-chlorophenol and 2,4,5-trichlorophenol could not be overcome by any additions. The ability of the laccase to alter the toxicity of the phenols appeared to be related to the capacity of the enzyme to decrease the levels of the parent compound by transformation or cross-coupling with another phenol.

Bollag, J.M.; Shuttleworth, K.L.; Anderson, D.H. (Pennsylvania State Univ., University Park (USA))

1988-12-01

35

Characterization of field isolates of Trichoderma antagonistic against Rhizoctonia solani.  

PubMed

The aim of the present study was to characterize sixteen isolates of Trichoderma originating from a field of sugar beet where disease patches caused by Rhizoctonia solani were observed. Use of both molecular and morphological characteristics gave consistent identification of the isolates. Production of water-soluble and volatile inhibitors, mycoparasitism and induced systemic resistance in plant host were investigated using in vitro and in vivo tests in both sterilized and natural soils. This functional approach revealed the intra-specific diversity as well as biocontrol potential of the different isolates. Different antagonistic mechanisms were evident for different strains. The most antagonistic strain, T30 was identified as Trichoderma gamsii. This is the first report of an efficient antagonistic strain of T. gamsii being able to reduce the disease in different conditions. The ability to produce water-soluble inhibitors or coil around the hyphae of the pathogen in vitro was not related to the disease reduction in vivo. Additionally, the strains collected from the high disease areas in the field were better antagonists. The antagonistic activity was not characteristic of a species but that of a population. PMID:20943179

Anees, Muhammad; Tronsmo, Arne; Edel-Hermann, Véronique; Hjeljord, Linda Gordon; Héraud, Cécile; Steinberg, Christian

2010-06-09

36

CHARACTERIZATION OF SHEATH BLIGHT PATHOGEN RHIZOCTONIA SOLANI AND ITS MOLECULAR INTERACTION WITH ORYZA SATIVA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Abstract: Little is known about mechanisms of molecular interaction of hosts with the necrotrophic pathogen Rhizoctonia solani. Detailed analysis of the pathogen population in Arkansas, the major rice producing state in the USA, led to the identification of the most virulent field isolate out of a...

37

RL-SAGE and microarray analysis of the rice defense transcriptome after Rhizoctonia solani infection  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sheath blight caused by the fungal pathogen Rhizoctonia solani is an emerging problem in rice production worldwide. To elucidate the molecular basis of rice defense to the pathogen, RNA isolated from R. solani-infected leaves of Jasmine 85 was used for both RL-SAGE library construction and microarra...

38

Studies on groundnut hypocotyl exudates and the behaviour of Rhizoctonia solani in influencing the disease  

Microsoft Academic Search

Summary The behaviour ofRhizoctonia solani on the surface of groundnut seedling hypocotyls was studied at different stages of growth. Characteristic variation in the growth and production on infection cushions was observed. No infection cushions were observed as the seedling reaches the age of three weeks. Hypocotyl exudates were collected at various stages of growth and analysed for total phenols, carbohydrates

M. N. Reddy

1980-01-01

39

Effect of Plant Spacing on Microclimate and Rhizoctonia Web Blight Development in Container Grown Azalea  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia web blight is a reoccurring problem in compact varieties of container-grown azalea (Rhododendron sp.) in the Gulf Coast States. During the summers of 2002 and 2003, disease severity was measured weekly in the inoculated center plant of plots consisting of 49 ‘Gumpo’ azalea plants. Plant ...

40

GENETIC CHARACTERIZATION OF BINUCLEATE RHIZOCTONIA SPECIES CAUSING WEB BLIGHT ON AZALEA IN MISSISSIPPI AND ALABAMA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Web blight on containerized azalea is an annual problem for commercial nurseries during the summer months in the southern US. Losses to web blight are associated with the cost of fungicides, delayed marketing of diseased plants, and plant death. Three hundred and nine isolates of Rhizoctonia recover...

41

SUPPRESSION OF RHIZOCTONIA ROOT ROT BY STREPTOMYCES IN BRASSICA NAPUS SEED MEAL AMENDED SOIL  

Technology Transfer Automated Retrieval System (TEKTRAN)

Amendment of soil with 0.5% Brassica napus (rape)seed meal (RSM) confers systemic protection against Rhizoctonia solani AG-5 root infection of apple seedlings. The development of a R. solani suppressive state in soil amended with low-glucosinolate B. napus var. Athena RSM was prevented by steam pas...

42

Evaluation of Commercially Available PGPR for Control of Rice Sheath Blight Caused by Rhizoctonia solani  

Microsoft Academic Search

Sheath blight disease of rice caused by Rhizoctonia solani is a major production constraint in all rice producing areas of the world. The annual losses due to sheath blight are estimated to be 25 % under optimum conditions of disease development. Disease management is currently focused on extensive use of fungicides which has created concerns about environmental pollution, pathogen resistance

K. Vijay Krishna Kumar; S. Krishnam Raju; M. S. Reddy; J. W. Kloepper; K. S. Lawrence; D. E. Groth; M. E. Miller; H. Sudini; Binghai Du

2009-01-01

43

Comparative analysis of putative pathogenesis-related gene expression in two Rhizoctonia solani pathosystems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani, teleomorph Thanatephoris cucumeris, is a polyphagous nectrotrophic plant pathogen of the Basidiomycete order that is split into fourteen different anastomosis groups (AGs) based on hyphal interactions and host range. Currently, little is known about the methods by which R. solan...

44

Development of an Agrobacterium-based transformation system for Rhizoctonia solani  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 8.7 kb binary vector containing the 1.9 kb hygromycin B phosphortransferase (hyg) gene was constructed with promoter and terminator regions from the glyceraldehyde-3-phosphate- dehydrogenase (gpd) gene of Rhizoctonia solani anastomosis group 3 (AG-3) at the 5'- and 3'- gene termini of hyg. Promot...

45

Geographic distribution of Rhizoctonia and Pythium species in soils throughout eastern Washington.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia and Pythium species cause substantial reductions in yield in eastern Washington. Both organisms are common in agricultural soils; however, the specific species or anastomosis group (AG) present can vary from site to site. Due to a wide range in virulence among these different groups, t...

46

Rhizoctonia Resistant Wheat -- Potential New Resources for Control for Soilborne Pathogens.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pacific Northwest (PNW) wheat, barley, legume and canola varieties are susceptible to the broad host-range soilborne pathogens that cause Rhizoctonia root rot and Pythium root rot. Effective control of these diseases will likely require additional approaches and resources. We have identified promisi...

47

CHARACTERIZATION OF RHIZOCTONIA SPP. FROM CROPPING SYSTEMS IN THE WESTERN CAPE PROVINCE OF SOUTH AFRICA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia spp. are important pathogens of a broad range of crop plants that are economically important to the farm economy of the Western Cape region of South Africa. However, there is little information concerning the identity and relative importance of these fungal pathogens. Isolates of Rhizo...

48

MOLECULAR AND PATHOLOGICAL CHARACTERIZATION OF THE RICE SHEATH BLIGHT PATHOGEN RHIZOCTONIA SOLANI IN ARKANSAS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice sheath blight, caused by the fungal pathogen Rhizoctonia solani (AG1-IA), is an economically important disease in Arkansas. To identify the sheath blight resistance gene(s) an extensive molecular and pathological characterization of R., solani was initiated. A wide range of pathogen isolates ...

49

RESPONSE OF COWPEA CULTIVARS TO RHIZOCTONIA SOLANI IN FIELD TESTS AT FOUR PLANTING DATES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani is an important pathogen of cowpea (Vigna unguiculata) in the southern U.S. and is the primary cause of seedling diseases in this crop. Stand losses caused by R. solani are especially severe when cowpea is planted in cold, spring soils. Three cowpea cultivars (Coronet, Knuckle P...

50

Brassica napus seed meal soil amendment modifies microbial community structure, nitric oxide production and incidence of Rhizoctonia root rot  

Microsoft Academic Search

A low glucosinolate content (21.8?molg?1) Brassica napus seed meal (RSM) applied to orchard soils altered communities of both pathogenic and saprophytic soil micro-organisms. RSM amendment reduced infection by native and introduced isolates of Rhizoctonia spp. and recovery of Pratylenchus spp. from apple roots. Root infection by Rhizoctonia solani AG-5 was also suppressed in split-root assays where a portion of the

M. F. Cohen; H. Yamasaki; M. Mazzola

2005-01-01

51

Hairpin Plasmids from the Plant Pathogenic Fungi Rhizoctonia solani and Fusarium oxysporum  

Microsoft Academic Search

This review focuses on the biology of the hairpin plasmids from the plant pathogenic fungi Rhizoctonia solani and Fusarium oxysporum. R. solani\\u000a linear plasmid is single-stranded with covalently closed hairpin loops at each end. F. oxysporum\\u000a plasmid, however, has a clothespin structure, which includes a terminal hairpin and noncovalently\\u000a linked ends at the other terminus. We present the nucleotide sequence of the hairpin

Teruyoshi Hashiba; Atsushi Nagasaka

52

Trichoderma harzianum elicits defence response genes in roots of potato plantlets challenged by Rhizoctonia solani  

Microsoft Academic Search

Biological control of Rhizoctonia solani with Trichoderma harzianum has been demonstrated in several studies. However, none have reported the dynamics of expression of defence response genes.\\u000a Here we investigated the expression of these genes in potato roots challenged by R. solani in the presence\\/absence of T. harzianum Rifai MUCL 29707. Analysis of gene expression revealed an induction of PR1 at

Adrien Gallou; Sylvie Cranenbrouck; Stéphane Declerck

2009-01-01

53

The identification and characterization of four laccases from the plant pathogenic fungus Rhizoctonia solani  

Microsoft Academic Search

Four distinct laccase genes,lcc1, lcc2, lcc3 andlcc4, have been identified in the fungusRhizoctonia solani. Both cDNA and genomic copies of these genes were isolated and characterized. Hybridization analyses indicate that each of the four laccase genes is present in a single copy in the genome. TheR. solani laccases can be divided into two groups based on their protein size, intron\\/exon

Jill A. Wahleithner; Feng Xu; Kim M. Brown; Stephen H. Brown; Elizabeth J. Golightly; Torben Halkier; Sakari Kauppinen; Anders Pederson; Palle Schneider

1996-01-01

54

Biotic changes in relation to local decrease in soil conduciveness to disease caused by Rhizoctonia solani  

Microsoft Academic Search

The relationships between biotic changes and local decrease in soil conduciveness in disease patches towards the disease incited\\u000a by Rhizoctonia solani AG 2-2 in a sugar beet field in France were investigated. Soil samples from healthy and diseased areas were analysed for\\u000a bacterial and fungal densities, molecular and physiological microbial community structures, and antagonistic abilities of\\u000a Trichoderma isolates collected from

Muhammad Anees; Arne Tronsmo; Véronique Edel-Hermann; Nadine Gautheron; Vincent Faloya; Christian Steinberg

2010-01-01

55

Efficacy of Trichoderma chitinases against Rhizoctonia solani , the rice sheath blight pathogen  

Microsoft Academic Search

Thirty-five strains ofTrichoderma viride andT. harzianum were screened for their antagonistic ability against the rice sheath blight pathogen,Rhizoctonia solani. The strains that inhibited\\/overgrew the phytopathogenic fungus were considered effective. Light microscopic studies showed\\u000a the antagonism of the hyphae of effectiveTrichoderma strains towards their host hyphae. Chitinase activity ofTrichoderma culture filtrates was enhanced, when colloidal chitin was used as the sole

J. Krishnamurthy; R. Samiyappan; P. Vidhyasekaran; S. Nakkeeran; E. Rajeswari; J. A. J. Raja; P. Balasubramanian

1999-01-01

56

Soil Pseudomonas Community Structure and Its Antagonism Towards Rhizoctonia solani Under the Stress of Acetochlor  

Microsoft Academic Search

In a microcosm experiment, the amplified ribosomal DNA restriction analysis was adopted to investigate the Pseudomonas community structure in soils applied with different concentrations (0, 50, 150, and 250 mg\\/kg) of acetochlor, and an in vitro\\u000a assay was made to examine the antagonistic activity of isolated Pseudomonas strains acting on soil-borne pathogen Rhizoctonia solani. The results showed that acetochlor application changed

Minna Wu; Xiaoli Zhang; Huiwen Zhang; Yan Zhang; Xinyu Li; Qixing Zhou; Chenggang Zhang

2009-01-01

57

Antagonism between Rhizoctonia solani causing damping — off and selected rhizospheric microflora of some egyptian cotton varieties  

Microsoft Academic Search

Summary Seven bacterial isolates and many species of fungi have been isolated from the rhizospheres of “Ashmouni” and “Karnak” cotton variety seedlings. Two strains ofBacillus subtilis and two fungi, namelyAspergillus terreus andAspergillus flavus proved to be antagonistic toRhizoctonia solani on glucose — peptone agar. Other antagonistic bacterial isolates were slow growers on the agar medium, and hence were not chosen

M. S. Naim; A. A. El-Esawy

1965-01-01

58

Antifungal characteristics of a fluorescent Pseudomonas strain involved in the biological control of Rhizoctonia solani  

Microsoft Academic Search

A plant growth-promoting isolate of a fluorescent Pseudomonas spp. EM85 was found strongly antagonistic to Rhizoctonia solani, a causal agent of damping-off of cotton. The isolate produced HCN (HCN+), siderophore (Sid+), fluorescent pigments (Flu+) and antifungal antibiotics (Afa+). Tn5::lacZ mutagenesis of isolate EM85 resulted in the production of a series of mutants with altered production of HCN, siderophore, fluorescent pigments

K. K. Pal; K. V. B. R. Tilak; A. K. Saxena; R. Dey; C. S. Singh

2000-01-01

59

Biocontrol Potential of Soybean Bacterial Endophytes Against Charcoal Rot Fungus, Rhizoctonia bataticola  

Microsoft Academic Search

A total of 137 bacterial isolates from surface sterilized root, stem, and nodule tissues of soybean were screened for their\\u000a antifungal activity against major phytopathogens like Rhizoctonia bataticola,\\u000a Macrophomina phaseolina, Fusarium udam, and Sclerotium rolfsii. Nine bacterial endophytes suppressed the pathogens under in vitro plate assay. These were characterized biochemically and\\u000a identified at the genus level based on their partial

M. Senthilkumar; K. Swarnalakshmi; V. Govindasamy; Young Keun Lee; K. Annapurna

2009-01-01

60

Linear plasmid DNAs of the plant pathogenic fungus Rhizoctonia solani with unique terminal structures  

Microsoft Academic Search

Three linear DNA plasmids were found in isolate RI-64 of anastomosis group 4 (AG-4) of Rhizoctonia solani. These plasmids, designated pRS64-1, -2, and -3, possessed the same size of 2.7 kb. Restriction mapping and Southern hybridization analysis of pRS64-1, -2, and -3 revealed the presence of homologous regions at both termini. The plasmid DNAs were resistant to both 3'-exonuclease and

Shun-ichiro Miyashita; Hirohiko Hirochika; Joh-E Ikeda; Teruyoshi Hashiba

1990-01-01

61

Isolation and characterization of a novel Burkholderia cepacia with strong antifungal activity against Rhizoctonia solani  

Microsoft Academic Search

Strain CF-66 with strong antifungal activity against Rhizoctonia solani was isolated from compost samples. It is clearly demonstrated that strain CF-66 is belonging to Burkholderia cepacia complex by the morphological and biochemical tests and 16S rDNA sequence. The B. cepacia complex consists of a group of bacteria currently organized into nine genomovars, among them genomovar II and genomovar III, contain

C. S. Quan; W. Zheng; Q. Liu; Y. Ohta; S. D. Fan

2006-01-01

62

Effect of inoculum density and soil tillage on the development and severity of rhizoctonia root rot.  

PubMed

Rhizoctonia spp. cause substantial yield losses in direct-seeded cereal crops compared with conventional tillage. To investigate the mechanisms behind this increased disease, soils from tilled or direct-seeded fields were inoculated with Rhizoctonia spp. at population densities from 0.8 to 250 propagules per gram and planted with barley (Hordeum vulgare). The incidence and severity of disease did not differ between soils with different tillage histories. Both R. solani AG-8 and R. oryzae stunted plants at high inoculum densities, with the latter causing pre-emergence damping-off. High inoculum densities of both species stimulated early production of crown roots in barley seedlings. Intact soil cores from these same tilled and direct-seeded fields were used to evaluate the growth of Rhizoctonia spp. from colonized oat seeds. Growth of R. oryzae was not affected by previous tillage history. However, R. solani AG-8 grew more rapidly through soil from a long-term direct-seeded field compared to tilled soils. The differential response between these two experiments (mixed, homogenized soil versus intact soil) suggests that soil structure plays a major role in the proliferation of R. solani AG-8 through soils with different tillage histories. PMID:18944081

Schroeder, K L; Paulitz, T C

2008-03-01

63

Timing of fungicides in relation to calendar date, weather, and disease thresholds to control Rhizoctonia web blight on container-grown azalea  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia web blight, caused by binucleate Rhizoctonia spp., is an annual problem in the southern United States on container-grown azaleas (Rhododendron spp.) that receive daily irrigation. Fungicides are the only practical control method, but a guideline for timing of fungicides is not available....

64

Simultaneous raw starch hydrolysis and ethanol fermentation by glucoamylase from Rhizoctonia solani and Saccharomyces cerevisiae.  

PubMed

Crude glucoamylase preparation from Rhizoctonia solani was used to saccharify raw and cooked starch. Various concentrations of potato starch and wheat flour from 10-40%, w/v were used for mashing but 30% was found to be the optimal and economical. The saccharified mash yielded 5.89%, v/v ethanol in a simultaneous saccharification and fermentation process using a yeast strain Saccharomyces cerevisiae (SC-39) at 35 degrees C for 4 days. Removal of inhibitory substances from the fermenting broth through dialysis caused considerable increase in ethanol production. PMID:7783000

Singh, D; Dahiya, J S; Nigam, P

1995-01-01

65

Basidiochrome – A Novel Siderophore of the Orchidaceous Mycorrhizal Fungi Ceratobasidium and Rhizoctonia spp  

Microsoft Academic Search

A novel trishydroxamate siderophore, named basidiochrome, was isolated as the principal siderophore from low-iron culture\\u000a filtrates of Ceratobasidium and Rhizoctonia species which are known as mycorrhizal fungi associated with orchid roots. Ion-exchange chromatography and preparative HPLC\\u000a yielded a pure compound which contained two components according to GC–MS analysis: l-N5-hydroxy-ornithine and 3-methyl-2-cis-pentenedioic acid (3-methyl-cis-glutaconic acid). FTICR-ESI-MS of both the iron-free and

K. Haselwandter; V. Passler; S. Reiter; D. G. Schmid; G. Nicholson; P. Hentschel; K. Albert; G. Winkelmann

2006-01-01

66

Interaction of Pratylenchus penetrans and Rhizoctonia fragariae in Strawberry Black Root Rot  

PubMed Central

A split-root technique was used to examine the interaction between Pratylenchus penetrans and the cortical root-rotting pathogen Rhizoctonia fragariae in strawberry black root rot. Plants inoculated with both pathogens on the same half of a split-root crown had greater levels of root rot than plants inoculated separately or with either pathogen alone. Isolation of R. fragariae from field-grown roots differed with root type and time of sampling. Fungal infection of structural roots was low until fruiting, whereas perennial root colonization was high. Isolation of R. fragariae from feeder roots was variable, but was greater from feeder roots on perennial than from structural roots. Isolation of the fungus was greater from structural roots with nematode lesions than from non-symptomatic roots. Rhizoctonia fragariae was a common resident on the sloughed cortex of healthy perennial roots. From this source, the fungus may infect additional roots. The direct effects of lesion nematode feeding and movement are cortical cell damage and death. Indirect effects include discoloration of the endodermis and early polyderm formation. Perhaps weakened or dying cells caused directly or indirectly by P. penetrans are more susceptible to R. fragariae, leading to increased disease.

LaMondia, J. A.

2003-01-01

67

Interaction of Pratylenchus penetrans and Rhizoctonia fragariae in Strawberry Black Root Rot.  

PubMed

A split-root technique was used to examine the interaction between Pratylenchus penetrans and the cortical root-rotting pathogen Rhizoctonia fragariae in strawberry black root rot. Plants inoculated with both pathogens on the same half of a split-root crown had greater levels of root rot than plants inoculated separately or with either pathogen alone. Isolation of R. fragariae from field-grown roots differed with root type and time of sampling. Fungal infection of structural roots was low until fruiting, whereas perennial root colonization was high. Isolation of R. fragariae from feeder roots was variable, but was greater from feeder roots on perennial than from structural roots. Isolation of the fungus was greater from structural roots with nematode lesions than from non-symptomatic roots. Rhizoctonia fragariae was a common resident on the sloughed cortex of healthy perennial roots. From this source, the fungus may infect additional roots. The direct effects of lesion nematode feeding and movement are cortical cell damage and death. Indirect effects include discoloration of the endodermis and early polyderm formation. Perhaps weakened or dying cells caused directly or indirectly by P. penetrans are more susceptible to R. fragariae, leading to increased disease. PMID:19265969

Lamondia, J A

2003-03-01

68

Genotypic and phenotypic variation among Lysobacter capsici strains isolated from Rhizoctonia suppressive soils.  

PubMed

Four Gram-negative bacterial strains, recovered from clay soils cultivated with different crops in the Netherland, were subjected to a polyphasic taxonomic study in order to clarify their taxonomic status. Comparative analysis of the 16S rRNA gene sequences revealed that they belong to the genus Lysobacter and to be highly related to the type strains of L. antibioticus DSM 2044(T), L. gummosus DSM 6980(T), and L. capsici DSM 19286(T), displaying 99.1-99.3%, 99.2-99.6% and 99.4-100% sequence similarities, respectively, to these species. The results of DNA-DNA hybridization studies unambigiously indicated that the four strains belonged to the species L. capsici. Nevertheless, DNA fingerprinting and phenotypic characterization indicated that there was a considerable diversification and niche differentiation among the strains belonging to L. capsici. The newly identified L. capsici strains strongly inhibit Rhizoctonia solani AG2 and originate from Rhizoctonia-suppressive soils where also populations of L. antibioticus and L. gummosus were present. This is the first report of the presence of combined populations of closely related Lysobacter spp. within agricultural soils. PMID:20399056

Postma, J; Nijhuis, E H; Yassin, A F

2010-04-15

69

Characterization and in vitro expression patterns of extracellular degradative enzymes from non-pathogenic binucleate Rhizoctonia AG-G  

Microsoft Academic Search

Many filamentous fungi produce an array of extracellular enzymes that acting in cell walls release elicitors of the plant defense response These enzymes may therefore be important in biocontrol applications. The aim of this study was to characterize extracellular degradative enzymes produced by a non-pathogenic binucleate isolate of Rhizoctonia AG-G. The fungus was grown in liquid culture supplemented with pectin,

Milagros F. Machinandiarena; Erika A. Wolski; Viviana Barrera; Gustavo R. Daleo; Adriana B. Andreu

2005-01-01

70

Composts from agricultural waste and the Trichoderma asperellum strain T-34 suppress Rhizoctonia solani in cucumber seedlings  

Microsoft Academic Search

Using composts in agriculture to minimize organic wastes and to reduce the addition of fertilizers and fungicides in crop production is highly effective. Our results show that among those tested composts aged 0.5–1 year, cork compost reduced diseases caused by Rhizoctonia solani in cucumber plants (53% of diseased plants) in comparison to peat (up to 89%). However, all composts aged

M. Isabel Trillas; Eva Casanova; Lurdes Cotxarrera; José Ordovás; Celia Borrero; Manuel Avilés

2006-01-01

71

Remote sensing to detect plant stress induced by Heterodera schachtii and Rhizoctonia solani in sugar beet fields  

Microsoft Academic Search

The characteristically clustered occurrence and low level of mobility of Heterodera schachtii and Rhizoctonia solani in the soil and the induction of stress symptoms in the sugar beet canopy make them ideal targets for site-specific arrangements with precision agriculture tools. A field site infested with H. schachtii and R. solani was investigated in 2009 with near-range and aerial hyperspectral sensors

C. Hillnhütter; A.-K. Mahlein; R. A. Sikora; E.-C. Oerke

2011-01-01

72

Continuity of air-filled pores and invasion thresholds for a soil-borne fungal plant pathogen, Rhizoctonia solani  

Microsoft Academic Search

Fundamental knowledge of the way fungi explore the pore volume within a soil is crucial if we are to understand how soil physical conditions affect population dynamics and invasion of many important fungal parasites and saprophytes within soil. In this study, spread of the fungus Rhizoctonia solani Kühn (AG4), an economically important soil-borne plant pathogen and saprophyte, was quantified in

W Otten; C. A Gilligan; C. W Watts; A. R Dexter; D Hall

1999-01-01

73

Pathogenicity, characterization and comparative virulence of Rhizoctonia spp. from insect-galled roots of Lepidium draba in Europe  

Technology Transfer Automated Retrieval System (TEKTRAN)

The association of Rhizoctonia spp. with insect-damaged and diseased tissue of the invasive perennial Lepidium draba was documented throughout the range of L. draba that was surveyed in Europe, including Hungary, Austria, Switzerland and France. Samples that could be both maintained under cooled con...

74

Growth vigour of some Egyptian cotton variety seedlings in relation to selected rhizospheric microflora antagonistic to Rhizoctonia solani Kuhn  

Microsoft Academic Search

Growth responses of ‘Ashmouni’ and ‘Karnak’ cotton variety seedlings toRhizoctonia solani, the damping-off fungus, or toBacillus subtilis (two different strains),Aspergillus terreus andAspergillus flavus isolated from the rhizosphere of cotton, and all antagonistic to the pathogen, were expressed in terms of growth-vigour criteria.

M. S. Naim; A. A. El-Esawy

1966-01-01

75

UP-PCR cross blot hybridization as a tool for identification of anastomosis groups in the Rhizoctonia solani complex  

Microsoft Academic Search

A universally primed (UP)-PCR cross hybridization assay was developed for rapid identification of isolates of Rhizoctonia solani into the correct anastomosis group (AG). Twenty-one AG tester isolates belonging to 11 AGs of R. solani were amplified with a single UP primer which generated multiple PCR fragments for each isolate. The amplified products were spotted onto a filter, immobilized and used

Mette Lübeck; Hanne Poulsen

2001-01-01

76

Activity of alkanediol alkanoates against pathogenic plant fungi Rhizoctonia solani and Sclerotium rolfsii.  

PubMed

Thirty known dialkanoates of ethylene, propylene and diethylene glycols were synthesized by reacting the glycols with acyl chlorides and their structures confirmed by IR, NMR and mass spectral analyses. They exhibited significant antifungal activity against two phytopathogenic fungi Rhizoctonia solani Kuehn and Sclerotium rolfsii Sacc in a dose dependent manner. Propylene glycol dipentanoate was the most active against R. solani. followed by diethylene glycol dibutanoate and ethylene glycol dibutanoate. Against S. rolfsii ethylene glycol diheptanoate was found to be most active followed by diethylene glycol diisobutanoate As compared to the standard reference benomyl (EC50 5.16 microg/mL), the potential alkanediol dialkanoates showed EC50 in the range of 33 - 60 microg/mL. PMID:23074913

Shukla, Paraj; Walia, Suresh; Ahluwalia, Vivek; Parmar, Balraj S; Nair, Muraleedharan G

2012-09-01

77

Characterization and taxonomic placement of Rhizoctonia-like endophytes from orchid roots.  

PubMed

Twenty-one Rhizoctonia-like fungal strains were isolated from the roots of four terrestrial orchid species from various locations in Hong Kong. The cultural morphology, nuclear number of the hyphal cell, pore ultrastructure, and RAPD and CAPS analyses of rDNA fragments revealed that most of these isolates were associated with the genera Ceratorhiza and Epulorhiza. RAPD analysis showed the presence of genetic diversity between the isolates from different hosts and locations. The compatibility between a selection of these Ceratorhiza and Epulorhiza isolates and 14 orchid species was determined using a symbiotic germination method. The germination and development of three orchid species, Arundina chinensis, Spathoglottis pubescens, and Spiranthes hongkongensis, were strongly stimulated by the Epulorhiza isolates. Habenaria dentata was found to form symbionts successfully with a Ceratorhiza isolate. PMID:21156492

Shan, X C; Liew, E C Y; Weatherhead, M A; Hodgkiss, I J

78

Biocontrol of Rhizoctonia solani damping-off disease in cucumber with Bacillus pumilus SQR-N43  

Microsoft Academic Search

Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Micrographs were used to investigate the ability of Bacillus pumilus (B. pumilus) SQR-N43 to control Rhizoctonia solani (R. solani) Q1 in cucumbers. The root colonization ability of B. pumilus SQR-N43 was analyzed in vivo with a green fluorescent protein (GFP) tag. A pot experiment was performed to

Xinqi Huang; Nan Zhang; Xiaoyu Yong; Xingming Yang; Qirong Shen

79

Biological control of Phytophthora parasitica var. Nicotianae on tobacco seedlings with non-pathogenic binucleate Rhizoctonia fungi  

Microsoft Academic Search

Nonpathogenic binucleate Rhizoctonia fungi (BNR) controlled black shank caused by Phytophthora parasitica var. nicotianae on greenhouse-grown tobacco seedlings in styrofoam float trays. Three BNR isolates were incorporated into a soil-less mix on colonized, pulverized, sifted rice particles; colonized whole rice grains; or on pelleted tobacco seeds coated with 0.5% methyl cellulose. Five-wk-old seedlings were inoculated with zoospores of P. parasitica

D. Kelly Cartwright; H. W Spurr

1998-01-01

80

The adaptive potential of a plant pathogenic fungus, Rhizoctonia solani AG3, under heat and fungicide stress  

Microsoft Academic Search

The ability to improve fitness via adaptive evolution may be affected by environmental change. We tested this hypothesis in\\u000a an in vitro experiment with the plant pathogen Rhizoctonia solani Anastomosis Group 3 (AG-3), assessing genetic and environmental variances under two temperatures (optimal and higher than\\u000a optimal) and three fungicide concentrations (no fungicide, low and high concentration of a copper-based fungicide).

Yvonne Willi; Aline Frank; Renate Heinzelmann; Andrea Kälin; Lena Spalinger; Paulo C. Ceresini

2011-01-01

81

The advancing identification and classification of Rhizoctonia spp. using molecular and biotechnological methods compared with the classical anastomosis grouping  

Microsoft Academic Search

Anamorphic classification of Rhizoctonia spp. has been based on young cell nuclear numbers and hyphal fusion to anastomosis groups (AGs), in addition to the teleomorph\\u000a classification. The widespread development of molecular biology techniques has added modern tools to support classification\\u000a of organisms according to their genetics and evolutionary processes. These various methods have also been used in recent years\\u000a for

Michal Sharon; Shiro Kuninaga; Mitsuro Hyakumachi; Baruch Sneh

2006-01-01

82

Sequence variation of the rDNA ITS regions within and between anastomosis groups in Rhizoctonia solani  

Microsoft Academic Search

Sequence analysis of the rDNA region containing the internal transcribed spacer (ITS) regions and the 5.8s rDNA coding sequence was used to evaluate the genetic diversity of 45 isolates within and between anastomosis groups (AGs)\\u000a in Rhizoctonia solani. The 5.8s rDNA sequence was completely conserved across all the AGs examined, whereas the ITS rDNA sequence was found to be highly

Shiro Kuninaga; Tomohide Natsuaki; Toru Takeuchi; Ryozo Yokosawa

1997-01-01

83

FT-ICR\\/MS and GC-EI\\/MS Metabolomics Networking Unravels Global Potato Sprout's Responses to Rhizoctonia solani Infection  

Microsoft Academic Search

The complexity of plant-pathogen interactions makes their dissection a challenging task for metabolomics studies. Here we are reporting on an integrated metabolomics networking approach combining gas chromatography\\/mass spectrometry (GC\\/MS) with Fourier transform ion cyclotron resonance\\/mass spectrometry (FT-ICR\\/MS) and bioinformatics analyses for the study of interactions in the potato sprout-Rhizoctonia solani pathosystem and the fluctuations in the global metabolome of sprouts.

Konstantinos A. Aliferis; Suha Jabaji

2012-01-01

84

Wide Variation in Virulence and Genetic Diversity of Binucleate Rhizoctonia Isolates Associated with Root Rot of Strawberry in Western Australia  

PubMed Central

Strawberry (Fragaria×ananassa) is one of the most important berry crops in the world. Root rot of strawberry caused by Rhizoctonia spp. is a serious threat to commercial strawberry production worldwide. However, there is no information on the genetic diversity and phylogenetic status of Rhizoctonia spp. associated with root rot of strawberry in Australia. To address this, a total of 96 Rhizoctonia spp. isolates recovered from diseased strawberry plants in Western Australia were characterized for their nuclear condition, virulence, genetic diversity and phylogenetic status. All the isolates were found to be binucleate Rhizoctonia (BNR). Sixty-five of the 96 BNR isolates were pathogenic on strawberry, but with wide variation in virulence, with 25 isolates having high virulence. Sequence analysis of the internal transcribed spacers of the ribosomal DNA separated the 65 pathogenic BNR isolates into six distinct clades. The sequence analysis also separated reference BNR isolates from strawberry or other crops across the world into clades that correspond to their respective anastomosis group (AG). Some of the pathogenic BNR isolates from this study were embedded in the clades for AG-A, AG-K and AG-I, while other isolates formed clades that were sister to the clades specific for AG-G, AG-B, AG-I and AG-C. There was no significant association between genetic diversity and virulence of these BNR isolates. This study demonstrates that pathogenic BNR isolates associated with root rot of strawberry in Western Australia have wide genetic diversity, and highlights new genetic groups not previously found to be associated with root rot of strawberry in the world (e.g., AG-B) or in Australia (e.g., AG-G). The wide variation in virulence and genetic diversity identified in this study will be of high value for strawberry breeding programs in selecting, developing and deploying new cultivars with resistance to these multi-genetic groups of BNR.

Fang, Xiangling; Finnegan, Patrick M.; Barbetti, Martin J.

2013-01-01

85

Induction of Laccase Activity in Rhizoctonia solani by Antagonistic Pseudomonas fluorescens Strains and a Range of Chemical Treatments  

Microsoft Academic Search

Fungi often produce the phenoloxidase enzyme laccase during interactions with other organisms, an obser- vation relevant to the development of biocontrols. By incorporating the laccase substrate 2,2*-azino-bis(3- ethylbenzthiazoline-6-sulfonic acid) (ABTS) into agar, we analyzed laccase induction in the plant-pathogenic fungus Rhizoctonia solani when paired against isolates of the soil bacterium Pseudomonas fluorescens. Substan- tial induction of R. solani laccase was

JONATHAN D. CROWE; STEFAN OLSSON

2001-01-01

86

Temperature, moisture, and fungicide effects in managing Rhizoctonia root and crown rot of sugar beet.  

PubMed

Rhizoctonia solani AG-2-2 is the causal agent of Rhizoctonia root and crown rot in sugar beet; however, recent increases in disease incidence and severity were grounds to reevaluate this pathosystem. To assess the capacity at which other anastomosis groups (AGs) are able to infect sugar beet, 15 AGs and intraspecific groups (ISGs) were tested for pathogenicity on resistant ('FC708 CMS') and susceptible ('Monohikari') seedlings and 10-week-old plants. Several AGs and ISGs were pathogenic on seedlings regardless of host resistance but only AG-2-2 IIIB and AG-2-2 IV caused significant disease on 10-week-old plants. Because fungicides need to be applied prior to infection for effective disease control, temperature and moisture parameters were assessed to identify potential thresholds that limit infection. Root and leaf disease indices were used to evaluate disease progression of AG-2-2 IIIB- and AG-2-2 IV-inoculated plants in controlled climate conditions of 7 to 22 growing degree days (GDDs) per day. Root disease ratings were positively correlated with increasing temperature of both ISGs, with maximum disease symptoms occurring at 22 GDDs/day. No disease symptoms were evident from either ISG at 10 GDDs/day but disease symptoms did occur in plants grown in growth chambers set to 11 GDDs/day. Using growth chambers adjusted to 22 GDDs/day, disease was evaluated at 25, 50, 75, and 100% moisture-holding capacity (MHC). Disease symptoms for each ISG were highest in soils with 75 and 100% MHC but disease still occurred at 25% MHC. Isolates were tested for their ability to cause disease at 1, 4, and 8 cm from the plant hypocotyl. Only AG-2-2 IIIB was able to cause disease symptoms at 8 cm during the evaluation period. In all experiments, isolates of AG-2-2 IIIB were found to be more aggressive than AG-2-2 IV. Using environmental parameters that we identified as the most conducive to disease development, azoxystrobin, prothioconazole, pyraclostrobin, difenoconazole/propiconazole, flutolanil, polyoxin D, and a water control were evaluated for their ability to suppress disease development by AG-2-2 IIIB and AG-2-2 IV 17 days after planting. Flutolanil, polyoxin-D, and azoxystrobin provided the highest level of disease suppression. Because R. solani AG-2-2 IIIB and AG-2-2 IV are affected by temperature and moisture, growers may be able to evaluate environmental parameters for optimization of fungicide application. PMID:20528187

Bolton, Melvin D; Panella, Lee; Campbell, Larry; Khan, Mohamed F R

2010-07-01

87

The supernatant of Bacillus pumilus SQR-N43 has antifungal activity towards Rhizoctonia solani.  

PubMed

For clarification of the antagonistic mechanism of Bacillus pumilus SQR-N43 (N43) against Rhizoctonia solani Q1, production of antibiotics by N43 was determined, and the effect of the antibiotics on the pathogen mycelium was microscopically observed. Further more, the control efficiencies of the antifungal compounds on damping-off disease were investigated. The results obtained are listed as follows: N43 produced antibiotic substances towards R. solani Q1 at logarithmic growth phase. The antibiotics caused hyphal deformation and enlargement of cytoplasmic vacuoles in R. solani Q1 mycelia. 70% saturation of ammonium sulfate made a complete precipitation of the antibiotics in culture broth. When treated with protease K and trypsase, the activities of antibiotics were decreased by 79% and 53%, respectively, compared with control. The antibiotics were sensitive to high temperature and were alkaline stable. The molecular weights of the substances were about 500-1000 Da. The bio-control efficiencies of the antibiotics had no significant difference with that of N43 cell suspension. It is a first report that B. pumilus strain produced oligopeptides which had inhibitory effect on R. solani Q1 at logarithmic growth phase. PMID:23417338

Huang, Xinqi; Yong, Xiaoyu; Zhang, Ruifu; Shen, Qirong; Yang, Xingming

2013-02-18

88

Antifungal effect of bean endochitinase on Rhizoctonia solani: ultrastructural changes and cytochemical aspects of chitin breakdown.  

PubMed

A chitinase, purified to homogeneity from ethylene-treated bean leaves, was applied to actively growing mycelial cells of Rhizoctonia solani to evaluate a potential antifungal activity. Light microscopic investigations at 30-min intervals following enzyme exposure revealed the induction of morphological changes such as swelling of hyphal tips and hyphal distortions. More precise information concerning fungal cell alteration was obtained by ultrastructural observation and cytochemical detection of chitin distribution in fungal cell walls. Chitin breakdown was found to be an early event preceding wall disruption and cytoplasm leakage. The large amounts of chitin present in the walls of control R. solani cells and the rapid chitin hydrolysis upon chitinase treatment lead us to suggest that this polysaccharide is one of the main components of this fungal cell wall and is readily accessible to chitinase, especially in the apical zone. By 60 min after enzyme treatment, labeled molecules were observed in the vicinity of some fungal cells, suggesting the release of chitin oligosaccharides from fungal cell walls. The antifungal activity of the bean chitinase on cells of R. solani grown in culture is discussed in relation to the potential of genetically modified transgenic plants to resist attack by R. solani through an antimicrobial activity in planta. PMID:8477352

Benhamou, N; Broglie, K; Broglie, R; Chet, I

1993-03-01

89

Strain-specific colonization pattern of Rhizoctonia antagonists in the root system of sugar beet.  

PubMed

To develop effective biocontrol strategies, basic knowledge of plant growth promotion (PGP) and root colonization by antagonists is essential. The survival and colonization patterns of five different biocontrol agents against Rhizoctonia solani AG2-2IIIB in the rhizosphere of greenhouse-grown sugar beet plants were analysed in single and combined treatments. The study included bacteria (Pseudomonas fluorescens L13-6-12, Pseudomonas trivialis RE(*) 1-1-14, Serratia plymuthica 3Re4-18) as well as fungi (Trichoderma gamsii AT1-2-4, Trichoderma velutinum G1/8). Microscopic analysis by confocal laser scanning microscopy revealed different colonization patterns for each DsRed2/green fluorescent protein-labelled strain. Bacteria and T. velutinum G1/8 colonized the root surface and the endorhiza in single and co-culture, while for T. gamsii AT1-2-4, only the transfer of spores was observed. Whereas Pseudomonas strains formed large microcolonies consisting of hundreds of cells, S. plymuthica was arranged in small endophytic clusters or clouds around the entire root system. In co-culture, each strain showed its typical pattern and occupied specific niches on the root, without clear evidence of morphological interactions. PGP was only observed for four strains with rhizosphere competence and not for T. gamsii AT1-2-4. The results provide useful information on which combination of strains to test in larger biocontrol experiments directed to applications. PMID:20618857

Zachow, Christin; Fatehi, Jamshid; Cardinale, Massimiliano; Tilcher, Ralf; Berg, Gabriele

2010-07-05

90

Biocontrol of Rhizoctonia solani Damping-Off of Tomato with Bacillus subtilis RB14  

PubMed Central

Bacillus subtilis RB14, which showed antibiotic activities against several phytopathogens in vitro by producing the antibiotics iturin A and surfactin, was subjected to a pot test to investigate its ability to suppress damping-off of tomato seedlings caused by Rhizoctonia solani. To facilitate recovery from soil, B. subtilis RB14-C, a spontaneous streptomycin-resistant mutant of RB14, was used. Damping-off was suppressed when the culture broth, cell suspension, or cell-free culture broth of RB14-C was inoculated into soil. Iturin A and surfactin were recovered from the soils inoculated with the cell suspension of RB14-C, confirming that RB14-C produced them in soil. The gene lpa-14, which was cloned from RB14 and required for the production of both antibiotics, was mutated in RB14-C, and a mutant, R(Delta)1, was constructed. The level of disease suppressibility of R(Delta)1 was low, but R(Delta)1(pC115), a transformant of R(Delta)1 with the plasmid pC115 carrying lpa-14, was restored in suppressibility. These results show that the antibiotics iturin A and surfactin produced by RB14 play a major role in the suppression of damping-off caused by R. solani. RB14-C, R(Delta)1, and R(Delta)1(pC115) persisted in soil during the experimental period and were recovered from the soil, mostly as spores.

Asaka, O.; Shoda, M.

1996-01-01

91

Methods and compositions for the simultaneous control of the root diseases caused by gaeumannomyces graminis, rhizoctonia, and pythium  

US Patent & Trademark Office Database

Methods and products useful to simultaneously control the root diseases caused by Gaeumannomyces graminis, Rhizoctonia, and Pythium in crops susceptible to these root diseases are described. These include a method to identify seed-treatment products for potential to simultaneously control the three kinds of root diseases; Bacillus strains having activity against the three kinds of root diseases and methods of obtaining the same, and compositions comprising a fungicide and a Bacillus strain having activity against the three kinds of root diseases, which compositions are useful for field control of the combination of the three kinds of root diseases.

Cook; R. James (Pullman, WA); Weller; David M. (Pullman, WA); Kim; Dal-Soo (Taejon, KR); Thomashow; Linda S. (Pullman, WA)

1999-10-26

92

Influence of Rotation Crops on the Strawberry Pathogens Pratylenchus penetrans, Meloidogyne hapla, and Rhizoctonia fragariae  

PubMed Central

Field microplot, small plot, and greenhouse experiments were conducted to determine the effects of rotation crops on Pratylenchus penetrans, Meloidogyne hapla, and Rhizoctonia fragariae populations. Extraction of P. penetrans from roots and soil in microplots and field plots planted to rotation crops was highest for Garry oat, lowest for Triple S sorgho-sudangrass and Saia oat, and intermediate for strawberry, buckwheat, and canola. Isolation of R. fragariae from bait roots was highest for strawberry and canola after 2 years of rotation and lowest for Saia oat. Nematode extraction from roots of rotation crops in field soils was generally higher than from roots in microplots. Grasses were nonhosts of M. hapla. Strawberry, canola, and buckwheat supported root-knot populations over time, but there were no differences in nematode numbers regardless of crop after one season of strawberry growth. Garry oat, canola, and, to a lesser extent, buckwheat supported large populations of P. penetrans without visible root symptoms. Strawberry plants supported fewer nematodes due to root damage. Nematode numbers from soil were less than from roots for all crops. While there were similar trends for pathogen recovery after more than 1 year of strawberry growth following rotation, differences in pathogen density and fruit yield were not significant. In the greenhouse, P. penetrans populations in roots and soil in pots were much higher for Garry oat than for Saia oat. Total P. penetrans adult and juvenile numbers per pot ranged from 40 to 880 (mean = 365.6) for Garry oat and 0 to 40 (mean = 8.7) for Saia oat. Production of Saia oat as a rotation crop may be a means of managing strawberry nematodes and black root rot in Connecticut.

LaMondia, J. A.

1999-01-01

93

Biocontrol of Rhizoctonia solani, the causal agent of bean damping-off by fluorescent pseudomonads.  

PubMed

Rhizosphere bacteria belonging to the fluorescent pseudomonads are receiving increasing attention for the protection of plants against soil-borne fungal pathogens. Among these pathogens, Rhizoctonia solani, the causal agent of bean damping- off is very important in bean fields of Iran. In this study, the antagonistic activity of 46 isolates of fluorescent pseudomonads (isolated from different area of Iran) and Pseudomonas fluorescens strain CHA0 investigated against one isolate of R. solani. About 64% of isolates revealed antagonistic activity against R. solani. Production of antifungal metabolites such as HCN, siderophore and protease was evaluated. The results showed that 97.8%, 17% and 78% of isolates produced siderophore, HCN and protease respectively. There was no significant correlation between antagonistic activity and production of these metabolites. Isolates P-5, P-10 and P-32 with strain CHA0 were selected in order to investigate involvement of siderophore, volatile metabolites (HCN), and non-volatile metabolites in reducing mycelial growth of R. olani. Isolate P-5 showed much more inhibitory effect by production of volatile metabolites and siderophore. Non-volatile metabolites in isolates P-32 and P-5 completely inhibited mycelial growth of the fungus. After the primary labrotory tests, isolates P-14, P-35, P-30, P-5 and strain CHA0 were selected for in vivo experiments. These selected isolates with benomyl fungicide were used as seed coating and soil drenching in sterile soil under greenhouse condition. The result indicated that in seed treatment method, isolates P-30 by 66% had the most effect in disease reduction while in soil treatment method, strain CHAO by 60% had the most effect, such that this two isolates showed significant differences in comparison with plants inoculated with R. solani inoculums. PMID:17390854

Afsharmanesh, H; Ahmadzadeh, M; Sharifi-Tehrani, A

2006-01-01

94

Mechanism of the Generation of New Somatic Compatibility Groups within Thanatephorus cucumeris (Rhizoctonia solani).  

PubMed

Single-basidiospore isolates (SBIs) were obtained from field isolates of Thanatephorus cucumeris (Rhizoctonia solani) AG-1 IC and AG-2-2 IV. Formation of distinctive tufts, a recognized feature of heterokaryon synthesis, was observed, and isolates derived from hyphal-tipped tuft hyphae were obtained following pairings between various strains. Three distinctive types of tufts were formed: the fibrous type of mating-compatible homokaryon-homokaryon (Hom-Hom) pairings, the sparse type between heterokaryon-homokaryon (Het-Hom) pairings originating from one parent, and the compact type between Het-Hom pairings originating from different parents. Amplified Fragment Length Polymorphism (AFLP) profile of fingerprints of these tuft isolates verified that they were all heterokaryotic. Because of heterokaryotic vigor, the growth and pathogenicity of the majority of tuft isolates increased compared with their contributing SBIs. New somatic compatibility groups (SCGs) that were different from parental field isolates occurred following heterokaryon formation within T. cucumeris. Tuft isolates produced by Hom-Hom and Het-Hom pairings among isolates of different parents yielded no somatic compatibility with the original parent isolates and a high frequency of new SCGs (62-100%). This was in contrast to those produced by Hom-Hom and Het-Hom pairings among isolates with a common parent that yielded only 12-37% new SCGs. The SCG diversity of R. solani in the field may be attributed to new fitter heterokaryons formed between a heterokaryon of one pair of parents and a homokaryon of another parent pair. This mechanism greatly contributes to genetic diversity in the field and accounts for the failure to recover the expected distribution of SCGs from a field population. PMID:23995511

Qu, Ping; Saldajeno, Mary Grace B; Hyakumachi, Mitsuro

2013-08-31

95

Effects of Meloidogyne spp. and Rhizoctonia solani on the Growth of Grapevine Rootings.  

PubMed

A disease complex involving Meloidogyne incognita and Rhizoctonia solani was associated with stunting of grapevines in a field nursery. Nematode reproduction was occurring on both susceptible and resistant cultivars, and pot experiments were conducted to determine the virulence of this M. incognita population, and of M. javanica and M. hapla populations, to V. vinifera cv. Colombard (susceptible) and to V. champinii cv. Ramsey (regarded locally as highly resistant). The virulence of R. solani isolates obtained from roots of diseased grapevines also was determined both alone and in combination with M. incognita. Ramsey was susceptible to M. incognita (reproduction ratio 9.8 to 18.4 in a shadehouse and heated glasshouse, respectively) but was resistant to M. javanica and M. hapla. Colombard was susceptible to M. incognita (reproduction ratio 24.3 and 41.3, respectively) and M. javanica. Shoot growth was suppressed (by 35%) by M. incognita and, to a lesser extent, by M. hapla. Colombard roots were more severely galled than Ramsey roots by all three species, and nematode reproduction was higher on Colombard. Isolates of R. solani assigned to putative anastomosis groups 2-1 and 4, and an unidentified isolate, colonized and induced rotting of grapevine roots. Ramsey was more susceptible to root rotting than Colombard. Shoot growth was inhibited by up to 15% by several AG 4 isolates and by 20% by the AG 2-1 isolate. AG 4 isolates varied in their virulence. Root rotting was higher when grapevines were inoculated with both M. incognita and R. solani and was highest when nematode inoculation preceded the fungus. Shoot weights were lower when vines were inoculated with the nematode 13 days before the fungus compared with inoculation with both the nematode and the fungus on the same day. It was concluded that both the M. incognita population and some R. solani isolates were virulent against both Colombard and Ramsey, and that measures to prevent spread in nursery stock were therefore important. PMID:19274149

Walker, G E

1997-06-01

96

Influence of Rotation Crops on the Strawberry Pathogens Pratylenchus penetrans, Meloidogyne hapla, and Rhizoctonia fragariae.  

PubMed

Field microplot, small plot, and greenhouse experiments were conducted to determine the effects of rotation crops on Pratylenchus penetrans, Meloidogyne hapla, and Rhizoctonia fragariae populations. Extraction of P. penetrans from roots and soil in microplots and field plots planted to rotation crops was highest for Garry oat, lowest for Triple S sorgho-sudangrass and Saia oat, and intermediate for strawberry, buckwheat, and canola. Isolation of R. fragariae from bait roots was highest for strawberry and canola after 2 years of rotation and lowest for Saia oat. Nematode extraction from roots of rotation crops in field soils was generally higher than from roots in microplots. Grasses were nonhosts of M. hapla. Strawberry, canola, and buckwheat supported root-knot populations over time, but there were no differences in nematode numbers regardless of crop after one season of strawberry growth. Garry oat, canola, and, to a lesser extent, buckwheat supported large populations of P. penetrans without visible root symptoms. Strawberry plants supported fewer nematodes due to root damage. Nematode numbers from soil were less than from roots for all crops. While there were similar trends for pathogen recovery after more than 1 year of strawberry growth following rotation, differences in pathogen density and fruit yield were not significant. In the greenhouse, P. penetrans populations in roots and soil in pots were much higher for Garry oat than for Saia oat. Total P. penetrans adult and juvenile numbers per pot ranged from 40 to 880 (mean = 365.6) for Garry oat and 0 to 40 (mean = 8.7) for Saia oat. Production of Saia oat as a rotation crop may be a means of managing strawberry nematodes and black root rot in Connecticut. PMID:19270931

Lamondia, J A

1999-12-01

97

Mungbean plants expressing BjNPR1 exhibit enhanced resistance against the seedling rot pathogen, Rhizoctonia solani.  

PubMed

Mungbean, Vigna radiata (L.) Wilczek is an important pulse crop that is widely cultivated in semi- arid tropics. The crop is attacked by various soil-borne pathogens like Rhizoctonia solani, which causes dry rot disease and seriously affects its productivity. Earlier we characterized the non-expressor of pathogenesis related gene-1(BjNPR1) of mustard, Brassica juncea, the counterpart of AtNPR1 of Arabidopsis thaliana. Here, we transformed mungbean with BjNPR1 via Agrobacterium tumefaciens. Because of the recalcitrant nature of mungbean, the effect of some factors like Agrobacterium tumefaciens strains (GV2260 and LBA4404), pH, L: -cysteine and tobacco leaf extract was tested in transformation. The transgenic status of 15 plants was confirmed by PCR using primers for nptII. The independent integration of T-DNA in transgenic plants was analyzed by Southern hybridization with an nptII probe and the expression of BjNPR1 was confirmed by RT-PCR. Some of the T(0) plants were selected for detached leaf anti-fungal bioassay using the fungus Rhizoctonia solani, which showed moderate to high level of resistance depending on the level of expression of BjNPR1. The seedling bioassay of transgenic T(2) plants indicated resistance against dry rot disease caused by R. solani. PMID:21584838

Vijayan, S; Kirti, P B

2011-05-17

98

Nuclear magnetic resonance: a tool for imaging belowground damage caused by Heterodera schachtii and Rhizoctonia solani on sugar beet  

PubMed Central

Belowground symptoms of sugar beet caused by the beet cyst nematode (BCN) Heterodera schachtii include the development of compensatory secondary roots and beet deformity, which, thus far, could only be assessed by destructively removing the entire root systems from the soil. Similarly, the symptoms of Rhizoctonia crown and root rot (RCRR) caused by infections of the soil-borne basidiomycete Rhizoctonia solani require the same invasive approach for identification. Here nuclear magnetic resonance imaging (MRI) was used for the non-invasive detection of belowground symptoms caused by BCN and/or RCRR on sugar beet. Excessive lateral root development and beet deformation of plants infected by BCN was obvious 28 days after inoculation (dai) on MRI images when compared with non-infected plants. Three-dimensional images recorded at 56 dai showed BCN cysts attached to the roots in the soil. RCRR was visualized by a lower intensity of the MRI signal at sites where rotting occurred. The disease complex of both organisms together resulted in RCRR development at the site of nematode penetration. Damage analysis of sugar beet plants inoculated with both pathogens indicated a synergistic relationship, which may result from direct and indirect interactions. Nuclear MRI of plants may provide valuable, new insight into the development of pathogens infecting plants below- and aboveground because of its non-destructive nature and the sufficiently high spatial resolution of the method.

Hillnhutter, C.; Sikora, R. A.; Oerke, E. -C.; van Dusschoten, D.

2012-01-01

99

Identification, molecular characterization, and evolution of group I introns at the expansion segment D11 of 28S rDNA in Rhizoctonia species.  

PubMed

The nuclear ribosomal DNA of Rhizoctonia species is polymorphic in terms of the nucleotide composition and length. Insertions of 349-410 nucleotides in length with characteristics of group I introns were detected at a single insertion point at the expansion segment D11 of 28S rDNA in 12 out of 64 isolates. Eleven corresponded to Rhizoctonia solani (teleomorph: Thanatephorous) and one (AG-Q) to Rhizoctonia spp. (teleomorph: Ceratobasidium). Sequence data showed that all but AG-Q contained conserved DNA catalytic core regions (P, Q, R, and S) essential for selfsplicing. The predicted secondary structure revealed that base-paired helices corresponded to subgroup IC1. Isolates from same anastomosis group and even subgroups within R. solani were variable with regard to possession of introns. Phylogenetic analyses indicated that introns were vertically transmitted. Unfortunately, sequence data from the conserved region from all 64 isolates were not useful for delimiting species. Analyses with IC1 introns at same insertion point, of both Ascomycota and Basidiomycota indicated the possibility of horizontal transfer at this site. The present study uncovered new questions on evolutionary pattern of change of these introns within Rhizoctonia species. PMID:24012302

González, Dolores

2013-06-28

100

Enzyme Diffusion from Trichoderma atroviride (= T. harzianum P1) to Rhizoctonia solani Is a Prerequisite for Triggering of Trichoderma ech42 Gene Expression before Mycoparasitic Contact  

Microsoft Academic Search

A plate confrontation experiment is commonly used to study the mechanism by which Trichoderma spp. antagonize and parasitize other fungi. Previous work with chitinase gene expression (ech42) during the precontact period of this process in which cellophane and dialysis membranes separated Trichoderma harzia- num and its host Rhizoctonia solani resulted in essentially opposite results. Here, we show that cellophane membranes

CORNELIA KULLNIG; ROBERT L. MACH; MATTEO LORITO; CHRISTIAN P. KUBICEK

2000-01-01

101

Yield responses of three onion cultivars to stunting caused by Rhizoctonia spp. in the Columbia Basin of Oregon and Washington, 2012.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia spp. cause patches of stunted onion plants in onion bulbs crop in the Columbia Basin of Washington and Oregon when onion crops are planted in sandy soils of this semi-arid region following winter cereal cover crops. A herbicide application is used to kill the cereal cover crop, usually ...

102

Efficacy of fungicides to manage onion stunting caused by Rhizoctonia spp. in the Columbia Basin of Oregon and Washington, 2011-2012  

Technology Transfer Automated Retrieval System (TEKTRAN)

Onion stunting, caused by Rhizoctonia spp., has become a significant soilborne problem of onion bulb crops planted in sandy soils in the semi-arid Columbia Basin of Oregon and Washington following winter cereal cover crops. Research on the epidemiology and management of this disease is in progress. ...

103

Rapid suppression of defence enzymes and compounds by sheath blight (Rhizoctonia solani) and sheath rot (Sarocladium oryzae) toxins in rice cell suspension cultures  

Microsoft Academic Search

To understand the suppression mechanisms against disease resistance in rice, we took advantage of the fact that suspension cultured cells exhibit many of the defence responses that are characteristic of intact tissues. In this study we constitutively measured the Rhizoctonia solani and Sarocladium oryzae toxins, induced and suppressed levels of phenylalanine ammonia lyase, peroxidase, superoxide dismutase, phenols, catalase, ?-1,3-glucanase and

A. Kandan; R. Radja Commare; R. Nandakumar; G. Amutha; A. Vijayasamundeeswari; A. Ramanathan; T. Raguchander; P. Balasubramanian; R. Samiyappan

2010-01-01

104

Effect of cropping system on composition of the Rhizoctonia populations recovered from canola and lupin in a winter rainfall region of South Africa  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia spp. are important pathogens of a broad range of crop plants that are economically important to the farm economy of the Western Cape region of South Africa. However, there is little information concerning the identity and relative importance of these fungal pathogens, and the effect of ...

105

High-resolution mapping of Rsn1, a locus controlling sensitivity of rice to a necrosis-inducing phytotoxin from Rhizoctonia solani AG1-IA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rhizoctonia solani is a necrotrophic fungal pathogen that causes disease on all major crop-plant species. Anastomosis group 1-IA is the causal agent of sheath blight of rice (Oryza sativa), one of the most important rice diseases worldwide. R. solani AG-IA produces a necrosis-inducing phytotoxin a...

106

Genome Sequence of Bacillus subtilis MB73/2, a Soil Isolate Inhibiting the Growth of Plant Pathogens Dickeya spp. and Rhizoctonia solani  

PubMed Central

Bacillus subilis MB73/2 is a Gram-positive bacterium isolated in Poland from a meadow soil sample. When tested in vitro, the strain shows strong antagonism toward plant pathogens—the soft rot-causing bacteria Dickeya spp. and the crown rot fungus Rhizoctonia solani. Here, we present the genome sequence of MB73/2.

Krzyzanowska, Dorota M.; Iwanicki, Adam; Ossowicki, Adam; Obuchowski, Michal

2013-01-01

107

Oxalic acid-induced resistance to Rhizoctonia solani in rice is associated with induction of phenolics, peroxidase and pathogenesis-related proteins  

Microsoft Academic Search

Oxalic acid (1 mM) when applied as a foliar spray to rice plants induced resistance to challenge infection with Rhizoctonia solani, the rice sheath blight pathogen. Maximum reduction in sheath blight incidence was observed when the plants were sprayed with oxalic acid three days before inoculation with the fungus. The biochemical alterations in rice plants treated with oxalic acid was

Jayaraman Jayaraj; Ranganathan Bhuvaneswari; Ramalingam Rabindran; Subbaratnam Muthukrishnan; Rethinasamy Velazhahan

2010-01-01

108

Optimizing Fungicide Timing for the Control of Rhizoctonia Crown and Root Rot of Sugar Beet Using Soil Temperature and Plant Growth Stages  

Microsoft Academic Search

Kirk, W. W., Wharton, P. S., Schafer, R. L., Tumbalam, P., Poindexter, S., Guza, C., Fogg, R., Schlatter, T., Stewart, J., Hubbell, L., and Ruppal, D. 2008. Optimizing fungicide timing for the control of Rhizoctonia crown and root rot of sugar beet using soil temperature and plant growth stages. Plant Dis. 92:1091-1098. Azoxystrobin is applied early in the sugar beet

W. W. Kirk; P. S. Wharton; R. L. Schafer; P. Tumbalam; S. Poindexter; C. Guza; R. Fogg; T. Schlatter; J. Stewart; L. Hubbell; D. Ruppal

2008-01-01

109

Growth inhibition of the cereal root pathogens Rhizoctonia solani AG8, R. oryzae and Gaeumannomyces graminis var. tritici by a recombinant 42-kDa endochitinase from Trichoderma harzianum  

Microsoft Academic Search

The objective of this study was to determine the effectiveness of a 42-kDa endochitinase coded by the ThEn42 gene from Trichoderma harzianum as a potential source of transgenic resistance to Rhizoctonia root rot of barley caused by Rhizoctonia solani AG8 and\\/or R. oryzae. The gene cThEn42 was codon optimized (GC content increased from 53.3 to 65.1%) and then synthesized to

Yongchun Wu; Diter Von Wettstein; C. Gamini Kannangara; Jayaveeramuthu Nirmala; R. James Cook

2006-01-01

110

Influence of depth of soil disturbance on root growth dynamics of wheat seedlings associated with Rhizoctonia solani AG8 disease severity in sandy and loamy sand soils of Western Australia  

Microsoft Academic Search

Rhizoctonia root rot (bare-patch disease) of cereals caused by Rhizoctonia solani AG-8 is reported to become more severe when the crop is sown under no-tillage practice. Disturbing the soil with tillage is an effective way to reduce the impact of disease. Glasshouse and field studies were conducted to evaluate the effects of the depth and intensity of soil disturbance and

J. S Gill; K Sivasithamparam; K. R. J Smettem

2001-01-01

111

Cloning and functional analysis of an endo-PG-encoding gene Rrspg1 of Rhizoctonia solani, the causal agent of rice sheath blight  

Microsoft Academic Search

By assembling the sequences of the cDNA obtained from RT-PCR, 5?-RACE and 3?-RACE, a full-length sequence of the endo-polygalacturonase (endo-PG) -encoding gene, Rrspg1, from the rice sheath blight fungus Rhizoctonia solani, was obtained. The alignment of cDNA and genomic DNA sequences indicated that there were three introns in the sequence of Rrspg1. Differences in six nucleotides and four amino acids

Ying-Qing Yang; Mei Yang; Ming-Hai Li; Er-Xun Zhou

2012-01-01

112

Identification of potential marker genes for Trichoderma harzianum strains with high antagonistic potential against Rhizoctonia solani by a rapid subtraction hybridization approach  

Microsoft Academic Search

A rapid subtraction hybridization approach was used to isolate genes differentially expressed during mycelial contact between\\u000a Trichoderma harzianum (Hypocrea lixii) and Rhizoctonia solani, and could serve as marker genes for selection of superior biocontrol strains. Putatively positive clones were evaluated\\u000a by transcription analysis during mycelial contact with R. solani versus growth on glucose, and for their differential transcription between two

Barbara Scherm; Monika Schmoll; Virgilio Balmas; Christian P. Kubicek; Quirico Migheli

2009-01-01

113

Phylogeography of the Solanaceae-infecting Basidiomycota fungus Rhizoctonia solani AG3 based on sequence analysis of two nuclear DNA loci  

Microsoft Academic Search

BACKGROUND: The soil fungus Rhizoctonia solani anastomosis group 3 (AG-3) is an important pathogen of cultivated plants in the family Solanaceae. Isolates of R. solani AG-3 are taxonomically related based on the composition of cellular fatty acids, phylogenetic analysis of nuclear ribosomal DNA (rDNA) and beta-tubulin gene sequences, and somatic hyphal interactions. Despite the close genetic relationship among isolates of

Paulo C Ceresini; H David Shew; Timothy Y James; Rytas J Vilgalys; Marc A Cubeta

2007-01-01

114

EVOLUTION OF BIOCHEMICAL PARAMETERS IN THE SUPPRESSION OF THE DAMPING-OFF CAUSED BY RHIZOCTONIA SOLANI AFTER THE ADDITION OF SEWAGE SLUDGE COMPOST  

Microsoft Academic Search

A calcareous clay loam soil, with low organic matter content (1.85%) was infected with Rhizoctonia solani, a pathogenic fungus responsible for the sugar beet damping-off. The suppression of the pathogen- ic activity was analyzed over a fifteen week period of incubation at 25ºC and 60% of the highest water retention capacity (HWRC), in the original soil, and in the infected

Y. Arribas; B. Alonso; D. J. López; C. Rad; S. González

115

Trichoderma harzianum strain SQR-T37 and its bio-organic fertilizer could control Rhizoctonia solani damping-off disease in cucumber seedlings mainly by the mycoparasitism  

Microsoft Academic Search

Damping-off disease is caused by Rhizoctonia solani and leads to serious loss in many crops. Biological control is an efficient and environmentally friendly way to prevent damping-off\\u000a disease. Optical micrographs, scanning electron micrographs, and the determination of hydrolytic enzymes were used to investigate\\u000a the antagonism of Trichoderma harzianum SQR-T37 (SQR-T37) against R. solani. Experiments were performed in pots to assess

Xinqi Huang; Lihua Chen; Wei Ran; Qirong Shen; Xingming Yang

116

Defense-related gene expression and enzyme activities in transgenic cotton plants expressing an endochitinase gene from Trichoderma virens in response to interaction with Rhizoctonia solani  

Microsoft Academic Search

There are many reports on obtaining disease-resistance trait in plants by overexpressing genes from diverse organisms that\\u000a encode chitinolytic enzymes. Current study represents an attempt to dissect the mechanism underlying the resistance to Rhizoctonia solani in cotton plants expressing an endochitinase gene from Trichoderma virens. Several assays were developed that provided a powerful demonstration of the disease protection obtained in

Vinod Kumar; Vilas Parkhi; Charles M. Kenerley; Keerti S. Rathore

2009-01-01

117

Effects of soil moisture and sowing depth on the development of bean plants grown in sterile soil infested by Rhizoctonia solani and Trichoderma harzianum  

Microsoft Academic Search

The effects of soil moisture (varying from 15% to 42% (v\\/v)) and sowing depth (1.5–6.0 cm) on the development of bean plants\\u000a grown in sterile soil infested by the pathogen Rhizoctonia solani and its antagonist Trichoderma harzianum were studied under greenhouse conditions. The four possible combinations of soil infestation with both fungi were tested.\\u000a Disease severity, percentage of plants emerged, plant

T. J. Paula Júnior; C. Rotter; B. Hau

2007-01-01

118

Variations in the cultural characteristics of Rhizoctonia solani, and its antagonists: Aspergillus terreus and Aspergillus flavus occurring in the rhizosphere of cotton  

Microsoft Academic Search

Summary Cultural studies onRhizoctonia solani, the causal agent of damping-off of cotton, as well as on two fungi of its antagonistic rhizospheric microflora, namelyAspergillus terreus andAspergillus flavus have shown coincidence of some of their cultural characteristics. However,R. solani produced mycelial growth far ahead both antagonists except at 37° C and at pH 4, at its optimum temperature. It is expected

M. S. Naim; A. A. El-Esawy

1965-01-01

119

A gene for plant protection: expression of a bean polygalacturonase inhibitor in tobacco confers a strong resistance against Rhizoctonia solani and two oomycetes.  

PubMed

We have tested whether a gene encoding a polygalacturonase-inhibiting protein (PGIP) protects tobacco against a fungal pathogen (Rhizoctonia solani) and two oomycetes (Phytophthora parasitica var. nicotianae and Peronospora hyoscyami f. sp. tabacina). The trials were performed in greenhouse conditions for R. solani and P. parasitica and in the field for P. hyoscyami. Our results show that expression of PGIP is a powerful way of engineering a broad-spectrum disease resistance. PMID:23264779

Borras-Hidalgo, Orlando; Caprari, Claudio; Hernandez-Estevez, Ingrid; Lorenzo, Giulia De; Cervone, Felice

2012-12-05

120

A gene for plant protection: expression of a bean polygalacturonase inhibitor in tobacco confers a strong resistance against Rhizoctonia solani and two oomycetes  

PubMed Central

We have tested whether a gene encoding a polygalacturonase-inhibiting protein (PGIP) protects tobacco against a fungal pathogen (Rhizoctonia solani) and two oomycetes (Phytophthora parasitica var. nicotianae and Peronospora hyoscyami f. sp. tabacina). The trials were performed in greenhouse conditions for R. solani and P. parasitica and in the field for P. hyoscyami. Our results show that expression of PGIP is a powerful way of engineering a broad-spectrum disease resistance.

Borras-Hidalgo, Orlando; Caprari, Claudio; Hernandez-Estevez, Ingrid; Lorenzo, Giulia De; Cervone, Felice

2012-01-01

121

A potent mitogenic lectin from the mycelia of a phytopathogenic fungus, Rhizoctonia bataticola , with complex sugar specificity and cytotoxic effect on human ovarian cancer cells  

Microsoft Academic Search

A lectin with strong mitogenic activity towards human peripheral blood mononuclear cells (PBMCs) and cytotoxic effect on human\\u000a ovarian cancer cells has been purified from the mycelium of a phytopathogenic fungus, Rhizoctonia bataticola, using ion exchange chromatography and affinity chromatography on asialofetuin-Sepharose. The lectin, termed RBL, is a tetramer\\u000a of 11-kDa subunits and has unique amino acid sequence at its

Nagaraja N. Nagre; Vishwanath B. Chachadi; Palaniswamy M. Sundaram; Ramachandra S. Naik; Radha Pujari; Padma Shastry; Bale M. Swamy; Shashikala R. Inamdar

2010-01-01

122

The double life of Ceratobasidium: orchid mycorrhizal fungi and their potential for biocontrol of Rhizoctonia solani sheath blight of rice.  

PubMed

Ceratobasidium includes orchid mycorrhizal symbionts, plant pathogens and biocontrol agents of soilborne plant pathogens. It is not known to what extent members of the first guild also can participate in the others. Ceratobasidium spp. were isolated from roots of Colombian orchids and identified by phylogeny based on nrITS sequences. Phylogenetic grouping of Ceratobasidium spp. isolates corresponded to orchid host substrate (epiphytic vs. terrestrial). Isolates were tested for virulence on rice and for biocontrol of Rhizoctonia solani, causal agent of sheath blight of rice. All Ceratobasidium spp. isolates caused some signs of sheath blight but significantly less than a pathogenic R. solani used as a positive control. When Ceratobasidium spp. isolates were inoculated on rice seedlings 3 d before R. solani, they significantly reduced disease expression compared to controls inoculated with R. solani alone. The use of Ceratobasidium spp. from orchids for biological control is novel, and biodiverse countries such as Colombia are promising places to look for new biocontrol agents. PMID:22962357

Mosquera-Espinosa, Ana Teresa; Bayman, Paul; Prado, Gustavo A; Gómez-Carabalí, Arnulfo; Otero, J Tupac

2012-09-06

123

Effect of Entomopathogenic Nematodes and Trichoderma harzianum on the Strawberry Black Root Rot Pathogens Pratylenchus penetrans and Rhizoctonia fragariae.  

PubMed

The effects of inundative releases of entomopathogenic Steinernema carpocapsae and S. feltiae infective juveniles and applications of the biological control fungus Trichoderma harzianum T-22 (RootShield) on Pratylenchus penetrans and strawberry black root rot caused by Rhizoctonia fragariae were determined in field microplots and small plots. Entomopathogenic nematodes were applied as a soil drench at rates of 7.4 or 14.8 billion per ha in May or August for 3 years. RootShield was applied as crown dips at planting or later as a soil drench. There were no differences in P. penetrans from plants drenched with water alone or with S. carpocapsae or S. feltiae nematodes, averaged over rates and timing. The nematode species applied and the rate or timing of application had no effect on lesion nematodes. Our results suggest that P. penetrans exposure to living or heat-killed S. feltiae and associated bacteria resulted in temporary lack of motility. A progressively increasing proportion of P. penetrans became active again and, after 8 days, had infected tomato roots in similar numbers to unexposed P. penetrans. In laboratory assays and field plots or microplots, S. carpocapsae and S. feltiae did not permanently affect P. penetrans in tomato or strawberry. PMID:19265955

Lamondia, J A; Cowles, R S

2002-12-01

124

Effect of Entomopathogenic Nematodes and Trichoderma harzianum on the Strawberry Black Root Rot Pathogens Pratylenchus penetrans and Rhizoctonia fragariae  

PubMed Central

The effects of inundative releases of entomopathogenic Steinernema carpocapsae and S. feltiae infective juveniles and applications of the biological control fungus Trichoderma harzianum T-22 (RootShield) on Pratylenchus penetrans and strawberry black root rot caused by Rhizoctonia fragariae were determined in field microplots and small plots. Entomopathogenic nematodes were applied as a soil drench at rates of 7.4 or 14.8 billion per ha in May or August for 3 years. RootShield was applied as crown dips at planting or later as a soil drench. There were no differences in P. penetrans from plants drenched with water alone or with S. carpocapsae or S. feltiae nematodes, averaged over rates and timing. The nematode species applied and the rate or timing of application had no effect on lesion nematodes. Our results suggest that P. penetrans exposure to living or heat-killed S. feltiae and associated bacteria resulted in temporary lack of motility. A progressively increasing proportion of P. penetrans became active again and, after 8 days, had infected tomato roots in similar numbers to unexposed P. penetrans. In laboratory assays and field plots or microplots, S. carpocapsae and S. feltiae did not permanently affect P. penetrans in tomato or strawberry.

Lamondia, J. A.; Cowles, R. S.

2002-01-01

125

Isolation and characterization of a novel wheat cysteine-rich receptor-like kinase gene induced by Rhizoctonia cerealis.  

PubMed

Cysteine-rich receptor kinases (CRKs) belong to the receptor-like kinase family. Little is known about CRK genes in wheat. We isolated a wheat CRK gene TaCRK1 from Rhizoctonia cerealis-resistant wheat CI12633 based on a differentially expressed sequence identified by RNA-Sequencing (RNA-Seq) analysis. TaCRK1 was more highly expressed in CI12633 than in susceptible Wenmai 6. Transcription of TaCRK1 in wheat was induced in CI12633 after R. cerealis infection and exogenous abscisic acid (ABA) treatment. The deduced TaCRK1 protein contained a signal peptide, two DUF26 domains, a transmembrane domain, and a serine/threonine protein kinase domain. Transient expression of a green fluorescence protein fused with TaCRK1 in wheat and onion indicated that TaCRK1 may localize to plasma membranes. Characterization of TaCRK1 silencing induced by virus-mediated method in CI12633 showed that the downregulation of TaCRK1 transcript did not obviously impair resistance to R. cerealis. This study paves the way to further CRK research in wheat. PMID:24149340

Yang, Kun; Rong, Wei; Qi, Lin; Li, Jiarui; Wei, Xuening; Zhang, Zengyan

2013-10-23

126

Screening, identification and evaluation of potential biocontrol fungal endophytes against Rhizoctonia solani AG3 on potato plants.  

PubMed

Rhizoctonia solani is an important soilborne pathogen of potato plants whose control typically depends on chemicals. Here, we screened six fungal endophytes for the suppression of R. solani growth both in vitro and in a greenhouse. These isolates were identified using morphology and internal transcribed spacer regions of rDNA as Alternaria longipes, Epicoccum nigrum, Phomopsis sp., and Trichoderma atroviride. Both T. atroviride and E. nigrum showed significant in vitro inhibition of mycelial growth of R. solani, with the greatest inhibition zone observed for E. nigrum species in dual cultures. The highest inhibition was observed for T. atroviride. The inhibition rate was also significantly correlated with the culture filtrates of these isolates. Confocal microscopy showed that T. atroviride acts as a mycoparasite and competitor. However, E. nigrum and A. longipes produce secondary metabolites, while Phomospsis sp. competes for nutrients and space. Greenhouse experiments confirmed that T. atroviride and E. nigrum improved potato yield significantly and decreased the stem disease severity index of sensitive potato. PMID:20738401

Lahlali, Rachid; Hijri, Mohamed

2010-08-25

127

Potential for the integration of biological and chemical control of sheath blight disease caused by Rhizoctonia solani on rice.  

PubMed

Biological control using antagonistic microbes to minimize the use of chemical pesticides has recently become more prevalent. In an attempt to find an integrated control system for sheath blight, caused by Rhizoctonia solani in rice, Streptomyces philanthi RM-1-138, commercial formulations of Bacillus subtilis as Larminar(®) and B. subtilis strain NSRS 89-24+MK-007 as Biobest(®) and chemical fungicides including carbendazim(®), validamycin(®), propiconazole(®) and mancozeb(®) were applied alone and in combination with S. philanthi RM-1-138. In vitro experiments showed that all treatments tested did provide some control against mycelial growth and sclerotia production by R. solani PTRRS-9. In addition, the four chemical fungicides had no detrimental effects on S. philanthi RM-1-138 even at high concentrations (up to 100 ?g/ml). The efficacy of S. philanthi RM-1-138, the commercial formulations of B. subtilis, chemical fungicides alone or in combination with S. philanthi RM-1-138 was also tested in a greenhouse experiment against sheath blight disease on rice plants. All treatments showed some protection of rice for sheath blight by 47-60 % when carbendazim(®) was applied alone and up to 74 % when combined with S. philanthi RM-1-138. PMID:23653261

Boukaew, Sawai; Klinmanee, Chanasirin; Prasertsan, Poonsuk

2013-05-08

128

FT-ICR/MS and GC-EI/MS Metabolomics Networking Unravels Global Potato Sprout's Responses to Rhizoctonia solani Infection  

PubMed Central

The complexity of plant-pathogen interactions makes their dissection a challenging task for metabolomics studies. Here we are reporting on an integrated metabolomics networking approach combining gas chromatography/mass spectrometry (GC/MS) with Fourier transform ion cyclotron resonance/mass spectrometry (FT-ICR/MS) and bioinformatics analyses for the study of interactions in the potato sprout-Rhizoctonia solani pathosystem and the fluctuations in the global metabolome of sprouts. The developed bioanalytical and bioinformatics protocols provided a snapshot of the sprout's global metabolic network and its perturbations as a result of pathogen invasion. Mevalonic acid and deoxy-xylulose pathways were substantially up-regulated leading to the biosynthesis of sesquiterpene alkaloids such as the phytoalexins phytuberin, rishitin, and solavetivone, and steroidal alkaloids having solasodine and solanidine as their common aglycons. Additionally, the perturbation of the sprout's metabolism was depicted in fluctuations of the content of their amino acids pool and that of carboxylic and fatty acids. Components of the systemic acquired resistance (SAR) and hypersensitive reaction (HR) such as azelaic and oxalic acids were detected in increased levels in infected sprouts and strategies of the pathogen to overcome plant defense were proposed. Our metabolic approach has not only greatly expanded the multitude of metabolites previously reported in potato in response to pathogen invasion, but also enabled the identification of bioactive plant-derived metabolites providing valuable information that could be exploited in biotechnology, biomarker-assisted plant breeding, and crop protection for the development of new crop protection agents.

Aliferis, Konstantinos A.; Jabaji, Suha

2012-01-01

129

Responses of 2 epiphytic yeasts to foliar infection by Rhizoctonia solani or mechanical wounding on the phylloplane of tall fescue.  

PubMed

A growth-chamber experiment was conducted to determine how foliar disease or wounding affects the ability of 2 phylloplane yeasts (Rhodotorula glutinis and Cryptococcus laurentii) to colonize leaves of tall fescue (Festuca arundinacea). Yeasts were applied separately and together onto healthy leaves, leaves infected with Rhizoctonia solani (diseased), and mechanically bruised (wounded) leaves. In all 3 trials, the leaf disturbance treatment significantly affected the abundance of yeast on the phylloplane of tall fescue. Yeast abundance on the diseased or wounded leaves was significantly greater than on the nontreated, healthy leaves. In 2 of the 3 trials, the yeast species applied also had a significant affect on yeast abundance. Typically, R. glutinis was significantly more abundant than C. laurentii when applied individually, but not significantly greater than the total yeast colony-forming units of the co-inoculated treatment. When the 2 yeasts were co-inoculated onto the leaves, R. glutinis comprised 89.7%, 75.4%, and 67.6% of the recovered yeast colony-forming units on healthy, diseased, and wounded leaves, respectfully. Our data suggest that these 2 species of yeasts will differentially colonize compromised leaf tissue with disease or wounds favoring populations of R. glutinis over C. laurentii. PMID:19935888

Nix, Shannon; Burpee, Leon L; Buck, James W

2009-10-01

130

Evidence from mycelial studies for differences in the sterol biosynthetic pathway of Rhizoctonia solani and Phytophthora cinnamomi.  

PubMed Central

Phytophthora cinnamomi, a member of the Pythiacease, does not synthesize sterols. Small amounts of squalene, but no squalene epoxide or sterol, were isolated from the dried mycelium of this fungus after growth in sterol-free medium. The dried mycelium of Rhizoctonia solani, a sterol-synthesizing fungus grown under the same conditions, contained small amounts of squalene and squalene epoxide and large amounts of ergosterol. When the two organisms were grown in the presence of [14C]acetate, only labelled geraniol, farnesol and squalene were recovered from the P. cinnamomi mycelium, whereas labelled geraniol, farnesol, squalene, squalene epoxide and ergosterol were recovered from the R. solani mycelium. Similar results were obtained when the organisms were incubated in the presence of [2(-14)C]mevalonate; in this case, labelled lanosterol was also detected in the R. solani mycelium. Both organisms, when incubated in the presence of unlabelled squalene, squalene epoxide or lanosterol, incorporated these compounds into their mycelia; however, only the R. solani mycelium was able to convert these substrates into products further along the sterol pathway. It appears that squalene is the terminal compound in the sterol biosynthetic pathway of P. cinnamomi.

Wood, S G; Gottlieb, D

1978-01-01

131

Isolation and characterization of a novel wheat cysteine-rich receptor-like kinase gene induced by Rhizoctonia cerealis  

PubMed Central

Cysteine-rich receptor kinases (CRKs) belong to the receptor-like kinase family. Little is known about CRK genes in wheat. We isolated a wheat CRK gene TaCRK1 from Rhizoctonia cerealis-resistant wheat CI12633 based on a differentially expressed sequence identified by RNA-Sequencing (RNA-Seq) analysis. TaCRK1 was more highly expressed in CI12633 than in susceptible Wenmai 6. Transcription of TaCRK1 in wheat was induced in CI12633 after R. cerealis infection and exogenous abscisic acid (ABA) treatment. The deduced TaCRK1 protein contained a signal peptide, two DUF26 domains, a transmembrane domain, and a serine/threonine protein kinase domain. Transient expression of a green fluorescence protein fused with TaCRK1 in wheat and onion indicated that TaCRK1 may localize to plasma membranes. Characterization of TaCRK1 silencing induced by virus-mediated method in CI12633 showed that the downregulation of TaCRK1 transcript did not obviously impair resistance to R. cerealis. This study paves the way to further CRK research in wheat.

Yang, Kun; Rong, Wei; Qi, Lin; Li, Jiarui; Wei, Xuening; Zhang, Zengyan

2013-01-01

132

Genetic and Genomic Analysis of Rhizoctonia solani Interactions with Arabidopsis; Evidence of Resistance Mediated through NADPH Oxidases  

PubMed Central

Rhizoctonia solani is an important soil-borne necrotrophic fungal pathogen, with a broad host range and little effective resistance in crop plants. Arabidopsis is resistant to R. solani AG8 but susceptible to R. solani AG2-1. A screen of 36 Arabidopsis ecotypes and mutants affected in the auxin, camalexin, salicylic acid, abscisic acid and ethylene/jasmonic acid pathways did not reveal any variation in response to R. solani and demonstrated that resistance to AG8 was independent of these defense pathways. The Arabidopsis Affymetrix ATH1 Genome array was used to assess global gene expression changes in plants infected with AG8 and AG2-1 at seven days post-infection. While there was considerable overlap in the response, some gene families were differentially affected by AG8 or AG2-1 and included those involved in oxidative stress, cell wall associated proteins, transcription factors and heat shock protein genes. Since a substantial proportion of the gene expression changes were associated with oxidative stress responses, we analysed the role of NADPH oxidases in resistance. While single NADPH oxidase mutants had no effect, a NADPH oxidase double mutant atrbohf atrbohd resulted in an almost complete loss of resistance to AG8, suggesting that reactive oxidative species play an important role in Arabidopsis's resistance to R. solani.

Foley, Rhonda C.; Gleason, Cynthia A.; Anderson, Jonathan P.; Hamann, Thorsten; Singh, Karam B.

2013-01-01

133

Induction of laccase activity in Rhizoctonia solani by antagonistic Pseudomonas fluorescens strains and a range of chemical treatments.  

PubMed

Fungi often produce the phenoloxidase enzyme laccase during interactions with other organisms, an observation relevant to the development of biocontrols. By incorporating the laccase substrate 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) into agar, we analyzed laccase induction in the plant-pathogenic fungus Rhizoctonia solani when paired against isolates of the soil bacterium Pseudomonas fluorescens. Substantial induction of R. solani laccase was seen only in pairings with strains of P. fluorescens known to produce antifungal metabolites. To study laccase induction further, a range of chemical treatments was applied to R. solani liquid cultures. p-Anisidine, copper(II), manganese(II), calcium ionophore A23187, lithium chloride, calcium chloride, cyclic AMP (cAMP), caffeine, amphotericin B, paraquat, ethanol, and isopropanol were all found to induce laccase; however, the P. fluorescens metabolite viscosinamide did not do so at the concentrations tested. The stress caused by these treatments was assessed by measuring changes in lipid peroxidation levels and dry weight. The results indicated that the laccase induction seen in pairing plate experiments was most likely due to calcium or heat shock signaling in response to the effects of bacterial metabolites, but that heavy metal and cAMP-driven laccase induction was involved in sclerotization. PMID:11319086

Crowe, J D; Olsson, S

2001-05-01

134

Biocontrol of Rhizoctonia solani damping-off disease in cucumber with Bacillus pumilus SQR-N43.  

PubMed

Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Micrographs were used to investigate the ability of Bacillus pumilus (B. pumilus) SQR-N43 to control Rhizoctonia solani (R. solani) Q1 in cucumbers. The root colonization ability of B. pumilus SQR-N43 was analyzed in vivo with a green fluorescent protein (GFP) tag. A pot experiment was performed to assess the in vivo disease-control efficiency of B. pumilus SQR-N43 and its bio-organic fertilizer. Results indicate that B. pumilus SQR-N43 induced hyphal deformation, enlargement of cytoplasmic vacuoles and cytoplasmic leakage in R. solani Q1 mycelia. A biofilm on the root surface was formed when the roots were inoculated with 10(7)-10(8)cells g(-1) of soil of GFP-tagged B. pumilus SQR-N43. In the pot experiment, the biocontrol reduced the concentration of R. solani. In contrast to applications of only B. pumilus SQR-N43 (N treatment), which produced control efficiencies of 23%, control efficiencies of 68% were obtained with applications of a fermented organic fertilizer inoculated with B. pumilus SQR-N43 (BIO treatment). After twenty days of incubation, significant differences in the number of CFUs and the percentage of spores of B. pumilus SQR-N43 were recorded between the N treatment (2.20×10(7)CFU g(-1) of soil and 79%, respectively) and the BIO treatment (1.67×10(8)CFU g(-1) of soil and 52%, respectively). The results indicate that B. pumilus SQR-N43 is a potent antagonist against R. solani Q1. The BIO treatment was more effective than the N treatment because it stabilized the population and increased the active form of the antagonist. PMID:21775112

Huang, Xinqi; Zhang, Nan; Yong, Xiaoyu; Yang, Xingming; Shen, Qirong

2011-07-19

135

An immunological approach to quantifying the saprotrophic growth dynamics of Trichoderma species during antagonistic interactions with Rhizoctonia solani in a soil-less mix.  

PubMed

Studies of the saprotrophic growth dynamics of Trichoderma species and their fungal hosts during antagonistic interactions are severely hampered by the absence of methods that allow the unambiguous identification and quantification of individual genera in complex environments such as soil or compost containing mixed populations of fungi. Furthermore, methods are required that allow discrimination between active hyphal growth and other components of fungal biomass such as quiescent spores that are produced in large numbers by Trichoderma species. This study details the use of monoclonal antibodies to quantify the saprotrophic growth dynamics of the soil-borne plant pathogen Rhizoctonia solani and biological control strains of Trichoderma asperellum and Trichoderma harzianum during antagonistic interactions in peat-based microcosms. Quantification was based on the immunological detection of constitutive, extracellular antigens that are secreted from the growing tip of Rhizoctonia and Trichoderma mycelium and, in the case of Trichoderma harzianum, from quiescent phialoconidia also. The Trichoderma-specific monoclonal antibody (MF2) binds to a protein epitope of the enzyme glucoamylase, which was shown by immunofluorescence and immunogold electron gold microscopy studies of Trichoderma virens in vitro to be produced at the origin of germ tube emergence in phialoconidia and from the growing tip of germ tubes. In addition, a non-destructive immunoblotting technique showed that the enzyme was secreted during active growth of Trichoderma asperellum mycelium in peat. The Rhizoctonia solani-specific monoclonal antibody (EH2) similarly binds to a protein epitope of a glycoprotein that is secreted during active mycelial growth. Extracts derived from lyophilized mycelium were used as a quantifiable and repeatable source of antigens for construction of calibration curves. These curves were used to convert the absorbance values obtained in ELISA tests of peat extracts to biomass equivalents, which allowed comparisons of the saprotrophic growth dynamics of the pathogen and antagonists to be made in single or mixed species microcosms. Trichoderma species were able to compete successfully with R. solani for nutrients and to prevent saprotrophic growth of the pathogen. Specificity of the Trichoderma quantitative assay was tested in non-sterile soil-based microcosms artificially inoculated with T. asperellum. The assay was highly specific and only detected T. asperellum population dynamics. No cross-reactivity was found with extracts from soil samples containing contaminant fungi. PMID:15008811

Thornton, Christopher R

2004-04-01

136

Intraspecific Evolution of Rhizoctonia solani AG1 IA Associated with Soybean and Rice in Brazil based on Polymorphisms at the ITS5.8S rDNA Operon  

Microsoft Academic Search

Rhizoctonia solani AG-1 IA causes leaf blight on soybean and rice. Despite the fact that R. solani AG-1 IA is a major pathogen affecting soybean and rice in Brazil and elsewhere in the world, little information is available\\u000a on its genetic diversity and evolution. This study was an attempt to reveal the origin, and the patterns of movement and amplification

Maisa B. Ciampi; Eiko E. Kuramae; Roseli C. Fenille; Maurício C. Meyer; Nilton L. Souza; Paulo C. Ceresini

2005-01-01

137

Use of strains of Bacillus isolated in China to suppress take-all and rhizoctonia root rot, and promote seedling growth of glasshouse-grown wheat in Australian soils  

Microsoft Academic Search

Several strains of Bacillus subtilis and B. cereus, isolated and selected in China for their ability to promote plant growth and control root disease (yield-increasing bacteria), were tested for their potential to control take-all, caused by Gaeumannomyces graminis var. tritici, and rhizoctonia root rot caused by R. solani AG-8 on wheat seedlings grown in field soils in a glasshouse. Bacillus

Maarten H Ryder; Zhinong Yan; Teri E Terrace; Albert D Rovira; Wenhua Tang; Raymond L Correll

1998-01-01

138

Determination of antibiotic activity on plasmids from fluorescent pseudomonads isolates CW2, WB15 and WB52 against pre-emergence damping-off caused by Pythium ultimum and Rhizoctonia solani in cucumber  

Microsoft Academic Search

Three fluorescent pseudomonads, isolates CW2, WB15 and WB52, were tested for their antagonistic activities against Pythium ultimum and Rhizoctonia solani isolates. In vitro experiments revealed pronounced inhibition zones on PDA agar medium against P. ultimum and R. solani by the isolates CW2 and WB15, respectively. Escherichia coli strains transformed with plasmids from the fluorescent pseudomonads isolates caused larger inhibition zones

M. Salman

2010-01-01

139

High activities and mRNA expression of pyrophosphate-fructose-6-phosphate-phosphotransferase and 6-phosphofructokinase are induced as a response to Rhizoctonia solani infection in rice leaf sheaths  

Microsoft Academic Search

Rice sheath blight disease caused by Rhizoctonia solani Kuhn results in significant yield and quality losses in rice growing areas worldwide. The glycolytic pathway is important in the resistance response to R. solani infection in rice. This study examined one of the regulatory steps in this pathway catalyzed by pyrophosphate- fructose-6-phosphate-phosphotransferase (PFP) and 6-phosphofructokinase (PFK). PFP and PFK activity in

J. M. Mutuku; A. Nose

140

The complete nucleotide sequence and characterization of the linear DNA plasmid pRS64-2 from the plant pathogenic fungus Rhizoctonia solani.  

PubMed

The complete nucleotide sequence of one of three linear DNA plasmids (pRS64-2) from the plant pathogenic fungus Rhizoctonia solani was determined. The pRS64-2 DNA consisted of 2877 nucleotides. The nucleotide sequences of the middle 2.2-kb regions of the other two plasmids (pRS64-1 and pRS64-3) were also determined. Comparison of the nucleotide sequences among the three plasmid DNAs indicated the presence of four regions with more than 86% sequence homology, suggesting the development of three plasmid DNAs from a common ancestor. A computer-based study of the pRS64-2 DNA-folding at both termini predicted hairpin loop structures. The hairpin loops consisted of the left- and right-hand terminal 113 and 105 nucleotides, respectively, and had no sequence homology. They had not undergone flip-flop inversion. The hairpins form cruciform base-paired structures. PMID:9388300

Katsura, K; Suzuki, F; Miyashita, S I; Nishi, T; Hirochika, H; Hashiba, T

1997-12-01

141

Identification of anastomosis group of Rhizoctonia solani, the causal agent of seed rot and damping-off of bean in Iran.  

PubMed

Bean is one of the major crops in Iran. Seed rot and damping-off caused by Rhizoctonia solani is the most important disease of bean. In this research, infected roots and seedlings of beans were collected from different fields of Tehran Province. The samples were sterilized with 10% sodium hypochloride (5% stock) and incubated on PDA surface in petri-dishes. The purified fungi kept on filter paper and identified, pathogenicity test of R. solani was carried out on 2 cultivars of bean (red bean cv. Naz and white bean cv. Dehghan) and it determined. For identification of the anastomosis groups, the discs of cultured media with 5 mm. diameter of standard AG placed on one side of microscopic slides covered with water agar (2%) of 1 mm. thick and the isolates of the fungus on another side of slide about 2 cm away from each other. Experiment carried out in 4 replications. The cultures were incubated in 25 +/- 1 degrees C incubator for 24 hours, then the mycelial contact stained with lactophenol, cotton blue and hyphal anastomosis looked for under the light microscope with 10 x 40 and 10 x 100 magnifications. As a result, anastomosis groups: AG4, AG4HGII, AG2-2-2B and AG6 determined, frequency of these groups were 64, 18, 2, 16%, respectively. The group AG6 and subgroups AG4HGII and AG2-2-2B are introduced as new anastomosis groups on bean in Iran. PMID:16637168

Bohlooli, A; Okhowat, S M; Javan-Nikkhah, M

2005-01-01

142

Characterization of genes involved in biosynthesis of a novel antibiotic from Burkholderia cepacia BC11 and their role in biological control of Rhizoctonia solani  

SciTech Connect

Genetic manipulation of fluorescent pseudomonads has provided major insight into their production of antifungal molecules and their role in biological control of plant disease. Burkholderia cepacia also produces antifungal activities, but its biological control activity is much less well characterized, in part due to difficulties in applying genetic tools. Here the authors report genetic and biochemical characterization of a soil isolate of B. cepacia relating to its production of an unusual antibiotic that is very active against a variety of soil fungi. Purification and preliminary structural analyses suggest that this antibiotic (called AFC-BC11) is a novel lipopeptide associated largely with the cell membrane. Analysis of conditions for optimal production of AFC-BC11 indicated stringent environmental regulation of its synthesis. Furthermore, the authors show that production of AFC-BC11 is largely responsible for the ability of B. cepacia BC11 to effectively control the damping-Off of cotton caused by the fungal pathogen Rhizoctonia solani in a gnotobiotic system. Using Tn5 mutagenesis, they identified, cloned, and characterized a region of the genome of strain BC11 that is required for production of this antifungal metabolite. DNA sequence analysis suggested that this region encodes proteins directly involved in the production of a nonribosomally synthesized lipopeptide.

Kang, Y.; Carlson, R.; Tharpe, W.; Schell, M.A. [Univ. of Georgia, Athens, GA (United States)

1998-10-01

143

Enrichment of perforate septal pore caps from the basidiomycetous fungus Rhizoctonia solani by combined use of French press, isopycnic centrifugation, and Triton X-100.  

PubMed

Septal pore caps occur in many filamentous basidiomycetes located at both sides of the dolipore septum and are at their base connected to the endoplasmic reticulum. The septal pore cap ultrastructure has been described extensively by the use of electron microscopy, but its composition and function are not yet known. To enable biochemical and functional analyses in the future, we here describe an enrichment method for perforate septal pore caps from Rhizoctonia solani. Our method is based on the combined use of French press and isopycnic centrifugation, using a discontinuous sucrose gradient followed by a treatment with Triton X-100. Enrichment was monitored by the use of scanning electron microscopy and transmission electron microscopy. Using the same isolation method, smaller septal pore caps were isolated from two other basidiomycetes as well. Furthermore, we showed pore-occluding material co-purified with the septal pore caps. This observation supports the hypothesis that septal pore caps play a key role in the plugging process of the septal pores in filamentous basidiomycetes. PMID:17949839

van Driel, Kenneth G A; van Peer, Arend F; Wösten, Han A B; Verkleij, Arie J; Boekhout, Teun; Müller, Wally H

2007-10-18

144

Redox-active pyocyanin secreted by Pseudomonas aeruginosa 7NSK2 triggers systemic resistance to Magnaporthe grisea but enhances Rhizoctonia solani susceptibility in rice.  

PubMed

Pseudomonas aeruginosa 7NSK2 induces resistance in dicots through a synergistic interaction of the phenazine pyocyanin and the salicylic acid-derivative pyochelin. Root inoculation of the monocot model rice with 7NSK2 partially protected leaves against blast disease (Magnaporthe grisea) but failed to consistently reduce sheath blight (Rhizoctonia solani). Only mutations interfering with pyocyanin production led to a significant decrease in induced systemic resistance (ISR) to M. grisea, and in trans complementation for pyocyanin production restored the ability to elicit ISR. Intriguingly, pyocyanin-deficient mutants, unlike the wild type, triggered ISR against R. solani. Hence, bacterial pyocyanin plays a differential role in 7NSK2-mediated ISR in rice. Application of purified pyocyanin to hydroponically grown rice seedlings increased H202 levels locally on the root surface as well as a biphasic H202 generation pattern in distal leaves. Co-application of pyocyanin and the antioxidant sodium ascorbate alleviated the opposite effects of pyocyanin on rice blast and sheath blight development, suggesting that the differential effectiveness of pyocyanin with respect to 7NSK2-triggered ISR is mediated by transiently elevated H202 levels in planta. The cumulative results suggest that reactive oxygen species act as a double-edged sword in the interaction of rice with the hemibiotroph M. grisea and the necrotroph R. solani. PMID:17153925

De Vleesschauwer, David; Cornelis, Pierre; Höfte, Monica

2006-12-01

145

Isolation, Identification and Optimal Culture Conditions of Streptomyces albidoflavus C247 Producing Antifungal Agents against Rhizoctonia solani AG2-2.  

PubMed

Streptomyces albidoflavus C247 was isolated from the soil of the Gyeongsan golf course in Korea. Physiological, biochemical and 16S rDNA gene sequence analysis strongly suggested that the isolate belonged to Streptomyces albidoflavus. Preliminary screening revealed that the isolate was active against fungi and bacteria. Self-directing optimization was employed to determine the best combination of parameters such as carbon and nitrogen source, pH and temperature. Nutritional and culture conditions for the production of antibiotics by this organism under shake-flask conditions were also optimized. Maltose (5%) and soytone (5%) were found to be the best carbon and nitrogen sources for the production of antibiotics by S. albidoflavus C247. Additionally, 62.89% mycelial growth inhibition was achieved when the organism was cultured at 30? and pH 6.5. Ethyl acetate (EtOAc) was the best extraction solvent for the isolation of the antibiotics, and 100 µg/ml of EtOAc extract was found to inhibit 60.27% of the mycelial growth of Rhizoctonia solani AG2-2(IV) when the poison plate diffusion method was conducted. PMID:23983519

Islam, Md Rezuanul; Jeong, Yong Tae; Ryu, Yeon Ju; Song, Chi Hyun; Lee, Yong Se

2009-06-30

146

Trichoderma harzianum strain SQR-T37 and its bio-organic fertilizer could control Rhizoctonia solani damping-off disease in cucumber seedlings mainly by the mycoparasitism.  

PubMed

Damping-off disease is caused by Rhizoctonia solani and leads to serious loss in many crops. Biological control is an efficient and environmentally friendly way to prevent damping-off disease. Optical micrographs, scanning electron micrographs, and the determination of hydrolytic enzymes were used to investigate the antagonism of Trichoderma harzianum SQR-T37 (SQR-T37) against R. solani. Experiments were performed in pots to assess the in vivo disease-control efficiency of SQR-T37 and bio-organic fertilizer. The results indicate that the mycoparasitism was the main mechanism accounting for the antagonistic activity of SQR-T37. In one experiment, the population of R. solani was decreased from 10(6) internal transcribed spacer (ITS) copies per gram soil to 10(4) ITS copies per gram soil by the presence of the antagonist. In this experiment, 45% of the control efficiency was obtained when 8 g of SQR-T37 hyphae per gram soil was applied. In a second experiment, as much as 81.82% of the control efficiency was obtained when bio-organic fertilizer (SQR-T37 fermented organic fertilizer, BIO) was applied compared to only 27.27% of the control efficiency when only 4 g of SQR-T37 hyphae per gram soil was applied. Twenty days after incubation, the population of T. harzianum was 4.12 × 10(7) ITS copies per gram soil in the BIO treatment, which was much higher than that in the previous treatment (8.77 × 10(5) ITS copies per gram soil), where only SQR-T37 was applied. The results indicated that SQR-T37 was a potent antagonist against R. solani in a mycoparasitic way that decreased the population of the pathogen. Applying BIO was more efficient than SQR-T37 application alone because it stabilized the population of the antagonist. PMID:21484203

Huang, Xinqi; Chen, Lihua; Ran, Wei; Shen, Qirong; Yang, Xingming

2011-04-12

147

Effect of carbon and nitrogen sources on growth and biological efficacy of Pseudomonas fluorescens and Bacillus subtilis against Rhizoctonia solani, the causal agent of bean damping-off.  

PubMed

One of the most important environmental factors that regulate the growth and antagonistic efficacy of biocontrol agents is the medium. The aim of this paper was to find the nitrogen and carbon sources that provide maximum biomass production of strains P-5 and P-6 (Pseudomonas fluorescens), B-3 and B-16 (Bacillus subtilis) and minimum cost of media, whilst maintaining biocontrol efficacy. All of the strains were grown in seven liquid media (pH=6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, nutrient broth, molasses and malt extract, at an initial inoculation of 1 x 10(5) CFU ml(-1). Cells from over night cultures used to inoculate soil at 1 x 10(9) CFU cm(-3) soil. At the same time, fungal inoculum (infected millet seed with Rhizoctonia solani) was added to soil at the rate of 2 g kg(-1) soil. Results indicated that growth of P-6, B-3 and B-16 in molasses + yeast extract (1:1 w/w) medium was significantly higher than in the other media. Molasses + yeast extract (1:1 and 2:1 w/w) media supported rapid growth and high cell yields in P-5. In greenhouse condition, results indicated that the influence of the media on the biocontrol efficacy of P-5, P-6, B-3 and B-16 was the same and Pseudomonas fluorescens P-5 in molasses and malt extract media reduced the severity of disease up to 72.8 percent. On the other hand, there were observed significant differences on bean growth after one month in greenhouse. P-5 in molasses + yeast extract (1:1 w/w) medium had the most effects on bean growth promotion. In this study molasses media showed good yield efficacy in all of the strains. The high sucrose concentration in molasses justifies the high biomass in all of the strains. Also, the low cost of molasses allows its concentration to be increased in media. On the other hand, yeast extract was the best organic nitrogen source for antagonist bacteria but it is expensive for an industrial process. So it should be replaced by another industrial product instead of yeast extract, which confirm by an economic and technological study. The results obtained in this study could be used to provide a reliable basis to increase the population of biocontrol agents in fermentation process. PMID:18396833

Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

2007-01-01

148

Rhizoctonia in Natural Grassland Soils  

Microsoft Academic Search

AN investigation into various aspects of the microbiology of natural grassland soils is being carried out in these laboratories to serve as a guide in future studies on the microbiology of soils under introduced pasture grasses.

R. H. Thornton

1956-01-01

149

Strain-specific SCAR markers for the detection of Trichoderma harzianum AS12-2, a biological control agent against Rhizoctonia solani, the causal agent of rice sheath blight.  

PubMed

In order to identify a specific marker for T. harzianum AS12-2, a strain capable of controlling rice sheath blight caused by Rhizoctonia solani, UP-PCR was performed using five universal primers (UP) both separately and in pairwise combinations. The application of two UP primers resulted in the amplification of unique fragments from the genomic DNA of T. harzianum AS12-2, clearly distinguishing it from other Trichoderma strains. The unique fragments had no significant sequence homology with any other known sequence available in databases. Based on the sequences of the unique fragments, 14 oligonucleotide primers were designed. Two primer sets amplified a fragment of expected size from the DNA of strain T. harzianum AS12-2 but not from any other examined strains belonging to T. harzianum, to other Trichoderma species assayed, or to other common fungi present in paddy fields of Mazandaran province, Iran. In conclusion, SCAR (sequence characterized amplified regions) markers were successfully identified and rapid, reliable tools were provided for the detection of an effective biocontrol Trichoderma strain, which can facilitate studies of its population dynamics and establishment after release into the natural environment. PMID:21388921

Naeimi, S; Kocsubé, S; Antal, Zsuzsanna; Okhovvat, S M; Javan-Nikkhah, M; Vágvölgyi, C; Kredics, L

2011-03-01

150

Early steps of slaframine and swainsonine biogenesis in Rhizoctonia leguminicola  

SciTech Connect

Pipecolic acid (PIP), a precursor of slaframine (SF) and swainsonine (SW) in the fungus R. leguminicola, is thought to arise from L-lysine (LYS). The epsilon-N atom of LYS constitutes the N atom of PIP. Interest in these reactions arises in relation to mechanisms of regulation of SF and SW, and perhaps to piperidine alkaloid biogenesis in general. The authors have not been able to demonstrate an L-LYS oxidase, reaction A, in R. leguminicola. Rather when (U-/sup 14/C)-L-LYS was incubated with cell-free R. leguminicola extracts together with ..cap alpha..-ketoglutarate and NADH,H/sup +/ and subsequently deproteinized and chromatographed (HPLC), large amounts of saccharopine (SAC) together with small amounts of two other radioactive metabolites (II, III) were formed. Compound III is PIP. Metabolite II appears to be an intermediate between SAC and PIP. Growing cultures of R. leguminicola also accumulate SAC. Thus, SAC formed via the aminoadipate pathway of LYS biosynthesis may be at a branch point in the pathways for LYS and PIP biogenesis and be subject to enzymic regulation with subsequent accumulation following formation of LYS, SF, and SW.

Wickwire, B.M.; Broquist, H.P.

1986-05-01

151

Effect of Brassicaceae seed meals with different glucosinolate profiles on Rhizoctonia root rot of wheat  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tissues of plants in the family Brassicaceae contain glucosinolates, compounds whose hydrolysis results in the release of various bioactive products including isothiocyanates. The broad spectrum of biological activity of these glucosinolate hydrolysis products has led to the promotion of brassicace...

152

INCREASE IN POPULATION OF RHIZOCTONIA SOLANI AND WIRESTEM OF COLLARD WITH VELVETBEAN COVER CROP MULCH  

Technology Transfer Automated Retrieval System (TEKTRAN)

Velvetbean has been used traditionally as a summer cover crop in the southeastern United States. We investigated the use of velvetbean as a killed cover crop mulch left on the soil surface before collard was transplanted in the fall. Control treatments were weed-free fallow and velvetbean that was...

153

Isolation and characterization of a phytotoxin from Rhizoctonia solani, the causal agent of rice sheath blight  

Technology Transfer Automated Retrieval System (TEKTRAN)

Phytotoxins (Rs-toxins) produced by R. solani are known to play an important role in the pathogenesis of this fungal pathogen, but the principal components of this phytotoxin were quite different from previous studies. To isolate and characterize the bioactive components of the Rs-toxin produced by ...

154

Optimum Timing for Spraying Out Greenbridge with Roundup to Control Rhizoctonia in Barley  

Technology Transfer Automated Retrieval System (TEKTRAN)

A field experiment was conducted in 2007 in a field at the ARS Palouse Conservation Farm with a high level of both R. solani and R. oryzae. Volunteer and weeds were allowed to grow over the winter, and plots were sprayed out with Roundup at 8 wks, 6 wks, 4 wks, 2 wks, 1 wk, and 2 days before plantin...

155

Seedling tolerance to Rhizoctonia and Pythium in wheat chromosome group 4 addition lines from Thinopyrum spp  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chromosome 4 from Thinopyrum spp. confers regrowth after a sexual cycle and senescence in hexaploid wheat (Triticum aestivum), and is associated with resistance to the necrotrophic eyespot pathogen, Tapesia yallundae. We sought to determine whether robust root growth or other traits expressed in ch...

156

Expression of a Chitinase Gene from Metarhizium anisopliae in Tobacco Plants Confers Resistance against Rhizoctonia solani  

Microsoft Academic Search

The chit1 gene from the entomopathogenic fungus Metarhizium anisopliae, encoding the endochitinase CHIT42, was placed under the control of the CaMV 35S promoter, and the resulting construct was\\u000a transferred to tobacco. Seventeen kanamycin-resistant transgenic lines were recovered, and the presence of the transgene was\\u000a confirmed by polymerase chain reactions and Southern blot hybridization. The number of chit1 copies was determined

Marcelo Fernando Kern; Simone de Faria Maraschin; Débora Vom Endt; Augusto Schrank; Marilene Henning Vainstein; Giancarlo Pasquali

2010-01-01

157

In vitro identification of cultivar responses to rice sheath blight pathogen Rhizoctonia solani  

Technology Transfer Automated Retrieval System (TEKTRAN)

The goal of this project is to identify critical genes for the control of sheath blight disease. To this end, an in vitro method to examine interactions of rice with the rice sheath blight pathogen Rhizocotnia solani was developed. The initial analysis of R. solani isolates from the Arkansas rice ...

158

The role of an extracellular chitinase from Trichoderma virens Gv29-8 in the biocontrol of Rhizoctonia solani  

Microsoft Academic Search

The role of extracellular chitinase in the biocontrol activity of Trichoderma virens was examined using genetically manipulated strains of this fungus. The T. virens strains in which the chitinase gene (cht42) was disrupted (KO) or constitutively over-expressed (COE) were constructed through genetic transformation. The resulting\\u000a transformants were stable and showed patterns similar to the wild-type (WT) strain with respect to

Jong-Min Baek; Charles R. Howell; Charles M. Kenerley

1999-01-01

159

Isolation of mycoparasitic-related transcripts by SSH during interaction of the mycoparasite Stachybotrys elegans with its host Rhizoctonia solani  

Microsoft Academic Search

Mycoparasitism by antagonistic fungi involves changes in the biochemistry and physiology of both partners. Analysis of genes\\u000a that are expressed during mycoparasite–host interaction represents a powerful strategy to obtain insight into the molecular\\u000a events underlying these changes. The aim of this study is to identify genes whose expression is upregulated when the mycoparasite\\u000a Stachybotrys elegans is in direct confrontation with

Danielle C. Morissette; Amélie Dauch; Robin Beech; Luke Masson; Roland Brousseau; Suha Jabaji-Hare

2008-01-01

160

Evaluation of fluorescent pseudomonads for plant growth promotion, antifungal activity against Rhizoctonia solani on common bean, and biocontrol potential  

Microsoft Academic Search

Fluorescent pseudomonads are ubiquitous bacteria that are common inhabitants of the rhizosphere and are the most studied group within the genus Pseudomonas. Bacterial isolates (n=103) from the rhizosphere of wheat and common bean were assessed as potential biocontrol agents in this study. Fungal inhibition tests were performed by a plate assay in which each isolate was tested directly for the

Masoud Ahmadzadeh; Abbas Sharifi Tehrani

2009-01-01

161

Transgenic indica rice expressing a bitter melon ( Momordica charantia ) class I chitinase gene ( McCHIT1 ) confers enhanced resistance to Magnaporthe grisea and Rhizoctonia solani  

Microsoft Academic Search

McCHIT1 chitinase (DQ407723), a class I secretory endochitinase from bitter melon (Momordica charantia), had been demonstrated to enhance resistance against Phytophthora nicotianae and Verticillium wilt in transgenic tobacco and cotton. In order to obtain disease-resistant transgenic rice, McCHIT1 was transformed into a restorer line JinHui35 (Oryza sativa subsp. indica) by using the herbicide-resistance gene Bar as the selection marker. Transgenic

Ping Li; Yan Pei; Xianchun Sang; Yinghua Ling; Zhenglin Yang; Guanghua He

2009-01-01

162

Effects of soil pH on rhizoctonia damping-off of sugar beet and disease suppression induced by soil amendment with crop residues  

Microsoft Academic Search

Effects of soil pH on damping-off of sugar beet by R. solani (AG2-2) and soil suppressiveness against the disease were studied by comparing disease incidences in pasteurized versus non-pasteurized,\\u000a infested soils. Soil pH was correlated neither to disease incidence in five soils ranging from pH 4.5 to 7.2 nor to indigenous\\u000a disease suppressiveness, the difference in disease incidences between non-treated soil

Kaori Watanabe; Mariko Matsui; Hitoshi Honjo; J. Ole Becker; Ryo Fukui

163

Distribution And Efficacy Of Drip-Applied Metam-Sodium Against The Survival Of Rhizoctonia Solani And Yellow Nutsedge In Plastic-Mulched Sandy Soil Beds  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of metam-sodium application rate on soil residence time, spatial and temporal distributions of methyl isothiocyanate and pest control efficacy were studied in a Georgia sandy soil. Metam-sodium 420 gL-1 SL was drip applied at rates of 147 and 295Lha-1 in plastic-mulched raised beds. Meth...

164

CONTROLLING RHIZOCTONIA ROOT ROT IN SPRING BARLEY WITH IN-FURROW APPLICATION OF QUADRIS PLUS SEED TREATMENT WITH DYNASTY AND DIVIDEND EXTREME, 2003.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Treatment with Nitropak alone or Quadris alone (4 fl oz/A) significantly increased barley yields. A T-test comparison of the control and Dynasty (0.16 fl oz/A) treatment was significant at P=0.086. When the Quadris-only treatments were analyzed separately, the effect of Quadris was significant at P...

165

Cloning of a chitinase-like cDNA ( hs2), its transfer to creeping bentgrass ( Agrostis palustris Huds.) and development of brown patch ( Rhizoctonia solani) disease resistant transgenic lines  

Microsoft Academic Search

We isolated a cDNA clone (hs2) encoding a chitinase-like protein from a triploid Dutch elm disease resistant American elm (Ulmus americana NPS-3-487). Amino acid sequence of this chitinase-like protein showed 65–78% homology to other plant chitinases. A plasmid KYLX71-pHS2 was constructed using the hs2 sequence under the control of cauliflower mosaic virus 35S promoter and nos terminator. This construct was

Benli Chai; Shahina B Maqbool; Ravindra K Hajela; David Green; Joseph M Vargas; Donald Warkentin; Robab Sabzikar; Mariam B Sticklen

2002-01-01

166

IDENTIFICATION OF PYTHIUM SPECIES ON WEST TEXAS PEANUTS AND SENSITIVITY OF ISOLATES TO MEFENOXAM AND AZOXYSTROBIN IN PETRI DISH ASSAYS.  

Technology Transfer Automated Retrieval System (TEKTRAN)

A survey was conducted in 107 peanut fields to determine the incidence of Rhizoctonia or Pythium pod rot. Rhizoctonia solani and Pythium spp. were isolated from rotted pods in 35 and 39% of the fields, respectively. Isolates of Pythium were collected and some were identified to species. The three...

167

Fungicidal activity of 2?[2?(arylthio)ethyl] pyrrolidine derivatives  

Microsoft Academic Search

Nineteen new compounds from the title group were prepared and their fungicidal activity was investigated. One compound showed moderate activity against Rhizoctonia solani, Fusarium culmorum and Aspergillus niger in the agar plate test. Two others were moderately active against Botrytis cinerea in the slide germination test and moderately or slightly active against Rhizoctonia solani in the agar plate test. All

J. Kaszubska; S. Bal; Z. Ziminska

1983-01-01

168

Controlling Soilborne Pathogens in Wheat Production Systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Pacific Northwest (PNW) wheat, barley, legume and canola varieties are susceptible to broad host-range soilborne pathogens that cause Rhizoctonia root rot and Pythium root rot. Controlling Rhizoctonia and Pythium will likely require multiple strategies. My laboratory focuses on three research areas:...

169

Cover: journal of basic microbiology. 8/2013.  

PubMed

Cover illustration: The antibiotics produced by a biocontrol agent Bacillus pumilus SQR-N43 induced hyphal deformation and enlargement of cytoplasmic vacuoles in Rhizoctonia solani Q1 mycelium. (Photo: Xinqi Huang, Nanjing, China). PMID:23943200

2013-08-01

170

Suppression of phytopathogenic fungi by hexane extract of Nepenthes ventricosa x maxima leaf.  

PubMed

The hexane extract of Nepenthes ventricosa x maxima leaf exhibited antifungal activity against Alternaria alternata, Aspergillus niger, Bipolaris oryzae, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani, Rhizopus stolonifer var. stolonifer and Sclerotinia sclerotiorum. PMID:17573203

Shin, Kwang-Soo; Lee, Samkeun; Cha, Byeong Jin

2007-05-24

171

WHEAT RHIZOSPHERE-MICROBE INTERACTIONS--FACTORS AND GENES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Host genes are likely to have important roles in interactions with both root pathogens and beneficial soil microbes that suppress such pathogens. Triticum aestivum (hexaploid wheat) has limited genetic resistance to the necrotrophic fungal pathogens Pythium, Rhizoctonia, Gaeumannomyces, and Fusarium...

172

Cloning, Sequencing, and Characterization of the Genetic Region Relevant to Biosynthesis of the Lipopeptides Iturin A and Surfactin in Bacillus subtilis  

Microsoft Academic Search

Bacillus subtilis B3 was found to produce lipopeptides iturins and fengycin that have activity against several plant pathogens such as Fusarium graminearum, Rhizoctonia solani, Rhizoctonia cerealis, and Pyricularia grisea. A 3642-bp genomic region of B. subtilis B3 comprising srfDB3, aspB3, lpaB3, and yczEB3 genes that resulted in biosynthesis of surfactin in B. subtilis 168 was cloned, sequenced, and characterized. Among

Shiyi Yao; Xuewen Gao; Norbert Fuchsbauer; Wolfgang Hillen; Joachim Vater; Jinsheng Wang

2003-01-01

173

A New Operation for Producing Disease-Suppressive Compost from Grass Clippings  

Microsoft Academic Search

This study evaluated the use of grass clippings discharged from golf courses as the raw material for production of a suppressive compost to control Rhizoctonia large-patch disease in mascarene grass. Bacillus subtilis N4, a mesophilic bacterium with suppressive effects on the pathogenic fungus Rhizoctonia solani AG2-2, was used as an inoculum in a procedure developed with the aim of controlling

KIYOHIKO NAKASAKI; SACHIKO HIRAOKA; HIROYUKI NAGATA

1998-01-01

174

Sterol-inhibiting fungicide impacts on soil microbial ecology in Atlantic Coastal Plain soils  

Microsoft Academic Search

Seventy-five percent of the peanuts (Arachus hypogaia) produced in the United States are grown in the Atlantic Coastal Plain region. Portions of this area, including Alabama and Georgia, exhibit a subtropical climate that promotes soil-borne plant fungal diseases. Most fields receive repeated fungicide applications during the growing season to suppress the disease causing organisms, such as Sclerotium rolfsii, Rhizoctonia solani,

P. M. White; T. L. Potter; T. C. Strickland

2008-01-01

175

Stimulation of nodulation and plant growth of chickpea ( Cicer arietinum L . ) by Pseudomonas spp. antagonistic to fungal pathogens  

Microsoft Academic Search

Two strains of Pseudomonas MRS23 and CRP55b showed antagonistic activity towards the pathogenic fungi Aspergillus sp., Fusarium oxysporum f. sp. ciceri, Pythium aphanidermatum and Rhizoctonia solani under culture conditions. Larger growth inhibition zones were obtained on nutrient agar (NA) and King's B media in comparison to potato dextrose agar and pigment production media. Both the strains produced siderophore in agar

A. K. Goel; S. S. Sindhu; K. R. Dadarwal

2002-01-01

176

Antifungal properties of essential oils from Thai medical plants against rice pathogenic fungi  

Microsoft Academic Search

This in vitro study was aimed to evaluate the mycelium growth and spore germination inhibition properties of essential oils. Two Thai medicinal plants; Frankincense oil (Boswellia carteri Bird.) and Cassia oil (Acacia farnesiana Linn) were applied against 7 species of economically important rice pathogenic fungi; Alternaria brassicicola, Aspergillus flavus, Bipolaris oryzae, Fusarium moniliforme, Fusarium proliferatum, Pyricularia arisea and Rhizoctonia solani.

Apinya Piyo; Pitipong Thobunluepop

177

Mungin, a Novel Cyclophilin-like Antifungal Protein from the Mung Bean  

Microsoft Academic Search

A protein designated mungin, isolated from mung bean (Phaseolus mungo) seeds, possessed activity against the fungi Rhizoctonia solani, Coprinus comatus, Mycosphaerella arachidicola, Botrytis cinerea, and Fusarium oxysporum. The 18-kDa protein also possessed a novel N-terminal sequence with similarity to cyclophilins. It exerts an inhibitory action against ?- and ?-glucosidases suppresses [3H]thymidine in corporation by mouse splenocytes.

X. Y. Ye; T. B. Ng

2000-01-01

178

Effect of Soluble Silica on Brown Patch and Dollar Spot of Creeping Bentgrass  

Microsoft Academic Search

Disease pressure on cool season turfgrasses is very high in the transition zone due to the heat and humidity of prolonged summers. Creeping bentgrass (Agrostis stolonifera L.) is susceptible to both brown patch (Rhizoctonia solani Kuhn) and dollar spot (Sclerotinia homoeocarpa F.T. Bennett) fungi. The objective of this study was to assess the potential of soluble silica for reducing the

Ricardo F. Uriarte; H. David Shew; Daniel C. Bowman

2005-01-01

179

Biological Control of Fusarium Wilt on Cotton by Use of Endophytic Bacteria  

Microsoft Academic Search

One hundred seventy bacterial strains isolated from internal tissues of cotton, 49 strains with known biological control activity against Rhizoctonia solani in cotton, and 25 strains known to induce systemic resistance to Collectotrichum orbiculare in cucumber, were screened for biological control potential against vascular wilt of cotton caused by Fusarium oxysporum f. sp. vasinfectum. The strains were introduced as endophytes

C. Chen; E. M. Bauske; G. Musson; R. Rodriguezkabana; J. W. Kloepper

1995-01-01

180

Rhizocticin A, an antifungal phosphono-oligopeptide of Bacillus subtilis ATCC 6633: biological properties  

Microsoft Academic Search

Rhizocticin A, the main component of the antifungal, hydrophilic phosphono-oligopeptides of Bacillus subtilis ATCC 6633, was used for sensitivity testing and experiments into the molecular mechanism of the antibiotic action. Budding and filamentous fungi as well as the cultivated nematode Caenorhabditis elegans were found to be sensitive, whereas bacteria and the protozoon Paramecium caudatum were insensitive. Rhizoctonia solani was inhibited

Martin Kugler; Wolfgang Loeffler; Claudius Rapp; Armin Kern; Giinther Jung

1990-01-01

181

Brassica cover cropping for management of sheath blight of rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sheath blight, caused by Rhizoctonia solani, is the most important disease limiting rice production in Texas and other rice-producing states. The fungal pathogen survives between crops as soilborne sclerotia and mycelium in infected plant debris. These sclerotia and colonized plant debris float on t...

182

Pre-breeding for root rot resistance using root morphology and shoot length.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our goal is to identify new wheat varieties that display field resistance/tolerance to root rot diseases, such as those caused by Rhizoctonia and Pythium. We are tapping into the genetic diversity of ‘synthetic’ hexaploid wheats (genome composition AABBDD), which were generated at CIMMYT by artifici...

183

Evaluation of the USDA Rice Core Collection for sheath blight disease using micro-chamber  

Technology Transfer Automated Retrieval System (TEKTRAN)

The USDA rice core collection, including 1,794 accessions from 114 countries, was developed using a stratified random sampling method to represent the entire NSGC collection including over 18,000 accessions. Sheath blight (Rhizoctonia solani) is one of the most important and widely distributed disea...

184

Beauveria bassiana: Endophytic colonization and plant disease control  

Microsoft Academic Search

Seed application of Beauveria bassiana 11-98 resulted in endophytic colonization of tomato and cotton seedlings and protection against plant pathogenic Rhizoctonia solani and Pythium myriotylum. Both pathogens cause damping off of seedlings and root rot of older plants. The degree of disease control achieved depended upon the population density of B. bassiana conidia on seed. Using standard plating techniques onto

Bonnie H. Ownley; Mary R. Griffin; William E. Klingeman; Kimberly D. Gwinn; J. Kevin Moulton; Roberto M. Pereira

2008-01-01

185

DISEASE NURSERIES...A TOOL TO EVALUATE RESISTANCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

For over 45 years the USDA-ARS Sugar Beet Research Unit at Fort Collins, CO, has established disease nurseries to evaluate sugarbeet resistance to Cercospora Leaf Spot and Rhizoctonia Root Rot. These nurseries, designed to produce relatively uniform and severe disease pressure each year, are part o...

186

Antifungal activity of Bacillus sp. isolated from compost.  

PubMed

Four strains of Bacillus isolated from lupine compost exhibited an antifungal activity against six plant fungal pathogens (Rhizoctonia solani, Bipolaris sorokiniana, Sclerotinia sclerotiorum, Trichothecium roseum, Fusarium solani, Fusarium oxysporum). It was significantly influenced by the composition of the cultivation media. PMID:11501422

Czaczyk, K; Stachowiak, B; Trojanowska, K; Gulewicz, K

2000-01-01

187

Development and characterization of RiceCAP QTL mapping population for sheath blight resistance  

Technology Transfer Automated Retrieval System (TEKTRAN)

RiceCAP is a USDA CSREES funded project that has as one of its main objectives developing genetic markers associated with sheath blight resistance. Sheath blight, caused by Rhizoctonia solani, is an important disease of rice in the southern US. Tolerance to the disease is quantitatively inherited an...

188

Isolation and partial characterization of antifungal protein from Bacillus polymyxa strain VLB16  

Microsoft Academic Search

An antifungal protein produced by Bacillus polymyxa strain VLB16 has been purified to homogeneity by ammonium sulfate precipitation and Sephadex-G-200 column chromatography. The purified protein inhibited the growth of Pyricularia grisea and Rhizoctonia solani, the causative agents of rice blast and sheath blight diseases, respectively. Microscopy studies revealed that the antifungal protein caused severe alterations in cell morphogenesis that gave

Saravanakumar Kavitha; Sivanesan Senthilkumar; Samuel Gnanamanickam; Mohammed Inayathullah; Rajadas Jayakumar

2005-01-01

189

Control of sheath blight disease in rice by thermostable secondary metabolites of Trichothecium roseum MML003  

Microsoft Academic Search

The aim of the study is to investigate the biocontrol mechanisms of Trichothecium roseum MML003 against the rice sheath blight (ShB) pathogen, Rhizoctonia solani as the former exhibited strong antagonistic activity against the latter. It has been found that T. roseum MML003 did not show any hyperparasitic interaction against R. solani. Further, it did not produce siderophores and hydrogen cyanide.

M. Jayaprakashvel; M. Selvakumar; K. Srinivasan; S. Ramesh; N. Mathivanan

2010-01-01

190

Registration of four rice germplasm lines with improved resistance to sheath blight and blast diseases  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice sheath blight (ShB) and blast caused by the fungal pathogens Rhizoctonia solani and Magnaporthe oryzae, respectively, are the two most serious diseases of rice worldwide. Four rice (Oryza sativa L.) germplasm lines designated as LJRIL103 (PI 660982), LJRIL158 (PI 660983), LJRIL186 (PI 660984),...

191

Current progress on genetic interactions of rice with rice blast and sheath blight fungi  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of genetic interactions between rice and its pathogenic fungi Magnaporthe oryzae and Rhizoctonia solani should lead to a better understanding of molecular mechanisms of host resistance, and the improvement of strategies to manage rice blast and sheath blight diseases. Presently dozens of ri...

192

FIELD EVALUATION OF SEED TREATMENT FUNGICIDES FOR CONTROL OF ROOT ROT AND DAMPING-OFF ON CHICKPEA, 2003  

Technology Transfer Automated Retrieval System (TEKTRAN)

In order to improve control of chickpea root rot and damping-off caused by Fusarium and Rhizoctonia solani, six seed treatments were evaluated for their effectiveness on a farm near Waitsburg, WA. The six treatments were: standard treatment (Apron and Mertect), Maxim (standard treatment plus Maxim)...

193

COMBINING BIOLOGICAL PRODUCTS AND GREEN SPROUTING FOR CONTROL OF SOILBORNE DISEASES OF POTATO  

Technology Transfer Automated Retrieval System (TEKTRAN)

Commercially-available biocontrol products were evaluated, alone and in combination with green sprouting to promote early emergence, for efficacy in controlling Rhizoctonia and other soilborne potato diseases in field tests in Newport, Maine. Two bacterial formulations, Deny (Burkholderia cepacia J...

194

Biofumigation potential of brassicas  

Microsoft Academic Search

Isothiocyanates (ITCs) released from Brassica crops or seed meal amendments incorporated into soil have the potential to suppress pest and disease organisms in soil. We investigated in vitro toxicity of six ITCs to the mycelial growth of five cereal root pathogens (Gaeumannomyces graminis var. tritici, Rhizoctonia solani, Fusarium graminearum, Bipolaris sorokiniana, Pythium irregulare) by either adding them to the headspace

M. Sarwar; J. A. Kirkegaard; P. T. W. Wong; J. M. Desmarchelier

1998-01-01

195

7 CFR 51.1575 - U.S. Grade A Small; U.S. Grade A Medium; U.S. Grade A Medium to Large; U.S. Grade A Large.  

Code of Federal Regulations, 2010 CFR

...States Consumer Standards for Potatoes Grades § 51.1575 ...U.S. Grade A Large. Potatoes of each of these grades...discoloration, cuts, shriveling, sprouting, scab, dry rot, rhizoctonia...mechanical or other means. Potatoes of these grades shall...

2010-01-01

196

7 CFR 51.1575 - U.S. Grade A Small; U.S. Grade A Medium; U.S. Grade A Medium to Large; U.S. Grade A Large.  

Code of Federal Regulations, 2010 CFR

...States Consumer Standards for Potatoes Grades § 51.1575 ...U.S. Grade A Large. Potatoes of each of these grades...discoloration, cuts, shriveling, sprouting, scab, dry rot, rhizoctonia...mechanical or other means. Potatoes of these grades shall...

2009-01-01

197

Efficacy of bacillus biocontrol agents for management of sheath blight and narrow brown leaf spot in organic rice  

Technology Transfer Automated Retrieval System (TEKTRAN)

Organic rice production has significantly increased in the U. S. over the last decade. Growers lack effective tools to manage sheath blight, caused by Rhizoctonia solani, and narrow brown leaf spot (NBLS), caused by Cercospora janseana, two major diseases affecting organic rice production. An experi...

198

Scanning electron microscopic investigation of different types of necroses in potato tubers  

Microsoft Academic Search

SEM was used to follow some changes in potato tissue resulting from pathogen infection and differences between different types of necroses in cultivars: Irga, Kuba, Rosalind and Vineta. Irga showed superficial necrotic symptoms caused by Fusarium spp., Alternaria solani, Streptomyces scabies, Rhizoctonia spp., and Phytophthora infestans. Fungal necrosis caused strong disintegration of cell walls with cell lysis. Bacteria affected deep

W. B?aszczak; M. Chrzanowska; J. Fornal; E. Zimnoch-Guzowska; M. C. Palacios; J. Vacek

2005-01-01

199

A ROOT-KNOT NEMATODE PATHOGENIC TO COCK'S COMB, CELOSIA ARGENTEA L  

Microsoft Academic Search

The presence of root-knot nematode, Meloidogyne incognita was assessed on roots and rhizosphere soil of cock's comb (Celosia argentea L.) planted in 5 lawns located at the campus of University of Agriculture, Faisalabad. The infected plants were stunted with galled and rotted roots. Four fungal pathogens including Fusarium, Pythium, Rhizoctonia and Sclerotia were isolated from nematode-fungal complex infected roots. Plant

S. A. ANWAR; A. ZIA; Q. SHAKEEL

200

Genetic and physiological relatedness of antagonistic Trichoderma isolates against soil borne plant pathogenic fungi  

Microsoft Academic Search

In this study, the in vitro potential of 42 Trichoderma spp. were evaluated against four isolates of soil borne phytopathogenic fungi viz., Rhizoctonia solani, Macrophomina sp., Sclerotium rolfsii and Pythium aphanidermatum in dual culture techniques and through production of volatile and non-volatile inhibitors. In vitro screening results showed that the proportion of isolates with antagonistic activities was highest for the

Krishna Kumar; Natarajan Amaresan; Someshwar Bhagat; Kutthum Madhuri; Palaniswamy Udhayaraj; Ramesh Chandra Srivastava

2011-01-01

201

Efficacy of Different Natural Products as Safe Management of Guar Damping-off Disease in Egypt  

Microsoft Academic Search

usarium oxysporum Shelct., Macrophomina phaseolina (Tassi) Goid., Rhizoctonia solani Kühn and Sclerotium rolfsii Sacc. were isolated from infected roots and basal stem parts of guar plants collected from different localities in Egypt. R. solani and S. rolfsii were the most pathogenic fungi in pathogenicity trials, whereas M. phaseolina was the least. Topsin M and Vitavax\\/Thiram as well as clove essential

I. A. I. Mohamed; M. A. M. Bauiomy; A. S. A. Ibrahim

202

Mycoflora and Potential for Mycotoxin Production of Freshly Harvested Black Bean from the Argentinean Main Production Area  

Microsoft Academic Search

A mycological survey was carried out, for the first time, on black bean samples from the northwestern Argentinean province of Salta in the 1999 harvest season. Ten varieties of black beans were evaluated at three locations. Species of the genus Alternaria were the most prevalent component of the black bean mycoflora. Species of Fusarium, Sclerotinia, Rhizoctonia and Acremonium were also

M. D. Castillo; H. H. L. González; E. J. Martínez; A. M. Pacin; S. L. Resnik

2004-01-01

203

Seedling damping-off in sugar beet in Michigan  

Technology Transfer Automated Retrieval System (TEKTRAN)

A number of pathogens can cause early season stand loss in sugar beet. In an ongoing survey, the most commonly identified damping-off pathogens were Rhizoctonia solani, Aphanomyces cochlioides, and Fusarium species. Pythium and Phoma also were isolated every year, but never as the sole or most commo...

204

Genetic and genomic dissection of resistance genes to the rice sheath blight pathogen  

Technology Transfer Automated Retrieval System (TEKTRAN)

Rice sheath blight disease caused by the anastomosis group AG1-IA of the fungal pathogen Rhizoctonia solani is one of the most serious rice diseases in the southern US and the world. The use of fungicides is a popular but costly method to control this disease worldwide. Genetic analysis of host re...

205

Antifungal activity of tobacco osmotin has specificity and involves plasma membrane permeabilization  

Microsoft Academic Search

Osmotin protein is able to inhibit in vitro the growth of a number of unrelated pathogens. A survey of 31 isolates representing 18 fungal genera indicated that sensitivity may be determined at the genus level. Hyphal growth of Aspergillus flavus, Aspergillus parasitica, Rhizoctonia solani and Macrophomina phaseolina was highly resistant to osmotin whereas the growth of Bipolaris, Fusarium and Phytophthora

Laura R. Abad; Matilde Paino D'Urzo; Dong Liu; Meena L. Narasimhan; Moshe Reuveni; Jian Kang Zhu; Xiaomu Niu; Narendra K. Singh; Paul M. Hasegawa; Ray A. Bressan

1996-01-01

206

Production of Pseudomonas fluorescens P-5 and P-6 for Bean Damping-off Disease  

Microsoft Academic Search

Growth and efficacy of two biological control agents, Pseudomonas fluorescens Flügge, P-5 and P-6, were evaluated in combinations of two carbon (sucrose & molasses) and two nitrogen (urea & yeast extract) sources to optimize control of Rhizoctonia solani Kühn, which is a causal agent of bean damping-off. Both strains were grown in five liquid media including: sucrose + yeast extract,

SAMIRA PEIGHAMI-ASHNAEI; ABBAS SHARIFI-TEHRANI; MASOOD AHMADZADEH; KEIVAN BEHBOUDI

207

Use of biocontrol organisms and compost amendments for improved control of soilborne diseases and increased potato production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soilborne potato diseases are persistent problems in potato production and alternative management practices are needed. In this research, biocontrol agents (Bacillus subtilis GB03 and Rhizoctonia solani hypovirulent isolate Rhs1A1) and compost amendments (from different source material), were evalua...

208

Cutting propagation of azaleas using hot water treatments to control pathogens  

Technology Transfer Automated Retrieval System (TEKTRAN)

Azalea web blight, caused by certain binucleate species of Rhizoctonia, occurs yearly on some azalea cultivars during nursery production in the southern and eastern U.S. Azalea shoots collected for cutting propagation can harbor the pathogen, thus allowing the disease to be perpetuated during the cu...

209

Increases in snap bean and soybean seedling diseases associated with a chloride salt and changes in the micro-partitioning of tap root calcium  

Technology Transfer Automated Retrieval System (TEKTRAN)

In a series of field experiments from 1995 through 2010, the incidence of seedling diseases of snap bean and soybean caused by Rhizoctonia solani, Macrophomina phaseolina, Pythium spp., and Fusarium spp. was greater with an application of KCl than with K2SO4 applied at 93 kg K/ha. To determine if th...

210

Molecular Characterization of Pseudomonas aeruginosa UPM P3 from Oil Palm Rhizosphere  

Microsoft Academic Search

Problem statement: Pseudomonas aeruginosa has been used in agriculture as biological agents. It has shown substantial control of a varie ty of soil-borne plant pathogens including Macrophomina phaseolina , Botrytis cinerea , Rhizoctonia solani , Colletotrichum truncatum , Pythium , Fusarium and others. Species aggregate of Pseudomonas aeruginosa strain UPM P3 was shown to have potential as a biocontrol agent

Badri Fariman Azadeh; Sariah Meon

2009-01-01

211

BIOCONTROL AGENTS APPLIED INDIVIDUALLY AND IN COMBINATION FOR SUPPRESSION OF SOILBORNE DISEASES OF CUCUMBER  

Technology Transfer Automated Retrieval System (TEKTRAN)

The soilborne pathogens Rhizoctonia solani, Pythium ultimum, and Meloidogyne incognita can cause severe economic losses to field-grown and greenhouse-grown cucumber. A large collection of bacterial isolates and isolates GL3 and GL21 of Trichoderma virens were screened for suppression of diseases ca...

212

Calcium and temperature effects on seedling exudation and root rot infection of common bean on an acid sandy soil  

Microsoft Academic Search

Soil born fungi such as Phytium ultimum, Fusarium ssp., and Rhizoctonia solani (Kühn) severely restrict stand establishment of common bean (Phaseolus vulgaris L.) on acid soils of the Tropics. Calcium application is known to alleviate fungal infection in many legumes but the causes are still unclear. To investigate environmental factors and physiological mechanisms involved, growth chamber experiments were conducted with

A. Buerkert; H. Marschner

1992-01-01

213

DEVELOPMENT OF MOLECULAR STRATEGIES TO CONTROL RICE SHEATH BLIGHT DISEASE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Little is known about mechanisms of molecular interaction of host with the necrotrophic pathogen Rhizoctonia solani. After a detailed analysis of the pathogen population in the major rice producing state, Arkansas, the most virulent field isolate was identified among 124 characterized isolates. Th...

214

BIOLOGICAL CONTROL OF SUGAR BEET DAMPING-OFF WITH TRICHODERMA SPP.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Biological control of damping-off in sugar beet seedlings with Trichoderma species. Isolates of Trichoderma virens and other Trichoderma species are effective biocontrol agents for diseases of several crops. Control of damping-off caused by Rhizoctonia solani has been observed in a number of c...

215

Induction of defense responses in common bean plants by arbuscular mycorrhizal fungi.  

PubMed

Interaction between arbuscular mycorrhizal fungi as a bio-agent and Rhizoctonia root rot disease of common bean plant was investigated in this study under natural conditions in pot experiment. A mixture of Egyptian formulated AM (Multi-VAM) in suspension form (1 × 10(6) unit L(-1) in concentration) was used at dilution of 5 ml L(-1) water. The results demonstrated that colonization of bean plants with AM fungi significantly increased growth parameters, yield parameters and mineral nutrient concentrations and reduced the negative effects on these parameters as well as both disease severity and disease incidence. Different physical and biochemical mechanisms have been shown to play a role in enhancement of plant resistance against Rhizoctonia solani, namely, improved plant nutrition, improved plant growth, increase in cell wall thickening, cytoplasmic granulation, and accumulation of some antimicrobial substances (phenolic compounds and defense related enzymes). PMID:20630727

Abdel-Fattah, G M; El-Haddad, S A; Hafez, E E; Rashad, Y M

2010-07-13

216

Synthesis of nalidixic acid based hydrazones as novel pesticides.  

PubMed

Thirty-one substituted hydrazones of nalidixic acid hydrazide were synthesized and characterized by spectral techniques. These compounds were evaluated for various biological activities, namely, fungicidal, insecticidal, and nitrification inhibitory activities. The antifungal activity was evaluated against five pathogenic fungi, namely, Rhizoctonia bataticola , Sclerotium rolfsii , Rhizoctonia solani , Fusarium oxysporum , and Alternaria porii . They showed maximum inihibition against A. porii with ED(50) = 34.2-151.3 microg/mL. The activity was comparable to that of a commercial fungicide, hexaconazole (ED(50) = 25.4 microg/mL). They were also screened for insecticidal activity against third-instar larvae of Spodoptera litura and adults of Callosobruchus maculatus and Tribollium castaneum . Most of them showed 70-100% mortality against S. litura through feeding method at 0.1% dose. These compounds were not found to be effective nitrification inhibitors. PMID:20131903

Aggarwal, Nisha; Kumar, Rajesh; Srivastva, Chitra; Dureja, Prem; Khurana, J M

2010-03-10

217

Induction of DIMBOA accumulation and systemic defense responses as a mechanism of enhanced resistance of mycorrhizal corn ( Zea mays L.) to sheath blight  

Microsoft Academic Search

Arbuscular mycorrhizas are the most important symbioses in terrestrial ecosystems and they enhance the plant defense against\\u000a numerous soil-borne pathogenic fungi and nematodes. Two corn (Zea mays) varieties, Gaoyou-115 that is susceptible to sheath blight disease caused by Rhizoctonia solani and Yuenong-9 that is resistant, were used for mycorrhizal inoculation in this study. Pre-inoculation of susceptible Gaoyou-115\\u000a with arbuscular mycorrhizal

Yuan Yuan Song; Man Cao; Li Jun Xie; Xiao Ting Liang; Ren Sen Zeng; Yi Juan Su; Jing Hua Huang; Rui Long Wang; Shi Ming Luo

218

Zur Bedeutung von Wurzelausscheidungen verschiedener Kulturpflanzen für das Auftreten der Tomaten-Umfallkrankheit und der Zwiebelwelke  

Microsoft Academic Search

Root exudates of wheat, sorghum and maize reduced growth ofRhizoctonia solani andFusarium oxysporum f. sp.cepae and increased growth ofBacillus subtilis in vitro. Analysis of these exudates showed that they were variable in their composition of sugars and amino acids. Growth of the tested microorganisms increased as the glucose content of the medium increased up to 3% for the bacterium and

M. S. Mohamed; M. A. Sellam; A. Abd-Elrazik; M. H. Rushdi

1983-01-01

219

Suppression of soil-borne plant diseases with composts: A review  

Microsoft Academic Search

Numerous container-based studies in greenhouses or growth rooms have consistently demonstrated a suppressive effect of composts on soil-borne diseases such as damping-off and root rots (Pythium ultimum, Rhizoctonia solani, Phytophthora spp.), and wilts (Fusarium oxysporum and Verticillium dahliae). Composts have also been shown to suppress several diseases in the field, although the effects have been generally smaller and more variable

R. Noble; E. Coventry

2005-01-01

220

Mitigation of growth retardation effect of plant defense activator, acibenzolar- S -methyl, in amaranthus plants by plant growth-promoting rhizobacteria  

Microsoft Academic Search

Four rhizobacterial strains and acibenzolar-S-methyl (ASM), a chemical activator, which suppressed foliar blight of amaranthus (Amaranthus tricolor L.) caused by Rhizoctonia solani K?hn were evaluated for their effect on plant growth. The experiments were performed both under sterile and non-sterile soil\\u000a conditions, in the presence or absence of the pathogen. In all cases, plants treated with ASM showed significant reduction

Chitra B. Nair; K. N. Anith; Janardhanan Sreekumar

2007-01-01

221

Effect of solarization of soil within plastic bags on root rot of gerbera ( Gerbera jamesonii L.)  

Microsoft Academic Search

Solarization of soil, (potting mix = coarse sand:Eucalyptus marginata fines = 1?1) infested with 3 fungi pathogenic to gerbera (Phytophthora cryptogea, Fusarium oxysporum andRhizoctonia solani), for 3 to 4 weeks within transparent polyethylene bags controlled root rot of gerbera. Solarization for 2 weeks however,\\u000a was less effective. All plants grown in the infested potting mix which had been kept in

W. Kaewruang; K. Sivasithamparam; G. E. Hardy

1989-01-01

222

Thaumatin gene confers resistance to fungal pathogens as well as tolerance to abiotic stresses in transgenic tobacco plants  

Microsoft Academic Search

We report here the development of transgenic tobacco plants with thaumatin gene of Thaumatococcus daniellii under the control of a strong constitutive promoter-CaMV 35S. Both polymerase chain reaction and genomic Southern analysis\\u000a confirmed the integration of transgene. Transgenic plants exhibited enhanced resistance with delayed disease symptoms against\\u000a fungal diseases caused by Pythium aphanidermatum and Rhizoctonia solani. The leaf extract from

M. V. Rajam; N. Chandola; P. Saiprasad Goud; D. Singh; V. Kashyap; M. L. Choudhary; D. Sihachakr

2007-01-01

223

Effect of acetic acid fumigation on soil-borne fungi and cucumber root rot disease under greenhouse conditions  

Microsoft Academic Search

The effect of acetic acid vapour on soil-borne fungi and root rot disease of cucumber plants under greenhouse conditions was studied. Acetic acid vapour at four concentrations was tested against linear growth and spore germination of some soil-borne fungi, in vitro. The most sensitive fungus to acetic acid vapours was Rhizoctonia solani which inhibited at 4 µl l, while Fusarium solani,

Farid Abd-El-Kareem

2009-01-01

224

In vitro fungitoxicity of the essential oil of Syzygium aromaticum  

Microsoft Academic Search

The in vitro antifungal activity of clove oil was studied against four test fungi namely Alternaria alternata, Fusarium chlamydosporum, Helminthosporum oryzae and Rhizoctonia bataticola by the agar well diffusion method. These test fungi were found to be highly sensitive to clove oil at a concentration of\\u000a 100 ?l\\/well. The inhibition zone diameter was found to be in the range of

Arina Zafar Beg; Iqbal Ahmad

2002-01-01

225

Screening of potential bacterial antagonists for control of sheath blight in rice and development of suitable bacterial formulations for effective application  

Microsoft Academic Search

Soil samples were taken from paddy rice fields in 14 provinces in the southern part of Thailand. Bacteria were isolated from\\u000a these soils using the soil dilution plate method on King’s B medium and Thornton’s standardised medium. Isolation yielded\\u000a 323 bacterial isolates which were subsequently tested for their effectiveness in inhibiting mycelial growth of Rhizoctonia solani, the causal agent of

Mana Kanjanamaneesathian; Chirasak Kusonwiriyawong; Ashara Pengnoo; Ladda Nilratana

1998-01-01

226

Brassica juncea seed meal particle size influences chemistry but not soil biology-based suppression of individual agents inciting apple replant disease  

Microsoft Academic Search

Apple replant disease is incited by a pathogen complex composed of multiple fungal, oomycete and nematode species. Rhizoctonia solani AG-5 can be a significant component of this complex and is effectively suppressed via multiple functional mechanisms in response\\u000a to Brassica juncea seed meal (SM) amendment. These mechanisms include those of both a biological and chemical nature. The effect of seed

Mark Mazzola; Xiaowen Zhao

2010-01-01

227

Improved biocontrol activity of Trichoderma harzianum by over-expression of the proteinase-encoding gene prb1  

Microsoft Academic Search

Transformation systems developed for Trichoderma spp. were utilized to improve the biocontrol efficiency of the mycoparasitic fungus Trichoderma harzianum by increasing the copy number of the basic proteinase gene prb1. The transformants were stable and carried from two to ten copies of prb1. High levels of expression of prb1 during fungus-fungus interaction were detected when T. harzianum and Rhizoctonia solani

Alberto Flores; Ilan Chet; Alfredo Herrera-Estrella

1997-01-01

228

Plant defense activation and management of tomato root rot by a chitin-fortified Trichoderma\\/Hypocrea formulation  

Microsoft Academic Search

Tomato root rot caused by Rhizoctonia solani is a major soilborne disease resulting in significant yield loss. The culture filtrates of six isolates of Trichoderma\\/Hypocrea species were evaluated for in vitro production of hydrolytic enzymes. Results demonstrated that all the six isolates were able to produce chitinase, ?-1, 3 glucanase\\u000a and protease in the range of 76–235 ?mol GlcNAc min-1 mg-1

Manoj Kumar Solanki; Nidhi Singh; Rajesh Kumar Singh; Pratiksha Singh; Alok K. Srivastava; Sudheer Kumar; Prem L. Kashyap; Dilip K. Arora

229

Evaluation of soil solar heating for control of damping-off fungi in two forest nurseries in France  

Microsoft Academic Search

Field experiments were carried out at two different forest nurseries during the summer of 1994 to examine the efficacy of\\u000a soil solarization for the control of damping-off. Both soils hosted Pythium spp., Fusarium spp. and Rhizoctonia solani as damping-off agents. Soil samples from solarized, steamed, fumigated and untreated plots were periodically collected and\\u000a assayed for soil infectivity. Solarization with a

B. Le Bihan; P. Camporota; M. L. Soulas; M. I. Salerno; R. Perrin

1997-01-01

230

Biological potantial of some Iranian Trichoderma isolates in the control of soil borne plant pathogenic fungi  

Microsoft Academic Search

In this study the in vitro potential of six selected Iranian isolates of three species of Trichoderma (Trichoderma hamatum T614, T. hamatum T612, Trichoderma harzianum T447, T. harzianum T969, Trichoderma virens T523 and Trichoderma sp. T) were evaluated against five isolates of soil borne phytopathogenic fungi (Fusarium graminearum, Rhizoctonia solani (AG4 and AG5), Macrophomina phaseoli and Phytophtora cacturum) in dual

Behzad Hajieghrari; Mousa Torabi-Giglou; Mohammad Reza Mohammadi

2008-01-01

231

Detoxification of substituted phenols by oxidoreductive enzymes through polymerization reactions  

Microsoft Academic Search

Laccases from the fungiRhizoctonia praticola andTrametes versicolor as well as horseradish peroxidase and tyrosinase were evaluated for their ability to polymerize phenolic contaminants. The removal of phenols through polymerization depended on the chemical structure and concentration of the substrate, pH of the reaction mixture, activity of the enzyme, length of incubation, and temperature. The enzymes retained their activity throughout a

J. Dec; J.-M. Bollag

1990-01-01

232

Microbial degradation of pendimethalin  

Microsoft Academic Search

Microbial degradation of pendimethalin (N?(l?Ethylpropyl)?3, 4?dimethyl?2, 6?dinitroaniline) in vitro was studied. Fusarium oxysporum and Paecilomyces varioti, two soil fungi, in culture media degraded pendimethalin to two metabolites namely N?(1?Ethylpro?pyl)?3, 4?dimethyl?2?nitrobenzene?l, 6?diamine (II) and 3, 4?Dimethyl?2, 6?dinitroaniline (IV). Rhizoctonia bataticola, another soil fungus, decomposed pendimethalin yielding only the latter metabolite (IV). Fungal decomposition of pendimethalin involved nitro reduction and dealkylation.

S. B. Singh; G. Kulshrestha

1991-01-01

233

Superoxide radical induces sclerotial differentiation in filamentous phytopathogenic fungi: a superoxide dismutase mimetics study.  

PubMed

This study shows that the superoxide radical (O(2) *( -)), a direct indicator of oxidative stress, is involved in the differentiation of the phytopathogenic filamentous fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii and Sclerotinia minor, shown by using superoxide dismutase (SOD) mimetics to decrease their sclerotial differentiation. The production rate of O(2) *(-) and SOD levels in these fungi, as expected, were significantly lowered by the SOD mimetics, with concomitant decrease of the indirect indicator of oxidative stress, lipid peroxidation. PMID:20007647

Papapostolou, Ioannis; Georgiou, Christos D

2009-12-10

234

Interactions between the arbuscular mycorrhizal fungus Glomus mosseae and plant growth-promoting fungi and their significance for enhancing plant growth and suppressing damping-off of cucumber ( Cucumis sativus L.)  

Microsoft Academic Search

This study investigated the interactions between the arbuscular mycorrhizal fungus (AMF) Glomus mosseae and the plant growth-promoting fungi (PGPF) Penicillium simplicissimum GP17-2 and Trichoderma harzianum GT3-2 in relation to their colonization of roots and the rhizosphere of cucumber (Cucumis sativus L.), and their effect on plant growth and suppression of the damping-off pathogen Rhizoctonia solani. Combined inoculation of T. harzianum

W. A. Chandanie; M. Kubota; M. Hyakumachi

2009-01-01

235

Secondary Metabolite and Endochitinase-Dependent Antagonism toward Plant-Pathogenic Microfungi of Pseudomonas fluorescens Isolates from Sugar Beet Rhizosphere  

Microsoft Academic Search

Forty-seven isolates representing all biovars of Pseudomonas fluorescens (biovars I to VI) were collected from the rhizosphere of field-grown sugar beet plants to select candidate strains for biological control of preemer- gence damping-off disease. The isolates were tested for in vitro antagonism toward the plant-pathogenic microfungi Pythium ultimum and Rhizoctonia solani in three different plate test media. Mechanisms of fungal

METTE NEIENDAM NIELSEN; JAN SØRENSEN; JOHANNES FELS; HANS CHRISTIAN; Novo Nordisk

1998-01-01

236

Molecular cloning, characterization, and expression of a cDNA encoding an endochitinase gene from the mycoparasite Stachybotrys elegans  

Microsoft Academic Search

Stachybotrys elegans is a mycoparasite of the soilborne plant pathogenic fungus Rhizoctonia solani. The mycoparasitic activity of S. elegans is correlated with the production of cell wall degrading enzymes such as chitinases. This report details the cloning by RACE-PCR and characterization of a full-length cDNA clone, sechi44, that appears to encode an extracellular endochitinase. An analysis of the sechi44 sequence

Danielle C. Morissette; Brian T. Driscoll; Suha Jabaji-Hare

2003-01-01

237

Isolation and In Vivo and In Vitro Antifungal Activity of Phenylacetic Acid and Sodium Phenylacetate from Streptomyces humidus  

Microsoft Academic Search

The antifungal substances SH-1 and SH-2 were isolated from Streptomyces humidus strain S5-55 cultures by various purification procedures and identified as phenylacetic acid and sodium phenylacetate, respectively, based on the nuclear magnetic resonance, electron ionization mass spectral, and inductively coupled plasma mass spectral data. SH-1 and SH-2 completely inhibited the growth of Pythium ultimum, Phytophthora capsici, Rhizoctonia solani, Saccharomyces cerevisiae,

BYUNG KOOK HWANG; SONG WON LIM; BEOM SEOK KIM; JUNG YEOP LEE; S. S. Moon

2001-01-01

238

Effects of soil fumigation on verticillium wilt, nematodes and other diseases of potato roots and tubers  

Microsoft Academic Search

Summary  Fumigation of soil was shown to affect subsequent potato crops by several different mechanisms.Rhizoctonia on roots and as black scurf on tubers,Verticillium wilt, pink eye of tubers, vascular browning in tubers, weeds and nematodes are involved. During the relatively dry years\\u000a herein reported, fumigation gave a maximum yield increase of about 20%. Of the fumigants tested, Vorlex was the most

P. M. Miller; L. V. Edgington; Arthur Hawkins

1967-01-01

239

Detection and identification of fluorescent compounds in potato tuber tissue with corky patch syndrome  

Microsoft Academic Search

A corky patch syndrome that effects potato tuber tissue may be a later manifestation of pink eye disease of potato although\\u000a an actual cause and effect relationship between the two diseases has not been firmly established. The causal agent for pink\\u000a eye of potato is unknown but the disease has been associated with the fungiVerticillium andRhizoctonia and the bacteriumPseudomonas fluorescens.

P. Nolte; G. A. Secor; N. C. Gudmestad; P. J. Henningson

1993-01-01

240

Immunology of the pathogen virulence and phytotoxin production in relation to disease severity: a case study in sheath blight of rice  

Microsoft Academic Search

Polyclonal antibodies against purifiedRhizoctonia solani toxin obtained from infected rice sheath tissues (sheath blight toxin, SBT) and culture filtrates (culture filtrate toxin,\\u000a CFT) were developed in rabbit and chicken. The IgG was isolated from serum and egg yolk of rabbit and chicken, respectively,\\u000a and their specificity was investigated by indirect ELISA. Antibodies developed against CFT and SBT in rabbits exhibited

V. Shanmugam; R. Viswanathan; T. Raguchander; P. Balasubramanian; R. Samiyappan

2002-01-01

241

Pythium irregulare can cause root rot of Platysace lanceolata  

Microsoft Academic Search

Cultivated Platysace lanceolata cv. Valentine Lace plants in south-east Queensland are affected by root rot that reduces shoot growth and flower production,\\u000a and leads to plant death. Pythium irregulare, Rhizoctonia solani and Cylindrocarpon lichenicola were isolated from diseased roots using selective media and their pathogenicities tested under glasshouse conditions. Parameters\\u000a used to assess disease severity included the proportion of the

J. R. Conway; D. C. Joyce; V. J. Galea; A. H. Wearing

2009-01-01

242

Influence of silicon on sheath blight of rice in Brazil  

Microsoft Academic Search

The effect of silicon (Si) on sheath blight (Rhizoctonia solani Kühn) of rice was studied under greenhouse conditions. The predominant commercial rice cultivars ‘BR-IRGA 409’, ‘Metica-1’, ‘EPAGRI-109’, ‘Rio Formoso’, ‘Javaé’, and ‘CICA-8’, were grown in pots containing low-Si soil amended with 0, 0.48, 0.96, 1.44 or 1.92g Si pot?1. Plants were inoculated at the maximum tillering stage. For all cultivars,

F. Á. Rodrigues; F. X. R. Vale; G. H. Korndörfer; A. S. Prabhu; L. E. Datnoff; A. M. A. Oliveira; L. Zambolim

2003-01-01

243

Reduced dosages of methyl bromide applied under gas-impermeable plastic films for controlling soilborne pathogens of vegetable crops  

Microsoft Academic Search

Four experimental trials were carried out at Albenga (Northern Italy) to evaluate the effectiveness of reduced dosages of methyl bromide (MB) applied under gas-impermeable films in controlling soilborne pathogens of vegetable crops. Forty and thirty g\\/m2 of MB applied under different types of gas-impermeable films controlled Rhizoctonia solani on bean, lettuce and basil, Fusarium oxysporum f. sp. basilici on basil

Andrea Minuto; Giovanna Gilardi; M. L. Gullino; Angelo Garibaldi

1999-01-01

244

Characterization of the anti-fungal activity of a Bacillus spp. associated with sclerotia from Sclerotinia sclerotiorum  

Microsoft Academic Search

Sclerotinia sclerotiorum fruiting bodies (sclerotia) were found to harbour bacteria that possess anti-fungal activity. Among 1,140 bacterial isolates collected, 32 were found to inhibit the growth of four common fungal pathogens of canola, S. sclerotiorum, Rhizoctonia solani, Alternaria brassicae and Leptosphaeria maculans. One of these broad-spectrum isolates, LEV-006, was found to be closely related to Bacillus subtilis based on 16S

Xingwei Hou; Susan M. Boyetchko; Myrtle Brkic; Doug Olson; Andrew Ross; Dwayne Hegedus

2006-01-01

245

Study of the antifungal activity of Acinetobacter baumannii LCH001 in vitro and identification of its antifungal components  

Microsoft Academic Search

An Acinetobacter strain, given the code name LCH001 and having the potential to be an endophytic antagonist, has been isolated from healthy\\u000a stems of the plant Cinnamomum camphora (L.) Presl, guided by an in vitro screening technique. The bacterium inhibited the growth of several phytopathogenic fungi\\u000a such as Cryphonectria parasitica, Glomerella glycines, Phytophthora capsici, Fusarium graminearum, Botrytis cinerea, and Rhizoctonia

C. H. Liu; X. Chen; T. T. Liu; B. Lian; Yucheng Gu; V. Caer; Y. R. Xue; B. T. Wang

2007-01-01

246

Chemical composition, antifungal and herbicidal effects of essential oil isolated from Chersodoma Argentina (Asteraceae).  

PubMed

Analysis of the hydrodistilled essential oil of the aerial parts of Chersodoma argentina Cabrera by GC-MS and NMR spectroscopy revealed that over 80% consisted of monoterpene hydrocarbons such as alpha-thujene, alpha-pinene and beta-pinene. Contact and headspace volatile exposure assays of the essential oil demonstrated antifungal activity against Sclerotinia sclerotiorum, Sclerotium rolfsii and Rhizoctonia solani with the contact assay showing greater activity than the headspace assay. Herbicidal activity was shown by reduced root growth of Allium porrum, Solanum lycopersicon and Sorghum halepense in both assays. PMID:22428265

Alarcón, Rosana; Ocampos, Soledad; Pacciaroni, Adriana; Sosa, Virginia

2012-01-01

247

Synthesis of novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones and evaluation of their biocidal effects.  

PubMed

Novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones have been synthesized in high yields by treatment of the corresponding oxo analogs with Lawesson's reagent. The structure has been confirmed by X-ray analysis. The compounds were tested for in vitro antifungal activity against Rhizoctonia bataticola, Sclerotium rolfsii, Fusarium oxysporum and Alternaria porii. The compounds exhibited moderate to good activity against all pathogens. Insecticidal activity of these compounds against Spodoptera litura was observed to be comparable to commercial pyrethroid insecticide, cypermethrin. The urease inhibitory activity has also been studied. PMID:23153816

Khurana, Jitender M; Magoo, Devanshi; Aggarwal, Komal; Aggarwal, Nisha; Kumar, Rajesh; Srivastava, Chitra

2012-10-25

248

Designing and Synthesis of Antifungal Active Macrocyclic Ligand and Its Complexes Derived from Diethylphthalate and Benzidine  

PubMed Central

Three novel complexes of Cu(II), Co(II) and Zn(II) using a macrocyclic ligand derived by the condensation of diethylphthalate and benzidine have been designed,synthesized and characterized by UV-Vis.,IR,Mass and Elemental analyses data in order to find out their antifungal activities. The stoichiometry of the complexes has been found to be 1 : 1 (Metal : Ligand). The analytical data indicate that the complexes exhibit square-planar geometry. The antifungal activity of the macrocyclic ligand and its metal complexes has been screened in vitro against fungi such as Aspergillus niger, A. flavus, Trichoderma harizanum, T. viridae and Rhizoctonia solani.

Parameswari, S.

2007-01-01

249

Phytophthora tropicalis on Hedera helix and Epipremnum aureum in Polish greenhouses.  

PubMed

Phytophthora tropicalis was isolated from Hedera helix and Epipremnum aureum showing discoloration of leaves, necrosis of shoot base, spread upwards and on roots. The species was detected from 7/8 plants of Hedera and 3/4 of Epipremnum. Additionally Botrytis cinerea, Fusarium avenaceum and Rhizoctonia solani were recovered from some of diseased plants. P. tropicalis caused leaf necrosis of 13 plant species and tomato seedlings. The quickest spread of necrosis was observed on leaves of Peperomia magnoliaefolia, Pelargonium zonale and Phalaenopsis x hybridum. The disease developed at temperature ranged from 10 degrees to 32.5 degrees C with optimum 30 degrees C. PMID:17390874

Orlikowski, L B; Trzewik, A; Wiejacha, K

2006-01-01

250

Cerinolactone, a hydroxy-lactone derivative from Trichoderma cerinum.  

PubMed

A novel metabolite, 3-hydroxy-5-(6-isopropyl-3-methylene-3,4,4a,5,6,7,8,8a-octahydronaphthalen-2-yl)dihydrofuran-2-one, trivially named cerinolactone (1), has been isolated from culture filtrates of Trichoderma cerinum together with three known butenolides containing the 3,4-dialkylfuran-2(5H)-one nucleus, harzianolide (2), T39butenolide (3), and dehydroharzianolide (4). The structure of 1 was determined by spectroscopic methods, including UV, MS, and 1D and 2D NMR analyses. In vitro tests with the purified compound exhibited activity against Pythium ultimum, Rhizoctonia solani, and Botrytis cinerea. PMID:22196692

Vinale, Francesco; Girona, Isabel Arjona; Nigro, Marco; Mazzei, Pierluigi; Piccolo, Alessandro; Ruocco, Michelina; Woo, Sheridan; Rosa, David Ruano; Herrera, Carlos López; Lorito, Matteo

2011-12-23

251

In Vivo Study of Trichoderma-Pathogen-Plant Interactions, Using Constitutive and Inducible Green Fluorescent Protein Reporter Systems  

PubMed Central

Plant tissue colonization by Trichoderma atroviride plays a critical role in the reduction of diseases caused by phytopathogenic fungi, but this process has not been thoroughly studied in situ. We monitored in situ interactions between gfp-tagged biocontrol strains of T. atroviride and soilborne plant pathogens that were grown in cocultures and on cucumber seeds by confocal scanning laser microscopy and fluorescence stereomicroscopy. Spores of T. atroviride adhered to Pythium ultimum mycelia in coculture experiments. In mycoparasitic interactions of T. atroviride with P. ultimum or Rhizoctonia solani, the mycoparasitic hyphae grew alongside the pathogen mycelia, and this was followed by coiling and formation of specialized structures similar to hooks, appressoria, and papillae. The morphological changes observed depended on the pathogen tested. Branching of T. atroviride mycelium appeared to be an active response to the presence of the pathogenic host. Mycoparasitism of P. ultimum by T. atroviride occurred on cucumber seed surfaces while the seeds were germinating. The interaction of these fungi on the cucumber seeds was similar to the interaction observed in coculture experiments. Green fluorescent protein expression under the control of host-inducible promoters was also studied. The induction of specific Trichoderma genes was monitored visually in cocultures, on plant surfaces, and in soil in the presence of colloidal chitin or Rhizoctonia by confocal microscopy and fluorescence stereomicroscopy. These tools allowed initiation of the mycoparasitic gene expression cascade to be monitored in vivo.

Lu, Zexun; Tombolini, Riccardo; Woo, Sheridan; Zeilinger, Susanne; Lorito, Matteo; Jansson, Janet K.

2004-01-01

252

Comparison of Pratylenchus penetrans Infection and Maladera castanea Feeding on Strawberry Root Rot.  

PubMed

The interaction of lesion nematodes, black root rot disease caused by Rhizoctonia fragariae, and root damage caused by feeding of the scarab larva, Maladera castanea, was determined in greenhouse studies. Averaged over all experiments after 12 weeks, root weight was reduced 13% by R. fragariae and 20% by M. castanea. The percentage of the root system affected by root rot was increased by inoculation with either R. fragariae (35% more disease) or P. penetrans (50% more disease) but was unaffected by M. castanea. Rhizoctonia fragariae was isolated from 9.2% of the root segments from plants not inoculated with R. fragariae. The percentage of R. fragariae-infected root segments was increased 3.6-fold by inoculation with R. fragariae on rye seeds. The presence of P. penetrans also increased R. fragariae root infection. The type of injury to root systems was important in determining whether roots were invaded by R. fragariae and increased the severity of black root rot. Pratylenchus penetrans increased R. fragariae infection and the severity of black root rot. Traumatic cutting action by Asiatic garden beetle did not increase root infection or root disease by R. fragariae. Both insects and diseases need to be managed to extend the productive life of perennial strawberry plantings. PMID:19262852

Lamondia, J A; Cowles, R S

2005-06-01

253

Morphological characteristics and pathogenicity of fungi associated with Roselle (Hibiscus Sabdariffa) diseases in Penang, Malaysia.  

PubMed

Roselle, or Jamaica sorrel (Hibiscus sabdariffa) is a popular vegetable in many tropical regions, cultivated for its leaves, seeds, stems and calyces which, the dried calyces are used to prepare tea, syrup, jams and jellies and as beverages. The main objectives of this study were to identify and characterise fungal pathogens associated with Roselle diseases based on their morphological and cultural characteristics and to determine the pathogenicity of four fungi infecting Roselle seedlings, namely Phoma exigua, Fusarium nygamai, Fusarium tgcq and Rhizoctonia solani in Penang. A total of 200 fungal isolates were obtained from 90 samples of symptomatic Roselle tissues. The isolates were identified based on cultural and morphological characteristics, as well as their pathogenicity. The fungal pathogen most frequently isolated was P. exigua (present in 45% of the samples), followed by F. nygamai (25%), Rhizoctonia solani (19%) and F. camptoceras (11%). Pathogenicity tests showed that P. exigua, F. nygamai, F. camptoceras and R. solani were able to infect both wounded and unwounded seedlings with different degrees of severity as indicated by the Disease severity (DS). R. solani was the most pathogenic fungus affecting both wounded and unwounded Roselle seedlings, followed by P. exigua that was highly pathogenic on wounded seedlings. F. nygamai was less pathogenic while the least pathogenic fungus was F. camptoceras, infecting only the unwounded seedlings but, surprisingly, not the wounded plants. PMID:21839160

Eslaminejad, Touba; Zakaria, Maziah

2011-08-03

254

Comparison of Pratylenchus penetrans Infection and Maladera castanea Feeding on Strawberry Root Rot  

PubMed Central

The interaction of lesion nematodes, black root rot disease caused by Rhizoctonia fragariae, and root damage caused by feeding of the scarab larva, Maladera castanea, was determined in greenhouse studies. Averaged over all experiments after 12 weeks, root weight was reduced 13% by R. fragariae and 20% by M. castanea. The percentage of the root system affected by root rot was increased by inoculation with either R. fragariae (35% more disease) or P. penetrans (50% more disease) but was unaffected by M. castanea. Rhizoctonia fragariae was isolated from 9.2% of the root segments from plants not inoculated with R. fragariae. The percentage of R. fragariae-infected root segments was increased 3.6-fold by inoculation with R. fragariae on rye seeds. The presence of P. penetrans also increased R. fragariae root infection. The type of injury to root systems was important in determining whether roots were invaded by R. fragariae and increased the severity of black root rot. Pratylenchus penetrans increased R. fragariae infection and the severity of black root rot. Traumatic cutting action by Asiatic garden beetle did not increase root infection or root disease by R. fragariae. Both insects and diseases need to be managed to extend the productive life of perennial strawberry plantings.

LaMondia, J. A.; Cowles, R. S.

2005-01-01

255

Fungi associated with the southern Eurasian orchid Spiranthes spiralis (L.) Chevall.  

PubMed

The hitherto unknown relationships between the European orchid Spiranthes spiralis (L.) Chevall and its internally associated fungi were explored by a combined approach involving microscopy-based investigations at a morpho-histological level as well as by molecular analyses of the identity of the eukaryotic endophytes present in the root tissue of the plant. We found that this orchid which is currently reported to have a vulnerable status in northern Italy, can host and interact with at least nine types of fungi. Some of these fungi show similarity to mycorrhizal genera found in orchids such as the Ceratobasidium-Rhizoctonia group. Other fungi found are from the genera Davidiella (Ascomycota), Leptosphaeria (Ascomycota), Alternaria (Ascomycota), and Malassezia (Basidiomycota), some of which until have not previously been reported to have an endophytic relationship with plants. The repeated occurrence of often pathogenic fungi such as Fusarium oxysporum, Bionectria ochroleuca, and Alternaria sp., within healthy specimens of this orchid suggests a tempered interaction with species that are sometimes deleterious to non-orchid plants. The fact is reminiscent of the symbiotic compromise established by orchids with fungi of the rhizoctonia group. PMID:22483052

Tondello, Alessandra; Vendramin, Elena; Villani, Mariacristina; Baldan, Barbara; Squartini, Andrea

2012-02-28

256

Purification and characterization of a novel antifungal protein from Bacillus subtilis strain B29*  

PubMed Central

An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatography on Bio-Gel® P-100. The protein was absorbed on DEAE-cellulose and Bio-Gel® P-100. The purified antifungal fraction was designated as B29I, with a molecular mass of 42.3 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), pI value 5.69 by isoelectric focusing (IEF)-PAGE, and 97.81% purity by high performance liquid chromatography (HPLC). B29I exhibited inhibitory activity on mycelial growth in Fusarium oxysporum, Rhizoctonia solani, Fusarium moniliforme, and Sclerotinia sclerotiorum. The 50% inhibitory concentrations (IC50) of its antifungal activity toward Fusarium oxysporum and Rhizoctonia solani were 45 and 112 ?mol/L, respectively. B29I also demonstrated an inhibitory effect on conidial spore germination of Fusarium oxysporum and suppression of germ-tube elongation, and induced distortion, tumescence, and rupture of a portion of the germinated spores.

Li, Jing; Yang, Qian; Zhao, Li-hua; Zhang, Shu-mei; Wang, Yu-xia; Zhao, Xiao-yu

2009-01-01

257

The post-harvest fruit rots of tomato (Lycopersicum esculentum) in Nigeria.  

PubMed

A survey of the post-harvest fruit rot diseases of tomato was conducted in five states of Nigeria. During severe infections, the diseases could cause 25% loss at harvest and 34% loss of the remaining product in transit, storage and market stalls; thus giving an overall loss of about 50% of the product. Two types of rots, soft and dry were recognised. The soft rot was found to account for about 85% and the dry rot about 15% of the overall loss. Erwinia carotovora, Rhizopus oryzae, R. stolonifer, Fusarium equiseti, F. nivale and F. oxysporum were established as the soft rot pathogens; while Aspergillus aculeatus, A. flavus, Cladosporium tenuissimum, Corynespora cassiicola, Curvularia lunata, Penicillium expansum P. multicolor and Rhizoctonia solani were established as the dry rot pathogens of tomato fruits in Nigeria. PMID:471028

Fajola, A O

1979-01-01

258

Synthesis and antimicrobical evaluation of a novel class of 1,3,4-thiadiazole: derivatives bearing 1,2,4-triazolo[1,5-a]pyrimidine moiety.  

PubMed

A series of novel 1,3,4-thiadiazole derivatives bearing 1,2,4-triazolo[1,5-a]pyrimidine moiety were synthesized by the method of splicing active substructures. Among these derivatives, compounds 12, 13, 15-22 and 24-31 were firstly reported. All the compounds were assayed for antimicrobial activities against five fungi strains and four bacteria strains. The preliminary results indicated that compounds 25 and 28-31 showed good antifungal activities against Physaclospora piricola and Rhizoctonia solani. Compound 26 exhibited good antifungal activities against Cercospora beticola and R. solani. Most of the compounds showed better antibacterial activities against Gram-negative bacteria strains than Gram-positive bacteria strains. Compounds 25 and 28 showed the best activities against Pseudomonas fluorescence while compounds 30-31 showed good activities against Escherichia coli. PMID:23644188

Luo, Yin; Zhang, Shuai; Liu, Zhi-Jun; Chen, Wu; Fu, Jie; Zeng, Qing-Fu; Zhu, Hai-Liang

2013-04-15

259

Synthesis and antifungal activity of 2-hydroxy-4,5-methylenedioxyaryl ketones as analogues of kakuol.  

PubMed

In a study aiming to determine the structural elements essential to the antifungal activity of kakuol, we synthesized a series of 2-hydroxy-4,5-methylenedioxyaryl ketones, and we assayed their in vitro antifungal activity. The most sensitive target organisms to the action of these class of compounds were Phytophthora infestans, Phytium ultimum, Cercospora beticola, Cladosporium cucumerinum, and Rhizoctonia solani. Most of the analogs showed a remarkable in vitro activity, and some of them appeared significantly more effective than the natural product. The biological activity was mainly affected by introducing structural modification on the carbonyl moiety of the natural-product molecule. In particular, compound 5a, bearing a C=C bond conjugated to the C=O group, was found active with a MIC value of 10 microg ml(-1) against Cladosporium cucumerinum. The results suggest that 2-hydroxy-4,5-methylenedioxyaryl ketones can be considered promising candidates in the development of new antifungal compounds. PMID:20397224

Musso, Loana; Dallavalle, Sabrina; Merlini, Lucio; Farina, Gandolfina

2010-04-01

260

Isolation of a New Mexican Strain of Bacillus subtilis with Antifungal and Antibacterial Activities  

PubMed Central

Although several strains of B. subtilis with antifungal activity have been isolated worldwide, to date there are no published reports regarding the isolation of a native B. subtilis strain from strawberry plants in Mexico. A native bacterium (Bacillus subtilis 21) demonstrated in vitro antagonistic activity against different plant pathogenic fungi. Under greenhouse conditions, it was shown that plants infected with Rhizoctonia solani and Fusarium verticillioides and treated with B. subtilis 21 produced augment in the number of leaves per plant and an increment in the length of healthy leaves in comparison with untreated plants. In addition, B. subtilis 21 showed activity against pathogenic bacteria. Secreted proteins by B. subtilis 21 were studied, detecting the presence of proteases and bacteriocin-like inhibitor substances that could be implicated in its antagonistic activity. Chitinases and zwittermicin production could not be detected. Then, B. subtilis 21 could potentially be used to control phytopathogenic fungi that infect strawberry plants.

Basurto-Cadena, M. G. L.; Vazquez-Arista, M.; Garcia-Jimenez, J.; Salcedo-Hernandez, R.; Bideshi, D. K.; Barboza-Corona, J. E.

2012-01-01

261

Spectral and thermal studies with anti-fungal aspects of some organotin(IV) complexes with nitrogen and sulphur donor ligands derived from 2-phenylethylamine  

NASA Astrophysics Data System (ADS)

Some complexes of 2-phenylethyl dithiocarbamate, thiohydrazides and thiodiamines with dibenzyltin(IV) chloride, tribenzyltin(IV) chloride and di( para-chlorobenzyl)tin(IV) dichloride have been synthesized and investigated in 1:2 and 1:1 molar ratio. The dithiocarbamate ligand act as monoanionic bidentate and thiohydrazide, thiodiamines act as neutral bidentate ligand. The synthesized complexes have been characterized by elemental analysis and molecular weight determination studies and their bonding pattern suggested on the basis of electronic, infrared, 1H and 13C NMR spectroscopy. Using thermogravimetric (TG) and differential thermal analysis (DTA) various thermodynamic and kinetic parameters viz. reaction order ( n), apparent activation energy ( Ea), apparent activation entropy ( S#) and heat of reaction (? H) have been calculated and correlated with the structural aspects for solid-state decomposition of complexes. The ligands and their tin complexes have also been screened for their fungitoxicity activity against Rhizoctonia solanii and Sclerotium rolfsii and their ED 50 values calculated.

Singh, Rajeev; Kaushik, N. K.

2008-11-01

262

Thiol redox state and related enzymes in sclerotium-forming filamentous phytopathogenic fungi.  

PubMed

Thiol redox state (TRS) reduced and oxidized components form profiles characteristic of each of the four main types of differentiation in the sclerotiogenic phytopathogenic fungi: loose, terminal, lateral-chained, and lateral-simple, represented by Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor, respectively. A common feature of these fungi is that as their undifferentiated mycelium enters the differentiated state, it is accompanied by a decrease in the low oxidative stress-associated total reduced thiols and/or by an increase of the high oxidative stress-associated total oxidized thiols either in the sclerotial mycelial substrate or in its corresponding sclerotium, indicating a relationship between TRS-related oxidative stress and sclerotial differentiation. Moreover, the four studied sclerotium types exhibit high activities of TRS-related antioxidant enzymes, indicating the existence of antioxidant protection of the hyphae of the sclerotium medulla until conditions become appropriate for sclerotium germination. PMID:18400483

Patsoukis, Nikolaos; Georgiou, D Christos

2007-11-01

263

Schiff bases as potential fungicides and nitrification inhibitors.  

PubMed

A number of substituted Schiff bases were synthesized and characterized by (1)H NMR and mass spectrometry. These compounds were screened for antifungal activity in vitro against pathogenic fungi, namely, Sclerotium rolfsii and Rhizoctonia bataticola, and for their effect on nitrification inhibition under laboratory conditions. Maximum antifungal activity was exhibited by (2,4-dichlorobenzylidene)-(2,4,5-trichlorophenyl)-amine and (3-nitrobenzylidene)-(2,4,5-trichlorophenyl)-amine against both fungi (ED(50) with range from 3 to 24 microg/mL). Maximum nitrification inhibition (NI) was exhibited by (2,4-dichlorobenzylidene)-(2-fluorophenyl)-amine, (4-fluorophenyl)-(3-nitrobenzylidene)-amine, (2,6-dichlorobenzylidene)-(4-fluorophenyl)-amine, and (2,6-dichlorobenzylidene)-(3 fluorophenyl)-amine (NI in the range 91-96%). PMID:19702271

Aggarwal, Nisha; Kumar, Rajesh; Dureja, Prem; Rawat, Diwan S

2009-09-23

264

The antifungal constituents from the seeds of Itoa orientalis.  

PubMed

Three new phenolic constituents, itolide A (1), itolide B (2), itoside P (3), and 1D-3-deoxy-3-hydroxymethyl-myo-inositol (4), which is described herein for the first time as a natural product, were isolated along with four other known compounds (5 to 8) from the methanol extract of the seeds of Itoa orientalis Hemsl by the activity-guided fractionation. Their structures were determined by spectroscopic means. Compounds 1 to 8 exhibited antifungal activities against Sclerotium rolfsii with IC?? values ranging from 60.12 to 240.00 ?M and against Rhizoctonia solani with IC?? values ranging from 45.34 to 233.14 ?M, respectively, and compounds 1, 2, 5 exhibited cytotoxic activity against Tn5B1-4 insect cell line with EC?? values of 203.68, 93.41 and 40.37 ?M, respectively. PMID:22233862

Tang, WenWei; Xu, HanHong; Zeng, DongQiang; Yu, LiJia

2011-12-30

265

A new furoquinoline alkaloid with antifungal activity from the leaves of Ruta chalepensis L.  

PubMed

Bioassay-guided separation with an eye toward antifungal activity led to the isolation of the new alkaloid 5-(1?,1?-dimethylallyl)-8-hydroxyfuro[2-3-b] quinoline (1) and the known biscoumarin daphnoretin (2) as the active constituents of the chloroform extract obtained from the leaves of Ruta chalepensis. The structures of the metabolites were elucidated on the basis of their spectral characteristics (NMR, UV, and MS) and were compared with the literature. The antifungal activity of the isolated compounds was evaluated against the phytopathogenic fungi Rhizoctonia solani, Sclerotium rolfsii, and Fusarium solani, which cause root-rot and wilt diseases in several economically important food crops such as potato, sugar beet, and tomato. PMID:22491304

Emam, A; Eweis, M; Elbadry, M

2010-12-01

266

[Studies on purification and properties of antagonistic protein from bacteria SS02 of Paenibacillus daejeonensis].  

PubMed

The antifungal, anti-bacterical, anti-brine shrimp activities of SD22 isolated from Paenibacillus daejeonensis Bacteria SS02 were studied. The separation steps included ultracentrifugation, ultrafiltration and (NH4)2SO4 fractional precipitation, further purification was performed by SephadexG-75 and DEAE-32 chromatography. Its molecular weight determined by SDS-PAGE was 56.0 kD and its isoelectfic point was 6.4. SD22 was thermostable to some extent and stable to ultraviolet, but sensitive to some of the enzyme. SD22 could kill most pathogens from propagation, such as Rhizoctonia cerealis, Sclerotinia sclerotiorum Physalospora piricala, Trichodema viride, Gliocladium viride, Curvularia leaf spot, Fusarium sp, Fusarium head blight, Beauveria Bassiana, Escherichia coli, Staphylococcus aureus, Bacillus subtilis , Candidal vaginitis, Fusarium oxysporum Schl. emend. Sayder & Hansem et al. The results will be helpful to find out a novel antifungal protein. PMID:17822044

Zhu, Kai; Zhang, Xiao-Yu; Ren, Zhi; Feng, Ding-Sheng; Wang, Yi-Ding

2007-07-01

267

[Effect of organic materials in controlling cucumber seedling diseases].  

PubMed

In this work, pot experiments with organic materials were carried out to study the alleviation of Fusarim wilt and Rhizictonia wilt of cucumber and the changes of soil microorganism. The results showed that rice straw, pig feces and wood chip could alleviate Fusarium wiltand Rhizoctonia wilt of cucumber, and the effect of rice strawwas most significant, followed by pig feces and wood chip. The amount of soil microbes was higher in organic materials treatments than in control. The total amount of actinomyces and epidhyte which can inhibit the growth of pathogen was the highest in rice straw treatment, followed by pig feces treatment. No significant change of soil microbial amount was found in wood chip treatment. PMID:15320412

Yuan, Fei; Peng, Yu; Zhang, Chunlan; Shen, Qirong

2004-05-01

268

Optimization for rapid synthesis of silver nanoparticles and its effect on phytopathogenic fungi  

NASA Astrophysics Data System (ADS)

In this present study, silver nanoparticles were synthesized by green chemistry approach using Acalypha indica leaf extract as reducing agents. The reaction medium employed in the synthesis process was optimized to attain better yield, controlled size and stability. Further, the biosynthesized silver nanoparticles were conformed through UV-vis spectrum, XRD and HR-TEM analyses. Different concentration of silver nanoparticles were tested to know the inhibitory effect of fungal plant pathogens namely Alternaria alternata, Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea and Curvularia lunata. Interestingly, 15 mg concentration of silver nanoparticles showed excellent inhibitory activity against all the tested pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

Krishnaraj, C.; Ramachandran, R.; Mohan, K.; Kalaichelvan, P. T.

269

Syntheses and biological activities of pyranyl-substituted cinnamates.  

PubMed

Twenty-two kinds of pyranyl-substituted cinnamates were synthesized by the reaction of 4-hydroxy-6-(2-phenylethyl)-2H-pyran-2-one or 4-hydroxy-6-methyl-2H-pyran-2-one (HMP) with a variety of substituted cinnamic acids, and their antifungal and plant growth inhibitory activities were investigated. Among the compounds prepared, 6-methyl-2-oxo-2H-pyran-4-yl 3-(4-isopropylphenyl)propenoate (H5) showed the strongest antifungal activity against Rhizoctonia solani and Sclerotium dellfinii, and 6-methyl-2-oxo-2H-pyran-4-yl 3-(2-methylphenyl)propenoate (H2) had the highest plant growth inhibitory activity toward Brassica rapa. PMID:11272821

Zhu, J; Majikina, M; Tawata, S

2001-01-01

270

Genes from mycoparasitic fungi as a source for improving plant resistance to fungal pathogens  

PubMed Central

Disease resistance in transgenic plants has been improved, for the first time, by the insertion of a gene from a biocontrol fungus. The gene encoding a strongly antifungal endochitinase from the mycoparasitic fungus Trichoderma harzianum was transferred to tobacco and potato. High expression levels of the fungal gene were obtained in different plant tissues, which had no visible effect on plant growth and development. Substantial differences in endochitinase activity were detected among transformants. Selected transgenic lines were highly tolerant or completely resistant to the foliar pathogens Alternaria alternata, A. solani, Botrytis cinerea, and the soilborne pathogen Rhizoctonia solani. The high level and the broad spectrum of resistance obtained with a single chitinase gene from Trichoderma overcome the limited efficacy of transgenic expression in plants of chitinase genes from plants and bacteria. These results demonstrate a rich source of genes from biocontrol fungi that can be used to control diseases in plants.

Lorito, Matteo; Woo, Sheridan L.; Fernandez, Irene Garcia; Colucci, Gabriella; Harman, Gary E.; Pintor-Toro, Jose A.; Filippone, Edgardo; Muccifora, Simona; Lawrence, Christopher B.; Zoina, Astolfo; Tuzun, Sadik; Scala, Felice

1998-01-01

271

Phytopathogenic fungal inhibitors from celery seeds.  

PubMed

Extract of celery (Apium graveolens L.) seeds was investigated against phytopathogenic fungi. The light petroleum extract showed promising inhibition activities in the tests against Rhizoctonia solani and Fusarium oxysporum f. sp. vasinfecum. Chromatographic separation of the extract gave 19 fractions, one of which, QCZ-4, possessed significant inhibitory rates of 64.6%, 88.4% and 54.7% at a concentration of 100 ppm against R. solani, F. oxysporium f. sp. vasinfecum and Alternaria alternata, respectively. Major components in the active fraction were identified by GC-MS as p-(2-aminoethyl)phenol (39.7%), 3-(3,4-dimethybenzoyl) propionic acid (32.6%) and p-heptylphenol (26.9%). PMID:22908573

Liu, Tao; Liu, Fu-Guang; Xie, Hui-Qin; Mu, Qing

2012-07-01

272

Physiological and biochemical characterization of Trichoderma harzianum, a biological control agent against soilborne fungal plant pathogens.  

PubMed Central

Monoconidial cultures of 15 isolates of Trichoderma harzianum were characterized on the basis of 82 morphological, physiological, and biochemical features and 99 isoenzyme bands from seven enzyme systems. The results were subjected to numerical analysis which revealed four distinct groups. Representative sequences of the internal transcribed spacer 1 (ITS 1)-ITS 2 region in the ribosomal DNA gene cluster were compared between groups confirming this distribution. The utility of the groupings generated from the morphological, physiological, and biochemical data was assessed by including an additional environmental isolate in the electrophoretic analysis. The in vitro antibiotic activity of the T. harzianum isolates was assayed against 10 isolates of five different soilborne fungal plant pathogens: Aphanomyces cochlioides, Rhizoctonia solani, Phoma betae, Acremonium cucurbitacearum, and Fusarium oxysporum f. sp. radicis lycopersici. Similarities between levels and specificities of biological activity and the numerical characterization groupings are both discussed in relation to antagonist-specific populations in known and potential biocontrol species.

Grondona, I; Hermosa, R; Tejada, M; Gomis, M D; Mateos, P F; Bridge, P D; Monte, E; Garcia-Acha, I

1997-01-01

273

Control and possible applications of a novel carrot-spoilage basidiomycete, Fibulorhizoctonia psychrophila  

PubMed Central

A novel cold-tolerant fungus, Fibulorhizoctonia psychrophila, was isolated from a refrigerated carrot storage facility and identified as an anamorph of Athelia, often classified in Rhizoctonia s.l. Growth of this fungus was observed between 0 and 20°C with an optimum at 9–12°C, while incubation of mycelium grown at 15–32°C resulted in absence of growth even after the fungus was transferred back to 15°C. Growth was inhibited in the presence of the antifungals sorbic acid or natamycin, in particular when the fungus was incubated at 18°C. F. psychrophila produces polysaccharide degrading enzymes that, when compared to enzymes from the ascomycete fungus Aspergillus niger, retain a larger proportion of their activity at lower temperatures. This indicates that F. psychrophila could be used as a source for novel industrial enzymes that are active at 4–15°C.

de Lange, Elvira S.; Wosten, Han A. B.; Stalpers, Joost A.

2008-01-01

274

The evolution and pathogenic mechanisms of the rice sheath blight pathogen  

PubMed Central

Rhizoctonia solani is a major fungal pathogen of rice (Oryza sativa L.) that causes great yield losses in all rice-growing regions of the world. Here we report the draft genome sequence of the rice sheath blight disease pathogen, R. solani AG1 IA, assembled using next-generation Illumina Genome Analyser sequencing technologies. The genome encodes a large and diverse set of secreted proteins, enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, which probably reflect an exclusive necrotrophic lifestyle. We find few repetitive elements, a closer relationship to Agaricomycotina among Basidiomycetes, and expand protein domains and families. Among the 25 candidate pathogen effectors identified according to their functionality and evolution, we validate 3 that trigger crop defence responses; hence we reveal the exclusive expression patterns of the pathogenic determinants during host infection.

Zheng, Aiping; Lin, Runmao; Zhang, Danhua; Qin, Peigang; Xu, Lizhi; Ai, Peng; Ding, Lei; Wang, Yanran; Chen, Yao; Liu, Yao; Sun, Zhigang; Feng, Haitao; Liang, Xiaoxing; Fu, Rongtao; Tang, Changqing; Li, Qiao; Zhang, Jing; Xie, Zelin; Deng, Qiming; Li, Shuangcheng; Wang, Shiquan; Zhu, Jun; Wang, Lingxia; Liu, Huainian; Li, Ping

2013-01-01

275

Biological control of collar rot disease with broad-spectrum antifungal bacteria associated with groundnut.  

PubMed

Bacteria associated with 6 habitats of groundnut were evaluated for their broad-spectrum antifungal activity and suppression of collar rot (Aspergillus niger) of groundnut. Three hundred and ninety-three strains were tested against 8 fungal pathogens of groundnut including 5 necrotrophic fungi, Aspergillus flavus, A. niger, Rhizoctonia bataticola, Rhizoctonia solani, and Sclerotium rolfsii, and 3 biotrophic fungi, Cercospora arachidicola, Phaeoisariopsis personata, and Puccinia arachidis. Pseudomonas sp. GRS 175, Pseudomonas aeruginosa GPS 21, GSE 18, GSE 19, and GSE 30, and their cell-free culture filtrates were highly antagonistic to all the test fungi. The cell-free culture filtrates of these bacteria were fungicidal and induced mycelial deformations including hyphal bulging and vacuolization in necrotrophic fungi. The cell-free culture filtrates at 10% (v/v) concentration significantly inhibited the spore germination of biotrophic fungi. In the greenhouse, P. aeruginosa GSE 18 emerged as an effective biocontrol agent of collar rot closely followed by P. aeruginosa GSE 19. The bacterium applied as a seed treatment reduced the pre-emergence rotting and postemergence wilting by > 60%. Pseudomonas aeruginosa GSE 18 effectively colonized the groundnut rhizosphere, both in native and in A. niger infested potting mixtures. Ninety-day-old peat formulation of P. aeruginosa GSE 18 had biocontrol ability comparable with the midlog-phase cells. Pseudomonas aeruginosa GSE 18, tolerant to thiram, in combination with the fungicide had an improved collar rot control. The present study was a successful attempt in selection of broad-spectrum and fungicide tolerant biocontrol agents that can be a useful component of integrated management of collar rot. PMID:16091770

Kishore, G Krishna; Pande, S; Podile, A R

2005-02-01

276

Efficacy of microorganisms selected from compost to control soil-borne pathogens.  

PubMed

Suppression of soil-borne plant pathogens with compost has been widely studied. Compost has been found to be suppressive against several soil-borne pathogens in various cropping systems. However, an increase of some diseases due to compost usage has also been observed, since compost is a product that varies considerably in chemical, physical and biotic composition, and, consequently, also in ability to suppress soil borne diseases. New opportunities in disease management can be obtained by the selection of antagonists from suppressive composts. The objective of the present work was to isolate microorganisms from a suppressive compost and to test them for their activity against soil-borne pathogens. A compost from green wastes, organic domestic wastes and urban sludge's that showed a good suppressive activity in previous trials was used as source of microorganisms. Serial diluted suspensions of compost samples were plated on five different media: selective for Fusarium sp., selective for Trichoderma sp., selective for oomycetes, potato dextrose agar (PDA) for isolation of fungi, lysogeny broth (LB) for isolation of bacteria. In total, 101 colonies were isolated from plates and tested under laboratory conditions on tomato seedlings growing on perlite medium in Petri plates infected with Fusarium oxysporum f.sp. radicis-lycopersici and compared to a commercial antagonist (Streptomyces griserovidis, Mycostop, Bioplanet). Among them, 28 showed a significant disease reduction and were assessed under greenhouse condition on three pathosystems: Fusarium oxysporum f.sp. basilica/basil, Phytophthora nicotianae/tomato and Rhizoctonia solani/bean. Fusarium spp. selected from compost generally showed a good disease control against Fusarium wilts, while only bacteria significantly controlled P. nicotianae on tomato under greenhouse conditions. None of the microorganisms was able to control the three soil-borne pathogens together, in particular Rhizoctonia solani. Results confirmed the good suppressive activity of the compost under study against soil-borne pathogens. The selection of antagonists from compost is a promising strategy for the development of new biological control agents against soil-borne pathogens. PMID:21534476

Pugliese, M; Gullino, M L; Garibaldi, A

2010-01-01

277

Genetic modification of potato against microbial diseases: in vitro and in planta activity of a dermaseptin B1 derivative, MsrA2.  

PubMed

Dermaseptin B1 is a potent cationic antimicrobial peptide found in skin secretions of the arboreal frog Phyllomedusa bicolor. A synthetic derivative of dermaseptin B1, MsrA2 (N-Met-dermaseptin B1), elicited strong antimicrobial activities against various phytopathogenic fungi and bacteria in vitro. To assess its potential for plant protection, MsrA2 was expressed at low levels (1-5 microg/g of fresh tissue) in the transgenic potato (Solanum tuberosum L.) cv. Desiree. Stringent challenges of these transgenic potato plants with a variety of highly virulent fungal phytopathogens--Alternaria, Cercospora, Fusarium, Phytophthora, Pythium, Rhizoctonia and Verticillium species--and with the bacterial pathogen Erwinia carotovora demonstrated that the plants had an unusually broad-spectrum and powerful resistance to infection. MsrA2 profoundly protected both plants and tubers from diseases such as late blight, dry rot and pink rot and markedly extended the storage life of tubers. Due to these properties in planta, MsrA2 is proposed as an ideal antimicrobial peptide candidate to significantly increase resistance to phytopathogens and improve quality in a variety of crops worldwide with the potential to obviate fungicides and facilitate storage under difficult conditions. PMID:15947906

Osusky, Milan; Osuska, Lubica; Kay, William; Misra, Santosh

2005-06-10

278

Prediction of invasion from the early stage of an epidemic  

PubMed Central

Predictability of undesired events is a question of great interest in many scientific disciplines including seismology, economy and epidemiology. Here, we focus on the predictability of invasion of a broad class of epidemics caused by diseases that lead to permanent immunity of infected hosts after recovery or death. We approach the problem from the perspective of the science of complexity by proposing and testing several strategies for the estimation of important characteristics of epidemics, such as the probability of invasion. Our results suggest that parsimonious approximate methodologies may lead to the most reliable and robust predictions. The proposed methodologies are first applied to analysis of experimentally observed epidemics: invasion of the fungal plant pathogen Rhizoctonia solani in replicated host microcosms. We then consider numerical experiments of the susceptible–infected–removed model to investigate the performance of the proposed methods in further detail. The suggested framework can be used as a valuable tool for quick assessment of epidemic threat at the stage when epidemics only start developing. Moreover, our work amplifies the significance of the small-scale and finite-time microcosm realizations of epidemics revealing their predictive power.

Perez-Reche, Francisco J.; Neri, Franco M.; Taraskin, Sergei N.; Gilligan, Christopher A.

2012-01-01

279

Insect growth inhibition, antifeedant and antifungal activity of compounds isolated/derived from Zingiber officinale Roscoe (ginger) rhizomes.  

PubMed

Fresh rhizomes of Zingiber officinale (ginger), when subjected to steam distillation, yielded ginger oil in which curcumene was found to be the major constituent. The thermally labile zingiberene-rich fraction was obtained from its diethyl ether extract. Column chromatography of ginger oleoresin furnished a fraction from which [6]-gingerol was obtained by preparative TLC. Naturally occurring [6]-dehydroshogaol was synthesised following condensation of dehydrozingerone with hexanal, whereas zingerone and 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)butane were obtained by hydrogenation of dehydrozingerone with 10% Pd/C. The structures of the compounds were established by 1H NMR, 13C NMR and mass (EI-MS and ES-MS) spectral analysis. The test compounds exhibited moderate insect growth regulatory (IGR) and antifeedant activity against Spilosoma obliqua, and significant antifungal activity against Rhizoctonia solani. Among the various compounds, [6]-dehydroshogaol exhibited maximum IGR activity (EC50 3.55 mg ml-1), while dehydrozingerone imparted maximum antifungal activity (EC50 86.49 mg litre-1). PMID:11455660

Agarwal, M; Walia, S; Dhingra, S; Khambay, B P

2001-03-01

280

Isolation of two aspartyl proteases from Trichoderma asperellum expressed during colonization of cucumber roots.  

PubMed

Trichoderma asperellum and cucumber seedlings were used as a model to study the modulation of Trichoderma gene expression during plant root colonization. Seedlings were grown in an aseptic hydroponics medium and inoculated with Trichoderma spore suspension. Proteins differentially secreted into the medium were isolated. Three major proteins of fungal origin were identified: two arabinofuranosidases (Abf1 and Abf2) and an aspartyl protease. Differential mRNA display was conducted on Trichoderma mycelia interacting and non-interacting, with the plant roots. Among the differentially regulated clones another aspartyl protease was identified. Sequencing of the genes revealed that the first aspartyl protease is a close homologue of PapA from T. harzianum and the other, of AP1 from Botryotinia fuckeliana. RT-PCR analysis confirms that the proteases are induced in response to plant roots attachment and are expressed in planta. papA, but not papB, is also induced in plate confrontation assays with the plant pathogen Rhizoctonia solani. These data suggest that the identified proteases play a role in Trichoderma both as a mycoparasite and as a plant opportunistic symbiont. PMID:15336416

Viterbo, Ada; Harel, Michal; Chet, Ilan

2004-09-01

281

Involvement of Trichoderma Trichothecenes in the Biocontrol Activity and Induction of Plant Defense-Related Genes  

PubMed Central

Trichoderma species produce trichothecenes, most notably trichodermin and harzianum A (HA), by a biosynthetic pathway in which several of the involved proteins have significant differences in functionality compared to their Fusarium orthologues. In addition, the genes encoding these proteins show a genomic organization differing from that of the Fusarium tri clusters. Here we describe the isolation of Trichoderma arundinaceum IBT 40837 transformants which have a disrupted or silenced tri4 gene, a gene encoding a cytochrome P450 monooxygenase that oxygenates trichodiene to give rise to isotrichodiol, and the effect of tri4 gene disruption and silencing on the expression of other tri genes. Our results indicate that the tri4 gene disruption resulted in a reduced antifungal activity against Botrytis cinerea and Rhizoctonia solani and also in a reduced ability to induce the expression of tomato plant defense-related genes belonging to the salicylic acid (SA) and jasmonate (JA) pathways against B. cinerea, in comparison to the wild-type strain, indicating that HA plays an important function in the sensitization of Trichoderma-pretreated plants against this fungal pathogen. Additionally, the effect of the interaction of T. arundinaceum with B. cinerea or R. solani and with tomato seedlings on the expressions of the tri genes was studied.

Malmierca, M. G.; Cardoza, R. E.; Alexander, N. J.; McCormick, S. P.; Hermosa, R.; Monte, E.

2012-01-01

282

RNA Interference of Endochitinases in the Sugarcane Endophyte Trichoderma virens 223 Reduces Its Fitness as a Biocontrol Agent of Pineapple Disease  

PubMed Central

The sugarcane root endophyte Trichoderma virens 223 holds enormous potential as a sustainable alternative to chemical pesticides in the control of sugarcane diseases. Its efficacy as a biocontrol agent is thought to be associated with its production of chitinase enzymes, including N-acetyl-ß-D-glucosaminidases, chitobiosidases and endochitinases. We used targeted gene deletion and RNA-dependent gene silencing strategies to disrupt N-acetyl-ß-D-glucosaminidase and endochitinase activities of the fungus, and to determine their roles in the biocontrol of soil-borne plant pathogens. The loss of N-acetyl-ß-D-glucosaminidase activities was dispensable for biocontrol of the plurivorous damping-off pathogens Rhizoctonia solani and Sclerotinia sclerotiorum, and of the sugarcane pathogen Ceratocystis paradoxa, the causal agent of pineapple disease. Similarly, suppression of endochitinase activities had no effect on R. solani and S. sclerotiorum disease control, but had a pronounced effect on the ability of T. virens 223 to control pineapple disease. Our work demonstrates a critical requirement for T. virens 223 endochitinase activity in the biocontrol of C. paradoxa sugarcane disease, but not for general antagonism of other soil pathogens. This may reflect its lifestyle as a sugarcane root endophyte.

Romao-Dumaresq, Aline S.; de Araujo, Welington Luiz; Talbot, Nicholas J.; Thornton, Christopher R.

2012-01-01

283

Agrobacterium tumefaciens mediated transformation of ChiV gene to Trichoderma harzianum.  

PubMed

As a soil-borne filamentous fungus, Trichoderma harzianum exhibits biological control properties because it parasitizes a large variety of phytopathogenic fungi. In this study, the vectors pBI121 and pCAMBIA1301 and cloning vector pUC18 were used to successfully construct expression vector pCA-GChiV for filamentous fungi transformation mediated by Agrobacterium tumefaciens.The ChiV gene was successfully transferred into the biocontrol fungus T. harzianum with an efficiency of 90-110 transformants per 10(7) spores using A. tumefaciens-mediated transformation. Putative transformants were analyzed to test the transformation by the southern blot, and the expression of ChiV was detected by reverse transcription PCR. The transformants were co-cultured to assay antifungal activities with Rhizoctonia solani. The inhibition rates of the transformants and no ChiV gene transferred T. harzianum were 98.56% and 82.42%, respectively, on the fourth day.The results showed that the ChiV transformants had significantly higher inhibition activity. PMID:20936373

Yang, Liming; Yang, Qian; Sun, Kening; Tian, Ye; Li, Hulun

2010-10-10

284

The ThPG1 endopolygalacturonase is required for the trichoderma harzianum-plant beneficial interaction.  

PubMed

Considering the complexity of the in vivo interactions established by a mycoparasitic biocontrol agent at the plant rhizosphere, proteomic, genomic, and transcriptomic approaches were used to study a novel Trichoderma gene coding for a plant cell wall (PCW)-degrading enzyme. A proteome analysis, using a three-component (Trichoderma spp.-tomato plantlets-pathogen) system, allowed us to identify a differentially expressed Trichoderma harzianum endopolygalacturonase (endoPG). Spot 0303 remarkably increased only in the presence of the soilborne pathogens Rhizoctonia solani and Pythium ultimum, and corresponded to an expressed sequence tag from a T. harzianum T34 cDNA library that was constructed in the presence of PCW polymers and used to isolate the Thpg1 gene. Compared with the wild-type strain, Thpg1-silenced transformants showed lower PG activity, less growth on pectin medium, and reduced capability to colonize tomato roots. These results were combined with microarray comparative data from the transcriptome of Arabidopsis plants inoculated with the wild type or a Thpg1-silenced transformant (ePG5). The endoPG-encoding gene was found to be required for active root colonization and plant defense induction by T. harzianum T34. In vivo assays showed that Botrytis cinerea leaf necrotic lesions were slightly smaller in plants colonized by ePG5, although no statistically significant differences were observed. PMID:19589077

Morán-Diez, Eugenia; Hermosa, Rosa; Ambrosino, Patrizia; Cardoza, Rosa E; Gutiérrez, Santiago; Lorito, Matteo; Monte, Enrique

2009-08-01

285

Functional analysis of the Trichoderma harzianum nox1 gene, encoding an NADPH oxidase, relates production of reactive oxygen species to specific biocontrol activity against Pythium ultimum.  

PubMed

The synthesis of reactive oxygen species (ROS) is one of the first events following pathogenic interactions in eukaryotic cells, and NADPH oxidases are involved in the formation of such ROS. The nox1 gene of Trichoderma harzianum was cloned, and its role in antagonism against phytopathogens was analyzed in nox1-overexpressed transformants. The increased levels of nox1 expression in these transformants were accompanied by an increase in ROS production during their direct confrontation with Pythium ultimum. The transformants displayed an increased hydrolytic pattern, as determined by comparing protease, cellulase, and chitinase activities with those for the wild type. In confrontation assays against P. ultimum the nox1-overexpressed transformants were more effective than the wild type, but not in assays against Botrytis cinerea or Rhizoctonia solani. A transcriptomic analysis using a Trichoderma high-density oligonucleotide (HDO) microarray also showed that, compared to gene expression for the interaction of wild-type T. harzianum and P. ultimum, genes related to protease, cellulase, and chitinase activities were differentially upregulated in the interaction of a nox1-overexpressed transformant with this pathogen. Our results show that nox1 is involved in T. harzianum ROS production and antagonism against P. ultimum. PMID:21421791

Montero-Barrientos, M; Hermosa, R; Cardoza, R E; Gutiérrez, S; Monte, E

2011-03-18

286

Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice.  

PubMed

Some pseudomands are being utilized as biofertilizers and biopesticides because of their role in plant growth promotion and plant protection against root parasites, respectively. Two strains of Pseudomonas, P. jessenii LHRE62 and P. synxantha HHRE81, recovered from wheat rhizosphere, have shown their potential in field bioinoculation tests under rice-wheat and pulse-wheat rotation systems. Normally, pseudomonads are cultivated on synthetic media-like King's B and used for inoculation on seeds/soil drench with talcum or charcoal as carrier material. Cow dung is being used for different purposes from the ancient time and has a significant role in crop growth because of the content in humic compounds and fertilizing bioelements available in it. Here, cow dung extract was tested as a growth medium for strains LHRE62 and HHRE81, in comparison with growth in King's B medium. The log phase was delayed by 2 h as compared to growth in King's B medium. The bacterial growth yield, lower in plain cow dung extract as compared to King's B medium, was improved upon addition of different carbon substrates. Growth of rice var. Pant Dhan 4 in pot cultures was increased using liquid formulation of cow dung extract and bacteria as foliar spray, compared to their respective controls. Biocontrol efficacy of the bioagents was assessed by challenging rice crop with Rhizoctonia solani, a sheath blight pathogen. The growth promotion and biocontrol efficiencies were more pronounced in the case of mixed inocula of strains LHRE62 and HHRE81. PMID:23100852

Srivastava, Rashmi; Aragno, Michel; Sharma, A K

2010-03-16

287

Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II).  

PubMed

Two Schiff base ligands L1 and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1 : 1 electrolytes. The IR data demonstrate the tetradentate binding of L1 and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1 and L2 have the crystallite sizes of 53 and 61 nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23990740

Joseyphus, R Selwin; Nair, M Sivasankaran

2008-06-30

288

Biological control of potato black scurf by rhizosphere associated bacteria  

PubMed Central

The present work was carried out to study the potential of plant rhizosphere associated bacteria for the biocontrol of potato black scurf disease caused by Rhizoctonia solani Khun AG-3. A total of twenty-eight bacteria isolated from diseased and healthy potato plants grown in the soil of Naran and Faisalabad, Pakistan were evaluated for their antagonistic potential. Nine bacterial strains were found to be antagonistic in vitro, reduced the fungal growth and caused the lysis of sclerotia of R. solani in dual culture assay as well as in extracellular metabolite efficacy test. The selected antagonistic strains were further tested for the production and efficacy of volatile and diffusible antibiotics, lytic enzymes and siderophores against R. solani. Selected antagonistic bacteria were also characterized for growth promoting attributes i.e., phosphate solubilization, nitrogen fixation and indole acetic acid production. Biocontrol efficacy and percent yield increase by these antagonists was estimated in greenhouse experiment. Statistical analysis showed that two Pseudomonas spp. StT2 and StS3 were the most effective with 65.1 and 73.9 percent biocontrol efficacy, as well as 87.3 and 98.3 percent yield increase, respectively. Potential antagonistic bacterial strain StS3 showed maximum homology to Pseudomonas sp. as determined by 16S rRNA gene sequencing. These results suggest that bacterial isolates StS3 and StT2 have excellent potential to be used as effective biocontrol agents promoting plant growth with reduced disease incidence.

Tariq, Mohsin; Yasmin, Sumera; Hafeez, Fauzia Y.

2010-01-01

289

Breeding for disease resistance in the major cool-season turfgrasses.  

PubMed

Over the past several decades, breeding cool-season turfgrasses for improved disease resistance has been the focus of many turfgrass breeding programs. This review article discusses the dramatic improvements made in breeding Kentucky bluegrass (Poa pratensis) for resistance to leaf spot (caused by Drechslera poae), stem rust (caused by Puccinia graminis), and stripe smut (caused by Ustilago striiformis); perennial ryegrass (Lolium perenne) for resistance to gray leaf spot (caused by Pyricularia grisea), stem rust and crown rust (caused by Puccinia coronata); tall fescue (Festuca arundinacea) for resistance to brown patch (Rhizoctonia solani) and stem rust; creeping bentgrass (Agrostis stolonifera) for resistance to dollar spot (caused by Sclerotinia homoeocarpa); and fine fescues (Festuca spp.) for improved disease resistance. Historically, the dramatic improvements in disease resistance of the cool-season grasses have been attributed to traditional/conventional breeding techniques; however, it is likely that functional genomics and molecular techniques will play a more significant role in the development of cultivated turfgrasses as the specific genes and mechanisms for disease resistance are identified in the future. PMID:17061916

Bonos, Stacy A; Clarke, Bruce B; Meyer, William A

2006-01-01

290

Linkage map construction in allotetraploid creeping bentgrass (Agrostis stolonifera L.).  

PubMed

Creeping bentgrass (Agrostis stolonifera L.) is one of the most adapted bentgrass species for use on golf course fairways and putting greens because of its high tolerance to low mowing height. It is a highly outcrossing allotetraploid species (2n=4x=28, A(2) and A(3) subgenomes). The first linkage map in this species is reported herein, and it was constructed based on a population derived from a cross between two heterozygous clones using 169 RAPD, 180 AFLP, and 39 heterologous cereal and 36 homologous bentgrass cDNA RFLP markers. The linkage map consists of 424 mapped loci covering 1,110 cM in 14 linkage groups, of which seven pairs of homoeologous chromosomes were identified based on duplicated loci. The numbering of all seven linkage groups in the bentgrass map was assigned according to common markers mapped on syntenous chromosomes of ryegrass and wheat. The number of markers linked in coupling and repulsion phase was in a 1:1 ratio, indicating disomic inheritance. This supports a strict allotetraploid inheritance in creeping bentgrass, as suggested by previous work based on chromosomal pairing and isozymes. This linkage map will assist in the tagging and eventually in marker-assisted breeding of economically important quantitative traits like disease resistance to dollar spot (Sclerotinia homoeocarpa F.T. Bennett) and brown patch (Rhizoctonia solani Kuhn). PMID:15981010

Chakraborty, N; Bae, J; Warnke, S; Chang, T; Jung, G

2005-06-25

291

Effect of foliar disease on the epiphytic yeast communities of creeping bentgrass and tall fescue.  

PubMed

The effect of mechanical wounding or foliar diseases caused by Sclerotinia homoeocarpa or Rhizoctonia solani on the epiphytic yeast communities on creeping bentgrass and tall fescue were determined by leaf washing and dilution plating. Total yeast communities on healthy bentgrass and tall fescue leaves ranged from 7.9 x 103 to 1.4 x 105 CFU.cm-2 and from 2.4 x 103 to 1.6 x 104 CFU.cm-2, respectively. Mechanically wounded leaves (1 of 2 trials) and leaves with disease lesions (11 of 12 trials) supported significantly larger communities of phylloplane yeasts. Total yeast communities on S. homoeocarpa infected or R. solani infected bentgrass leaves were 3.6-10.2 times and 6.2-6.4 times larger, respectively, than the communities on healthy leaves. In general, healthy and diseased bentgrass leaves supported larger yeast communities than healthy or diseased tall fescue leaves. We categorized the majority of yeasts as white-pigmented species, including Cryptococcus laurentii, Cryptococcus flavus, Pseudozyma antarctica, Pseudozyma aphidis, and Pseudozyma parantarctica. The percentage of pink yeasts in the total yeast community ranged from 2.6% to 9.9% on healthy leaves and increased to 32.0%-44.7% on S. homoeocarpa infected leaves. Pink-pigmented yeasts included Rhodotorula glutinis, Rhodotorula mucilaginosa, Sakaguchia dacryoidea, and Sporidiobolus pararoseus. Foliar disease significantly affected community size and composition of epiphytic yeasts on bentgrass and tall fescue. PMID:15644900

Allen, Tom W; Quayyum, Habib A; Burpee, Leon L; Buck, James W

2004-10-01

292

Biologically active endophytic streptomycetes from Nothofagus spp. and other plants in Patagonia.  

PubMed

Endophytic streptomycetes have been isolated and characterized from several species of Nothofagus and other plants growing in the southern reaches of Patagonia. No endophytic streptomycete was obtained from any plant species studied in Northern Patagonia. However, from Southern Patagonia, biologically active Streptomyces spp. from several plant species were isolated. Each isolate, as studied by scanning electron microscopy (SEM), has small hyphae, some produce typical barrel-shaped spores in culture and each has some unique hyphal surface structures. Interestingly, although none has any detectable antibacterial killing properties, each has demonstrable killing activity against one or more pathogenic fungi including representative plant pathogenic organisms such as Phytophthora erythroseptica, Pythium ultimum, Sclerotinia sclerotiorum, Mycosphaerella fijiensis, and Rhizoctonia solani. The 16S rDNA sequences of the isolates were distinct from all other genetic accessions of Streptomyces in GenBank. However, isolate C-2 from Chiliotrichum diffusum (Compositae) is identical, in all respects, to isolate C-4 obtained from Misodendrum punctulatum (Loranthaceae). These results confirm that endophytic streptomycetes represent a novel source of biologically active microorganisms. PMID:16944339

Castillo, Uvidello F; Browne, Lindsey; Strobel, Gary; Hess, W M; Ezra, Sigal; Pacheco, Gladys; Ezra, David

2006-08-31

293

Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II)  

PubMed Central

Two Schiff base ligands L1 and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1 : 1 electrolytes. The IR data demonstrate the tetradentate binding of L1 and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1 and L2 have the crystallite sizes of 53 and 61 nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium.

Joseyphus, R. Selwin

2008-01-01

294

Brevibacillus laterosporus strain BPM3, a potential biocontrol agent isolated from a natural hot water spring of Assam, India.  

PubMed

A bacterial strain designated as BPM3 isolated from mud of a natural hot water spring of Nambar Wild Life Sanctuary, Assam, India, strongly inhibited growth of phytopathogenic fungi (Fusarium oxysporum f. sp. ciceri, F. semitectum, Magnaporthe grisea and Rhizoctonia oryzae) and gram-positive bacterium (Staphylococcus aureus). The maximum growth and antagonistic activity was recorded at 30°C, pH 8.5 when starch and peptone were amended as carbon and nitrogen sources, respectively. In greenhouse experiment, this bacterium (BPM3) suppressed blast disease of rice by 30-67% and protected the weight loss by 35-56.5%. The maximum disease protection (67%) and weight loss protection (56.5%) were recorded when the bacterium was applied before 2 days of the pathogen inoculation. Antifungal and antibacterial compounds were isolated from the bacterium which also inhibited the growth of these targeted pathogens. The compounds were purified and on spectroscopic analysis of a purified fraction having R(f) 0.22 which showed strong antifungal and antibacterial activity indicated the presence of C-H, carbonyl group, dimethyl group, -CH(2) and methyl group. The bacterium was characterized by morphological, biochemical and molecular approaches and confirmed that the strain BPM3 is Brevibacillus laterosporus. PMID:20630733

Saikia, R; Gogoi, D K; Mazumder, S; Yadav, A; Sarma, R K; Bora, T C; Gogoi, B K

2010-07-13

295

Molecular cloning, structural analysis, and expression in Escherichia coli of a chitinase gene from Enterobacter agglomerans.  

PubMed Central

The gene chiA, which codes for endochitinase, was cloned from a soilborne Enterobacter agglomerans. Its complete sequence was determined, and the deduced amino acid sequence of the enzyme designated Chia_Entag yielded an open reading frame coding for 562 amino acids of a 61-kDa precursor protein with a putative leader peptide at its N terminus. The nucleotide and polypeptide sequences of Chia_Entag showed 86.8 and 87.7% identity with the corresponding gene and enzyme, Chia_Serma, of Serratia marcescens, respectively. Homology modeling of Chia_Entag's three-dimensional structure demonstrated that most amino acid substitutions are at solvent-accessible sites. Escherichia coli JM109 carrying the E. agglomerans chiA gene produced and secreted Chia_Entag. The antifungal activity of the secreted endochitinase was demonstrated in vitro by inhibition of Fusarium oxysporum spore germination. The transformed strain inhibited Rhizoctonia solani growth on plates and the root rot disease caused by this fungus in cotton seedlings under greenhouse conditions.

Chernin, L S; De la Fuente, L; Sobolev, V; Haran, S; Vorgias, C E; Oppenheim, A B; Chet, I

1997-01-01

296

Molecular cloning, structural analysis, and expression in Escherichia coli of a chitinase gene from Enterobacter agglomerans.  

PubMed

The gene chiA, which codes for endochitinase, was cloned from a soilborne Enterobacter agglomerans. Its complete sequence was determined, and the deduced amino acid sequence of the enzyme designated Chia_Entag yielded an open reading frame coding for 562 amino acids of a 61-kDa precursor protein with a putative leader peptide at its N terminus. The nucleotide and polypeptide sequences of Chia_Entag showed 86.8 and 87.7% identity with the corresponding gene and enzyme, Chia_Serma, of Serratia marcescens, respectively. Homology modeling of Chia_Entag's three-dimensional structure demonstrated that most amino acid substitutions are at solvent-accessible sites. Escherichia coli JM109 carrying the E. agglomerans chiA gene produced and secreted Chia_Entag. The antifungal activity of the secreted endochitinase was demonstrated in vitro by inhibition of Fusarium oxysporum spore germination. The transformed strain inhibited Rhizoctonia solani growth on plates and the root rot disease caused by this fungus in cotton seedlings under greenhouse conditions. PMID:9055404

Chernin, L S; De la Fuente, L; Sobolev, V; Haran, S; Vorgias, C E; Oppenheim, A B; Chet, I

1997-03-01

297

Chitinolytic Enterobacter agglomerans Antagonistic to Fungal Plant Pathogens  

PubMed Central

Three Enterobacter agglomerans strains which produce and excrete proteins with chitinolytic activity were found while screening soil-borne bacteria antagonistic to fungal plant pathogens. The chitinolytic activity was induced when the strains were grown in the presence of colloidal chitin as the sole carbon source. It was quantitated by using assays with chromogenic p-nitrophenyl analogs of disaccharide, trisaccharide, and tetrasaccharide derivatives of N-acetylglucosamine. A set of three fluorescent substrates with a 4-methylumbelliferyl group linked by (beta)-1,4 linkage to N-acetylglucosamine mono- or oligosaccharides were used to identify the chitinolytic activities of proteins which had been renatured following their separation by electrophoresis. This study provides the most complete evidence for the presence of a complex of chitinolytic enzymes in Enterobacter strains. Four enzymes were detected: two N-acetyl-(beta)-d-glucosaminidases of 89 and 67 kDa, an endochitinase with an apparent molecular mass of 59 kDa, and a chitobiosidase of 50 kDa. The biocontrol ability of the chitinolytic strains was demonstrated under greenhouse conditions. The bacteria decreased the incidence of disease caused by Rhizoctonia solani in cotton by 64 to 86%. Two Tn5 mutants of one of the isolates, which were deficient in chitinolytic activity, were unable to protect plants against the disease.

Chernin, L.; Ismailov, Z.; Haran, S.; Chet, I.

1995-01-01

298

Genetic analysis of the antifungal activity of a soilborne Pseudomonas aureofaciens strain.  

PubMed Central

Pseudomonas aureofaciens Q2-87 produces the antibiotic 2,4-diacetophloroglucinol (Phl), which inhibits Gaeumannomyces graminis var. tritici and other fungi in vitro. Strain Q2-87 also provides biological control of take-all, a root disease of wheat caused by this fungus. To assess the role of Phl in the antifungal activity of strain Q2-87, a genetic analysis of antibiotic production was conducted. Two mutants of Q2-87 with altered antifungal activity were isolated by site-directed mutagenesis with Tn5. One mutant, Q2-87::Tn5-1, did not inhibit G. graminis var. tritici in vitro and did not produce Phl. Two cosmids were isolated from a genomic library of the wild-type strain by probing with the mutant genomic fragment. Antifungal activity and Phl production were coordinately restored in Q2-87::Tn5-1 by complementation with either cosmid. Mobilization of one of these cosmids into two heterologous Pseudomonas strains conferred the ability to synthesize Phl and increased their activity against G. graminis var. tritici, Pythium ultimum, and Rhizoctonia solani in vitro. Subcloning and deletion analysis of these cosmids identified a 4.8-kb region which was necessary for Phl synthesis and antifungal activity. Images

Vincent, M N; Harrison, L A; Brackin, J M; Kovacevich, P A; Mukerji, P; Weller, D M; Pierson, E A

1991-01-01

299

Cloning, heterologous expression, and functional characterization of a chitinase gene, Lbchi32, from Limonium bicolor.  

PubMed

In the present study, an endochitinase gene, Lbchi32, was cloned from Limonium bicolor. The cDNA sequence of Lbchi32 was 1,443 bp in length and encoded 319 amino acid residues. The DNA sequence of Lbchi32 was 2,512 bp in length and contained three exons and two introns. The Lbchi32 gene was inserted into a pPIC9 vector and transferred into Pichia pastoris strains GS115 and KM71 for heterologous expression. SDS-PAGE analyses indicated that LbCHI32 was expressed in both GS115 and KM71 and that it was secreted extracellularly. The optimal reaction conditions for LbCHI32 activity are 45 degrees C, pH 5.0, and 5 mM Ba(2+). The LbCHI32 enzyme can efficiently degrade chitin, chitin derivatives, and the cell walls of different pathogenic fungi, including phytopathogenic Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum, Valsa sordida, Septoria tritici, and Phytophthora sojae. These findings suggest that Lbchi32 has potential use in the degradation of chitin and chitin derivatives. PMID:20512617

Liu, Zhi Hua; Yang, Chuan Ping; Qi, Xiao Tian; Xiu, Li Li; Wang, Yu Cheng

2010-05-30

300

Cloning and characterization of a chitinase gene Lbchi31 from Limonium bicolor and identification of its biological activity.  

PubMed

Chitinases are digestive enzymes that break down glycosidic bonds in chitin. In the current study, an endochitinase gene Lbchi31 was cloned from Limonium bicolor. The cDNA sequence of Lbchi31 was 1,107 bp in length, encoding 322 amino acid residues with a calculated molecular mass of 31.7 kDa. Clustal analysis showed that there was a highly conserved chitin-binding domains in Lbchi31 protein, containing four sulfide bridges. The Lbchi31 gene was inserted into the pPIC9 vector and transferred into yeast Pichia pastoris GS115 and KM71 for heterologous expression. The transformant harboring the Lbchi31 gene showed a clearly visible protein band with a molecular mass of more than 31 kDa in the SDS-PAGE gel, indicating that it had been translated in P. pastoris. Enzyme characterization showed that the optimal reaction condition for chitinase LbCHI31 activity was: 40 degrees C, pH of 5.0 and 5 mmol l(-1) of Mn(2+). The maximum enzyme activity was 0.88 U ml(-1) following exposure to the cell wall chitin of Valsa sordida. The LbCHI31 enzyme can efficiently degrade cell wall chitin of the phytopathogenic Rhizoctonia solani, Fusarium oxysporum, Sclerotinia sclerotiorum, V. sordida, Septoria tritici and Phytophthora sojae, suggesting that it has the biocontrol function to fungal phytopathogen. PMID:19685157

Liu, Zhi Hua; Wang, Yu Cheng; Qi, Xiao Tian; Yang, Chuan Ping

2009-08-15

301

The inhibitory effect of the various seed coating substances against rice seed borne fungi and their shelf-life during storage.  

PubMed

Presently, chemical seed treatments are in discussion due to their directly or indirectly impacts on human health or other living organisms. They may also negatively affect the ecosystem and the food chain. In rice seeds, chemicals may cause phytotoxic effects including seed degradation. Eugenol is the main component of clove (Eugenia caryophillis) oil, which was proved to act simultaneously as bactericide, virocide and especially fungicide. The in vitro study was aimed to compare the inhibitory effect of the following seed treatment substances against seed borne fungi and their shelf-life during 12 months of storage; conventional captan (CA), chitosan-lignosulphonate polymer (CL), eugenol incorporated into chitosan-lignosulphonate polymer (E+CL) and control (CO). The obtained results of fungi inhibition were classified in three groups, which showed at first that CA treatment led to a better, i.e., longer, inhibitory effect on Alternaria padwickii, Rhizoctonia solani, Curvularia sp., Aspergillus flavus and Aspergillus niger than E+CL. Secondly, E+CL coating polymer showed the longest inhibitory effect against Bipolaris oryzae and Nigrospora oryzae compared to CA and CL coating polymer. Finally, both CA and E+CL coating polymer had non-significant difference inhibitory effect on Fusarium moniliforme. The variant of CL coating polymer for seed coating was only during the first 6 months of storage able to inhibit all species of the observed seed borne fungi, whereas CA and E+CL coating polymer were capable to inhibit most of the fungi until 9 months of storage. PMID:19899320

Thobunluepop, Pitipong

2009-08-15

302

Four genes from Pseudomonas fluorescens that encode the biosynthesis of pyrrolnitrin.  

PubMed Central

Pyrrolnitrin is a secondary metabolite of Pseudomonas and Burkholderia sp. strains with strong antifungal activity. Production of pyrrolnitrin has been correlated with the ability of some bacteria to control plant diseases caused by fungal pathogens, including the damping-off pathogen Rhizoctonia solani. Pseudomonas fluorescens BL915 has been reported to produce pyrrolnitrin and to be an effective biocontrol agent for this pathogen. We have isolated a 32-kb genomic DNA fragment from this strain that contains genes involved in the biosynthesis of pyrrolnitrin. Marker-exchange mutagenesis of this DNA with Tn5 revealed the presence of a 6.2-kb region that contains genes required for the synthesis of pyrrolnitrin. The nucleotide sequence of the 6.2-kb region was determined and found to contain a cluster of four genes that are required for the production of pyrrolnitrin. Deletion mutations in any of the four genes resulted in a pyrrolnitrin-nonproducing phenotype. The putative coding sequences of the four individual genes were cloned by PCR and fused to the tac promoter from Escherichia coli. In each case, the appropriate tac promoter-pyrrolnitrin gene fusion was shown to complement the pyrrolnitrin-negative phenotype of the corresponding deletion mutant. Transfer of the four gene cluster to E. coli resulted in the production of pyrrolnitrin by this organism, thereby demonstrating that the four genes are sufficient for the production of this metabolite and represent all of the genes required to encode the pathway for pyrrolnitrin biosynthesis.

Hammer, P E; Hill, D S; Lam, S T; Van Pee, K H; Ligon, J M

1997-01-01

303

Antifungal efficacy of chitosan and its thiourea derivatives upon the growth of some sugar-beet pathogens.  

PubMed

Chitosan (CS) was modified by reaction with benzoyl thiocyanate to give a thiourea derivative (TUCS). The antifungal behavior of chitosan and its thiourea derivative was investigated in vitro on the mycelial growth, sporulation and germination of conidia or sclerotia of the following sugar-beet: Beta vulgaris pathogens isolated in Egypt, Rhizoctonia solani Kühn (AG(2-2)) Sclerotium rolfsii Sacc. and Fusarium solani (Mart.) Sacc. All the prepared thiourea derivatives had a significant inhibiting effect on the different stages of development on the germination of conidia or sclerotia of all the investigated fungi in the polymer concentration range of 5-1000 microg ml(-1). In the absence of chitosan and its derivative, R. solani exhibited the fastest growth of the fungi studied. However, growth tolerance of the modified chitosan was highest for F. solani and lowest for R. solani. The most sensitive to the modified chitosan stress with regard to their germination and number produced were the sclerotia of S. rolfsii. It has been found that the TUCS is a much better fungicidal agent (about 60 times more) than the pure CS against most of the fungal strains tested. The molecular weight and the degree of deacetylation were found to have an important effect on the growth activities of the pathogens. PMID:16413607

Eweis, M; Elkholy, S S; Elsabee, M Z

2006-01-18

304

Endophytic bacteria from Ocimum sanctum and their yield enhancing capabilities.  

PubMed

Endophytes are beneficial microbes that reside intercellularly inside the plants. Interaction of endophytes with the host plants and their function within their host are important to address ecological relevance of endophyte. Four endophytic bacteria OS-9, OS-10, OS-11, and OS-12 were isolated from healthy leaves of Ocimum sanctum. These isolated microbes were screened in dual culture against various phytopathogenic fungi viz. Rhizoctonia solani, Sclerotium rolfsii, Fusarium solani, Alternaria solani, and Colletotrichum lindemuthianum. Of these, strain OS-9 was found to be antagonistic to R. solani, A. solani, F. solani, and C. lindemuthianum while OS-11 was found antagonistic against A. solani only. The growth-promoting benefits of the endophytes were initially evaluated in the glasshouse by inoculated seeds of O. sanctum. Treatment with endophytes OS-10 and OS-11 resulted in significant enhancement of growth as revealed by increase in fresh as well as dry weight. Further, field trials involving two genotypes OS Purple and CIM-Angana were conducted with strains OS-10 and OS-11. The growth-promoting effect was visible on both the genotypes tested as the endophytes significantly enhanced fresh herbage yield (t/ha). Interestingly, these endophytes increased the content of essential oil particularly in cultivar OS Purple and thereby increasing the total oil yields. Molecular characterization of strain OS-11 indicated the strain to be highly related to the type strain of Bacillus subtilis. PMID:19826860

Tiwari, Rashmi; Kalra, Alok; Darokar, M P; Chandra, Mahesh; Aggarwal, Nitin; Singh, A K; Khanuja, S P S

2009-10-14

305

Fungitoxicity of lyophilized and spray-dried garlic extracts.  

PubMed

Among the compounds discussed for anti-microbial and anti-fungal use allicin (allylthiosulfinate, diallyl disulfide-S-monoxide), an active ingredient of garlic, has attracted considerable attention. The objective of this study is to determine the antifungal activity of a local garlic ecotype (Voghiera) extracts against different pathogens. Primary screening was carried out by the agar plates technique using ethanol garlic extract at four final concentrations against the following organisms: Alternaria alternata, Aspergillus spp., Colletotrichum acutatum, Didymella bryoniae, Fusarium culmorum, Fusarium avenaceum, Fusarium gramineareum, Gliocladium roseum 47, Pythium splendens, Rhizoctonia solani, Sclerotium rolfsii, Stemphylium vesicarium, Trichoderma longibranchiatum, and Botrytis cinerea. Secondary screening was carried out using a lyophilized and a spray-dried preparation at different concentrations against the organisms selected for the high inhibition garlic effect in the primary screening and compared with the commercial fungicides mancozeb and iprodione. The best results were observed for the spray-dried garlic compound that showed a good fungicidal activity at the concentration of 1.5 g/10 mL while lyophilized garlic at the same concentration exhibited less inhibition activity against the four fungi analyzed in the second screening. PMID:17763036

Tedeschi, Paola; Maietti, Annalisa; Boggian, Marisa; Vecchiati, Giorgio; Brandolini, Vincenzo

306

Superoxide radical is involved in the sclerotial differentiation of filamentous phytopathogenic fungi: identification of a fungal xanthine oxidase.  

PubMed

This study shows that the direct indicator of oxidative stress superoxide radical (O·??) is involved in the sclerotial differentiation of the phytopathogenic filamentous fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor. The production rate of O·?? and the antioxidant enzyme superoxide dismutase (SOD) levels in the sclerotiogenic fungi were significantly higher and lower, respectively, than those of their non-differentiating counterpart strains, which strongly suggests that the oxidative stress of the sclerotium differentiating fungi is higher than that of the non-differentiating ones. Xanthine oxidase (XO), which was detected for the first time in fungi in general, was localized in the cytoplasmic membrane. The contribution of XO in the overall O·??production was very significant, reaching 30-70% among the strains, especially in the transition developmental stage between the undifferentiated and the differentiated state, suggesting a sclerotium triggering and a phytopathogenic role of XO during plant infection. The additional finding that these fungi secrete extracellular SOD can be related to their protection from the response of plants to produce O·?? at infection sites. PMID:20943149

Papapostolou, Ioannis; Georgiou, Christos D

2010-03-11

307

Overlapping and distinct functions of two Trichoderma virens MAP kinases in cell-wall integrity, antagonistic properties and repression of conidiation.  

PubMed

We have studied the functions of the Trichoderma virens TmkB, a homologue of the yeast cell-wall integrity MAP kinase Slt2, using gene knockout. The functions of TmkB were compared to those of the pathogenicity MAP kinase homologue (TmkA). Like the tmkA loss-of-function mutants, tmkB mutants exhibited reduced radial growth and constitutive conidiation in dark as well as in liquid shake cultures. The tmkB mutants, in contrast to tmkA mutants, had cell-wall integrity defects, as shown by autolysis of the mycelia and increased sensitivity to cell-wall degrading enzymes. Interestingly, the tmkB mutants were not autolytic on the synthetic Vogels minimal medium. The tmkB mutants had attenuated ability to overgrow the plant pathogen Sclerotium rolfsii, while retaining the ability to overgrow Rhizoctonia solani and Pythium spp., a phenotype also exhibited by the tmkA mutants. This first functional analysis of a cell-wall integrity MAPK in Trichoderma spp., a group of economically important fungi, shows the importance of this signaling pathway in biocontrol. Common phenotypes of the TmkA and TmkB pathways suggest that the two MAPKs may share some substrates, perhaps subunits of key transcription factors, thus dependent on two phosphorylation events for their activity. PMID:20633533

Kumar, Ashish; Scher, Keren; Mukherjee, Mala; Pardovitz-Kedmi, Ella; Sible, George V; Singh, Uma S; Kale, Sharad P; Mukherjee, Prasun K; Horwitz, Benjamin A

2010-07-13

308

Cell surface display of Chi92 on Escherichia coli using ice nucleation protein for improved catalytic and antifungal activity.  

PubMed

The gene encoding chitinase 92 (Chi92) from Aeromonas hydrophila JP10 has been displayed on the cell surface of Escherichia coli using the N-terminal region of ice nucleation proteins (INPN) as an anchoring motif. Immunofluorescence microscopy confirmed that Chi92 was anchored on the cell surface. Western blot analysis further identified the synthesis of INP derivatives containing the N-terminal domain INPN-Chi92 fusion protein of the expected size (112 kDa). Whole cell enzyme assay indicated that the displayed Chi92 showed enhanced catalytic activity toward colloidal chitin. In addition, the Chi92-displayed cells exhibited inhibitory effects on the mycelial growth of phytopathogenic fungi, including Fusarium decemcellulare, Sclerotium rolfsii, Rhizoctonia solani kuhn, and Fusarium oxysporum f.sp. melonis. This study suggested that the INP-based display systems can be used to express a large protein (90 kDa Chi92) on the cell surface of E. coli without growth inhibition. In addition, the display of chitinase on the cell surface may provide an attractive method for the development of biocontrol agents against phytopathogenic fungi. PMID:16487328

Wu, Mei Li; Tsai, Chun Yung; Chen, Tsai Hsia

2006-03-01

309

Spectral and thermal studies with anti-fungal aspects of some organotin(IV) complexes with nitrogen and sulphur donor ligands derived from 2-phenylethylamine.  

PubMed

Some complexes of 2-phenylethyl dithiocarbamate, thiohydrazides and thiodiamines with dibenzyltin(IV) chloride, tribenzyltin(IV) chloride and di(para-chlorobenzyl)tin(IV) dichloride have been synthesized and investigated in 1:2 and 1:1 molar ratio. The dithiocarbamate ligand act as monoanionic bidentate and thiohydrazide, thiodiamines act as neutral bidentate ligand. The synthesized complexes have been characterized by elemental analysis and molecular weight determination studies and their bonding pattern suggested on the basis of electronic, infrared, 1H and 13C NMR spectroscopy. Using thermogravimetric (TG) and differential thermal analysis (DTA) various thermodynamic and kinetic parameters viz. reaction order (n), apparent activation energy (Ea), apparent activation entropy (S#) and heat of reaction (DeltaH) have been calculated and correlated with the structural aspects for solid-state decomposition of complexes. The ligands and their tin complexes have also been screened for their fungitoxicity activity against Rhizoctonia solanii and Sclerotium rolfsii and their ED50 values calculated. PMID:18337163

Singh, Rajeev; Kaushik, N K

2008-01-19

310

Synthesis, spectral, thermal and anti-fungal studies of organotin(IV) thiohydrazone complexes.  

PubMed

The reaction of tribenzyltin(IV) chloride and di(para-chlorobenzyl)tin(IV) dichloride with thiohydrazones derived by condensation of 2-phenylethyl N-thiohydrazide with benzaldehyde, salicaldehyde, p-methylacetophenone and cinnamaldehyde have been investigated in 1:1 molar ratio. These ligands act as neutral, bidentate species and coordinate to the central tin (IV) atom through the thiosulphur and azomethine nitrogen. The newly synthesized complexes have been characterized by elemental analysis and molecular weight determination. The mode of bonding of the complexes has been suggested on the basis of infrared, electronic and (1)H NMR spectroscopy, and probable structures have been assigned to these complexes. Phenomenological and kinetic parameters have been calculated using thermogravimetric (TG) and differential thermal analytical (DTA) curves and their variations have been correlated with some structural parameters of the complexes. The ligands and their tin(IV) complexes have been screened in vitro for their fungicidal activity against Rhizoctonia solanii and Sclerotium rolfsii and found to be quite active in this respect. PMID:19162535

Singh, Rajeev; Kaushik, N K

2008-06-19

311

Trichoderma mitogen-activated protein kinase signaling is involved in induction of plant systemic resistance.  

PubMed

The role of a mitogen-activated protein kinase (MAPK) TmkA in inducing systemic resistance in cucumber against the bacterial pathogen Pseudomonas syringae pv. lacrymans was investigated by using tmkA loss-of-function mutants of Trichoderma virens. In an assay where Trichoderma spores were germinated in proximity to cucumber roots, the mutants were able to colonize the plant roots as effectively as the wild-type strain but failed to induce full systemic resistance against the leaf pathogen. Interactions with the plant roots enhanced the level of tmkA transcript in T. virens and its homologue in Trichoderma asperellum. At the protein level, we could detect the activation of two forms reacting to the phospho-p44/42 MAPK antibody. Biocontrol experiments demonstrated that the tmkA mutants retain their biocontrol potential against Rhizoctonia solani in soil but are not effective against Sclerotium rolfsii in reducing disease incidence. Our results show that, unlike in many plant-pathogen interactions, Trichoderma TmkA MAPK is not involved in limited root colonization. Trichoderma, however, needs MAPK signaling in order to induce full systemic resistance in the plant. PMID:16204544

Viterbo, Ada; Harel, Michal; Horwitz, Benjamin A; Chet, Ilan; Mukherjee, Prasun K

2005-10-01

312

Molecular cloning, characterization, and expression of a chitinase from the entomopathogenic fungus Paecilomyces javanicus.  

PubMed

Paecilomyces javanicus is an entomopathogenic fungus of coleopteran and lepidopteran insects. Here we report on cloning, characterization, and expression patterns of a chitinase from P. javanicus. A strong chitinase activity was detected in P. javanicus cultures added to chitin. The full-length cDNA, designated PjChi-1, was cloned from mycelia by using both degenerate primer/reverse transcription polymerase chain reaction (RT-PCR) amplification and 5'-/3'-RACE extension. The 1.18-kb cDNA gene contains a 1035-bp open reading frame and encodes a 345-amino acid polypeptide with a deduced molecular mass of 37 kDa. A conserved motif for chitinase activity -F82DGIDIDWE90- was present in deduced amino acid sequence. Both RT-PCR and Northern analysis revealed that the expression of the PjChi gene was constitutive at low level, but enhanced to high level when chitin was the substrate. Fungal inhibitory assay showed that PjChi-1 inhibited the growth of phytopathogenic fungi such as Sclerotium rolfsii, Colletotrichum gloeosporioides, Aspergillus nidulans, and Rhizoctonia solani. PMID:17551789

Chen, Chien-Cheng; Kumar, H G Ashok; Kumar, Senthil; Tzean, Shean-Shong; Yeh, Kai-Wun

2007-06-05

313

Antagonistic and antimicrobial activities of some bacterial isolates collected from soil samples.  

PubMed

Thirty seven bacterial cultures isolated from soil samples obtained from different locations were tested for their antagonistic activity against some fungal pathogens, viz., Sclerotium rolfsii, Fusarium oxysporum and Rhizoctonia solani, causal agents of collar rot of sunflower, wilts and root rots, respectively. Among them, 5 bacterial strains, viz., A1 6 (Bacillus sphaericus), K1 24 (Pseudomonas fluorescens), M1 42 (Bacillus circulans), M1 66 (Bacillus brevis) and T1 22 (Bacillus brevis) showed positive antagonistic activity. M1 66 was the most effective in inhibiting mycelial growth of S. rolfsii in vitro followed by M1 42, T1 22, K1 24 and A1 6. Only one bacterial strain i.e. M1 42 exhibited antagonistic activity against F. oxysporum, and none of the bacterial strains gave positive activity against R. solani. Furthermore, antimicrobial activities of all the 5 strains were checked against different test organisms. These strains showed their extensive inhibition effect particularly against gram-positive test bacteria (Staphylococcus aureus and Bacillus subtilis) and the test fungal strain (Candida albicans). On the other hand, B. brevis M1 66 and B. brevis T1 22 strains had an inhibitory effect against gram positive and gram-negative test bacteria (Escherichia coli and Proteus vulgaris) as well as the test fungal strain. PMID:23100644

Ghai, S; Sood, S S; Jain, R K

2007-06-14

314

Cloning and expression analysis of a chitinase gene Crchi1 from the mycoparasitic fungus Clonostachys rosea (syn. Gliocladium roseum).  

PubMed

Clonostachys rosea (syn. Gliocladium roseum) is a well-known biocontrol agent and widely distributed around the world. In this study, an endochitinase gene Crchi1 was isolated from the mycoparasitic fungus C. rosea using the DNA walking strategy. The Crchi1 ORF is 1,746 bp long and interrupted by three introns. The cloned gene Crchi1 encodes 426 amino acid residues and shares a high degree of similarity with other chitinases from entomopathogenic and mycoparasitic fungi. Several putative binding sites for transcriptional regulation of Crchi1 in response to carbon (5'-SYGGRG-3') and nitrogen (5'-GATA-3') were identified in the upstream of Crchi1. Expression of Crchi1 gene in different carbon sources was analyzed using real-time PCR (RT-PCR). We found that the Crchi1 expression was suppressed by glucose but strongly stimulated by chitin or solubilized components of the cell wall from Rhizoctonia solani. Phylogenetic analysis of chitinases from entomopathogenic and mycoparasitic fungi suggests that these chitinases have probably evolved from a common ancestor. PMID:17978802

Gan, Zhongwei; Yang, Jinkui; Tao, Nan; Yu, Zefen; Zhang, Ke-Qin

2007-10-01

315

DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes  

NASA Astrophysics Data System (ADS)

Few transition metal complexes of tetradentate N2O2 donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL1/KHL2 have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL1/KHL2 are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen (1O2) and superoxide anion radical (O2rad -) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method.

Raman, N.; Sobha, S.; Selvaganapathy, M.; Mahalakshmi, R.

2012-10-01

316

In Vitro Antifungal Activity of Burkholderia gladioli pv. agaricicola against Some Phytopathogenic Fungi  

PubMed Central

The trend to search novel microbial natural biocides has recently been increasing in order to avoid the environmental pollution from use of synthetic pesticides. Among these novel natural biocides are the bioactive secondary metabolites of Burkholderia gladioli pv. agaricicola (Bga). The aim of this study is to determine antifungal activity of Bga strains against some phytopathogenic fungi. The fungicidal tests were carried out using cultures and cell-free culture filtrates against Botrytis cinerea, Aspergillus flavus, Aspergillus niger, Penicillium digitatum, Penicillium expansum, Sclerotinia sclerotiorum and Phytophthora cactorum. Results demonstrated that all tested strains exert antifungal activity against all studied fungi by producing diffusible metabolites which are correlated with their ability to produce extracellular hydrolytic enzymes. All strains significantly reduced the growth of studied fungi and the bacterial cells were more bioactive than bacterial filtrates. All tested Bulkholderia strains produced volatile organic compounds (VOCs), which inhibited the fungal growth and reduced the growth rate of Fusarium oxysporum and Rhizoctonia solani. GC/MS analysis of VOCs emitted by strain Bga 11096 indicated the presence of a compound that was identified as 1-methyl-4-(1-methylethenyl)-cyclohexene, a liquid hydrocarbon classified as cyclic terpene. This compound could be responsible for the antifungal activity, which is also in agreement with the work of other authors.

Elshafie, Hazem S.; Camele, Ippolito; Racioppi, Rocco; Scrano, Laura; Iacobellis, Nicola S.; Bufo, Sabino A.

2012-01-01

317

[Screening, identification, and biocontrol effect of antagonistic bacteria against Phytophthora capsici].  

PubMed

A total of 98 isolates with antagonistic activity against Phytophthora capsici were isolated from the rhizosphere soil of healthy pepper plants in the fields seriously infected by pepper Phytophthora capsicit, and two strains named as HL-3 and LZ-8 were screened, which had the characteristics of wide-spectrum antagonism and good growth under poor soil condition. The HL-3 and LZ-8 were identified as Paenibacillus polymyxa and Bacillus pumilus, respectively, based on their morphological and biochemical characteristics and 16S rDNA sequences. The two strains could inhibit the mycelium growth of P. capsici, and the inhibitory effect of HL-3 and LZ-8 was 72% and 68%, respectively. The two strains also had antifungal activities toward other plant pathogens such as Verticillium dahliae, Fusarium oxysporum f. sp. cucumerinum, F. oxysporum f. sp. vasinfectum, Rhizoctonia solani, Phtophthora parasitica var. nicotiana, and Ralstonia solanacearum. Pot experiment showed that the biocontrol effects of HL-3 and LZ-8 against P. capsici at the seedling stage of pepper were 72% and 83%, respectively, and both of the strains had significant growth-promoting effect on pepper plants. PMID:21328956

Mei, Xin-lan; Zhao, Qing-yun; Tan, Shi-yong; Xu, Yang-chun; Shen, Biao; Shen, Qi-rong

2010-10-01

318

Endophytic bacterial communities in ginseng and their antifungal activity against pathogens.  

PubMed

Plant roots are associated with diverse communities of endophytic bacteria which do not exert adverse effects. The diversity of bacterial endophytes associated with ginseng roots cultivated in three different areas in Korea was investigated. Sixty-three colonies were isolated from the interior of ginseng roots. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates belonged to three major phylogenetic groups: the high G+C Gram-positive bacteria (HGCGPB), low G+C Gram-positive bacteria (LGCGPB), and the Proteobacteria. The dominant species at the three different ginseng growing areas were: HGCGPB at Ganghwa (55.0%), LGCGPB at Geumsan (45.5%), and Proteobacteria at Jinan (61.9%). Most cellulase-, xylanase-, and pectinase-producing colonies among the isolates belong to the LGCGPB group, except for Pectobacterium carotovora which belonged to the Proteobacteria. The 13 isolates belonging to LGCGPB and Proteobacteria were assessed for their antifungal activity against phytopathogenic fungi such as Rhizoctonia solani. Among them, Paenibacillus polymyxa GS01, Bacillus sp. GS07, and Pseudomonas poae JA01 show potential activity as biocontrol agents against phytopathogenic fungi. Finally, most of the low G+C Gram-positive bacteria with antifungal activity against phytopathogenic microorganisms showed cellulolytic enzyme activity while some Proteobacteria with the antifungal activity and the high G+C Gram-positive bacteria did not show any cellulolytic activity. PMID:17492474

Cho, Kye Man; Hong, Su Young; Lee, Sun Mi; Kim, Yong Hee; Kahng, Goon Gjung; Lim, Yong Pyo; Kim, Hoon; Yun, Han Dae

2007-05-11

319

Arbuscular mycorrhizal fungal spores host bacteria that affect nutrient biodynamics and biocontrol of soil-borne plant pathogens  

PubMed Central

Summary The aim of this research was to isolate and characterize bacteria from spores of arbuscular mycorrhizal fungi (AMF). We designated these bacteria ‘probable endobacteria’ (PE). Three bacterial strains were isolated from approximately 500 spores of Gigaspora margarita (Becker and Hall) using a hypodermic needle (diameter, 200??m). The bacteria were identified by morphological methods and on the basis of ribosomal gene sequences as Bacillus sp. (KTCIGM01), Bacillus thuringiensis (KTCIGM02), and Paenibacillus rhizospherae (KTCIGM03). We evaluated the effect of these probable endobacteria on antagonistic activity to the soil-borne plant pathogens (SBPPs) Fusarium oxysporum f. sp. lactucae MAFF 744088, Rosellinia necatrix, Rhizoctonia solani MAFF 237426, and Pythium ultimum NBRC 100123. We also tested whether these probable endobacteria affected phosphorus solubilization, ethylene production, nitrogenase activity (NA), and stimulation of AMF hyphal growth. In addition, fresh samples of spores and hyphae were photographed using an in situ scanning electron microscope (SEM) (Quanta 250FEG; FEI Co., Japan). Bacterial aggregates (BAs), structures similar to biofilms, could be detected on the surface of hyphae and spores. We demonstrate that using extraction with an ultrathin needle, it is possible to isolate AMF-associated bacterial species that are likely derived from inside the fungal spores.

Cruz, Andre Freire; Ishii, Takaaki

2012-01-01

320

Increased virulence of transgenic Trichoderma koningi strains to the Asian corn borer larvae by overexpressing heterologous chit42 gene with chitin-binding domains.  

PubMed

The chit42 gene cloned from Metarhizium anisopliae lacks chitin-binding domain (chBD), which plays important roles in binding insoluble chitin. Five kinds of hybrid chitinase Trichoderma transformants were constructed in this study, where the chit42 gene was fused to chBDs derived from plant, bacterial, and insect sources. The transformant Mc4 harboring chBDs from bitter melon (Momordica charantia) displayed the highest chitinase activity among all chBDs. The chitinase activities of Mc4, chit42 Trichoderma transformant Mchit3, and wild-type strain T30 were 44.94, 32.48, and 12.38 U/mL, respectively. The mortality rate of corn borer larvae in Mc4 fermentation liquid treatment increased by 10% and 30% compared with Mchit3 and T30, respectively. The midgut microvilli and goblet cell microvilli of the corn borer larvae exhibited distinct pathological changes after 48 h of feeding in Mc4 treatment. Mc4 also exhibited the strongest antifungal activity against Fusarium verticillioides and Rhizoctonia solani. PMID:23431975

Li, Yingying; Fu, Kehe; Gao, Shigang; Wu, Qiong; Fan, Lili; Li, Yaqian; Chen, Jie

2013-01-01

321

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10  

PubMed Central

Summary Xanthomonas campestris is a phytopathogenic bacterium and causes many diseases of agricultural relevance. Volatiles were shown to be important in inter- and intraorganismic attraction and defense reactions. Recently it became apparent that also bacteria emit a plethora of volatiles, which influence other organisms such as invertebrates, plants and fungi. As a first step to study volatile-based bacterial–plant interactions, the emission profile of Xanthomonas c. pv. vesicatoria 85-10 was determined by using GC/MS and PTR–MS techniques. More than 50 compounds were emitted by this species, the majority comprising ketones and methylketones. The structure of the dominant compound, 10-methylundecan-2-one, was assigned on the basis of its analytical data, obtained by GC/MS and verified by comparison of these data with those of a synthetic reference sample. Application of commercially available decan-2-one, undecan-2-one, dodecan-2-one, and the newly synthesized 10-methylundecan-2-one in bi-partite Petri dish bioassays revealed growth promotions in low quantities (0.01 to 10 ?mol), whereas decan-2-one at 100 ?mol caused growth inhibitions of the fungus Rhizoctonia solani. Volatile emission profiles of the bacteria were different for growth on media (nutrient broth) with or without glucose.

Weise, Teresa; Kai, Marco; Gummesson, Anja; Troeger, Armin; von Reuss, Stephan; Piepenborn, Silvia; Kosterka, Francine; Sklorz, Martin; Zimmermann, Ralf; Francke, Wittko

2012-01-01

322

DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes.  

PubMed

Few transition metal complexes of tetradentate N(2)O(2) donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL(1)/KHL(2) have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL(1)/KHL(2) are found to act as tetradentate ligands using N(2)O(2) donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen ((1)O(2)) and superoxide anion radical (O(2)(-)) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method. PMID:22885083

Raman, N; Sobha, S; Selvaganapathy, M; Mahalakshmi, R

2012-07-20

323

Rice phosphate transporters include an evolutionarily divergent gene specifically activated in arbuscular mycorrhizal symbiosis  

PubMed Central

Using a genome-wide approach, we asked how many transporter genes contribute to symbiotic phosphate uptake and analyzed their evolutionary conservation. Considering the sequenced rice genome at hand, only the Oryza sativa phosphate transporter (OsPT) gene OsPT11 was specifically induced during the arbuscular mycorrhizal symbiosis. This induction was confined to the root system and was tightly correlated with the degree of root colonization by Glomus intraradices. OsPT11 activation was independent of the nutritional status of the plant and phosphate availability in the rhizosphere. Moreover, infection of roots with the fungal pathogens Rhizoctonia solani and Fusarium moniliforme did not activate OsPT11, corroborating the high signal specificity for OsPT11 activation in the arbuscular mycorrhizal symbiosis. OsPT11 expression complemented a defect in phosphate uptake in a yeast strain mutated in its high-affinity Pi transporter (pho84), thereby confirming its function. Recently, a phosphate transporter gene in potato was shown to be induced during arbuscular mycorrhizal symbiosis. Assessment of the phylogenetic relationship of the rice and potato protein revealed that the rice is nonorthologous to the potato protein. Further, there are no structural commonalities in the promoter regions. Thus, although cytological and physiological features of the arbuscular mycorrhizal symbiosis seem to be conserved, the molecular components may differ significantly between distantly related plant species.

Paszkowski, Uta; Kroken, Scott; Roux, Christophe; Briggs, Steven P.

2002-01-01

324

Ocatin. A novel tuber storage protein from the andean tuber crop oca with antibacterial and antifungal activities.  

PubMed

The most abundant soluble tuber protein from the Andean crop oca (Oxalis tuberosa Mol.), named ocatin, has been purified and characterized. Ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kD and an isoelectric point of 4.8. This protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. Ocatin inhibits the growth of several phytopathogenic bacteria (Agrobacterium tumefaciens, Agrobacterium radiobacter, Serratia marcescens, and Pseudomonas aureofaciens) and fungi (Phytophthora cinnamomi, Fusarium oxysporum, Rhizoctonia solani, and Nectria hematococcus). Ocatin displays substantial amino acid sequence similarity with a widely distributed group of intracellular pathogenesis-related proteins with a hitherto unknown biological function. Our results showed that ocatin serves as a storage protein, has antimicrobial properties, and belongs to the Betv 1/PR-10/MLP protein family. Our findings suggest that an ancient scaffolding protein was recruited in the oca tuber to serve a storage function and that proteins from the Betv 1/PR-10/MLP family might play a role in natural resistance to pathogens. PMID:11950978

Flores, Teresita; Alape-Girón, Alberto; Flores-Díaz, Marietta; Flores, Hector E

2002-04-01

325

Broad-spectrum antimicrobial activity in vitro of the synthetic peptide D4E1.  

PubMed

Broad-spectrum antimicrobial activity of a synthetic peptide, D4E1, is documented in this paper. D4E1 inhibited the growth of several fungal phytopathogens belonging to four classes-Ascomycetes, Basidiomycetes, Deuteromycetes, and Oomycetes, and two bacterial pathogens, Pseudomonas syringae pv. tabaci and Xanthomonas campestris pv. malvacearum race 18. The minimum inhibitory concentration (MIC) of D4E1 required to completely inhibit the growth of all fungi studied ranged from 4.67 to 25 microM. Fungal pathogens highly sensitive to D4E1 include Thielaviopsis basicola, Verticillium dahliae, Fusarium moniliforme, Phytophthora cinnamomi, and Phytophthora parasitica. Comparatively, the least sensitive fungal pathogens were Alternaria alternata, Colletotrichum destructivum, and Rhizoctonia solani. The two bacterial pathogens, P. syringae pv. tabaci and X. campestris pv. malvacearum race 18, were most sensitive to D4E1 with MIC values of 2.25 and 1.25 microM, respectively. Microscopic analysis of D4E1 effects on fungal morphology of Aspergillus flavus and R. solani revealed abnormal hyphal growth and discontinuous cytoplasm. After 8 h of exposure to 25 microM D4E1, A. flavus spore germination was reduced by 75%. The suitability of peptide D4E1 to enhance disease resistance in transgenic crop plants is discussed. PMID:11409968

Rajasekaran, K; Stromberg, K D; Cary, J W; Cleveland, T E

2001-06-01

326

Effect of three organophosphorous nematicides on non-target nematodes and soil microbial community.  

PubMed

The toxicity of three organophosphorous nematicides, imicyafos, fosthiazate and cadusafos, to non-target organisms in soil was evaluated. Imicyafos and fosthiazate had no significant inhibitory effect on the growth of fungal (Fusarium oxysporum f. sp. lactucae, Rhizoctonia solani and Trichoderma viride) and bacterial (Ralstonia solanacearum and Pseudomonas fluorescens) strains in media at 12.5 to 200 mg L(-1). Cadusafos, however, significantly inhibited the growth of all these strains except R. solanacearum. A pot test was conducted using a soil naturally infested with Pratylenchus penetrans, and treated with imicyafos or fosthiazate, which are less toxic to non-target organisms. The density of P. penetrans decreased to less than 10% of the control level after exposure to imicyafos and fosthiazate at 3 kg active ingredient ha(-1), the conventional dose. No significant effect was observed on the density of free-living nematodes, cellulose decomposition activity, microbial biomass evaluated with the ATP method and number of ammonia oxidizers between the soil treated with imicyafos or fosthiazate and the untreated control soil. Our results revealed that imicyafos and fosthiazate effectively suppressed a plant-parasitic nematode, P. penetrans, but had little impact on free-living nematodes and the soil microbial community. PMID:21558727

Wada, Satoko; Toyota, Koki

2008-01-01

327

Antimicrobial Constituents of the Leaves of Mikania micrantha H. B. K  

PubMed Central

Background To isolate plant-derived compounds with antimicrobial activity from the leaves of Mikania micrantha, to determine the compounds configuration, and to evaluate their antimicrobial activity against eight plant pathogenic fungi (Exserohilum turcicum, Colletotrichum lagenarium, Pseudoperonispora cubensis, Botrytis cirerea, Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, and Pythium aphanidermatum,) and four plant pathogenic bacteria (gram negative bacteria: Ralstonia dolaanacearum, Xanthomonas oryzae pv. Oryzae, Xanthomonas Campestris pv. Vesicatoria, and Xanthomonas campestris pv. Citri), and four bacteria (gram positive bacteria: Staphyloccocus aureus, Bacillus subtilis, Micrococcus luteus, and Bacillus cereus). Methods and Results Antimicrobial constituents of the leaves of M. micrantha were isolated using bioactivity- guided fractionation. The antifungal activity of the isolated compounds was evaluated by the inhibit hypha growth method and inhibit spore germination method. Characterization of antibacterial activity was carried out using the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs). MIC and MBC were determined by the broth microdilution method. Six compounds – deoxymikanolide, scandenolide, dihydroscandenolide, mikanolide, dihydromikanolide, and m - methoxy benzoic acid – have been isolated from leaves of Mikania micrantha H. B. K. Deoxymikanolide, scandenolide, and dihydroscandenolide were new compounds. The result of bioassay showed that all of isolated compounds were effective against tested strains and deoxymikanolide showed the strongest activity. Conclusions and Significance The leaves of M. micrantha may be a promising source in the search for new antimicrobial drugs due to its efficacy and the broadest range. Meanwhile, adverse impact of M. micrantha will be eliminated.

Wang, Xia-xia; Cao, Ao-cheng

2013-01-01

328

Characterization of the volatile constituents in the essential oil of Pistacia lentiscus L. from different origins and its antifungal and antioxidant activity.  

PubMed

Essential oil (EO) from aerial parts (leaves, juvenile branches, and flowers when present) of Pistacia lentiscus L. growing wild in five localities of Sardinia (Italy) was extracted by steam-distillation (SD) and analyzed by gas chromatography (GC), FID, and GC-ion trap mass spectrometry (ITMS). Samples of P. lentiscus L. were harvested between April and October to study the seasonal chemical variability of the EO. A total of 45 compounds accounting for 97.5-98.4% of the total EO were identified, and the major compounds were alpha-pinene (14.8-22.6%), beta-myrcene (1-19.4%), p-cymene (1.6-16.2%), and terpinen-4-ol (14.2-28.3%). The yields of EO (v/dry w) ranged between 0.09 and 0.32%. Similar content of the major compounds was found in samples from different origins and seasonal variability was also observed. The EOs were tested for their antifungal activity against Aspergillus flavus, Rhizoctonia solani, Penicillium commune, Fusarium oxysporum. Two samples were weakly effective against Aspergillus flavus. Furthermore, terpinenol and alpha-terpineol, two of the major components of EO of Pistacia lentiscus L., totally inhibited the mycelian growth of A. flavus. Quite good antioxidant activity of the EO was also found. PMID:17658828

Barra, Andrea; Coroneo, Valentina; Dessi, Sandro; Cabras, Paolo; Angioni, Alberto

2007-07-21

329

Statistical optimization of medium components for production of extracellular chitinase by Basidiobolus ranarum: a novel biocontrol agent against plant pathogenic fungi.  

PubMed

The influence of concentration of medium components such as colloidal chitin, lactose, malt extract, yeast extract, and peptone on the chitinase production from Basidiobolous ranarum at the flask level were studied by using statistical tool Central Composite Design (CCD) and analysed by Response Surface Methodology (RSM). The results revealed that colloidal chitin, malt extract and peptone had significant effect (P < 0.01) on the chitinase production at their individual levels. The polynomial equation of the model developed incorporates 3 linear, 3 quadratic and 5 interactive terms. Maximum chitinase production of 3.47 U ml(-1) was achieved with 1.5% colloidal chitin, 0.125% lactose, 0.025% malt extract and 0.075% peptone. After optimization, chitinase activity was increased by 7.71 fold. A second order polynomial equation was found to be useful for the development of efficient bioprocess for chitinase production. To screen the biotechnological potential of this enzyme, degradation of fungal mycelia by ammonium sulphate precipitate of the same was studied for several pathogenic fungi-in vitro which showed promising results particularly against Rhizoctonia solani and Fusarium solani. This study provides the first evidence showing the effectiveness of RSM for the development of a robust statistical model for the chitinase production by Basidiobolus and for its application in the biocontrol of phytopathogenic fungi. PMID:22359366

Mishra, P; Kshirsagar, P R; Nilegaonkar, S S; Singh, S K

2012-02-23

330

Selection of available suicide vectors for gene mutagenesis using chiA (a chitinase encoding gene) as a new reporter and primary functional analysis of chiA in Lysobacter enzymogenes strain OH11.  

PubMed

Here, three different suicide vectors were evaluated for the possibility of performing gene mutagenesis in strain OH11 using the chiA gene (accession number: DQ888611) as a new reporter. Suicide vector pEX18GM was selected, and it was successfully applied for disruption and in-frame deletions in the chiA gene in strain OH11, which was confirmed by PCR amplification and Southern hybridization. The chiA-deletion mutant OH11-3 did not have the ability to produce chitinase on chitine selection medium. Interestingly, the chiA-deletion mutants displayed wild-type antimicrobial activity against Saccharomyces cerevisiae, Magnaporthe grisea, Phytophthora capsici, Rhizoctonia solani, Sclerotinia sclerotiorum and Pythium ultimum. Our data suggest that chitinase might not be a unique lytic enzyme in controlling S. cerevisiae, M. grisea, P. capsici, and P. ultimum. R. solani, S. sclerotiorum. Also, suicide vector pEX18GM might be explored as a potential tool for gene deletions in L. enzymogenes, which will facilitate the molecular study of mechanisms of biological control in L. enzymogenes. PMID:22806850

Qian, Guoliang; Wang, Yansheng; Qian, Dongyu; Fan, Jiaqin; Hu, Baishi; Liu, Fengquan

2011-07-17

331

Indigenous populations of three closely related Lysobacter spp. in agricultural soils using real-time PCR.  

PubMed

Previous research had shown that three closely related species of Lysobacter, i.e., Lysobacter antibioticus, Lysobacter capsici, and Lysobacter gummosus, were present in different Rhizoctonia-suppressive soils. However, the population dynamics of these three Lysobacter spp. in different habitats remains unknown. Therefore, a specific primer-probe combination was designed for the combined quantification of these three Lysobacter spp. using TaqMan. Strains of the three target species were efficiently detected with TaqMan, whereas related non-target strains of Lysobacter enzymogenes and Xanthomonas campestris were not or only weakly amplified. Indigenous Lysobacter populations were analyzed in soils of 10 organic farms in the Netherlands during three subsequent years with TaqMan. These soils differed in soil characteristics and crop rotation. Additionally, Lysobacter populations in rhizosphere and bulk soil of different crops on one of these farms were studied. In acid sandy soils low Lysobacter populations were present, whereas pH neutral clay soils contained high populations (respectively, <4.0-5.87 and 6.22-6.95 log gene copy numbers g(-1) soil). Clay content, pH and C/N ratio, but not organic matter content in soil, correlated with higher Lysobacter populations. Unexpectedly, different crops did not significantly influence population size of the three Lysobacter spp. and their populations were barely higher in rhizosphere than in bulk soil. PMID:21448673

Postma, Joeke; Schilder, Mirjam T; van Hoof, Richard A

2011-03-30

332

Effects of plant genotype and growth stage on the structure of bacterial communities associated with potato (Solanum tuberosum L.).  

PubMed

The effects of genotype, plant growth and experimental factors (soil and year) on potato-associated bacterial communities were studied. Cultivars Achirana Inta, Désirée, Merkur and transgenic Désirée line DL12 (containing T4 lysozyme gene) were assessed in two field experiments. Cross-comparisons between both experiments were made using Désirée plants. Culture-dependent and -independent approaches were used to demonstrate effects on total bacterial, actinobacterial and Pseudomonas communities in bulk and rhizosphere soils and endospheres. PCR-denaturing gradient gel electrophoresis fingerprints prepared with group-specific primers were analyzed using multivariate analyses and revealed that bacterial communities in Achirana Inta plants differed most from those of Désirée and Merkur. No significant effects were found between Désirée and DL12 lines. Plant growth stage strongly affected different plant-associated communities in both experiments. To investigate the effect of plant-associated communities on plant health, 800 isolates from rhizospheres and endospheres at the flowering stage were tested for suppression of Ralstonia solanacearum biovar 2 and/or Rhizoctonia solani AG3. A group of isolates closely resembling Lysobacter sp. dominated in young plants. Its prevalence was affected by plant growth stage and experiment rather than by plant genotype. It was concluded that plant growth stage overwhelmed any effect of plant genotype on the bacterial communities associated with potato. PMID:18355298

van Overbeek, Leo; van Elsas, Jan Dirk

2008-03-18

333

Purification and characterization of an antifungal protein, C-FKBP, from Chinese cabbage.  

PubMed

An antifungal protein was isolated from Chinese cabbage (Brassica campestris L. ssp. pekinensis) by buffer-soluble extraction and two chromatographic procedures. The results of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry revealed that the isolated Chinese cabbage protein was identical to human FK506-binding protein (FKBP). A cDNA encoding FKBP was isolated from a Chinese cabbage leaf cDNA library and named C-FKBP. The open reading frame of the gene encoded a 154-amino acid polypeptide. The amino acid sequence of C-FKBP exhibits striking degrees of identity with the corresponding mouse (61%), human (60%), and yeast (56%) proteins. Genomic Southern blot analyses using the full-length C-FKBP cDNA probe revealed a multigene family in the Chinese cabbage genome. The C-FKBP mRNA was highly expressed in vegetative tissues. We also analyzed the antifungal and peptidyl-prolyl cis-trans isomerase activity of recombinant C-FKBP protein expressed in Escherichia coli. This protein inhibited pathogenic fungal strains, including Candida albicans, Botrytis cinerea, Rhizoctonia solani, and Trichoderma viride, whereas it exhibited no activity against E. coli and Staphylococcus aureus. These results suggest that recombinant C-FKBP is an excellent candidate as a lead compound for the development of antifungal agents. PMID:17550265

Park, Seong-Cheol; Lee, Jung Ro; Shin, Sun-Oh; Jung, Ji Hyun; Lee, Young Mee; Son, Hyosuk; Park, Yoonkyung; Lee, Sang Yeol; Hahm, Kyung-Soo

2007-06-06

334

The Effect of Heterogeneity on Invasion in Spatial Epidemics: From Theory to Experimental Evidence in a Model System  

PubMed Central

Heterogeneity in host populations is an important factor affecting the ability of a pathogen to invade, yet the quantitative investigation of its effects on epidemic spread is still an open problem. In this paper, we test recent theoretical results, which extend the established “percolation paradigm” to the spread of a pathogen in discrete heterogeneous host populations. In particular, we test the hypothesis that the probability of epidemic invasion decreases when host heterogeneity is increased. We use replicated experimental microcosms, in which the ubiquitous pathogenic fungus Rhizoctonia solani grows through a population of discrete nutrient sites on a lattice, with nutrient sites representing hosts. The degree of host heterogeneity within different populations is adjusted by changing the proportion and the nutrient concentration of nutrient sites. The experimental data are analysed via Bayesian inference methods, estimating pathogen transmission parameters for each individual population. We find a significant, negative correlation between heterogeneity and the probability of pathogen invasion, thereby validating the theory. The value of the correlation is also in remarkably good agreement with the theoretical predictions. We briefly discuss how our results can be exploited in the design and implementation of disease control strategies.

Neri, Franco M.; Bates, Anne; Fuchtbauer, Winnie S.; Perez-Reche, Francisco J.; Taraskin, Sergei N.; Otten, Wilfred; Bailey, Douglas J.; Gilligan, Christopher A.

2011-01-01

335

Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes  

PubMed Central

New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml.

Sakthivel, A.; Rajasekaran, K.

2007-01-01

336

Antagonistic and plant growth activity of Trichoderma isolates of Western Himalayas.  

PubMed

The genus Trichoderma is rapidly growing colonies bearing tufted or postulate, repeatedly branched conidiophores with lageniform phialides and hyaline or green conidia born in slimy heads. 62 isolates of Trichoderma species were isolated from different rhizospheric soil samples collected from different places located in Western Himalayas region. Out of these only two species were found i.e. Trichoderma hazianum and Trichoderma viride. Their efficacy against soil borne plant pathogens like Sclerotium rolfsii, Rhizoctonia solani and Sclerotinia sclerotiorum revealed that only three isolates amounting to 5% of the total collected isolates of this region were found highly antagonist. Among them 5% isolates were found against S. rolfsii, 13% isolates against R. solani, 10% against sclerotium caused above 80% inhibition of mycelial growth respectively. 6% isolates out of twenty seven utilized chitin by more than 80 and 16% isolates consumed cellulose by above 80% and therefore are producers of chitinase and cellulases. 58% isolates produced colonies having cottony texture and 41% produced dark green colonies. Pigmentation as observed from reverse side of the colony revealed that 70% of them did not produced pigment in the medium. Plant growth promotion measured as root and shoot lengths were significantly higher than in control. The maximum root length and shoot length were recorded when seeds were treated with isolates were recorded at Srinagar Garhwal was 4.70 and 4.75 cm out of all the isolates in which isolate recorded from Srinagar no 3 caused maximum percent seed germination which was significantly higher 79.49%. PMID:21506476

Joshi, B B; Bhatt, R P; Bahukhandi, D

2010-11-01

337

Characterization of a newly identified rice chitinase-like protein (OsCLP) homologous to xylanase inhibitor  

PubMed Central

Background During rice blast fungal attack, plant xylanase inhibitor proteins (XIPs) that inhibit fungal xylanase activity are believed to act as a defensive barrier against fungal pathogens. To understand the role of XIPs in rice, a xylanase inhibitor was cloned from rice. The expression of this gene was examined at the transcriptional/translational levels during compatible and incompatible interactions, and the biochemical activity of this protein was also examined. Results Sequence alignment revealed that the deduced amino acid sequence of OsCLP shares a high degree of similarity with that of other plant TAXI-type XIPs. However, recombinant OsCLP did not display inhibitory activity against endo-1,4-?-xylanase enzymes from Aureobasidium pullulans (A. pullulans) or Trichoderma viride (T. viride). Instead, an in-gel activity assay revealed strong chitinase activity. The transcription and translation of OsCLP were highly induced when rice was exposed to pathogens in an incompatible interaction. In addition, exogenous treatment with OsCLP affected the growth of the basidiomycete fungus Rhizoctonia solani through degradation of the hyphal cell wall. These data suggest that OsCLP, which has chitinase activity, may play an important role in plant defenses against pathogens. Conclusions Taken together, our results demonstrate that OsCLP may have antifungal activity. This protein may directly inhibit pathogen growth by degrading fungal cell wall components through chitinase activity.

2013-01-01

338

Fusant Trichoderma HF9 with enhanced extracellular chitinase and protein content.  

PubMed

Strain improvement was carried out to obtain higher chitinase and protein by inter-specific protoplast fusion between Trichoderma harzianum and Trichoderma viride. Fusant HF9 and parental strains of Trichoderma were compared for chitinase and protein production. 1% of glucose, sucrose and fungal cell wall (Rhizoctonia solani), were used as carbon source for cultivation of Trichoderma and fungal cell wall was the best to induce chitinase and protein. Usage of 0.5% colloidal chitin for the fungal growth under aerated conditions at pH 6.5 and 28 degrees C led to higher chitinase and protein production. In these conditions fusant Trichoderma HF9 in comparison with parent strains had 3-, 2.5- and 1.5-fold increase of total chitinase, specific chitinase and protein, respectively. SDS-PAGE analysis revealed that it had 9 major protein bands with up-regulation compared to parent strains. Amino acid analysis showed that protein of culture filtrate of T. harzianum, T. viride and fusant Trichoderma HF9 had 8, 6 and 10 amino acids, respectively. The results obtained suggested that fusant HF9 could be an integration of T. harzianum and T. viride through protoplast fusion. PMID:23035579

Balasubramanian, N; Priya, V Thamil; Gomathinayagam, S; Lalithakumari, D

339

Evaluation of the potential of Trichoderma viride in the control of fungal pathogens of Roselle (Hibiscus sabdariffa L.) in vitro.  

PubMed

The potential of Trichoderma viride as a bio-control agent was evaluated in vitro against Roselle pathogens i.e. Phoma exigua, Fusarium nygamai and Rhizoctonia solani[1] using the dual culture technique. Volatile and non-volatile inhibitors of Trichoderma were also evaluated for this purpose. T. viride[2] was shown to have a marked inhibitory effect on the tested pathogens in vitro. Maximum inhibition occurred against P. exigua, with 71.76% reduction in mycelial radial growth. The three pathogens, P. exigua, F. nygamai and R. solani were also found to be susceptible to the volatile inhibitors produced by T. viride, giving rise to growth inhibition of about 68% in each case. When T. viride non-volatile metabolites were tested against the pathogens, maximum inhibition occurred against R. solani (73.95% mycelial growth inhibition), followed by P. exigua (37.17% inhibition). The inhibitory effect of the non-volatile metabolites on F. nygamai was, however, minimal. PMID:22261114

Eslaminejad Parizi, T; Ansaria, Mehdi; Elaminejad, Tahereh

2012-01-12

340

Molecular and phenotypic characterization of Sebacina vermifera strains associated with orchids, and the description of Piriformospora williamsii sp. nov.  

PubMed

Sebacinales was described in 2004 and is currently recognized as the earliest diverging lineage of mycorrhizal Basidiomycota. In addition, recent research has demonstrated that no other known fungal order harbours a broader spectrum of mycorrhizal types. Yet because of the character poor morphology of these inconspicuous fungi, a reliable systematic framework for Sebacinales is still out of reach. In order to increase the body of comparative data on Sebacinales, we followed a polyphasic approach using a sampling of seven diverse Sebacinales strains, including several isolates of Australian orchid mycorrhizae, Piriformospora indica, and a multinucleate rhizoctonia isolated from a pot culture of Glomus fasciculatum (Williams 1985) with clover. We performed molecular phylogenetic analyses from candidate barcoding regions [rDNA: internal transcribed spacer (ITS)1-5.8-ITS2, 28S; translation elongation factor 1-? (TEF)], enzymatic profiling, genome size estimation by quantitative polymerase chain reaction (PCR), and karyotype analysis using pulsed field gel electrophoresis. Here, we report significant differences in the physiological and molecular parameters inferred from these morphologically very similar strains. Particularly, our results indicate that intron sequences of the TEF gene are useful markers for Sebacinales at the species level. As a first taxonomic consequence, we describe Piriformospora williamsii as a new member of the so far monotypic genus Piriformospora and show that this genus contains still undescribed species that were recently discovered as endophytes of field-collected specimens of Anthyllis, Medicago, and Lolium in Germany. PMID:22289766

Basiewicz, Magdalena; Weiss, Michael; Kogel, Karl-Heinz; Langen, Gregor; Zorn, Holger; Zuccaro, Alga

2011-11-18

341

Synthesis and antifungal evaluation of (1,2,3-triazol-4-yl)methyl nicotinate chitosan.  

PubMed

With an aim to discover novel chitosan derivatives with significant activities against crop-threatening fungi, (1,2,3-triazol-4-yl)methyl nicotinate chitosan (TAMNCS) was prepared via azide-alkyne click reaction. Its structure was characterized by FT-IR, (1)H NMR, elemental analysis, DSC, and SEM. In vitro antifungal properties of TAMNCS against Rhizoctonia solani Kühn (R. solani), Stemphylium solani weber (S. solani), and Alternaria porri (A. porri) were studied at the concentrations ranged from 0.25mg/mL to 1.0mg/mL. Experiments conducted displayed the derivative had obviously enhanced antifungal activity after chemical modification compared with original chitosan. Moreover, it was shown that TAMNCS can 94.2% inhibit growth of A. porri at 1.0mg/mL, while dose at which the fungicide triadimefon had lower inhibitory index (62.2%). The primary antifungal results described here indicate this derivative may be a promising candidate as an antifungal agent. PMID:23732332

Qin, Yukun; Liu, Song; Xing, Ronge; Li, Kecheng; Yu, Huahua; Li, Pengcheng

2013-05-31

342

Bamboozled again! Inadvertent isolation of fungal rDNA sequences from bamboos (Poaceae: Bambusoideae).  

PubMed

Polymerase chain reaction (PCR) amplification of the nuclear internal transcribed spacer (ITS) and 5.8S regions of rDNA from woody bamboos (Bambuseae) led to the recovery of fungal instead of bamboo sequences under a variety of PCR conditions and irrespective of whether the plant DNA was extracted from fresh leaves or silica gel-dried material. Phylogenetic analyses based on the 5.8S sequences indicated that the fungi were most likely basidiomycetes and that none was an ascomycete. A diverse assemblage of nonascomycetous fungi was isolated from different bamboos, and various fungi coexisted in the same host plant. There was no evidence that closely related fungi consistently associate with closely related host bamboos. Phylogenetic analysis based on 5.8S sequences showed that some fungi were in lineages near Volvariella, Lentinula, Peniophora, and Rhizoctonia, but the insufficiency of basidiomycete and zygomycete ITS sequences in sequence data bases precluded more precise fungal identifications. Bamboo ITS regions were amplified only when fresh leaves were surface sterilized before DNA extraction, suggesting that the fungal associates are epiphyllous rather than endophytic. This study highlights the possibility of inadvertent PCR amplification of contaminating DNAs in molecular phylogenetic studies, particularly when using "universal" amplification primers. PMID:9299225

Zhang, W; Wendel, J F; Clark, L G

1997-10-01

343

Effect of different chemical and mechanical defolation methods on the skin quality of potatoes.  

PubMed

Without foliage destruction an efficient harvest is impossible. Potatoes for the fresh market are often harvested when the foliage is still heavy green due to tuber size and starch content that must be limited. Tubers from immature vines are typically very susceptible to skinning and mechanical injury during harvest. Young tubers from immature vines need more time after foliage destruction to set periderm than tubers from senescent vines where the formation of periderm is already started. Spray schemes based on metoxuron, carfentrazone-ethyl and diquat at a dose of 300 g/ha caused slower leaf and stem desiccation. Over the 3 growing seasons it could be concluded that mechanical foliage destruction in combination with carfentrazone-ethyl + mineral oil promoted periderm formation better than the other desiccation schemes tested. A split treatment with diquat at 300 g/ha or carfentrazone-ehtyl + mineral oil followed by a second application of diquat or carfentrazone-ethyl can led to a slower periderm formation and even give secondary growth. A double treatment of diquat (300 g/ha) or carfentrazone-ethyl + mineral oil followed by diquat (600 g/ha) after 3 days gave satisfactory results. Rhizoctonia tuber infection increased with a longer field period after treatment. In general the increase was more pronounced for the spray schemes where skin set of the tubers was less fast. PMID:15756866

Haesaert, G; Derycke, V; Deroo, B; Latré, J

2004-01-01

344

Production of lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using soybean flour and rice straw as the substrate.  

PubMed

This work was aimed to produce lipopeptides by Bacillus amyloliquefaciens XZ-173 in solid state fermentation using agro-industrial byproducts. A central composite design was used to get the highest lipopeptides production. Results revealed that the optimal conditions for maximum lipopeptides production were 1.79% starch and 1.91% yeast extract by employing 5.58 g soybean flour and 3.67 g rice straw as the solid substrate with initial pH 7.5, moisture content 55% and a 10% inoculum level at 30°C for 2 days. Under these conditions, the experimental yield of lipopeptides reached 50.01 mg/gds, which was very close to the predicted value (49.91 mg/gds). At high concentration, the lipopeptides extracted from fermented substrates showed strong antibiotic activity against Rhizoctonia solani and Ralstonia solanacearum and certain emulsification but good emulsion stability. This is the first report on lipopeptides production that uses rice straw as a major substrate. PMID:22418084

Zhu, Zhen; Zhang, Guoyi; Luo, Yi; Ran, Wei; Shen, Qirong

2012-02-21

345

Comparative Analyses of Exoproteinases Produced by Three Phytopathogenic Microorganisms  

PubMed Central

Proteinases secreted by the oomycete Phytophthora infestans (Mont.) de Bary, Rhizoctonia solani, and Fusarium culmorum belonging to different families of fungi have been studied to determine if the exoenzyme secretion depends on the environmental conditions and the phylogenetic position of the pathogen. The substrate specificity of the extracellular proteinases of F. culmorum, R. solani, and P. infestans and their sensitivity to the action of synthetic and protein inhibitors suggest that they contain trypsin-like and subtilisin-like enzymes regardless of culture medium composition. The relation of trypsin-like and subtilisin-like enzymes is dependent on the culture medium composition, especially on the form of nitrogen nutrition, particularly in the case of the exoenzymes secreted by R. solani. Phylogenetic analyses have shown that the exoproteinase set of ascomycetes and oomycetes has more similarities than basidiomycetes although they are more distant relatives. Our data suggests that the multiple proteinases secreted by pathogenic fungi could play different roles in pathogenesis, increasing the adaptability and host range, or could have different functions in survival in various ecological habitats outside the host.

Valueva, Tatiana A.; Kudryavtseva, Natalia N.; Sof'in, Alexis V.; Revina, Tatiana A.; Gvozdeva, Ekaterina L.; Ievleva, Elena V.

2011-01-01

346

Spoilage of vegetable crops by bacteria and fungi and related health hazards.  

PubMed

After harvest, vegetables are often spoiled by a wide variety of microorganisms including many bacterial and fungal species. The most common bacterial agents are Erwinia carotovora, Pseudomonas spp., Corynebacterium, Xanthomonas campestris, and lactic acid bacteria with E. carotovora being the most common, attacking virtually every vegetable type. Fungi commonly causing spoilage of fresh vegetables are Botrytis cinerea, various species of the genera Alternaria, Aspergillus, Cladosporium, Colletotrichum, Phomopsis, Fusarium, Penicillium, Phoma, Phytophthora, Pythium and Rhizopus spp., Botrytis cinerea, Ceratocystis fimbriata, Rhizoctonia solani, Sclerotinia sclerotiorum, and some mildews. A few of these organisms show a substrate preference whereas others such as Botrytis cinerea, Colletotrichum, Alternaria, Cladosporium, Phytophthora, and Rhizopus spp., affect a wide variety of vegetables causing devastating losses. Many of these agents enter the plant tissue through mechanical or chilling injuries, or after the skin barrier has been broken down by other organisms. Besides causing huge economic losses, some fungal species could produce toxic metabolites in the affected sites, constituting a potential health hazard for humans. Additionally, vegetables have often served as vehicles for pathogenic bacteria, viruses, and parasites and were implicated in many food borne illness outbreaks. In order to slow down vegetable spoilage and minimize the associated adverse health effects, great caution should be taken to follow strict hygiene, good agricultural practices (GAPs) and good manufacturing practices (GMPs) during cultivation, harvest, storage, transport, and marketing. PMID:15839403

Tournas, V H

2005-01-01

347

Anti-fungal activity of cold and hot water extracts of spices against fungal pathogens of Roselle (Hibiscus sabdariffa) in vitro.  

PubMed

Crude extracts of seven spices, viz. cardamom, chilli, coriander, onion, garlic, ginger, and galangale were made using cold water and hot water extraction and they were tested for their anti-fungal effects against the three Roselle pathogens i.e. Phoma exigua, Fusarium nygamai and Rhizoctonia solani using the 'poisoned food technique'. All seven spices studied showed significant anti-fungal activity at three concentrations (10, 20 and 30% of the crude extract) in-vitro. The cold water extract of garlic exhibited good anti-fungal activity against all three tested fungi. In the case of the hot water extracts, garlic and ginger showed the best anti-fungal activity. Of the two extraction methods, cold water extraction was generally more effective than hot water extraction in controlling the pathogens. Against P. exigua, the 10% cold water extracts of galangale, ginger, coriander and cardamom achieved total (100%) inhibition of pathogen mycelial growth. Total inhibition of F. nygamai mycelial growth was similarly achieved with the 10% cold water extracts garlic. Against R. solani, the 10% cold water extract of galangale was effective in imposing 100% inhibition. Accordingly, the 10% galangale extract effectively controlled both P. exigua and R. solani in vitro. None of the hot water extracts of the spices succeeded in achieving 100% inhibition of the pathogen mycelial growth. PMID:22138549

Touba, Eslaminejad Parizi; Zakaria, Maziah; Tahereh, Eslaminejad

2011-11-28

348

Signaling via the Trichoderma atroviride mitogen-activated protein kinase Tmk 1 differentially affects mycoparasitism and plant protection.  

PubMed

Trichoderma atroviride is a mycoparasite of a number of plant pathogenic fungi thereby employing morphological changes and secretion of cell wall degrading enzymes and antibiotics. The function of the tmk 1 gene encoding a mitogen-activated protein kinase (MAPK) during fungal growth, mycoparasitic interaction, and biocontrol was examined in T. atroviride. Deltatmk 1 mutants exhibited altered radial growth and conidiation, and displayed de-regulated infection structure formation in the absence of a host-derived signal. In confrontation assays, tmk 1 deletion caused reduced mycoparasitic activity although attachment to Rhizoctonia solani and Botrytis cinerea hyphae was comparable to the parental strain. Under chitinase-inducing conditions, nag 1 and ech 42 transcript levels and extracellular chitinase activities were elevated in a Deltatmk 1 mutant, whereas upon direct confrontation with R. solani or B. cinerea a host-specific regulation of ech 42 transcription was found and nag 1 gene transcription was no more inducible over an elevated basal level. Deltatmk 1 mutants exhibited higher antifungal activity caused by low molecular weight substances, which was reflected by an over-production of 6-pentyl-alpha-pyrone and peptaibol antibiotics. In biocontrol assays, a Deltatmk 1 mutant displayed a higher ability to protect bean plants against R. solani. PMID:17509915

Reithner, Barbara; Schuhmacher, Rainer; Stoppacher, Norbert; Pucher, Marion; Brunner, Kurt; Zeilinger, Susanne

2007-04-12

349

Diversities in Virulence, Antifungal Activity, Pigmentation and DNA Fingerprint among Strains of Burkholderia glumae  

PubMed Central

Burkholderia glumae is the primary causal agent of bacterial panicle blight of rice. In this study, 11 naturally avirulent and nine virulent strains of B. glumae native to the southern United States were characterized in terms of virulence in rice and onion, toxofalvin production, antifungal activity, pigmentation and genomic structure. Virulence of B. glumae strains on rice panicles was highly correlated to virulence on onion bulb scales, suggesting that onion bulb can be a convenient alternative host system to efficiently determine the virulence of B. glumae strains. Production of toxoflavin, the phytotoxin that functions as a major virulence factor, was closely associated with the virulence phenotypes of B. glumae strains in rice. Some strains of B. glumae showed various levels of antifungal activity against Rhizoctonia solani, the causal agent of sheath blight, and pigmentation phenotypes on casamino acid-peptone-glucose (CPG) agar plates regardless of their virulence traits. Purple and yellow-green pigments were partially purified from a pigmenting strain of B. glumae, 411gr-6, and the purple pigment fraction showed a strong antifungal activity against Collectotrichum orbiculare. Genetic variations were detected among the B. glumae strains from DNA fingerprinting analyses by repetitive element sequence-based PCR (rep-PCR) for BOX-A1R-based repetitive extragenic palindromic (BOX) or enterobacterial repetitive intergenic consensus (ERIC) sequences of bacteria; and close genetic relatedness among virulent but pigment-deficient strains were revealed by clustering analyses of DNA fingerprints from BOX-and ERIC-PCR.

Karki, Hari S.; Shrestha, Bishnu K.; Han, Jae Woo; Groth, Donald E.; Barphagha, Inderjit K.; Rush, Milton C.; Melanson, Rebecca A.; Kim, Beom Seok; Ham, Jong Hyun

2012-01-01

350

Rhizobacteria of Cotton and Their Repression of Seedling Disease Pathogens  

PubMed Central

During the 1983 field season, the rhizobacteria (including organisms from rhizosphere soil and the root rhizoplane) of cotton plants at one location in Mississippi were inventoried at different plant growth stages. Isolates (1,000) were identified to the genus level and characterized for repression of Pythium ultimum and Rhizoctonia solani. Cotton seedlings were initially colonized by bacteria of many different genera, and populations quickly reached 108 CFU/g of root tissue. As the season progressed, the bacterial populations declined as root mass increased and the roots became more woodlike in consistency. Fluorescent pseudomonads were the most numerous gram-negative rhizobacterial isolates of those that were randomly collected and identified, and they provided the largest number of isolates with fungal repressive activity. Several other gram-negative bacterial genera were recovered throughout the growing season, and some gram-positive bacteria were also isolated routinely, but at lower numbers. There was no correlation between the proportion of rhizobacterial isolates that possessed fungal repressive activity and the plant growth stage from which the isolates were obtained. Approximately twice as many bacterial isolates demonstrated fungal repression in the agar assay compared with the inplanta assay, and isolates were found more frequently with fungal repressive activity against P. ultimum than against R. solai.

Hagedorn, C.; Gould, W. D.; Bardinelli, T. R.

1989-01-01

351

Effect of Biocontrol Agent Pseudomonas fluorescens 2P24 on Soil Fungal Community in Cucumber Rhizosphere Using T-RFLP and DGGE  

PubMed Central

Fungi and fungal community play important roles in the soil ecosystem, and the diversity of fungal community could act as natural antagonists of various plant pathogens. Biological control is a promising method to protect plants as chemical pesticides may cause environment pollution. Pseudomonas fluorescens 2P24 had strong inhibitory on Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani, etc., and was isolated from the wheat rhizosphere take-all decline soils in Shandong province, China. However, its potential effect on soil fungal community was still unknown. In this study, the gfp-labeled P. fluorescens 2P24 was inoculated into cucumber rhizosphere, and the survival of 2P24 was monitored weekly. The amount decreased from 108 to 105 CFU/g dry soils. The effect of 2P24 on soil fungal community in cucumber rhizosphere was investigated using T-RFLP and DGGE. In T-RFLP analysis, principle component analysis showed that the soil fungal community was greatly influenced at first, digested with restriction enzyme Hinf I and Taq I. However, there was little difference as digested by different enzymes. DGGE results demonstrated that the soil fungal community was greatly shocked at the beginning, but it recovered slowly with the decline of P. fluorescens 2P24. Four weeks later, there was little difference between the treatment and control. Generally speaking, the effect of P. fluorescens 2P24 on soil fungal community in cucumber rhizosphere was just transient.

Gao, Guanpeng; Yin, Danhan; Chen, Shengju; Xia, Fei; Yang, Jie; Li, Qing; Wang, Wei

2012-01-01

352

Occurrence of arbuscular mycorrhizal fungi in bromeliad species from the tropical Atlantic forest biome in Brazil.  

PubMed

The mycorrhizal status of epiphytic, rupicolous, and terrestrial bromeliad species from the Brazilian Atlantic Rain Forest has been examined. Roots of 13 species of bromeliads were analyzed for the presence of mycorrhizal structures such as arbuscules, hyphae, and vesicles as well as other fungal structures. Rhizosphere soil was sampled to identify arbuscular mycorrhizal fungal (AMF) species associated only with terrestrial bromeliad species. Most specimens collected were epiphytic bromeliads in the genera Aechmea, Bilbergia, Nidularium, Tillandsia, and Vriesea. Differentiating structures of AMF were found in only three species of bromeliads. The pattern of mycorrhizal colonization was mainly internal, and external mycelium and arbuscules were observed only in the terrestrial Nidularium procerum. Root endophytes with dark brown septate mycelium, thin external hyphae, and Rhizoctonia-like sclerotia were also detected in some root segments. A total of ten spore morphotypes were recovered from the rhizosphere of N. procerum, with Acaulospora mellea, A. foveata, and Glomus sp. being the most common species recovered. Our study demonstrated that most of the epiphytic species are not associated with AMF. We attribute this mainly to the exposed bare root conditions found in epiphytic bromeliads. PMID:17151876

Grippa, Carlos Roberto; Hoeltgebaum, Marcia Patricia; Stürmer, Sidney Luiz

2006-12-07

353

Pr-1, a novel antifungal protein from pumpkin rinds.  

PubMed

A novel antifungal protein, M(r) = ca. 40 kDa, was isolated from pumpkin rind and designated Pr-1. When purified by anion exchange chromatography and HPLC, it inhibited growth of several fungi including Botrytis cinerea, Fusarium oxysporum, Fusarium solani and Rhizoctonia solani, as well as the yeast, Candida albicans, at 10-20 microM. It did not inhibit growth of Escherichia coli or Staphylococcus aureus even at 200 microM. Laser scanning microscopy of fungal cells exposed to rhodamine-labeled Pr-1 revealed that the protein accumulated and was localized on the cell surface. Uptake of the vital stain, SYTOX Green, was enhanced when fungal conidia were treated with Pr-1 suggesting that the protein has membrane permeabilization activity. Pr-1 was thermostable at 70 degrees C and did not lyse human red blood cells at 128 microM suggesting that the protein may be useful as an antifungal agent with little, if any human cytotoxicity. PMID:19760117

Park, Seong-Cheol; Lee, Jung Ro; Kim, Jin-Young; Hwang, Indeok; Nah, Jae-Woon; Cheong, Hyeonsook; Park, Yoonkyung; Hahm, Kyung-Soo

2009-09-17

354

A mannose-specific tetrameric lectin with mitogenic and antibacterial activities from the ovary of a teleost, the cobia (Rachycentron canadum).  

PubMed

A tetrameric lectin, with hemagglutinating activity toward rabbit erythrocytes and with specificity toward D-mannosamine and D(+)-mannose, was isolated from the ovaries of a teleost, the cobia Rachycentron canadum. The isolation protocol comprised ion exchange chromatography on CM-cellulose and Q-Sepharose, ion exchange chromatography by fast protein liquid chromatography (FPLC) on Mono Q, and finally gel filtration by FPLC on Superose 12. The lectin was adsorbed on all ion exchangers used. It exhibited a molecular mass of 180 kDa in gel filtration on Superose 12 and a single 45-kDa band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it is a tetrameric protein. The hemagglutinating activity of the lectin was stable up to 40 degrees C and between pH 4 and pH 10. All hemagglutinating activity disappeared at 60 degrees C and at pH 1 and pH 13. The hemagglutinating activity was doubled in the presence of 0.1 microM FeCl3. The lectin exerted antibacterial activity against Escherichia coli with 50% inhibition at 250 microg. There was no antifungal activity toward Coprinus comatus, Fusarium oxysporum, Mycosphaerella arachidicola, and Rhizoctonia solani at a dose of 300 microg. The lectin exhibited maximal mitogenic response from mouse splenocytes at a concentration of 14 microM. PMID:17109173

Ngai, Patrick H K; Ng, T B

2006-11-16

355

Phytophthora capsici Epidemic Dispersion on Commercial Pepper Fields in Aguascalientes, Mexico  

PubMed Central

Chili pepper blight observed on pepper farms from north Aguascalientes was monitored for the presence of Phytophthora capsici during 2008–2010. Initially, ELISA tests were directed to plant samples from greenhouses and rustic nurseries, showing an 86% of positive samples. Later, samples of wilted plants from the farms during the first survey were tested with ELISA. The subsequent survey on soil samples included mycelia isolation and PCR amplification of a 560?bp fragment of ITS-specific DNA sequence of P. capsici. Data was analyzed according to four geographical areas defined by coordinates to ease the dispersal assessment. In general, one-third of the samples from surveyed fields contained P. capsici, inferring that this may be the pathogen responsible of the observed wilt. Nevertheless, only five sites from a total of 92 were consistently negative to P. capsici. The presence of this pathogen was detected through ELISA and confirmed through PCR. The other two-thirds of the negative samples may be attributable to Fusarium and Rhizoctonia, both isolated instead of Phytophthora in these areas. Due to these striking results, this information would be of interest for local plant protection committees and farmers to avoid further dispersal of pathogens to new lands.

Zapata-Vazquez, Adrian; Sanchez-Sanchez, Mario; del-Rio-Robledo, Alicia; Silos-Espino, Hector; Perales-Segovia, Catarino; Flores-Benitez, Silvia; Gonzalez-Chavira, Mario Martin; Valera-Montero, Luis Lorenzo

2012-01-01

356

Detection and assessment of chemical hormesis on the radial growth in vitro of oomycetes and fungal plant pathogens.  

PubMed

Although plant diseases can be caused by bacteria, viruses, and protists, most are caused by fungi and fungus-like oomycetes. Intensive use of fungicides with the same mode of action can lead to selection of resistant strains increasing the risk of unmanageable epidemics. In spite of the integrated use of nonchemical plant disease management strategies, agricultural productivity relies heavily on the use of chemical pesticides and biocides for disease prevention and treatment and sanitation of tools and substrates. Despite the prominent use of fungi in early hormesis studies and the continuous use of yeast as a research model, the relevance of hormesis in agricultural systems has not been investigated by plant pathologists, until recently. A protocol was standardized for detection and assessment of chemical hormesis in fungi and oomycetes using radial growth as endpoint. Biphasic dose-responses were observed in Pythium aphanidermatum exposed to sub-inhibitory doses of ethanol, cyazofamid, and propamocarb, and in Rhizoctonia zeae exposed to ethanol. This report provides an update on chemical hormesis in fungal plant pathogens and a perspective on the potential risks it poses to crop productivity and global food supply. PMID:23983664

Flores, Francisco J; Garzon, Carla D

2012-09-29

357

DNA interaction, antimicrobial, electrochemical and spectroscopic studies of metal(II) complexes with tridentate heterocyclic Schiff base derived from 2?-methylacetoacetanilide  

NASA Astrophysics Data System (ADS)

A new Schiff base ligand (HL) was synthesized by the condensation reaction between 2?-methyleacetoacetanilide and 2-amino-3-hydroxypyridine. Its Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared by the interaction of the ligand with metal(II) chloride. They were characterized by elemental analysis, IR, 1H NMR, EPR, UV-Vis, magnetic susceptibility measurements, conductivity measurements and FAB-mass spectra. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption, viscosity and cyclic voltammetry methods, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. It was found to be oxidative hydroxyl radical cleavage in the presence of 3-mercaptopropionic acid (MPA). The Schiff base and its complexes have been screened for their antibacterial (Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Rhizopus stolonifer, Rhizoctonia bataicola and Candida albicans) activities and the data reveal that the complexes have higher activity than the free ligand.

Raman, Natarajan; Pothiraj, Krishnan; Baskaran, Thanasekaran

2011-08-01

358

First report of a bifunctional chitinase/lysozyme produced by Bacillus pumilus SG2.  

PubMed

Bacillus pumilus SG2 isolated from high salinity ecosystem in Iran produces two chitinases (ChiS and ChiL) and secretes them into the medium. In this study, chiS and chiL genes were cloned in pQE-30 expression vector and were expressed in the cytoplasm of Escherichia coli strain M15. The recombinant proteins were purified using Ni-NTA column. The optimum pH and optimum temperature for enzyme activity of ChiS were pH 6, 50°C; those of ChiL were pH 6.5, 40°C. The purified chitinases showed antifungal activity against Fusarium graminearum, Rhizoctonia solani, Magnaporthe grisea, Sclerotinia sclerotiorum, Trichoderma reesei, Botrytis cinerea and Bipolaris sp. Moreover, purified ChiS was identified as chitinase/lysozyme, which are capable of degrading the chitin component of fungal cell walls and the peptidoglycan component of cell walls with many kinds of bacteria (Xanthomonas translucens pv. hordei, Xanthomonas axonopodis pv. citri, Bacillus licheniformis, E. coli C600, E. coli TOP10, Pseudomonas aeruginosa and Pseudomonas putida). Strong homology was found between the three-dimensional structures of ChiS and a chitinase/lysozyme from Bacillus circulans WL-12. This is the first report of a bifunctional chitinase/lysozyme from B. pumilus. PMID:22112904

Ghasemi, Seyedhadi; Ahmadian, Gholamreza; Sadeghi, Mehdi; Zeigler, Daniel R; Rahimian, Heshmatollah; Ghandili, Soheila; Naghibzadeh, Neda; Dehestani, Ali

2010-11-12

359

Characterization of an endophytic whorl-forming Streptomyces from Catharanthus roseus stems producing polyene macrolide antibiotic.  

PubMed

An endophytic whorl-forming Streptomyces sp. designated as TS3RO having antifungal activity against a large number of fungal pathogens, including Sclerotinia sclerotiorum, Rhizoctonia solani, Colletotrichum gloeosporioides, Cryphonectria parasitica, Fusarium oxysporum, Pyrenophora tritici-repentis, Epidermophyton floccosum, and Trichophyton rubrum, was isolated from surface-sterilized Catharanthus roseus stems. Preliminary identification showed that Streptomyces cinnamoneus subsp. sparsus was its closest related species. However, strain TS3RO could readily be distinguished from this species using a combination of phenotypic properties, 16S rDNA sequence similarity, and phylogenetic analyses. Thus, the whorl-forming Streptomyces sp. strain TS3RO is likely a new subspecies within the Streptomyces cinnamoneus group. Direct bioautography on a thin-layer chromatography plate with Cladosporium cucumerinum was conducted throughout the purification steps for bioassay-guided isolation of the active antifungal compounds from the crude extract. Structural elucidation of the isolated bioactive compound was obtained via LC-MS spectrometry, UV-visible spectra, and nuclear magnetic resonance data. It revealed that fungichromin, a known methylpentaene macrolide antibiotic, was the main antifungal component of TS3RO strain, as shown by thin-layer chromatography bioautography. This is the first report of an endophytic whorl-forming Streptomyces isolated from the medically important plant Catharanthus roseus. PMID:22524528

Rakotoniriana, Erick Francisco; Chataigné, Gabrielle; Raoelison, Guy; Rabemanantsoa, Christian; Munaut, Françoise; El Jaziri, Mondher; Urveg-Ratsimamanga, Suzanne; Marchand-Brynaert, Jacqueline; Corbisier, Anne-Marie; Declerck, Stéphane; Quetin-Leclercq, Joëlle

2012-04-23

360

Identification of Mycoparasitism-Related Genes in Trichoderma atroviride ? † ‡  

PubMed Central

A high-throughput sequencing approach was utilized to carry out a comparative transcriptome analysis of Trichoderma atroviride IMI206040 during mycoparasitic interactions with the plant-pathogenic fungus Rhizoctonia solani. In this study, transcript fragments of 7,797 Trichoderma genes were sequenced, 175 of which were host responsive. According to the functional annotation of these genes by KOG (eukaryotic orthologous groups), the most abundant group during direct contact was “metabolism.” Quantitative reverse transcription (RT)-PCR confirmed the differential transcription of 13 genes (including swo1, encoding an expansin-like protein; axe1, coding for an acetyl xylan esterase; and homologs of genes encoding the aspartyl protease papA and a trypsin-like protease, pra1) in the presence of R. solani. An additional relative gene expression analysis of these genes, conducted at different stages of mycoparasitism against Botrytis cinerea and Phytophthora capsici, revealed a synergistic transcription of various genes involved in cell wall degradation. The similarities in expression patterns and the occurrence of regulatory binding sites in the corresponding promoter regions suggest a possible analog regulation of these genes during the mycoparasitism of T. atroviride. Furthermore, a chitin- and distance-dependent induction of pra1 was demonstrated.

Reithner, Barbara; Ibarra-Laclette, Enrique; Mach, Robert L.; Herrera-Estrella, Alfredo

2011-01-01

361

Plant-parasitic nematodes and fungi associated with root rot of peas on prince edward island.  

PubMed

Eight commercial pea fields on Prince Edward Island were sampled in June and July over a 2-year period (1986-87) to determine soil population densities and the incidence of nematodes and fungi associated with root rot of peas. Root lesion nematodes (Pratylenchus spp.) were the dominant endoparasitic nematodes recovered from roots and soil. Low populations of the northern root-knot nematode (Meloidogyne hapla) were also present. Tylenchorhynchus spp. and Paratylenchus spp. were recovered frequently from soil in the root zone, and Helicotylenchus spp. were also frequent, but in low numbers. Fusarium solani was the most common fungal species isolated from the epicotyl and hypocotyl tissues of pea. Fusarium oxysporum was also isolated frequently, and both Fusarium species were found in soil from all fields. Rhizoctonia solani and Verticillium albo-atrum were common in hypocotyl tissue, but V. dahliae was isolated infrequently. Root rot was rated as severe in all fields and was positively and significantly correlated (P

Celetti, M J; Johnston, H W; Kimpinski, J; Platt, H W

1990-10-01

362

Isolation, selection, and characterization of beneficial rhizobacteria from pea, lentil, and chickpea grown in western Canada.  

PubMed

The use of beneficial soil microorganisms as agricultural inputs for improved crop production requires selection of rhizosphere-competent microorganisms with plant growth-promoting attributes. A collection of 563 bacteria originating from the roots of pea, lentil, and chickpea grown in Saskatchewan was screened for several plant growth-promoting traits, for suppression of legume fungal pathogens, and for plant growth promotion. Siderophore production was detected in 427 isolates (76%), amino-cyclopropane-1-carboxylic acid (ACC) deaminase activity in 29 isolates (5%), and indole production in 38 isolates (7%). Twenty-six isolates (5%) suppressed the growth of Pythium sp. strain p88-p3, 40 isolates (7%) suppressed the growth of Fusarium avenaceum, and 53 isolates (9%) suppressed the growth of Rhizoctonia solani CKP7. Seventeen isolates (3%) promoted canola root elongation in a growth pouch assay, and of these, 4 isolates promoted the growth of lentil and one isolate promoted the growth of pea. Fatty acid profile analysis and 16S rRNA sequencing of smaller subsets of the isolates that were positive for the plant growth-promotion traits tested showed that 39%-42% were members of the Pseudomonadaceae and 36%-42% of the Enterobacteriaceae families. Several of these isolates may have potential for development as biofertilizers or biopesticides for western Canadian legume crops. PMID:18388997

Hynes, Russell K; Leung, Grant C Y; Hirkala, Danielle L M; Nelson, Louise M

2008-04-01

363

Characterization of Bacillus isolates of potato rhizosphere from andean soils of Peru and their potential PGPR characteristics  

PubMed Central

Bacillus spp. are well known rhizosphere residents of many crops and usually show plant growth promoting (PGP) activities that include biocontrol capacity against some phytopatogenic fungi. Potato crops in the Andean Highlands of Peru face many nutritional and phytophatogenic problems that have a significant impact on production. In this context is important to investigate the natural presence of these microorganisms in the potato rhizosphere and propose a selective screening to find promising PGP strains. In this study, sixty three Bacillus strains isolated from the rhizosphere of native potato varieties growing in the Andean highlands of Peru were screened for in vitro antagonism against Rhizoctonia solani and Fusarium solani. A high prevalence (68%) of antagonists against R. solani was found. Ninety one percent of those strains also inhibited the growth of F. solani. The antagonistic strains were also tested for other plant growth promotion activities. Eighty one percent produced some level of the auxin indole-3-acetic acid, and 58% solubilized tricalcium phosphate. Phylogenetic analysis revealed that the majority of the strains belonged to the B. amyloliquefaciens species, while strains Bac17M11, Bac20M1 and Bac20M2 may correspond to a putative new Bacillus species. The results suggested that the rhizosphere of native potatoes growing in their natural habitat in the Andes is a rich source of Bacillus fungal antagonists, which have a potential to be used in the future as PGP inoculants to improve potato crop.

Calvo, Pamela; Ormeno-Orrillo, Ernesto; Martinez-Romero, Esperanza; Zuniga, Doris

2010-01-01

364

Effect of Compost on Rhizosphere Microflora of the Tomato and on the Incidence of Plant Growth-Promoting Rhizobacteria  

PubMed Central

Four commercial composts were added to soil to study their effect on plant growth, total rhizosphere microflora, and incidence of plant growth-promoting rhizobacteria (PGPR) in the rhizosphere of tomato plants. Three of the compost treatments significantly improved plant growth, while one compost treatment significantly depressed it. Compost amendments caused only small variations in the total numbers of bacteria, actinomycetes, and fungi in the rhizosphere of tomato plants. A total of 709 bacteria were isolated from the four compost treatments and the soil control to determine the percentage of PGPR in each treatment. The PGPR tests measured antagonism to soilborne root pathogens, production of indoleacetic acid, cyanide, and siderophores, phosphate solubilization, and intrinsic resistance to antibiotics. Our results show that the addition of some composts to soil increased the incidence in the tomato rhizosphere of bacteria exhibiting antagonism towards Fusarium oxysporum f. sp. radicis-lycopersici, Pyrenochaeta lycopersici, Pythium ultimum, and Rhizoctonia solani. The antagonistic effects observed were associated with marked increases in the percentage of siderophore producers. No significant differences were observed in the percentage of cyanogens, whereas the percentages of phosphate solubilizers and indoleacetic acid producers were affected, respectively, by one and two compost treatments. Intrinsic resistance to antibiotics was only marginally different among the rhizobacterial populations. Our results suggest that compost may stimulate the proliferation of antagonists in the rhizosphere and confirm previous reports indicating that the use of composts in container media has the potential to protect plants from soilborne root pathogens.

de Brito, Alvarez M. A.; Gagne, S.; Antoun, H.

1995-01-01

365

Disruption of the Eng18B ENGase Gene in the Fungal Biocontrol Agent Trichoderma atroviride Affects Growth, Conidiation and Antagonistic Ability  

PubMed Central

The recently identified phylogenetic subgroup B5 of fungal glycoside hydrolase family 18 genes encodes enzymes with mannosyl glycoprotein endo-N-acetyl-?-D-glucosaminidase (ENGase)-type activity. Intracellular ENGase activity is associated with the endoplasmic reticulum associated protein degradation pathway (ERAD) of misfolded glycoproteins, although the biological relevance in filamentous fungi is not known. Trichoderma atroviride is a mycoparasitic fungus that is used for biological control of plant pathogenic fungi. The present work is a functional study of the T. atroviride B5-group gene Eng18B, with emphasis on its role in fungal growth and antagonism. A homology model of T. atroviride Eng18B structure predicts a typical glycoside hydrolase family 18 (??)8 barrel architecture. Gene expression analysis shows that Eng18B is induced in dual cultures with the fungal plant pathogens Botrytis cinerea and Rhizoctonia solani, although a basal expression is observed in all growth conditions tested. Eng18B disruption strains had significantly reduced growth rates but higher conidiation rates compared to the wild-type strain. However, growth rates on abiotic stress media were significantly higher in Eng18B disruption strains compared to the wild-type strain. No difference in spore germination, germ-tube morphology or in hyphal branching was detected. Disruption strains produced less biomass in liquid cultures than the wild-type strain when grown with chitin as the sole carbon source. In addition, we determined that Eng18B is required for the antagonistic ability of T. atroviride against the grey mould fungus B. cinerea in dual cultures and that this reduction in antagonistic ability is partly connected to a secreted factor. The phenotypes were recovered by re-introduction of an intact Eng18B gene fragment in mutant strains. A putative role of Eng18B ENGase activity in the endoplasmic reticulum associated protein degradation pathway of endogenous glycoproteins in T. atroviride is discussed in relation to the observed phenotypes.

Dubey, Mukesh K.; Ubhayasekera, Wimal; Sandgren, Mats; Funck Jensen, Dan; Karlsson, Magnus

2012-01-01

366

Ubiquitous urease affects soybean susceptibility to fungi.  

PubMed

The soybean ubiquitous urease (encoded by GmEu4) is responsible for recycling metabolically derived urea. Additional biological roles have been demonstrated for plant ureases, notably in toxicity to other organisms. However, urease enzymatic activity is not related to its toxicity. The role of GmEu4 in soybean susceptibility to fungi was investigated in this study. A differential expression pattern of GmEu4 was observed in susceptible and resistant genotypes of soybeans over the course of a Phakopsora pachyrhizi infection, especially 24 h after infection. Twenty-nine adult, transgenic soybean plants, representing six independently transformed lines, were obtained. Although the initial aim of this study was to overexpress GmEu4, the transgenic plants exhibited GmEu4 co-suppression and decreased ureolytic activity. The growth of Rhizoctonia solani, Phomopsis sp., and Penicillium herguei in media containing a crude protein extract from either transgenic or non-transgenic leaves was evaluated. The fungal growth was higher in the protein extracts from transgenic urease-deprived plants than in extracts from non-transgenic controls. When infected by P. pachyrhizi uredospores, detached leaves of urease-deprived plants developed a significantly higher number of lesions, pustules and erupted pustules than leaves of non-transgenic plants containing normal levels of the enzyme. The results of the present work show that the soybean plants were more susceptible to fungi in the absence of urease. It was not possible to overexpress active GmEu4. For future work, overexpression of urease fungitoxic peptides could be attempted as an alternative approach. PMID:22382992

Wiebke-Strohm, Beatriz; Pasquali, Giancarlo; Margis-Pinheiro, Márcia; Bencke, Marta; Bücker-Neto, Lauro; Becker-Ritt, Arlete B; Martinelli, Anne H S; Rechenmacher, Ciliana; Polacco, Joseph C; Stolf, Renata; Marcelino, Francismar C; Abdelnoor, Ricardo V; Homrich, Milena S; Del Ponte, Emerson M; Carlini, Celia R; De Carvalho, Mayra C C G; Bodanese-Zanettini, Maria Helena

2012-03-01

367

Muscodor albus E-6, an endophyte of Guazuma ulmifolia making volatile antibiotics: isolation, characterization and experimental establishment in the host plant.  

PubMed

Muscodor albus is an endophytic fungus, represented by a number of isolates from tropical tree and vine species in several of the world's rainforests, that produces volatile organic compounds (VOCs) with antibiotic activity. A new isolate, E-6, of this organism, with unusual biochemical and biological properties, has been obtained from the branches of a mature Guazuma ulmifolia (Sterculiaceae) tree growing in a dry tropical forest in SW Ecuador. This unique organism produces many VOCs not previously observed in other M. albus isolates, including butanoic acid, 2-methyl-; butanoic acid, 3-methyl-; 2-butenal, 2-methyl-; butanoic acid, 3-methylbutyl ester; 3-buten-1-ol, 3-methyl; guaiol; 1-octene, 3-ethyl-; formamide, N-(1-methylpropyl); and certain azulene and naphthalene derivatives. Some compounds usually seen in other M. albus isolates also appeared in the VOCs of isolate E-6, including caryophyllene; phenylethyl alcohol; acetic acid, 2-phenylethyl ester; bulnesene; and various propanoic acid, 2-methyl- derivatives. The biological activity of the VOCs of E-6 appears different from the original isolate of this fungus, CZ-620, since a Gram-positive bacterium was killed, and Sclerotinia sclerotiorum and Rhizoctonia solani were not. Scanning electron micrographs of the mycelium of isolate E-6 showed substantial intertwining of the hyphal strands. These strands seemed to be held together by an extracellular matrix accounting for the strong mat-like nature of the mycelium, which easily lifts off the agar surface upon transfer, unlike any other isolate of this fungus. The ITS-5.8S rDNA partial sequence data showed 99 % similarity to the original M. albus strain CZ-620. For the first time, successful establishment of M. albus into its natural host, followed by recovery of the fungus, was accomplished in seedlings of G. ulmifolia. Overall, isolates of M. albus, including E-6, have chemical, biological and structural characteristics that make them potentially useful in medicine, agricultural and industrial applications. PMID:17660425

Strobel, Gary A; Kluck, Katreena; Hess, Wilford M; Sears, Joe; Ezra, David; Vargas, Percy N

2007-08-01

368

Transfer of a plant chitinase gene into a nitrogen-fixing Azospirillum and study of its expression.  

PubMed

Azospirillum is used extensively in rice and other cereal crops as a biofertilizer. There is a substantial opportunity to improve the efficiency of this bacterium through the transfer of genes of agricultural importance from other organisms. Chitinases are antifungal proteins, and expression of chitinase genes in Azospirillum would help to develop strains with potential antifungal activities. So far there are no reports about transfer of plant genes into Azospirillum and their expression. The present study was aimed at expressing an antifungal gene (a rice chitinase) of plant origin in Azospirillum brasilense. A rice chitinase cDNA (RC 7) that codes for a 35 kDa protein was subcloned into a broad host range plasmid pDSK519 under the control of LacZ promoter. The plasmid was mobilized into the nitrogen-fixing bacterium, Azospirillum brasilense strain SP51eFL1, through biparental mating. The conjugation frequency was in the range of 35-40 x 10(-6). The transconjugants grew in nitrogen-free media and fixed gaseous nitrogen in vitro. However, their growth and nitrogen-fixing ability were slightly less than those of the wild-type. Expression of the protein was demonstrated through western blotting of the total cell protein, which detected a 35 kDa band that was immuno-reactive to a barley chitinase antibody. The cell lysates also hydrolyzed various chitin substrates, which resulted in release of free sugars demonstrating the chitinase activity of transconjugants. The expressed protein also had antifungal activity as demonstrated by inhibition of growth of the plant pathogenic fungus, Rhizoctonia solani. PMID:15381976

Jayaraj, Jayaraman; Muthukrishnan, Subbaratnam; Liang, George H

2004-07-01

369

Fungal diversity, dominance, and community structure in the rhizosphere of clonal Picea mariana plants throughout nursery production chronosequences.  

PubMed

Fungal diversity in the rhizosphere of healthy and diseased clonal black spruce (Picea mariana) plants was analyzed with regard to nursery production chronosequences. The four key production stages were sampled: mother plants (MP), 8-week-old cuttings (B + 0), second-year cuttings (B + 1), and third-year cuttings (B + 2). A total of 45 fungal taxa were isolated and identified based on cultural, phenotypic, and molecular characters. Members of phylum Ascomycota dominated, followed by Basidiomycota and Zygomycota. Diagnosis characters and distance analysis of the internal transcribed spacer rDNA sequences allowed the identification of 39 ascomycetous taxa. Many belong to the order Hypocreales, families Hypocreaceae and Nectriaceae, which contain many clusters of potentially pathogenic taxa (Cylindrocladium, Fusarium, and Neonectria) and are also ecologically associated with antagonistic taxa (Chaetomium, Hypocrea, Microsphaeropsis, Penicillium, Paecilomyces, Verticillium, Trichoderma, and Sporothrix). This is also the first report of a Cylindrocladium canadense association with disease symptoms and relation with Pestalotiopsis, Fusarium, Exserochilum, Rhizoctonia, and Xenochalara fungal consortia. Both production chronosequence and plant health considerably influenced fungal taxa assemblages. Unweighted pair-group arithmetic average clustering showed that isolates from MP, B + 0, and B + 1 plant rhizospheres clustered together within healthy or diseased health classes, whereas isolates from healthy and diseased B + 2 plants clustered together. Canonical correspondence analysis revealed substantial alteration in community assemblages with regard to plant health and yielded a principal axis direction that regrouped taxa associated with diseased plant rhizosphere soil, whereas the opposite axis direction was associated with healthy plants. Two diversity indices were defined and applied to assess the fungal taxa contribution (Tc) and persistence (Pi) throughout the production. PMID:17347891

Vujanovic, V; Hamelin, R C; Bernier, L; Vujanovic, G; St-Arnaud, M

2007-03-09

370

Heterologous expression of an aspartic protease gene from biocontrol fungus Trichoderma asperellum in Pichia pastoris.  

PubMed

Trichoderma asperellum parasitizes a large variety of phytopathogenic fungi. The mycoparasitic activity of T. asperellum depends on the secretion of complex mixtures of hydrolytic enzymes able to degrade the host cell wall and proteases which are a group of enzymes capable of degrading proteins from host. In this study, a full-length cDNA clone of aspartic protease gene, TaAsp, from T. asperellum was obtained and sequenced. The 1,185 bp long cDNA sequence was predicted to encode a 395 amino acid polypeptide with molecular mass of 42.3 kDa. The cDNA of TaAsp was inserted into the pPIC9K vector and transformed into yeast Pichia pastoris GS115 for heterologous expression. A clearly visible band with molecular mass about 42 kDa in the SDS-PAGE gel indicated that the transformant harboring the gene TaAsp had been successfully translated in P. pastoris and produced a recombinant protein. Enzyme characterization test showed that the optimum fermentation time for P. pastoris GS115 transformant was 72 h. Enzyme activity of the recombinant aspartic proteinase remained relatively stable at 25-60 °C and pH 3.0-9.0, which indicated its good prospect of application in biocontrol. The optimal pH value and temperature of the enzyme activity were pH 4.0 and 40 °C, and under this condition, with casein as the substrate, the recombinant protease activity was 18.5 U mL(-1). In order to evaluate antagonistic activity of the recombinant protease against pathogenic fungi, five pathogenic fungi, Fusarium oxysporum, Alternaria alternata, Cytospora chrysosperma, Sclerotinia sclerotiorum and Rhizoctonia solani, were applied to the test of in vitro inhibition of their mycelial growth by culture supernatant of P. pastoris GS115 transformant. PMID:23677580

Yang, Xiaoxue; Cong, Hua; Song, Jinzhu; Zhang, Junzheng

2013-05-16

371

TmkA, a Mitogen-Activated Protein Kinase of Trichoderma virens, Is Involved in Biocontrol Properties and Repression of Conidiation in the Dark  

PubMed Central

Trichoderma virens is a mycoparasitic fungus used in biocontrol of soilborne plant pathogens. It inhibits or kills plant-pathogenic fungi through production of antifungal antibiotics and parasitism of hyphae and sclerotia. Conidiation, or the production of asexual spores, an inducible process triggered by light or nutrient stress, is an important trait in survival and also development of formulation products. In many fungi, signaling pathways, including mitogen-activated protein kinase (MAPK) cascades, have been implicated in parasitism of host plants as well as in the production of asexual spores. Here, we have studied the role of a MAPK gene, that for TmkA, in conidiation and antagonistic properties of a biocontrol strain of T. virens. Through single- and double-crossover recombination, we obtained three tmkA loss-of-function mutants. The TmkA transcript was not detectable in these mutants. The mutants conidiated in the dark, although photoinduction was normal and the light sensitivities of the wild type and the mutant were the same. The mutants had, overall, normal colony morphology, but their radial growth rate was reduced by about 16%, with no decrease in biomass production. Against Rhizoctonia solani hyphae, the knockout mutants exhibited mycoparasitic coiling and lysis of host hyphae similar to that of the wild type. The mutants, however, were less effective in colonizing the sclerotia of R. solani. On Sclerotium rolfsii, the MAPK loss-of-function mutants had reduced antagonistic properties in confrontation assays and failed to parasitize the sclerotia. TmkA-dependent and -independent pathways are thus involved in antagonism against different hosts. Finally, in contrast to the case for other filamentous fungi studied so far, signaling through a MAPK represses, rather than induces, asexual sporulation.

Mukherjee, Prasun K.; Latha, Jagannathan; Hadar, Ruthi; Horwitz, Benjamin A.

2003-01-01

372

Effect of abiotic stress on phosphate solubilization by biocontrol fungus Trichoderma sp.  

PubMed

This study was undertaken to explore the role of Trichoderma sp. in phosphate (P) solubilization and antagonism against fungal phytopathogens. All fungal isolates (SE(6), KT(6), KT(28), and BRT(11)) and a standard culture of T. harzianum (Th-std) were able to antagonize two fungal phytopathogens (Sclerotium rolfsii and Rhizoctonia solani) of chickpea (Cicer arietinum L.) wilt complex. Transmission electron microscopic studies (TEM) further confirmed ultra-cytological changes in the sclerotia of S. rolfsii parasitized by Trichoderma sp. All fungal cultures exhibited production of NH(3) and siderophore, but only BRT(11), SE(6), and Th-std could produce HCN. Among all the cultures tested, isolate KT(6) was found to be most effective for solubilization of ferric phosphate releasing 398.4 ?g ml(-1) phosphate while isolates BRT(11) and SE(6) showed more potential for tricalcium phosphate (TCP) solubilization releasing 449.05 and 412.64 ?g ml(-1) phosphate, respectively, in their culture filtrates. Part of this study focused on the influence of abiotic stress conditions such as pH, temperature, and heavy metal (cadmium) on phosphate (TCP) solubilizing efficiency. Two selected cultures KT(6) and T. harzianum retained their P solubilizing potential at varying concentrations of cadmium (0-1000 ?g ml(-1)). Isolate KT(6) and standard culture of T. harzianum released 278.4 and 287.6 ?g ml(-1) phosphate, respectively, at 1000 ?g ml(-1)cadmium. Maximum solubilization of TCP was obtained at alkaline pH and at 28°C temperature. Isolate BRT(11) was found most alkalo-tolerant releasing 448.0 ?g ml(-1) phosphate at pH 9. PMID:21327557

Rawat, Rekha; Tewari, Lakshmi

2011-02-16

373

cAMP signalling is involved in growth, germination, mycoparasitism and secondary metabolism in Trichoderma virens.  

PubMed

An adenylate-cyclase-encoding gene, tac1, of Trichoderma virens, a soil fungus used in the biocontrol of plant pathogens, has been cloned and sequenced. The tac1 ORF spanned 7032 bp, encoding a protein of 2153 aa, which shared an identity of 65 % with the adenylate cyclase of Colletotrichum lagenarium. Deletion of tac1, through double-crossover homologous recombination, lowered the intracellular cAMP levels to below the detection limit. The mutants showed only 5-6 % of the wild-type growth rate on agar, but grew normally in shake culture. The mutants did not sporulate in darkness, and the spores failed to germinate in water. In the confrontation assay, the mutants did not overgrow the test plant pathogens Sclerotium rolfsii, Rhizoctonia solani and Pythium sp. Against Pythium sp., the mutants produced a clear zone of inhibition in the confrontation assay. HPLC analysis and bioassay showed reduced secondary metabolite production in the mutants. Using suppression subtractive hybridization (SSH), the genes that were underexpressed in the mutants were identified. Based on an array of 53 SSH library clones, 11 clones were identified as strongly downregulated in the Deltatac1 mutants; of these 11 clones, nine sequences were homologous to secondary metabolism-related gene sequences. Therefore, cAMP signalling positively regulates secondary metabolism in T. virens. This is believed to be the first direct genetic study on the role of cAMP signalling in a Trichoderma sp. Tac1 is also believed to be the first regulatory protein to be identified in T. virens that is involved in growth, germination, mycoparasitism and secondary metabolism. PMID:17526831

Mukherjee, Mala; Mukherjee, Prasun K; Kale, Sharad P

2007-06-01

374

Fungistatic activity of iron-free bovin lactoferrin against several fungal plant pathogens and antagonists.  

PubMed

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins. It is also a multifunctional protein of 80 kDa that is synthesized by glandular epithelial cells and secreted into mucosal fluid. High levels of LF are present in colostrom and milk and low levels in tears, saliva, and gastrointestinal and reproductive secretions. Data regarding the antifungal effects of LF are limited. Studies have been performed on Candida albicans, which demonstrated that LF inhibits the growth of this fungus. This study reports the results of experiments carried out in order to evaluate the effects of LF on the growth of 11 fungi, which were isolated from plants and soils. These experiments employed the methods of amended agar utilizing nine different concentration levels of LF (0, 0.001, 0.01, 0.1, 1, 10, 100, 1000, 5000 mg L(-1)). The effects of LF on the growth of these fungi were based on measures of the radial growth of the fungal colonies expressed both as percentage of inhibition and as IC(50) values (the concentration at which the fungal growth was inhibited by 50% relative to controls). LF had no effects on Alternaria alternata, Gliocladium roseum, Fusarium solani and Colletotrichum lindemuthianum. It did, however, inhibit the growth of Aspergillus niger, Trichoderma viride, Sclerotinia sclerotiorum, Sclerotium rolfsii, Rhizoctonia solani and Phoma exigua to the point that their IC(50) values ranged from 31.1 mg L(-1) for S. sclerotiorum to 952 mg L(-1) for T. viride. PMID:18629710

Lahoz, Ernesto; Pisacane, Anna; Iannaccone, Marco; Palumbo, Daniela; Capparelli, Rosanna

2008-01-01

375

Microwave synthesis and antifungal evaluations of some chalcones and their derived diaryl-cyclohexenones.  

PubMed

Microwave irradiation (MWI) of acetophenones and substituted benzaldehydes in water resulted in a "green-chemistry" procedure for the preparation of chalcones (1-14), through base catalyzed Claisen-Schmidt condensation reaction, in good yields. Further 3,5-diaryl-6-carbethoxy-2-cyclohexen-1-ones (1a-14a) were prepared through base catalyzed cyclocondensation of above chalcones with ethylacetoacetate using MWI as the energy source and silica as support. Out of fourteen cyclohexenones, ten (1a, 4a, 5a, 6a, 7a, 9a, 10a, 11a, 12a and 13a) are reported for the first time in literature. The synthesized compounds were characterized using various spectroscopic techniques, viz. ((1)H NMR and IR) and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be active against R. solani whereas against S. rolfsii, moderate activity was observed, as evident from LC(50) values. The most potent compounds against R. solani were 1-(4-Fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-Diphenyl-propenone (14) having LC(50) values of 2.36 and 2.49 mg L(- 1) respectively (LC(50) of Hexaconazole = 1.12 mg L(- 1)) and against S. rolfsii 3-(4-Fluoro-phenyl)-5-(3-nitro-phenyl)-6-carbethoxy-2-cyclohexen-1-one (12a) was most active having LC(50) value of 285 mg L(- 1)compared to Hexaconazole (LC(50) = 1.27 mg L(- 1)). PMID:20574873

Shakil, N A; Singh, Manish K; Kumar, Jitendra; Sathiyendiran, M; Kumar, Gaurav; Singh, Mukesh K; Pandey, Ravi Prakash; Pandey, Alka; Parmar, V S

2010-08-01

376

Synthesis and pesticidal activity of new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines.  

PubMed

A series of novel N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were synthesized as potential new agents to control pests. Their structures were confirmed on the basis of IR, NMR and elemental analyses. Six new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were prepared by reduction of corresponding Schiff bases using sodium borohydride in 80-87 % yields. These compounds were tested for their antifungal activity against two pathogenic fungi viz., Rhizoctonia bataticola ITCC 0482 and Sclerotium rolfsii ITCC 5226 and for insecticidal activity against insects of stored grain pest Callosobruchus analis. Fungicidal bioassay revealed that compound N-Decyl-N-[1-(2-hydroxyphenyl)ethyl]amine, was highly effective against R. bataticola (ED(50) 6.86 mg L(-1)) which was comparable with that of commercial fungicide hexaconazole (ED(50) 6.35 mg L(-1)). Also compounds N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine, N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine and N-Nonyl-N-[1-(2-hydroxyphenyl)ethyl]amine displayed promising fungitoxicity against same pathogen. However, compound N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine was also found to be effective against S. rolfsii (ED(50) 4.92 mg L(-1) as against 1.27 mg L(-1) for hexaconazole). Compound N-Hexyl-N-[1-(2-hydroxyphenyl)ethyl]amine was most effective as insecticide followed by compound N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine. LC(50) values for these compounds were 155.0 and 275.0 mg L(-1) respectively as against 36.70 mg L(-1) for commercial insecticide dichlorovos. The results obtained from bioassays indicate that this class of compounds can be utilized for the design of new substances endowed with pesticidal activities. PMID:19365749

Shakil, Najam Akhtar; Kumar, Jitendra; Pandey, Alka; Ahluwalia, Vivek; Singh, Manish K; Srivastava, Chitra

2009-05-01

377

Biological Control of Pathogens Causing Root Rot Complex in Field Pea Using Clonostachys rosea Strain ACM941.  

PubMed

ABSTRACT Pea root rot complex (PRRC), caused by Alternaria alternata, Aphanomyces euteiches, Fusarium oxysporum f. sp. pisi, F. solani f. sp. pisi, Mycosphaerella pinodes, Pythium spp., Rhizoctonia solani, and Sclerotinia sclerotiorum, is a major yield-limiting factor for field pea production in Canada. A strain of Clonostachys rosea (syn. Gliocladium roseum), ACM941 (ATCC 74447), was identified as a mycoparasite against these pathogens. When grown near the pathogen, ACM941 often was stimulated to produce lateral branches that grew directly toward the pathogen mycelium, typically entwining around the pathogen mycelium. When applied to the seed, ACM941 propagated in the rhizosphere and colonized the seed coat, hypocotyl, and roots as the plant developed and grew. ACM941 significantly reduced the recovery of all fungal pathogens from infected seed, increased in vitro seed germination by 44% and seedling emergence by 22%, and reduced root rot severity by 76%. The effects were similar to those of thiram fungicide, which increased germination and emergence by 33 and 29%, respectively, and reduced root rot severity by 65%. When soil was inoculated with selected PRRC pathogens in a controlled environment, seed treatment with ACM941 significantly increased emergence by 26, 38, 28, 13, and 21% for F. oxysporum f. sp. pisi, F. solani f. sp. pisi, M. pinodes, R. solani, and S. sclerotiorum, respectively. Under field conditions from 1995 to 1997, ACM941 increased emergence by 17, 23, 22, 13, and 18% and yield by 15, 6, 28, 6, and 19% for the five respective pathogens. The seed treatment effects of ACM941 on these PRRC pathogens were greater or statistically equivalent to those achieved with thiram. Results of this study suggest that ACM941 is an effective bioagent in controlling PRRC and is an alternative to existing chemical products. PMID:18944343

Xue, Allen G

2003-03-01

378

Production of a monoclonal antibody specific to the genus Trichoderma and closely related fungi, and its use to detect Trichoderma spp. in naturally infested composts.  

PubMed

Studies of the interactions between hyperparasitic fungi and their hosts are severely hampered by the absence of methods that allow the unambiguous identification of individual genera in complex environments that contain mixed populations of fungi, such as soil or compost. This study details the development of a monoclonal antibody (MF2) that allows the detection and recovery of Trichoderma spp. in naturally infested composts, and the visualization of hyperparasitic strains of Trichoderma during antagonistic interactions with their hosts. Murine monoclonal antibody MF2, of immunoglobulin class M (IgM), was raised against a protein epitope of a glycoprotein antigen(s) specific for species of the genus Trichoderma and for the closely related fungi Gliocladium viride, Hypomyces chrysospermus, Sphaerostilbella spp. and Hypocrea spp. MF2 did not react with antigens from Gliocladium catenulatum, Gliocladium roseum, Nectria ochroleuca and Clonostachys spp., nor with a range of unrelated soil- and compost-borne fungi. Extracellular production of the MF2 antigen was constitutive. Western-blotting analysis showed that MF2 bound to a ladder of proteins with apparent molecular masses in the range 35-200 kDa. Immunofluorescence studies showed that MF2 bound strongly to the cell walls of hyphae and phialides and the intercalary and terminal chlamydospores of Trichoderma spp., whereas immunogold electron microscopy revealed strong binding of MF2 to the cell walls and septa of hyphae and to the cell walls of phialoconidia. In immunofluorescence studies of dual cultures of Trichoderma and Rhizoctonia solani, only the cell walls of the hyperparasite, which coiled around the host, were stained by MF2. The specificity of MF2 enabled the development of a combined baiting-ELISA technique for the detection of Trichoderma spp. in naturally infested composts. The specificity of this technique was confirmed by phylogenetic analysis based on sequences of the ITS1-5.8S-ITS2 rRNA-encoding regions of the isolates. PMID:11988501

Thornton, Christopher R; Pitt, Dennis; Wakley, Gavin E; Talbot, Nicholas J

2002-05-01

379

Host growth can cause invasive spread of crops by soilborne pathogens.  

PubMed

Invasive soilborne plant pathogens cause substantial damage to crops and natural populations, but our understanding of how to prevent their epidemics or reduce their damage is limited. A key and experimentally-tested concept in the epidemiology of soilborne plant diseases is that of a threshold spacing between hosts below which epidemics (invasive spread) can occur. We extend this paradigm by examining how plant-root growth may alter the conditions for occurrence of soilborne pathogen epidemics in plant populations. We hypothesise that host-root growth can 1) increase the probability of pathogen transmission between neighbouring plants and, consequently, 2) decrease the threshold spacing for epidemics to occur. We predict that, in systems initially below their threshold conditions, root growth can trigger soilborne pathogen epidemics through a switch from non-invasive to invasive behaviour, while in systems above threshold conditions root growth can enhance epidemic development. As an example pathosystem, we studied the fungus Rhizoctonia solani on sugar beet in field experiments. To address hypothesis 1, we recorded infections within inoculum-donor and host-recipient pairs of plants with differing spacing. We translated these observations into the individual-level concept of pathozone, a host-centred form of dispersal kernel. To test hypothesis 2 and our prediction, we used the pathozone to parameterise a stochastic model of pathogen spread in a host population, contrasting scenarios of spread with and without host growth. Our results support our hypotheses and prediction. We suggest that practitioners of agriculture and arboriculture account for root system expansion in order to reduce the risk of soilborne-disease epidemics. We discuss changes in crop design, including increasing plant spacing and using crop mixtures, for boosting crop resilience to invasion and damage by soilborne pathogens. We speculate that the disease-induced root growth observed in some pathosystems could be a pathogen strategy to increase its population through host manipulation. PMID:23667560

Leclerc, Melen; Doré, Thierry; Gilligan, Christopher A; Lucas, Philippe; Filipe, João A N

2013-05-08

380

Mannose-specific lectins bind alpha-2-macroglobulin and an unknown protein from human plasma.  

PubMed Central

GNA, the mannose-specific lectin from Galanthus nivalis was confirmed to bind alpha-2-macroglobulin (A2M) but another protein was copurified with A2M from total human plasma. A total of 23 other lectins with diverse specificities were tested for reaction with human A2M and with three other members of the A2M family. NPA, a mannose-specific lectin isolated from Narcissus pseudonarcissus bulbs, and RSA, the Rhizoctonia solani agglutinin, were selected for further testing. For isolation of A2M, immobilized NPA was superior to GNA because its binding capacity was an order of magnitude higher. The specificity of these lectins must be very similar however, because the same unknown plasma protein was also bound by NPA. A2M and the unknown protein must share a unique mannose carbohydrate structure not present in any other human plasma protein. The copurified protein subunit size of 185 kDa is very similar to that of A2M, but the native molecular mass of 350 kDa indicated a noncovalent homodimer structure. Together with the acid isoelectric point this is not typical for any known plasma protein nor for any unidentified spot on the two-dimensional map of human plasma proteins. No immunological reaction with available antisera was evident. A specific antiserum raised to the unknown protein demonstrated its presence in all human plasma samples examined. The N-terminal residue was blocked, whereas internal protein sequences obtained after CNBr fragmentation and proteolysis were not homologous to any known protein sequence. These data demonstrate that this protein is unknown and not a proteinase inhibitor of the A2M family.

Van Leuven, F.; Torrekens, S.; Van Damme, E.; Peumans, W.; Van den Berghe, H.

1993-01-01

381

Transcriptomic response of the mycoparasitic fungus Trichoderma atroviride to the presence of a fungal prey  

SciTech Connect

BACKGROUND: Combating the action of plant pathogenic microorganisms by mycoparasitic fungi has been announced as an attractive biological alternative to the use of chemical fungicides since two decades. The fungal genus Trichoderma includes a high number of taxa which are able to recognize, combat and finally besiege and kill their prey. Only fragments of the biochemical processes related to this ability have been uncovered so far, however. RESULTS: We analyzed genome-wide gene expression changes during the begin of physical contact between Trichoderma atroviride and two plant pathogens Botrytis cinerea and Rhizoctonia solani, and compared with gene expression patterns of mycelial and conidiating cultures, respectively. About 3000 ESTs, representing about 900 genes, were obtained from each of these three growth conditions. 66 genes, represented by 442 ESTs, were specifically and significantly overexpressed during onset of mycoparasitism, and the expression of a subset thereof was verified by expression analysis. The upregulated genes comprised 18 KOG groups, but were most abundant from the groups representing posttranslational processing, and amino acid metabolism, and included components of the stress response, reaction to nitrogen shortage, signal transduction and lipid catabolism. Metabolic network analysis confirmed the upregulation of the genes for amino acid biosynthesis and of those involved in the catabolism of lipids and aminosugars. CONCLUSION: The analysis of the genes overexpressed during the onset of mycoparasitism in T. atroviride has revealed that the fungus reacts to this condition with several previously undetected physiological reactions. These data enable a new and more comprehensive interpretation of the physiology of mycoparasitism, and will aid in the selection of traits for improvement of biocontrol strains by recombinant techniques.

Seidl, Verena; Song, Lifu; Lindquist, Erika; Gruber, Sabine; Koptchinskiy, Alexeji; Zeilinger, Susanne; Schmoll, Monika; Martinez, Pedro; Sun, Jibin; Grigoriev, Igor; Herrera-Estrella, Alfredo; Baker, Scott E; Kubicek, Christian P.

2010-07-23

382

Lysobacter capsici sp. nov., with antimicrobial activity, isolated from the rhizosphere of pepper, and emended description of the genus Lysobacter.  

PubMed

The taxonomic position of a novel bacterial strain, YC5194(T), with antimicrobial activity, isolated from the rhizosphere of pepper in Jinju, South Korea, was studied using a polyphasic approach. Cells of the strain were Gram-negative, rod-shaped, facultative anaerobes. It grew at a temperature of 15-37 degrees C (optimum 28 degrees C). Growth of the strain occurred between pH 5.5 and 8.5, with an optimum of pH 7.0-7.5. The strain inhibited mycelial growth of Pythium ultimum, Colletotrichum gloeosporioides, Fusarium oxysporum, Botrytis cinerea, Rhizoctonia solani and Botryosphaeria dothidea and growth of Bacillus subtilis. The G+C content of the total DNA was 65.4 mol%. The 16S rRNA gene sequence of the strain was most closely related to species of the genus Lysobacter (<94.0 to >99.0 % sequence similarity). Chemotaxonomic data (major quinone, Q-8; major polar lipids, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidyl-N-methylethanolamine; major fatty acids, iso-C(15 : 0), summed feature 3, C(16 : 0), iso-C(17 : 1)omega9c and C(18 : 1)omega7c) supported the affiliation of strain YC5194(T) to the genus Lysobacter. Phylogenetic analysis based on 16S rRNA gene sequences, DNA-DNA hybridization data and biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strain YC5194(T) from species of Lysobacter with validly published names. Strain YC5194(T) therefore represents a novel species, for which the name Lysobacter capsici sp. nov. is proposed. The type strain is YC5194(T) (=KCTC 22007(T) =DSM 19286(T)). PMID:18218936

Park, Joo Hwang; Kim, Rumi; Aslam, Zubair; Jeon, Che Ok; Chung, Young Ryun

2008-02-01

383

Collophora aceris, a Novel Antimycotic Producing Endophyte Associated with Douglas Maple.  

PubMed

A novel endophyte designated Collophora aceris, was obtained from stem tissues of Douglas Maple (Acer glabrum var. douglasii) in a Pacific Northwest temperate rainforest. Colonies were slow growing, white, creamy, moist, and translucent to opaque on potato dextrose agar and other media with few aerial hyphae. It also produced solid, dark sclerotia (200-400 ?m) on oatmeal agar and no evidence of pseudopycnidia as per other Collophora spp. Conidia were rod-like in the size ranging from 2.2-8.4?×?0.8-1.8 ?m and produced holoblastically on conidiogenous cells by budding with no collarette at the budding site. Phylogenetic analyses, based on 18S rDNA sequence data, showed that C. aceris possessed 99 % similarity to other Collophora spp. However, ITS-5.8S rDNA sequence data indicated that the organism was potentially related to Allantophomopsis spp. Finally, combined morphological, physiological, and molecular genetics data indicated that this organism is most like Collophora spp. but it is distinctly unique when compared to all other fungi in this group. It is to be noted that this is the first report of any member of this genus existing as an endophyte. This fungus makes a wide spectrum antimycotic agent (Collophorin) with biological activity against such pathogenic fungi as Pythium ultimum, Phytophthora cinnamomi, Phytophthora palmivora, and Rhizoctonia solani. Collophorin was purified to homogeneity and shown to have a unique mass of 120.0639, an empirical formula of C8H8O1, and UV absorption bands at 260 and 378 nm. This work also indicates that C. aceris possesses the biological potential to provide protection of its host against an array of common plant pathogens. PMID:23996143

Xie, Jie; Strobel, Gary A; Mends, Morgan T; Hilmer, Jonathan; Nigg, Jared; Geary, Brad

2013-09-03

384

Host Growth Can Cause Invasive Spread of Crops by Soilborne Pathogens  

PubMed Central

Invasive soilborne plant pathogens cause substantial damage to crops and natural populations, but our understanding of how to prevent their epidemics or reduce their damage is limited. A key and experimentally-tested concept in the epidemiology of soilborne plant diseases is that of a threshold spacing between hosts below which epidemics (invasive spread) can occur. We extend this paradigm by examining how plant-root growth may alter the conditions for occurrence of soilborne pathogen epidemics in plant populations. We hypothesise that host-root growth can 1) increase the probability of pathogen transmission between neighbouring plants and, consequently, 2) decrease the threshold spacing for epidemics to occur. We predict that, in systems initially below their threshold conditions, root growth can trigger soilborne pathogen epidemics through a switch from non-invasive to invasive behaviour, while in systems above threshold conditions root growth can enhance epidemic development. As an example pathosystem, we studied the fungus Rhizoctonia solani on sugar beet in field experiments. To address hypothesis 1, we recorded infections within inoculum-donor and host-recipient pairs of plants with differing spacing. We translated these observations into the individual-level concept of pathozone, a host-centred form of dispersal kernel. To test hypothesis 2 and our prediction, we used the pathozone to parameterise a stochastic model of pathogen spread in a host population, contrasting scenarios of spread with and without host growth. Our results support our hypotheses and prediction. We suggest that practitioners of agriculture and arboriculture account for root system expansion in order to reduce the risk of soilborne-disease epidemics. We discuss changes in crop design, including increasing plant spacing and using crop mixtures, for boosting crop resilience to invasion and damage by soilborne pathogens. We speculate that the disease-induced root growth observed in some pathosystems could be a pathogen strategy to increase its population through host manipulation.

Leclerc, Melen; Dore, Thierry; Gilligan, Christopher A.; Lucas, Philippe; Filipe, Joao A. N.

2013-01-01

385

Identity, diversity, and molecular phylogeny of the endophytic mycobiota in the roots of rare wild rice (Oryza granulate) from a nature reserve in Yunnan, China.  

PubMed

Rice (Oryza sativa L.) is, on a global scale, one of the most important food crops. Although endophytic fungi and bacteria associated with rice have been investigated, little is known about the endophytic fungi of wild rice (Oryza granulate) in China. Here we studied the root endophytic mycobiota residing in roots of O. granulate by the use of an integrated approach consisting of microscopy, cultivation, ecological indices, and direct PCR. Microscopy confirmed the ubiquitousness of dark septate endophytes (DSEs) and sclerotium-like structures in root tissues. Isolations from 204 root segments from 15 wild rice plants yielded 58 isolates, for which 31 internal transcribed spacer (ITS)-based genotypes were recorded. The best BLAST match indicated that 34.5% of all taxa encountered may represent hitherto undescribed species. Most of the fungi were isolated with a very low frequency. Calculation of ecological indices and estimation of taxon accumulation curves indicated a high diversity of fungal species. A culture-independent approach was also performed to analyze the endophytic fungal community. Three individual clone libraries were constructed. Using a threshold of 90% similarity, 35 potentially different sequences (phylotypes) were found among 186 positive clones. Phylogenetic analysis showed that frequently detected clones were classified as Basidiomycota, and 60.2% of total analyzed clones were affiliated with unknown taxa. Exophiala, Cladophialophora, Harpophora, Periconia macrospinosa, and the Ceratobasidium/Rhizoctonia complex may act as potential DSE groups. A comparison of the fungal communities characterized by the two approaches demonstrated distinctive fungal groups, and only a few taxa overlapped. Our findings indicate a complex and rich endophytic fungal consortium in wild rice roots, thus offering a potential bioresource for establishing a novel model of plant-fungal mutualistic interactions. PMID:20038691

Yuan, Zhi-Lin; Zhang, Chu-Long; Lin, Fu-Cheng; Kubicek, Christian P

2009-12-28

386

Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 show increased susceptibility to a group of fungal and oomycete pathogens.  

PubMed

SUMMARY The behaviour of Nicotiana plumbaginifolia plants silenced for the ATP-binding cassette transporter gene NpPDR1 was investigated in response to fungal and oomycete infections. The importance of NpPDR1 in plant defence was demonstrated for two organs in which NpPDR1 is constitutively expressed: the roots and the petal epidermis. The roots of the plantlets of two lines silenced for NpPDR1 expression were clearly more sensitive than those of controls to the fungal pathogens Botrytis cinerea, Fusarium oxysporum sp., F. oxysporum f. sp. nicotianae, F. oxysporum f. sp. melonis and Rhizoctonia solani, as well as to the oomycete pathogen Phytophthora nicotianae race 0. The Ph gene-linked resistance of N. plumbaginifolia to P. nicotianae race 0 was totally ineffective in NpPDR1-silenced lines. In addition, the petals of the NpPDR1-silenced lines were spotted 15%-20% more rapidly by B. cinerea than were the controls. The rapid induction (after 2-4 days) of NpPDR1 expression in N. plumbaginifolia and N. tabacum mature leaves in response to pathogen presence was demonstrated for the first time with fungi and one oomycete: R. solani, F. oxysporum and P. nicotianae. With B. cinerea, such rapid expression was not observed in healthy mature leaves. NpPDR1 expression was not observed during latent infections of B. cinerea in N. plumbaginifolia and N. tabacum, but was induced when conditions facilitated B. cinerea development in leaves, such as leaf ageing or an initial root infection. This work demonstrates the increased sensitivity of NpPDR1-silenced N. plumbaginifolia plants to all of the fungal and oomycete pathogens investigated. PMID:19694955

Bultreys, Alain; Trombik, Tomasz; Drozak, Anna; Boutry, Marc

2009-09-01

387

Rice WRKY45 plays important roles in fungal and bacterial disease resistance.  

PubMed

Plant 'activators', such as benzothiadiazole (BTH), protect plants from various diseases by priming the plant salicylic acid (SA) signalling pathway. We have reported previously that a transcription factor identified in rice, WRKY45 (OsWRKY45), plays a pivotal role in BTH-induced disease resistance by mediating SA signalling. Here, we report further functional characterization of WRKY45. Different plant activators vary in their action points, either downstream (BTH and tiadinil) or upstream (probenazole) of SA. Rice resistance to Magnaporthe grisea, induced by both types of plant activator, was markedly reduced in WRKY45-knockdown (WRKY45-kd) rice, indicating a universal role for WRKY45 in chemical-induced resistance. Fungal invasion into rice cells was blocked at most attempted invasion sites (pre-invasive defence) in WRKY45-overexpressing (WRKY45-ox) rice. Hydrogen peroxide accumulated within the cell wall underneath invading fungus appressoria or between the cell wall and the cytoplasm, implying a possible role for H(2)O(2) in pre-invasive defence. Moreover, a hypersensitive reaction-like reaction was observed in rice cells, in which fungal growth was inhibited after invasion (post-invasive defence). The two levels of defence mechanism appear to correspond to Type I and II nonhost resistances. The leaf blast resistance of WRKY45-ox rice plants was much higher than that of other known blast-resistant varieties. WRKY45-ox plants also showed strong panicle blast resistance. BTH-induced resistance to Xanthomonas oryzae pv. oryzae was compromised in WRKY45-kd rice, whereas WRKY45-ox plants were highly resistant to this pathogen. However, WRKY45-ox plants were susceptible to Rhizoctonia solani. These results indicate the versatility and limitations of the application of this gene. PMID:21726399

Shimono, Masaki; Koga, Hironori; Akagi, Aya; Hayashi, Nagao; Goto, Shingo; Sawada, Miyuki; Kurihara, Takayuki; Matsushita, Akane; Sugano, Shoji; Jiang, Chang-Jie; Kaku, Hisatoshi; Inoue, Haruhiko; Takatsuji, Hiroshi

2011-07-04

388

Purification and Characterization of a CkTLP Protein from Cynanchum komarovii Seeds that Confers Antifungal Activity  

PubMed Central

Background Cynanchum komarovii Al Iljinski is a desert plant that has been used as analgesic, anthelminthic and antidiarrheal, but also as a herbal medicine to treat cholecystitis in people. We have found that the protein extractions from C. komarovii seeds have strong antifungal activity. There is strong interest to develop protein medication and antifungal pesticides from C. komarovii for pharmacological or other uses. Methodology/Principal Findings An antifungal protein with sequence homology to thaumatin-like proteins (TLPs) was isolated from C. komarovii seeds and named CkTLP. The three-dimensional structure prediction of CkTLP indicated the protein has an acid cleft and a hydrophobic patch. The protein showed antifungal activity against fungal growth of Verticillium dahliae, Fusarium oxysporum, Rhizoctonia solani, Botrytis cinerea and Valsa mali. The full-length cDNA was cloned by RT-PCR and RACE-PCR according to the partial protein sequences obtained by nanoESI-MS/MS. The real-time PCR showed the transcription level of CkTLP had a significant increase under the stress of abscisic acid (ABA), salicylic acid (SA), methyl jasmonate (MeJA), NaCl and drought, which indicates that CkTLP may play an important role in response to abiotic stresses. Histochemical staining showed GUS activity in almost the whole plant, especially in cotyledons, trichomes and vascular tissues of primary root and inflorescences. The CkTLP protein was located in the extracellular space/cell wall by CkTLP::GFP fusion protein in transgenic Arabidopsis. Furthermore, over-expression of CkTLP significantly enhanced the resistance of Arabidopsis against V. dahliae. Conclusions/Significance The results suggest that the CkTLP is a good candidate protein or gene for contributing to the development of disease-resistant crops.

Wang, Qinghua; Li, Fuguang; Zhang, Xue; Zhang, Yongan; Hou, Yuxia; Zhang, Shengrui; Wu, Zhixia

2011-01-01

389

Isolate Identity Determines Plant Tolerance to Pathogen Attack in Assembled Mycorrhizal Communities  

PubMed Central

Arbuscular mycorrhizal fungi (AMF) are widespread soil microorganisms that associate mutualistically with plant hosts. AMF receive photosynthates from the host in return for various benefits. One of such benefits is in the form of enhanced pathogen tolerance. However, this aspect of the symbiosis has been understudied compared to effects on plant growth and its ability to acquire nutrients. While it is known that increased AMF species richness positively correlates with plant productivity, the relationship between AMF diversity and host responses to pathogen attack remains obscure. The objective of this study was to test whether AMF isolates can differentially attenuate the deleterious effects of a root pathogen on plant growth, whether the richest assemblage of AMF isolates provides the most tolerance against the pathogen, and whether AMF-induced changes to root architecture serve as a mechanism for improved plant disease tolerance. In a growth chamber study, we exposed the plant oxeye daisy (Leucanthemum vulgare) to all combinations of three AMF isolates and to the plant root pathogen Rhizoctonia solani. We found that the pathogen caused an 81% reduction in shoot and a 70% reduction in root biomass. AMF significantly reduced the highly deleterious effect of the pathogen. Mycorrhizal plants infected with the pathogen produced 91% more dry shoot biomass and 72% more dry root biomass relative to plants solely infected with R. solani. AMF isolate identity was a better predictor of AMF-mediated host tolerance to the pathogen than AMF richness. However, the enhanced tolerance response did not result from AMF-mediated changes to root architecture. Our data indicate that AMF communities can play a major role in alleviating host pathogen attack but this depends primarily on the capacity of individual AMF isolates to provide this benefit.

Lewandowski, Thaddeus J.; Dunfield, Kari E.; Antunes, Pedro M.

2013-01-01

390

Genetic and functional diversity among the antagonistic potential fluorescent pseudomonads isolated from tea rhizosphere.  

PubMed

Twenty-five fluorescent pseudomonads from rhizospheric soil of six tea gardens in four district of Upper Assam, India were isolated and screened for antagonistic activity against fungal pathogens such as Fusarium oxysporum f. sp. raphani (For), Fusarium oxysporum f. sp. ciceri (Foc), Fusarium semitectum (Fs), and Rhizoctonia solani (Rs); and bacterial pathogens-Staphylococcus aureus (Sa), Escherichia coli (Ec), and Klebsiella pneumoniae (Kp). Most of the isolates exhibited strong antagonistic activity against the fungal pathogens and gram-positive bacterium i.e. Staphylococcus aureus. Productions of siderophore, salicylic acid (SA), hydrogen cyanide (HCN), and cell wall-degrading enzyme (chitinase) were studied to observe the possible mechanisms of antagonistic activity of the isolates. Correlation between the antagonistic potentiality of some isolates and their levels of production of siderophore, salicylic acid, and hydrogen cyanide was observed. Out of the 25 isolates, antibiotic-coding genes, 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT) were detected in the isolates, Pf12 and Pf373, respectively. Genetic diversity of these fluorescent pseudomonads were analyzed with reference to four strains of Pseudomonas fluorescens NICM 2099(T), P. aeruginosa MTCC 2582(T), P. aureofaciens NICM 2026(T), and P. syringae MTCC 673(T). 16S rDNA-RFLP analysis of these isolates using three tetra cutter restriction enzymes (HaeIII, AluI and MspI) revealed two distinct clusters. Cluster A comprised only two isolates Pf141 and 24-PfM3, and cluster B comprised 23 isolates along with four reference strains. PMID:20689953

Saikia, Ratul; Sarma, Rupak K; Yadav, Archana; Bora, Tarun C

2010-08-06

391

Isolation and Identification of Antifungal Compounds from Bacillus subtilis C9 Inhibiting the Growth of Plant Pathogenic Fungi  

PubMed Central

Antagonistic microorganisms against Rhizoctonia solani were isolated and their antifungal activities were investigated. Two hundred sixteen bacterial isolates were isolated from various soil samples and 19 isolates were found to antagonize the selected plant pathogenic fungi with varying degrees. Among them, isolate C9 was selected as an antagonistic microorganism with potential for use in further studies. Treatment with the selected isolate C9 resulted in significantly reduced incidence of stem-segment colonization by R. solani AG2-2(IV) in Zoysia grass and enhanced growth of grass. Through its biochemical, physiological, and 16S rDNA characteristics, the selected bacterium was identified as Bacillus subtilis subsp. subtilis. Mannitol (1%) and soytone (1%) were found to be the best carbon and nitrogen sources, respectively, for use in antibiotic production. An antibiotic compound, designated as DG4, was separated and purified from ethyl acetate extract of the culture broth of isolate C9. On the basis of spectral data, including proton nuclear magneric resonance (1H NMR), carbon nuclear magneric resonance (13C NMR), and mass analyses, its chemical structure was established as a stereoisomer of acetylbutanediol. Application of the ethyl acetate extract of isolate C9 to several plant pathogens resulted in dose-dependent inhibition. Treatment with the purified compound (an isomer of acetylbuanediol) resulted in significantly inhibited growth of tested pathogens. The cell free culture supernatant of isolate C9 showed a chitinase effect on chitin medium. Results from the present study demonstrated the significant potential of the purified compound from isolate C9 for use as a biocontrol agent as well as a plant growth promoter with the ability to trigger induced systemic resistance of plants.

Islam, Md. Rezuanul; Jeong, Yong Tae; Lee, Yong Se

2012-01-01

392

Role of Two G-Protein Alpha Subunits, TgaA and TgaB, in the Antagonism of Plant Pathogens by Trichoderma virens  

PubMed Central

G-protein ? subunits are involved in transmission of signals for development, pathogenicity, and secondary metabolism in plant pathogenic and saprophytic fungi. We cloned two G-protein ? subunit genes, tgaA and tgaB, from the biocontrol fungus Trichoderma virens. tgaA belongs to the fungal G?i class, while tgaB belongs to the class defined by gna-2 of Neurospora crassa. We compared loss-of-function mutants of tgaA and tgaB with the wild type for radial growth, conidiation, germination of conidia, the ability to overgrow colonies of Rhizoctonia solani and Sclerotium rolfsii in confrontation assays, and the ability to colonize the sclerotia of these pathogens in soil. Both mutants grew as well as the wild type, sporulated normally, did not sporulate in the dark, and responded to blue light by forming a conidial ring. The tgaA mutants germinated by straight unbranched germ tubes, while tgaB mutants, like the wild type, germinated by wavy and highly branched germ tubes. In confrontation assays, both tgaA and tgaB mutants and the wild type overgrew, coiled, and lysed the mycelia of R. solani, but tgaA mutants had reduced ability to colonize S. rolfsii colonies. In the soil plate assay, both mutants parasitized the sclerotia of R. solani, but tgaA mutants were unable to parasitize the sclerotia of S. rolfsii. Thus, tgaA is involved in antagonism against S. rolfsii, but neither G protein subunit is involved in antagonism against R. solani. T. virens, which has a wide host range, thus employs a G-protein pathway in a host-specific manner.

Mukherjee, Prasun K.; Latha, Jagannathan; Hadar, Ruthi; Horwitz, Benjamin A.

2004-01-01

393

Plant resistance to fungal infection induced by nontoxic pokeweed antiviral protein mutants.  

PubMed

Pokeweed antiviral protein (PAP), a 29-kD protein isolated from Phytolacca americana inhibits translation by catalytically removing a specific adenine residue from the large rRNA of the 60S subunit of eukaryotic ribosomes. Transgenic plants expressing PAP are resistant to a broad spectrum of plant viruses. Nontoxic PAP mutants have been isolated by random mutagenesis and selection in yeast. One of these mutants, PAP-X, had a point mutation at the active-site (E176V) that abolished enzymatic activity, and another mutant, delta C25PAP, had a nonsense mutation near the C-terminus (W237stop) that deleted 25 C-terminal amino acids. Unlike the wild-type PAP, expression of neither mutant was toxic to transgenic plants. We show that both class I (basic) and class II (acidic) isoforms of pathogenesis-related (PR) proteins are overexpressed in transgenic plants expressing PAP and the nontoxic PAP mutants. Although PR-proteins are constitutively expressed, no increase in salicylic acid levels was detected. Homozygous progeny of transgenic plants expressing either PAP or the nontoxic PAP mutants displayed resistance to the fungal pathogen Rhizoctonia solani. These results show that expression of PAP or the nontoxic PAP mutants activates multiple plant defense pathways independently of salicylic acid and confers resistance to fungal infection. The C-terminal 25 amino acids of PAP, which are required for toxicity in vivo, are not critical for resistance to viral or fungal infection, indicating that toxicity of PAP can be separated from pathogen resistance. PMID:9335052

Zoubenko, O; Uckun, F; Hur, Y; Chet, I; Tumer, N

1997-10-01

394

Diversity of endophytic fungi from roots of Panax ginseng and their saponin yield capacities.  

PubMed

Endophytes of medicinal plants have the capacity to synthesis same or similar active substances with their hosts. To investigate the diversity and capacity to produce saponins of endophytic fungi of Panax ginseng, thirty-eight strains of were isolated. Polymerase chain reaction (PCR) and sequencing were used to identify the isolates, and saponins concentrations in the cultures were measured. Agar diffusion method was used to test antimicrobial activity. High-performance liquid chromatography (HPLC) was used to analyze ginsenosides produced by representative strains. Nectria, Aspergillus, Fusarium, Verticillium, Engyodontium, Plectosphaerella, Penicillium, Cladosporium, and Ascomycete species were isolated. Overall, 18.4% of the isolates belonged to Nectria (Nectria haematococca), 13.2% belonged to Aspergillus, and 10.5% belonged to Penicillium. The highest concentration of triterpenoid saponin was 0.181 mg/ml (Pg27), followed by 0.144 mg/ml (Pg30 and Pg42-1). According to the results of the phylogenetic results, these isolates were species of Fusarium, Aspergillus and Verticillium, respectively. The culture filtrate of Pg30 exhibited its antibacterial activity Staphylococcus aureus. Pg 27 and Pg30 could excrete the substances to inhibit the growth of Rhizoctonia solani. Pg42-1 showed strong inhibition against Klebsiella pneumoniae. From HPLC results, the ginsenoside Rb2 was detected in both Pg27 and Pg30 cultures. The ginsenoside Rc was found in Pg42-1 cultures. In conclusion, thirty-eight endophytic fungal strains were isolated and Pg27 (Fusarium sp.) has a potential application value in saponins production. PMID:23543782

Wu, Hao; Yang, Hong-Yan; You, Xiang-Lin; Li, Yu-Hua

2013-03-13

395

Allelic Analysis of Sheath Blight Resistance with Association Mapping in Rice  

PubMed Central

Sheath blight (ShB) caused by the soil-borne pathogen Rhizoctonia solani is one of the most devastating diseases in rice world-wide. Global attention has focused on examining individual mapping populations for quantitative trait loci (QTLs) for ShB resistance, but to date no study has taken advantage of association mapping to examine hundreds of lines for potentially novel QTLs. Our objective was to identify ShB QTLs via association mapping in rice using 217 sub-core entries from the USDA rice core collection, which were phenotyped with a micro-chamber screening method and genotyped with 155 genome-wide markers. Structure analysis divided the mapping panel into five groups, and model comparison revealed that PCA5 with genomic control was the best model for association mapping of ShB. Ten marker loci on seven chromosomes were significantly associated with response to the ShB pathogen. Among multiple alleles in each identified loci, the allele contributing the greatest effect to ShB resistance was named the putative resistant allele. Among 217 entries, entry GSOR 310389 contained the most putative resistant alleles, eight out of ten. The number of putative resistant alleles presented in an entry was highly and significantly correlated with the decrease of ShB rating (r?=??0.535) or the increase of ShB resistance. Majority of the resistant entries that contained a large number of the putative resistant alleles belonged to indica, which is consistent with a general observation that most ShB resistant accessions are of indica origin. These findings demonstrate the potential to improve breeding efficiency by using marker-assisted selection to pyramid putative resistant alleles from various loci in a cultivar for enhanced ShB resistance in rice.

Jia, Limeng; Yan, Wengui; Zhu, Chengsong; Agrama, Hesham A.; Jackson, Aaron; Yeater, Kathleen; Li, Xiaobai; Huang, Bihu; Hu, Biaolin; McClung, Anna; Wu, Dianxing

2012-01-01

396

Induce systemic resistance in lupine against root rot diseases.  

PubMed

Root rot caused by soil borne pathogenic fungi is the most sever disease attacks lupine plants. Isolation trials from diseased plants in some areas of Dakahlia Province (Egypt) was carried out. Rhizoctonia solani and Fusarium solani proved to be the most dominant isolates. Meanwhile, Fusarium oxysporum and Sclerotium rolfsii were less frequent. Efficacies of some plant resistance elicitors viz.: chitosan (CHI), Salicylic Acid (SA) and hydroquinone (HQ) in comparing to the fungicide Rhizolex T-50 as seed treatments showed significant reduction in the fungal growth in vitro. Chitosan at 8 g L(-1) and fungicide completely inhibited the growth of all isolated fungi, while SA at 1.4 g L(-1) and HQ at 1.2 g L(-1) inhibited the growth of Fusarium solani and F. oxysporum, respectively. The greenhouse experiments showed that S. rolfesii (No. 6) and R. solani (No. 2) followed by F. solani (No. 5) and F. oxysporum (No. 9) were the most aggressive root rot fungi. Soaking susceptible lupine seeds (Giza 1) in each one of the three selected elicitors showed a significant reduction in seedlings mortality. CHI at 8 g L(-1) was superior in increasing the percentage of healthy plants to record 72.5, 80.9, 62.7and 64.3%, when seeds were grown in soil infested with of F. solani, F. oxysporum, R. solani and S. rolfesii, respectively. These results were confirmed under field conditions in two different locations i.e., Tag El-Ezz and El-Serow Research Stations. CHI 8 g L(-1) proved to be the best elicitor after fungicide, in reducing lupine root rot disease. It showed 41 and 60% reduction in the plants mortality comparing to 56.37 and 69.13% in case of Rhizolex-T in Tag El-Ezz and El-Serow locations, respectively. The treatments were accompanied with a significant increase in lupine growth parameters, yield components and physiological aspects. Application of CHI at 8 g L(-1) or HQ at 1.2 g L(-1) was the most potent in this respect as compared to check treatment. PMID:19579949

Ali, Abeer A; Ghoneem, K M; El-Metwally, M A; Abd El-Hai, K M

2009-02-01

397

Production and Characterization of a Monoclonal Antibody Raised Against Surface Antigens from Mycelium of Gaeumannomyces graminis var. tritici: Evidence for an Extracellular Polyphenol Oxidase.  

PubMed

ABSTRACT A murine monoclonal antibody (MAb) of immunoglobulin class M (IgM) was raised against surface antigens from Gaeumannomyces graminis var. tritici and, by enzyme-linked immunosorbent assay, recognized isolates of G. graminis var. tritici, G. graminis var. avenae and G. graminis var. graminis. Characterization of the antigen by heat and protease treatments showed that the epitope recognized by the MAb was a protein. Antigen production was detected only in live mycelia. Immunofluorescence studies showed that the antigen was associated with both the broad melanized macrohyphae and hyaline mycelia of G. graminis var. tritici. Secretion of antigen into an aqueous minimal medium was promoted only by exposure of live mycelia to certain phenolic substrates, including monophenols ortho-, para-, and meta-cresol; 3,4,5-trihydroxybenzoic acid (gallic acid); and phenolic amino acid L-3-(3,4-dihydroxyphenyl) alanine (L-DOPA). Antigen secretion was not promoted by 3-(4-hydroxyphenyl) alanine (L-tyrosine). The MAb reacted strongly with purified enzyme laccase (polyphenol oxidase, EC 1.10.3.2) but did not recognize purified tyrosinase (monophenol oxidase, EC 1.14.18.1). Moreover, chemicals that bind to copper and inhibit copper-containing enzymes such as laccase completely inhibited antigen secretion in response to L-DOPA. The MAb was tested for specificity against a wide range of fungi, common yeast species, and gram positive and negative bacteria. It did not recognize antigens from a broad range of unrelated fungi, including Gliocladium roseum, Fusarium sp., Phoma exigua, Phialophora fastigiata, Penicillium crustosum, Pythium ultimum, Rhizopus stolonifer, Rhizoctonia carotae, R. oryzae, R. tuliparum, and Trichoderma viride, nor did it recognize surface antigens from yeasts or bacteria. The MAb cross-reacted with antigens from Botrytis spp., Chaetomium globosum, R. cerealis, and R. solani. However, secretion of antigen by R. solani and R. cerealis was not promoted by L-DOPA, and secretion by C. globosum in response to the phenolic amino acid was significantly less compared to G. graminis var. tritici. PMID:18945163

Thornton, C R; Dewey, F M; Gilligan, C A

1997-01-01

398

Comparative degradation of oomycete, ascomycete, and basidiomycete cell walls by mycoparasitic and biocontrol fungi.  

PubMed

Fourteen fungi (primarily representing mycoparasitic and biocontrol fungi) were tested for their ability to grow on and degrade cell walls (CWs) of an oomycete (Pythium ultimum), ascomycete (Fusarium equisetii), and basidiomycete (Rhizoctonia solani), and their hydrolytic enzymes were characterized. Protein was detected in the cultural medium of eleven of the test isolates, and these fungi significantly degraded CWs over the 14-day duration of the experiment. In general, a greater level of CW degradation occurred for F. equisetii and P. ultimum than for R. solani. Fungi that degraded F. equisetii CWs were Coniothyrium minitans, Gliocladium roseum, Myrothecium verrucaria, Talaromyces flavus, and Trichoderma harzianum. Taxa degrading P ultimum CWs included Chaetomium globosum, Coniothyrium minitans, M. verrucaria, Seimatosporium sp., Talaromyces flavus, Trichoderma hamatum, Trichoderma harzianum, and Trichoderma viride. Production of extracellular protein was highly correlated with CW degradation. Considerable variation in the molecular weights of CW-degrading enzymes were detected among the test fungi and the CW substrates in zymogram electrophoresis. Multivariate analysis between CW degradation and hydrolysis of barley beta-glucan (beta1,3- and beta1,4-glucanases), laminarin (beta1,3- and beta1,6-glucanases), carboxymethyl cellulose (endo-beta1,4-glucanases), colloidal chitin (chitinases), and chitosan (chitosanases) was conducted. For F. equisetii CWs, the regression model accounted for 80% of the variability, and carboxymethyl cellulases acting together with beta-glucanases contributed an R2 of 0.52, whereas chitinases and beta-glucanases alone contributed an R2 of 0.11 and 0.12, respectively. Only 61% of the variability observed in the degradation of P. ultimum CWs was explained by the enzyme classes tested, and primarily beta-glucanases (R2 of 0.53) and carboxymethyl cellulases (R2 of 0.08) alone contributed to CW break down. Too few of the test fungi degraded R. solani CWs to perform multivariate analysis effectively. This study identified several fungi that degraded ascomyceteous and oomyceteous, and to a lesser extent, basidiomycetous CWs. An array of enzymes were implicated in CW degradation. PMID:11888164

Inglis, G D; Kawchuk, L M

2002-01-01

399

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde.  

PubMed

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m. PMID:22728967

Anitha, C; Sheela, C D; Tharmaraj, P; Sumathi, S

2012-06-02

400

Functional Alteration of a Dimeric Insecticidal Lectin to a Monomeric Antifungal Protein Correlated to Its Oligomeric Status  

PubMed Central

Background Allium sativum leaf agglutinin (ASAL) is a 25-kDa homodimeric, insecticidal, mannose binding lectin whose subunits are assembled by the C-terminal exchange process. An attempt was made to convert dimeric ASAL into a monomeric form to correlate the relevance of quaternary association of subunits and their functional specificity. Using SWISS-MODEL program a stable monomer was designed by altering five amino acid residues near the C-terminus of ASAL. Methodology/Principal Findings By introduction of 5 site-specific mutations (-DNSNN-), a ? turn was incorporated between the 11th and 12th ? strands of subunits of ASAL, resulting in a stable monomeric mutant ASAL (mASAL). mASAL was cloned and subsequently purified from a pMAL-c2X system. CD spectroscopic analysis confirmed the conservation of secondary structure in mASAL. Mannose binding assay confirmed that molecular mannose binds efficiently to both mASAL and ASAL. In contrast to ASAL, the hemagglutination activity of purified mASAL against rabbit erythrocytes was lost. An artificial diet bioassay of Lipaphis erysimi with mASAL displayed an insignificant level of insecticidal activity compared to ASAL. Fascinatingly, mASAL exhibited strong antifungal activity against the pathogenic fungi Fusarium oxysporum, Rhizoctonia solani and Alternaria brassicicola in a disc diffusion assay. A propidium iodide uptake assay suggested that the inhibitory activity of mASAL might be associated with the alteration of the membrane permeability of the fungus. Furthermore, a ligand blot assay of the membrane subproteome of R. solani with mASAL detected a glycoprotein receptor having interaction with mASAL. Conclusions/Significance Conversion of ASAL into a stable monomer resulted in antifungal activity. From an evolutionary aspect, these data implied that variable quaternary organization of lectins might be the outcome of defense-related adaptations to diverse situations in plants. Incorporation of mASAL into agronomically-important crops could be an alternative method to protect them from dramatic yield losses from pathogenic fungi in an effective manner.

Banerjee, Nilanjana; Ghosh, Prithwi; Das, Kalipada; Das, Sampa

2011-01-01

401

The causal agents of damping-off disease of buglosse from Iran.  

PubMed

Iran is considered a major genetic for medicinal plant in the world. Because of this significant diversity and historical background in identification and utilization to remedy human and animal diseases, export of medicinal plant can help to strengthen local as well as natural economy. Buglosse (Fig. 1) is one of the most important and common medicinal plants in Iran and exist as Echium amoneum and Borago officinalis. This work was conducted in order to identify the causal agent(s) of damping off disease in buglosse. Plant disease samples were taken from Esfahan and Tehran provinces. Symptoms on original plant including root, crown rot, dark tissue, pith and hallow root were collected in order to isolate disease agent(s). Symptomatic root and crown tissues after surface sterilization with 96% ethanol were transferred on to PDA and WA media and also on moist filter paper in petri dishes. Two fungal colonies grew from tissue segments and spore culture was subsequently purified. The fungal isolate identified as Rhizoctonia solani based on the following test. Hyphal tip was removed from colony margin placed on PDA and PSA media and incubated in dark. Colony diameter of one hundred hyphae measured and nucleus was stained according to Bandoni (1979), Kronland and Stanghellini (1988). It was observed that in each cell of hyphae there are more than two nuclei. Single spore culture were obtained from macroconidia of Fusarium isolate. After 24 hr of incubation, growing single spore were transferred to KCL medium to detect spore chains. Fungal isolates transferred to PSA and PDA media for sporulation. After 7 days colonies appeared as white cream to pinkish on top and cream to dark pink at the bottom of petri dish with abundant micro and macro conidia. Colonies were snow white, felting shape, with ample causal hyphae on PSA medium. On KCL medium, fungal growth was superficial and colonies were colorless with long macroconidia and individual sausage-shape macroconidia being thinner one side and having maximum four septa. Microconidia were long double compartment round on both side, straight to slightly curved. Base on morphology and dimension of conidia and production of chlamidospore the funguses identify as Fusarium solani. PMID:16637194

Okhovvat, S M; Zakeri, Z; Moshashai, R

2005-01-01

402

PacC and pH-dependent transcriptome of the mycotrophic fungus Trichoderma virens  

PubMed Central

Background In fungi, environmental pH is an important signal for development, and successful host colonization depends on homeostasis. Surprisingly, little is known regarding the role of pH in fungal-fungal interactions. Species of Trichoderma grow as soil saprobes but many are primarily mycotrophic, using other fungi as hosts. Therefore, Trichoderma spp. are studied for their potential in biocontrol of plant diseases. Particularly in alkaline soil, pH is a critical limiting factor for these biofungicides, whose optimal growth pH is 4–6. Gaining an understanding of pH adaptability is an important step in broadening the activity spectrum of these economically important fungi. Results We studied the pH-responsive transcription factor PacC by gene knockout and by introduction of a constitutively active allele (pacCc). ?pacC mutants exhibited reduced growth at alkaline pH, while pacCc strains grew poorly at acidic pH. In plate confrontation assays ?pacC mutants showed decreased ability to compete with the plant pathogens Rhizoctonia solani and Sclerotium rolfsii. The pacCc strain exhibited an overgrowth of R. solani that was comparable to the wild type, but was unable to overgrow S. rolfsii. To identify genes whose expression is dependent on pH and pacC, we designed oligonucleotide microarrays from the transcript models of the T. virens genome, and compared the transcriptomes of wild type and mutant cultures exposed to high or low pH. Transcript levels from several functional classes were dependent on pacC, on pH, or on both. Furthermore, the expression of a set of pacC-dependent genes was increased in the constitutively-active pacCc strain, and was pH-independent in some, but not all cases. Conclusions PacC is important for biocontrol-related antagonism of other fungi by T. virens. As much as 5% of the transcriptome is pH-dependent, and of these genes, some 25% depend on pacC. Secondary metabolite biosynthesis and ion transport are among the relevant gene classes. We suggest that ?pacC mutants may have lost their full biocontrol potential due to their inability to adapt to alkaline pH, to perceive ambient pH, or both. The results raise the novel possibility of genetically manipulating Trichoderma in order to improve adaptability and biocontrol at alkaline pH.

2013-01-01

403

Improvement of Biocontrol of Damping-off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide.  

PubMed

Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seeds soaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the combination between biocontrol agents and chemical inducers recorded the best results for controlling damping-off and root rot/wilt diseases in greenhouse and field with addition improved plant growth and increased yield components in field. PMID:23610539

Abdel-Monaim, Montaser Fawzy

2013-03-28

404

Improvement of Biocontrol of Damping-off and Root Rot/Wilt of Faba Bean by Salicylic Acid and Hydrogen Peroxide  

PubMed Central

Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were able to attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] and hydrogen peroxide) individually or in combination were examined for biological control of damping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seeds soaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the combination between biocontrol agents and chemical inducers recorded the best results for controlling damping-off and root rot/wilt diseases in greenhouse and field with addition improved plant growth and increased yield components in field.

2013-01-01

405

Fine mapping of qSB-11(LE), the QTL that confers partial resistance to rice sheath blight.  

PubMed

Sheath blight (SB), caused by Rhizoctonia solani kühn, is one of the most serious global rice diseases. No major resistance genes to SB have been identified so far. All discovered loci are quantitative resistance to rice SB. The qSB-11(LE) resistance quantitative trait locus (QTL) has been previously reported on chromosome 11 of Lemont (LE). In this study, we report the precise location of qSB-11 (LE) . We developed a near isogenic line, NIL-qSB11(TQ), by marker-assisted selection that contains susceptible allele(s) from Teqing (TQ) at the qSB-11 locus in the LE genetic background. NIL-qSB11(TQ) shows higher susceptibility to SB than LE in both field and greenhouse tests, suggesting that this region of LE contains a QTL contributing to SB resistance. In order to eliminate the genetic background effects and increase the accuracy of phenotypic evaluation, a total of 112 chromosome segment substitution lines (CSSLs) with the substituted segment specific to the qSB-11 (LE) region were produced as the fine mapping population. The genetic backgrounds and morphological characteristics of these CSSLs are similar to those of the recurrent parent LE. The donor TQ chromosomal segments in these CSSL lines contiguously overlap to bridge the qSB-11 (LE) region. Through artificial inoculation, all CSSLs were evaluated for resistance to SB in the field in 2005. For the recombinant lines, their phenotypes were evaluated in the field for another 3 years and during the final year were also evaluated in a controlled greenhouse environment, showing a consistent phenotype in SB resistance across years and conditions. After comparing the genotypic profile of each CSSL with its phenotype, we are able to localize qSB-11 (LE) to the region defined by two cleaved-amplified polymorphic sequence markers, Z22-27C and Z23-33C covering 78.871 kb, based on the rice reference genome. Eleven putative genes were annotated within this region and three of them were considered the most likely candidates. The results of this study will greatly facilitate the cloning of the genes responsible for qSB-11 (LE) and marker-assisted breeding to incorporate qSB-11 (LE) into other rice cultivars. PMID:23423653

Zuo, Shimin; Yin, Yuejun; Pan, Cunhong; Chen, Zongxiang; Zhang, Yafang; Gu, Shiliang; Zhu, Lihuang; Pan, Xuebiao

2013-02-20

406

A defensin with highly potent antipathogenic activities from the seeds of purple pole bean.  

PubMed

A 5443 Da peptide with sequence homology to defensins was purified from purple pole beans (Phaseolus vulgaris cv. 'Extra-long Purple Pole bean'). This peptide was isolated by adsorption on an affinity chromatographic medium Affi-Gel Blue gel and ion-exchange chromatographic media SP-Sepharose (sulfopropyl-Sepharose) and Mono S and by gel filtration on Superdex peptide. The peptide inhibited mycelial growth in Mycosphaerella arachidicola, Helminthosporium maydis, Fusarium oxysporum, Verticillium dahliae, Rhizoctonia solani, Candida albicans and Setosphaeria turcica with an IC50 of 0.8, 0.9, 2.3, 3.2, 4.3, 4.8 and 9.8 microM respectively. Its antifungal potency was higher than that of the plant defensin coccinin (IC50>50 microM). It induced membrane permeabilization in C. albicans as evidenced by SYTOX Green uptake, but did not affect erythrocyte membrane permeability. It inhibited growth in M. arachidicola by inducing chitin accumulation at hyphal tips as was shown by Congo Red staining. The antifungal activity was pH stable and thermostable. The peptide inhibited the proliferation of hepatoma (HepG2), breast cancer (MCF7), colon cancer (HT29) and cervical cancer (SiHa) cells but not that of human embryonic liver (WRL68) cells. Its anti-HepG2 activity (IC50=4.1+/-0.8 microM, n=3) was higher than that of another plant defensin, gymnin (IC50>50 microM). Its anti-MCF7 activity (IC50=8.3+/-0.3 microM, n=3) was similar to that of other plant defensins. It reduced the activity of HIV-1 reverse transcriptase with an IC50 of 0.5+/-0.1 microM, n=3, much more potently than other plant defensins (IC50>40 microM). There is the possibility of using the purple pole bean defensin for producing antifungal drugs and/or transgenic plants with fungal resistance. PMID:19335335

Lin, Peng; Wong, Jack Ho; Ng, Tzi Bun

2009-11-10

407

Microbial diversity during maturation and natural processing of coffee cherries of Coffea arabica in Brazil.  

PubMed

The magnitude and diversity of the microbial population associated with dry (natural) processing of coffee (Coffea arabica) has been assessed during a 2-year period on 15 different farms in the Sul de Minas region of Brazil. Peptone water-washed samples were taken of maturing cherries on trees (cherries, raisins and dried cherries) and from ground fermentations. The microbial load varied from 3 x 10(4) to 2.2 x 10(9) cfu/cherry with a median value of 1.6 x 10(7) cfu/cherry. The microbial load increased after heavy rainfall on cherries that were drying on the ground. At all stages, bacteria were usually the most abundant group, followed by filamentous fungi and finally yeasts. Counts of bacteria, yeasts and fungi varied considerably between farms and at different stages of maturation and processing and no consistent pattern could be seen. Yeasts showed an increase during the fermentation process. Median counts were not significantly different for fungi, yeasts and bacteria between the 2 years although Gram-negative bacteria dominated in the wet year and Gram-positive bacteria dominated in the dry year. Of a total of 754 isolates, 626 were identified to at least genus level comprising 44 genera and 64 different species. The 164 isolates of Gram-negative bacteria included 17 genera and 26 species, the most common of which were members of the genera Aeromonas, Pseudomonas, Enterobacter and Serratia. Of 191 isolates of Gram-positive bacteria, 23 were spore-forming and included six Bacillus species, and 118 were non-spore-formers of which over half were Cellulomonas with lesser numbers of Arthrobacter, Microbacterium, Brochothrix, Dermabacter and Lactobacillus. Of the 107 yeast isolates, 90 were identified into 12 genera and 24 different species and almost all were fermentative. The most common genera, in decreasing frequency, were Pichia, Candida, Arxula and Saccharomycopsis. There were many rarely described yeasts including Pichia lynferdii and Arxula adeninivorans. Almost all 292 fungal isolates were identified to genus level and 52 were identified to species level. Cladosporium, Fusarium and Penicillium each comprised about one third of the isolates and were found on all farms. Only 3% of the isolates were Aspergillus. Beauvaria, Monilia, Rhizoctonia and Arthrobotrys species were also occasionally found. The microbial flora is much more varied and complex than found in wet fermentations. The genera and species identified include members known to have all types of pectinase and cellulase activities. PMID:11016614

Silv, C F; Schwan, R F; Sousa Dias, E S; Wheals, A E

2000-09-25

408

Inhibitory effects of essential oils of medicinal plants from growth of plant pathogenic fungi.  

PubMed

Plant cells produce a vast amount of secondary metabolites. Production of some compounds is restricted to a single species. Some compounds are nearly always found only in certain specific plant organs and during a specific developmental period of the plant. Some secondary metabolites of plants serve as defensive compounds against invading microorganisms. Nowadays, it is attempted to substitute the biological and natural agents with chemically synthesized fungicides. In the present research, the antifungal activities of essential oils of seven medicinal plants on mycelial growth of three soilborne plant pathogenic fungi were investigated. The plants consisted of Zataria multiflora, Thymus carmanicus, Mentha pieperata, Satureja hortensis, Lavandual officinolis, Cuminum cyminum and Azadirachta indica. The first five plants are from the family Labiatae. Examined fungi, Fusarium oxysporum f.sp. lycopersici, Fusarium solani and Rhizoctonia solani are the causal agents of tomato root rot. Essential oils of Z. multiflora, T. carmanicus, M. pieperata, S. hortensis and C. cyminum were extracted by hydro-distillation method. Essential oils of L. officinalis and A. indica were extracted by vapor-distillation method. A completely randomized design with five replicates was used to examine the inhibitory impact of each concentration (300, 600 and 900 ppm) of each essential oil. Poisoned food assay using potato dextrose agar (PDA) medium was employed. Results showed that essential oils of A. indica, Z. multiflora, T. carmanicus and S. hortensis in 900 ppm at 12 days post-inoculation, when the control fungi completely covered the plates, prevented about 90% from mycelial growth of each of the fungi. While, the essential oils of M. pieperata, C. cyminum and L. officinalis in the same concentration and time prevented 54.86, 52.77 and 48.84%, respectively, from F. solani growth. These substances did not prevent from F. oxysporum f.sp. lycopersici and R. solani growth. Minimum inhibitory concentration (MIC) of essential oils of T. carmanicus, Z. multiflora and A. indica from R. solani and F. solani growth was 900 and 600 ppm, respectively. In addition, the MIC of essential oils of these plants and essential oil of S. hortensis from F. oxysporum f.sp. lycopersici growth was 900 ppm. The MIC of essential oils of M. pieperata, C. cyminum and L. officinalis from F. solani growth was 900 ppm. PMID:22702190

Panjehkeh, N; Jahani Hossein-Abadi, Z

2011-01-01

409

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde  

NASA Astrophysics Data System (ADS)

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m.

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Sumathi, S.

2012-10-01