Genomic resources for gene discovery, functional genome annotation, and evolutionary studies of maize and its close relatives.

PubMed

Wang, Chao; Shi, Xue; Liu, Lin; Li, Haiyan; Ammiraju, Jetty S S; Kudrna, David A; Xiong, Wentao; Wang, Hao; Dai, Zhaozhao; Zheng, Yonglian; Lai, Jinsheng; Jin, Weiwei; Messing, Joachim; Bennetzen, Jeffrey L; Wing, Rod A; Luo, Meizhong

2013-11-01

Maize is one of the most important food crops and a key model for genetics and developmental biology. A genetically anchored and high-quality draft genome sequence of maize inbred B73 has been obtained to serve as a reference sequence. To facilitate evolutionary studies in maize and its close relatives, much like the Oryza Map Alignment Project (OMAP) (www.OMAP.org) bacterial artificial chromosome (BAC) resource did for the rice community, we constructed BAC libraries for maize inbred lines Zheng58, Chang7-2, and Mo17 and maize wild relatives Zea mays ssp. parviglumis and Tripsacum dactyloides. Furthermore, to extend functional genomic studies to maize and sorghum, we also constructed binary BAC (BIBAC) libraries for the maize inbred B73 and the sorghum landrace Nengsi-1. The BAC/BIBAC vectors facilitate transfer of large intact DNA inserts from BAC clones to the BIBAC vector and functional complementation of large DNA fragments. These seven Zea Map Alignment Project (ZMAP) BAC/BIBAC libraries have average insert sizes ranging from 92 to 148 kb, organellar DNA from 0.17 to 2.3%, empty vector rates between 0.35 and 5.56%, and genome equivalents of 4.7- to 8.4-fold. The usefulness of the Parviglumis and Tripsacum BAC libraries was demonstrated by mapping clones to the reference genome. Novel genes and alleles present in these ZMAP libraries can now be used for functional complementation studies and positional or homology-based cloning of genes for translational genomics.

Technical note: whole-pen assessments of nutrient excretion and digestibility from dairy replacement heifers housed in sand-bedded freestalls.

PubMed

Coblentz, W K; Hoffman, P C; Esser, N M; Bertram, M G

2013-10-01

Our objectives were to describe and test refined procedures for quantifying excreta produced from whole pens of dairy heifers. Previous research efforts attempting to make whole-pen measurements of excreta output have been complicated by the use of organic bedding, which requires cumbersome analytical techniques to quantify excreta apart from the bedding. Research pens equipped with sand-bedded freestalls offer a unique opportunity for refinement of whole-pen fecal collection methods, primarily because sand-bedded freestall systems contain no organic bedding; therefore, concentrations of ash within the manure, sand, and feces can be used to correct for contamination of manure by sand bedding. This study was conducted on a subset of heifers from a larger production-scale feeding trial evaluating ensiled eastern gamagrass [Tripsacum dactyloides (L.) L.] haylage (EGG) that was incorporated into a corn silage/alfalfa haylage-based blended diet at rates of 0, 9.1, 18.3, or 27.4% of total DM. The diet without EGG also was offered on a limit-fed basis. Eighty Holstein dairy heifers were blocked (heavy weight, 424 ± 15.9 kg; light weight, 324 ± 22.4 kg) and then assigned to 10 individual pens containing 8 heifers/pen. One pen per block was assigned to each of the 5 research diets, and whole-pen fecal collections were conducted twice for each pen. Grab fecal samples also were gathered from individual heifers within each pen, and subsequent analysis of these whole-pen composites allowed reasonable estimates of OM and NDF excreta output. Under the conditions of our experimental design, pooled SEM for the excreta DM, OM, NDF, and NDF (ash corrected) output were 0.113, 0.085, 0.093, and 0.075 kg·heifer(-1)·d(-1), respectively. For DM excretion, this represented about one-third of the SEM reported for previous whole-pen collections from bedded-pack housing systems. Subsequent calculations of apparent DM and OM digestibilities indicated that the technique was sensitive, and

Stable centromere positioning in diverse sequence contexts of complex and satellite centromeres of maize and wild relatives.

PubMed

Gent, Jonathan I; Wang, Na; Dawe, R Kelly

2017-06-21

Paradoxically, centromeres are known both for their characteristic repeat sequences (satellite DNA) and for being epigenetically defined. Maize (Zea mays mays) is an attractive model for studying centromere positioning because many of its large (~2 Mb) centromeres are not dominated by satellite DNA. These centromeres, which we call complex centromeres, allow for both assembly into reference genomes and for mapping short reads from ChIP-seq with antibodies to centromeric histone H3 (cenH3). We found frequent complex centromeres in maize and its wild relatives Z. mays parviglumis, Z. mays mexicana, and particularly Z. mays huehuetenangensis. Analysis of individual plants reveals minor variation in the positions of complex centromeres among siblings. However, such positional shifts are stochastic and not heritable, consistent with prior findings that centromere positioning is stable at the population level. Centromeres are also stable in multiple F1 hybrid contexts. Analysis of repeats in Z. mays and other species (Zea diploperennis, Zea luxurians, and Tripsacum dactyloides) reveals tenfold differences in abundance of the major satellite CentC, but similar high levels of sequence polymorphism in individual CentC copies. Deviation from the CentC consensus has little or no effect on binding of cenH3. These data indicate that complex centromeres are neither a peculiarity of cultivation nor inbreeding in Z. mays. While extensive arrays of CentC may be the norm for other Zea and Tripsacum species, these data also reveal that a wide diversity of DNA sequences and multiple types of genetic elements in and near centromeres support centromere function and constrain centromere positions.

Effect of Fertilizers and Neem Cake Amendment in Soil on Spore Germination of Arthrobotrys dactyloides

PubMed Central

Kumar, D.; Jaiswal, R. K.

2005-01-01

Application of fertilizers such as urea, diammonium phosphate (DAP) and muriate of potash in soil adversely affected the spore germination of Arthrobotrys dactyloides. Amendment of soil with urea at the concentrations of 1.0%, 0.5% and 0.1% completely inhibited spore germination and direct trap formation on the conidium, whereas muriate of potash delayed and reduced the spore germination even at the lowest concentration. DAP also inhibited spore germination at 1.0% concentration, while at lower concentration the percentage of spore germination was reduced. Application of neem cake at the concentration of 0.5% also inhibited spore germination after 24 h of amendment. The inhibitory effect of neem cake was reduced after 15 days of amendment, while after 30 days after amendment the inhibitory effect was completely lost and the spore germinated by direct trap as in unamended soil. Nematodes were not attracted to ungerminated spores after 24 h of amendment. After 15 days of amendment nematodes were attracted to agar blocks containing fewer germinated spores after 24 h of incubation but after 48 h of incubation large number of nematodes were attracted and trapped by the germinated spores with direct traps. After 30 days of amendment, larger number of nematodes were attracted and trapped by direct traps. PMID:24049500

Identification of a locus characteristic of male individuals of buffalo grass [Buchloe dactyloides (Nutt.) Engelm.] by using an RAPD marker.

PubMed

Li, Y X; Wang, X G; Yang, C H; Cong, L L; Wu, F F; Xue, J G; Han, Y H

2013-09-27

Buffalo grass [Buchloe dactyloides (Nutt.) Engelm.] plants can be either male, female, or hermaphrodite (monoecious). As there is no morphological difference in the early vegetative growth of these three classes of plants, it is worthwhile to use molecular biological methods to attempt to identify the sex of a plant at this early growth period. In this study, we identified 23 plants that had a stable sex for over at least 3 years. Of these, 9 were male plants, 10 were female plants, and 4 were hermaphrodites. Screening of 300 RAPD primers identified a primer, namely S211 (5'-ttccccgcga-3'), which is capable of identifying male plants. The specific fragment was cloned, sequenced, and submitted to the GenBank database (accession No. JN982469). When used to identify the sex of 188 plants during their first growing season, the S211 primer correctly identified 85.8% of all male plants. Our results showed that the S211 primer can identify the male, and in doing so, it facilitates buffalo grass breeding work.

Changes in inflorescence protein during advanced stages of floret development in Buchloe dactyloides (Poaceae).

PubMed

Zhou, Y-J; Xue, J-G; Wang, X-G; Zhang, X-Q

2012-11-12

Buffalograss, Buchloe dactyloides, is a dioecious species native to the Great Plains of North America. The florets at the early stages of development possess both gynoecium and androecium organ primordia but later become unisexual. Very little is known about the proteomic changes that occur when the florets change from hermaphroditism to unisexuality. We compared the protein composition of florets at the hermaphroditic stage with that at the unisexual stage. The development stage of the floret was determined by stereomicroscopic observation. Two-dimensional gel electrophoresis was used to separate the proteins extracted from female and male inflorescences. Stage- specific protein maps, with an average of about 400 spots per map, were analyzed with the protein analysis software. Eighteen spots were found to be differentially expressed between the hermaphrodite and unisexual stages. Of these, 12 were present at both stages but with a different expression value. Four specific spots appeared at the hermaphrodite stage and disappeared at the unisexual stage. Two specific protein spots were associated with female and male floret differentiation. One appears to be associated with contabescence in the female floret and the final protein appears to lead to the abortion of gynoecium in the male floret. The MALDI TOF/TOF technique was used for peptide mass fingerprinting of the differentially expressed proteins and the MASCOT software was used to search the protein database. However, only two protein spots were identified from the database. These were aldolase1 and Os05g0574400 (similar to malate dehydrogenase). This type of proteomic study can help to identify novel protein products and determine the mechanisms involved in the floral sex differentiation process in buffalo grass.

Selective-placement burial of drilling fluids: 2. Effects on buffalograss and fourwing saltbrush. [Atriplex canescens; Buchloe dactyloides

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFarland, M.L.; Hartmann, S.; Ueckert, D.N.

Surface disposal of spent drilling fluids used in petroleum and natural gas exploration causes surface soil contamination that severely inhibits secondary plant succession and artificial revegetation efforts. Selective-placement burial was evaluated at two locations in western Texas for on-site disposal of drilling fluids in arid and semiarid regions. Establishment, yield, and chemical composition of fourwing saltbrush (Atriplex canescens (Pursh Nutt.)) and buffalograss (Buchloe dactyloides (Nutt.) Engelm.) transplants on undisturbed soils and on plots with spent drilling fluids and cuttings buried 30, 90 (with and without a 30-cm coarse limestone capillary barrier) and 150 cm were compared. Survival of both speciesmore » was 97 to 100% 17 months after planting on plots with buried drilling wastes. Canopy cover and aboveground biomass of fourwing saltbrush were greater over buried drilling wastes than on untreated plots, whereas canopy cover and aboveground biomass of buffalograss were not affected by the treatments. Significant increases in Na, M, and Mg concentrations in buffalograss after 17 months on plots with drilling fluids buried 30 cm deep at one location indicated plant uptake of some drilling fluid constituents. Elevated Zn concentrations in fourwing saltbush indicated that a portion of the Zn in the drilling fluids was available for plant uptake, while no evidence of plant accumulation of Ba, Cr, Cu, or Ni from drilling fluids was detected.« less

The role of teosinte glume architecture (tga1) in coordinated regulation and evolution of grass glumes and inflorescence axes.

PubMed

Preston, Jill C; Wang, Huai; Kursel, Lisa; Doebley, John; Kellogg, Elizabeth A

2012-01-01

• Hardened floral bracts and modifications to the inflorescence axis of grasses have been hypothesized to protect seeds from predation and/or aid seed dispersal, and have evolved multiple times independently within the family. Previous studies have demonstrated that mutations in the maize (Zea mays ssp. mays) gene teosinte glume architecture (tga1) underlie a reduction in hardened structures, yielding free fruits that are easy to harvest. It remains unclear whether the causative mutation(s) occurred in the cis-regulatory or protein-coding regions of tga1, and whether similar mutations in TGA1-like genes can explain variation in the dispersal unit in related grasses. • To address these questions TGA1-like genes were cloned and sequenced from a number of grasses and analyzed phylogenetically in relation to morphology; protein expression was investigated by immunolocalization. • TGA1-like proteins were expressed throughout the spikelet in the early development of all grasses, and throughout the flower of the grass relative Joinvillea. Later in development, expression patterns differed between Tripsacum dactyloides, maize and teosinte (Z. mays ssp. parviglumis). • These results suggest an ancestral role for TGA1-like genes in early spikelet development, but do not support the hypothesis that TGA1-like genes have been repeatedly modified to affect glume and inflorescence axis diversification. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

RAPD and Internal Transcribed Spacer Sequence Analyses Reveal Zea nicaraguensis as a Section Luxuriantes Species Close to Zea luxurians

PubMed Central

Wang, Pei; Lu, Yanli; Zheng, Mingmin; Rong, Tingzhao; Tang, Qilin

2011-01-01

Genetic relationship of a newly discovered teosinte from Nicaragua, Zea nicaraguensis with waterlogging tolerance, was determined based on randomly amplified polymorphic DNA (RAPD) markers and the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA using 14 accessions from Zea species. RAPD analysis showed that a total of 5,303 fragments were produced by 136 random decamer primers, of which 84.86% bands were polymorphic. RAPD-based UPGMA analysis demonstrated that the genus Zea can be divided into section Luxuriantes including Zea diploperennis, Zea luxurians, Zea perennis and Zea nicaraguensis, and section Zea including Zea mays ssp. mexicana, Zea mays ssp. parviglumis, Zea mays ssp. huehuetenangensis and Zea mays ssp. mays. ITS sequence analysis showed the lengths of the entire ITS region of the 14 taxa in Zea varied from 597 to 605 bp. The average GC content was 67.8%. In addition to the insertion/deletions, 78 variable sites were recorded in the total ITS region with 47 in ITS1, 5 in 5.8S, and 26 in ITS2. Sequences of these taxa were analyzed with neighbor-joining (NJ) and maximum parsimony (MP) methods to construct the phylogenetic trees, selecting Tripsacum dactyloides L. as the outgroup. The phylogenetic relationships of Zea species inferred from the ITS sequences are highly concordant with the RAPD evidence that resolved two major subgenus clades. Both RAPD and ITS sequence analyses indicate that Zea nicaraguensis is more closely related to Zea luxurians than the other teosintes and cultivated maize, which should be regarded as a section Luxuriantes species. PMID:21525982

Evolution of DUF1313 family members across plant species and their association with maize photoperiod sensitivity.

PubMed

Li, Jia; Hu, Erliang; Chen, Xueying; Xu, Jie; Lan, Hai; Li, Chuan; Hu, Yaodong; Lu, Yanli

2016-05-01

Proteins of the DUF1313 family contain a highly conserved domain and are only found in plants; they play important roles in most plant functions. In this study, 269 DUF1313 genes from 81 photoautotrophic species were identified; they were classified into three major types based on the amino acid substitutions in the conserved region: IARV, I(S/T/F)(K/R)V, and IRRV. Phylogenic tree constructed from 51 DUF1313 genes from graminoids revealed three clades: A, B1, and B2. Clade B1 was found to have undergone episodic positive selection after a gene duplication event and included four amino acid sites under positive selection. The association between DUF1313 family members and traits investigated in maize indicated that three of four genes (GRMZM2G025646, GRMZM5G877647, GRMZM2G359322, and GRMZM2G382774) were associated with the target traits such as days to silking, days to tasselling, and plant height. The nucleotide diversity of the most primitive and highly conserved DUF1313 gene, ELF4-like4, was the highest in Tripsacum and the lowest in maize. Tajima's D and Fu and Li's D tests revealed that significant purifying selection had occurred in the coding sequence region of this DUF1313 gene in teosinte and maize. No significant signal was detected in the 5'-untranslated region of this gene in each of the three species (maize, teosinte, and Tripsacum) or in any gene regions of Tripsacum. Phylogenetic analyses revealed that the 103 accessions of maize, teosinte, and Tripsacum can be grouped into four clades based on the ELF4-like4 gene sequence similarity. Thus, this gene can be used to determine the relationships between maize and its relatives, and the DUF1313 family members and alleles identified in this study might be valuable genetic resources for molecular marker-assisted breeding in maize. Copyright © 2016 Elsevier Inc. All rights reserved.

Economic feasibility analysis of conventional and dedicated energy crop production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, R.G.; Langemeier, M.R.; Krehbiel, L.R.

Economic feasibilities (net return per acre) associated with conventional agricultural crop production versus that of dedicated bioenergy crop (herbaceous energy crops) were investigated for northeastern Kansas. Conventional agricultural crops examined were corn, soybeans, wheat, sorghum and alfalfa and dedicated herbaceous energy crops included big bluestem/indiangrass, switchgrass, eastern gamagrass, brome, fescue and cane hay. Costs, prices and government program information from public and private sources were used to project the net return per acre over a six-year period beginning in 1997. Three soil productivity levels (low, average and high), which had a direct effect on the net return per acre, weremore » used to model differences in expected yield. In all three soil productivity cases, big bluestem/indiangrass, switchgrass and brome hay provided a higher net return per acre versus conventional crops grown on both program and non-program acres. Eastern gamagrass, fescue hay and cane hay had returns that were similar or less than returns provided by conventional crops.« less

Effect of Tylenchorhynchus robustoides on Growth of Buffalo Grass and Western Wheatgrass.

PubMed

Smolik, J D

1982-10-01

Tylenchorhynchus robustoides reduced (P = 0.05) growth of Agropyron smithii (western wheatgrass) at soil temperatures of 20, 25, 30, and 35 C. Growth reduction increased with increasing soil temperatures. Highest populations of T. robustoides were recovered at 25 and 30 C. Clipping weights of Buchloe dactyloides (buffalo grass) were reduced at 25 and 30 C; however, root/crown weights were reduced at 15, 20, 30, and 35 C in nematode infested vs. noninfested soil. Reproduction of T. robustoides was greater at 25, 30, and 35 C than at 20 C on B. dactyloides. In a greenhouse study, T. robustoides reduced clipping and root/crown weights of both grasses 24-64%.

Corn Culture: A Story of Intelligent Design

ERIC Educational Resources Information Center

Todd, Jude

2008-01-01

Scientists are not sure of how corn was created. There were two competing genetic theories about how corn came to be. One theory maintains that corn had been teased out of a wheatlike grass called teosinte (genus Zea), and the other contends that one now-extinct ancestor of corn had crossed with another grass, "Tripsacum," several millennia ago.…

Optimization of Plant Growth-Promoting Bacteria-Assisted Phytostabilization of Mine Tailings

PubMed Central

Grandlic, Christopher J.; Palmer, Michael W.; Maier, Raina M.

2009-01-01

Recent studies have indicated that plant growth-promoting bacteria (PGPB) can improve revegetation of arid mine tailings as measured by increased biomass production. The goals of the present study were first to evaluate how mode of application of known PGPB affects plant growth, and second to evaluate the effect of this inoculation on rhizosphere microbial community structure. PGPB application strategies investigated include preliminary surface sterilization of seeds (a common practice in phytoremediation trials) followed by a comparison of two application methods; immersion and alginate encapsulation. Results with two native desert plant species, Atriplex lentiformis and Buchloe dactyloides, suggest that seed surface sterilization prior to inoculation is not necessary to achieve beneficial effects of introduced PGPB. Both PGPB application techniques generally enhanced plant growth although results were both plant and PGPB specific. These results demonstrate that alginate encapsulation, which allows for long-term storage and easier application to seeds, is an effective way to inoculate PGPB. In addition, the influence of PGPB application on B. dactyloides rhizosphere community structure was evaluated using PCR-DGGE (denaturing gradient gel electrophoresis) analysis of bacterial DNA extracted from rhizosphere samples collected 75 d following planting. A comparative analysis of DGGE profiles was performed using canonical correspondence analysis (CCA). DGGE-CCA showed that rhizosphere community profiles from PGPB-inoculated treatments are significantly different from both uninoculated tailings rhizosphere profiles and profiles from the compost used to amend the tailings. Further, community profiles from B. dactyloides inoculated with the best performing PGPB (Arthro mix) were significantly different from two other PGPB tested. These results suggest that introduced PGPB have the potential to influence the development of the rhizosphere community structure found in

Environmental Assessment to Construct a FAMCAMP, Sheppard Air Force Base, Texas

DTIC Science & Technology

2013-01-05

Bennuda (Cynodon dactylon), buffalo grass (Buchloe dactyloides), Texas wintergrass (Stipa leucotricha), Johnson grass (Sorghum halepense), and...previously disturbed areas within the developed area of the base. The proposed project area is composed of grasses that are periodically mowed including...consist of approved mixtures of grass species. Periodically, herbicide would be applied as necessary to control undesirable plant species. Therefore

7 CFR 201.48 - Kind or variety considered pure seed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of the grass family listed in § 201.47a(b) (1) through (5) if a caryopsis with some degree of...) and (2) of this section. Refer to §§ 201.48(h) and 201.51(a)(5) when nematode galls and fungal bodies... grass families listed below: (1) Intact burs of buffalograss (Buchloe dactyloides) shall be considered...

7 CFR 201.48 - Kind or variety considered pure seed.

Code of Federal Regulations, 2011 CFR

2011-01-01

... of the grass family listed in § 201.47a(b) (1) through (5) if a caryopsis with some degree of...) and (2) of this section. Refer to §§ 201.48(h) and 201.51(a)(5) when nematode galls and fungal bodies... grass families listed below: (1) Intact burs of buffalograss (Buchloe dactyloides) shall be considered...

Physiologically mediated self/non-self discrimination in roots

PubMed Central

Gruntman, Michal; Novoplansky, Ariel

2004-01-01

Recent evidence suggests that self/non-self discrimination exists among roots; its mechanisms, however, are still unclear. We compared the growth of Buchloe dactyloides cuttings that were grown in the presence of neighbors that belonged to the same physiological individual, were separated from each other for variable periods, or originated from adjacent or remote tillers on the same clone. The results demonstrate that B. dactyloides plants are able to differentiate between self and non-self neighbors and develop fewer and shorter roots in the presence of other roots of the same individual. Furthermore, once cuttings that originate from the very same node are separated, they become progressively alienated from each other and eventually relate to each other as genetically alien plants. The results suggest that the observed self/non-self discrimination is mediated by physiological coordination among roots that developed on the same plant rather than allogenetic recognition. The observed physiological coordination is based on an as yet unknown mechanism and has important ecological implications, because it allows the avoidance of competition with self and the allocation of greater resources to alternative functions. PMID:15004281

Sporophytic control of pollen tube growth and guidance in maize.

PubMed

Lausser, Andreas; Kliwer, Irina; Srilunchang, Kanok-orn; Dresselhaus, Thomas

2010-03-01

Pollen tube germination, growth, and guidance (progamic phase) culminating in sperm discharge is a multi-stage process including complex interactions between the male gametophyte as well as sporophytic tissues and the female gametophyte (embryo sac), respectively. Inter- and intra-specific crossing barriers in maize and Tripsacum have been studied and a precise description of progamic pollen tube development in maize is reported here. It was found that pollen germination and initial tube growth are rather unspecific, but an early, first crossing barrier was detected before arrival at the transmitting tract. Pollination of maize silks with Tripsacum pollen and incompatible pollination of Ga1s/Ga1s-maize silks with ga1-maize pollen revealed another two incompatibility barriers, namely transmitting tract mistargeting and insufficient growth support. Attraction and growth support by the transmitting tract seem to play key roles for progamic pollen tube growth. After leaving transmitting tracts, pollen tubes have to navigate across the ovule in the ovular cavity. Pollination of an embryo sac-less maize RNAi-line allowed the role of the female gametophyte for pollen tube guidance to be determined in maize. It was found that female gametophyte controlled guidance is restricted to a small region around the micropyle, approximately 50-100 microm in diameter. This area is comparable to the area of influence of previously described ZmEA1-based short-range female gametophyte signalling. In conclusion, the progamic phase is almost completely under sporophytic control in maize.

Sporophytic control of pollen tube growth and guidance in maize

PubMed Central

Lausser, Andreas; Kliwer, Irina; Srilunchang, Kanok-orn; Dresselhaus, Thomas

2010-01-01

Pollen tube germination, growth, and guidance (progamic phase) culminating in sperm discharge is a multi-stage process including complex interactions between the male gametophyte as well as sporophytic tissues and the female gametophyte (embryo sac), respectively. Inter- and intra-specific crossing barriers in maize and Tripsacum have been studied and a precise description of progamic pollen tube development in maize is reported here. It was found that pollen germination and initial tube growth are rather unspecific, but an early, first crossing barrier was detected before arrival at the transmitting tract. Pollination of maize silks with Tripsacum pollen and incompatible pollination of Ga1s/Ga1s-maize silks with ga1-maize pollen revealed another two incompatibility barriers, namely transmitting tract mistargeting and insufficient growth support. Attraction and growth support by the transmitting tract seem to play key roles for progamic pollen tube growth. After leaving transmitting tracts, pollen tubes have to navigate across the ovule in the ovular cavity. Pollination of an embryo sac-less maize RNAi-line allowed the role of the female gametophyte for pollen tube guidance to be determined in maize. It was found that female gametophyte controlled guidance is restricted to a small region around the micropyle, approximately 50–100 μm in diameter. This area is comparable to the area of influence of previously described ZmEA1-based short-range female gametophyte signalling. In conclusion, the progamic phase is almost completely under sporophytic control in maize. PMID:19926683

Pistil Smut Infection Increases Ovary Production, Seed Yield Components, and Pseudosexual Reproductive Allocation in Buffalograss

PubMed Central

Chandra, Ambika; Huff, David R.

2014-01-01

Sex expression of dioecious buffalograss [Bouteloua dactyloides Columbus (syn. Buchloë dactyloides (Nutt.) Engelm.)] is known to be environmentally stable with approximate 1:1, male to female, sex ratios. Here we show that infection by the pistil smut fungus [Salmacisia buchloëana Huff & Chandra (syn. Tilletia buchloëana Kellerman and Swingle)] shifts sex ratios of buffalograss to be nearly 100% phenotypically hermaphroditic. In addition, pistil smut infection decreased vegetative reproductive allocation, increased most seed yield components, and increased pseudosexual reproductive allocation in both sex forms compared to uninfected clones. In female sex forms, pistil smut infection resulted in a 26 fold increase in ovary production and a 35 fold increase in potential harvest index. In male sex forms, pistil smut infection resulted in 2.37 fold increase in floret number and over 95% of these florets contained a well-developed pistil. Although all ovaries of infected plants are filled with fungal teliospores and hence reproductively sterile, an average male-female pair of infected plants exhibited an 87 fold increase in potential harvest index compared to their uninfected clones. Acquiring an ability to mimic the effects of pistil smut infection would enhance our understanding of the flowering process in grasses and our efforts to increase seed yield of buffalograss and perhaps other grasses. PMID:27135522

Growth performance and sorting characteristics of corn silage-alfalfa haylage diets with or without forage dilution offered to replacement Holstein dairy heifers.

PubMed

Coblentz, W K; Esser, N M; Hoffman, P C; Akins, M S

2015-11-01

Gravid heifers consuming high-quality forage diets are susceptible to excessive weight gains and overconditioning. One approach for controlling this problem is to dilute diets with low-energy forages, such as straw, that reduce the caloric density and dry matter intake (DMI) of that diet by heifers. These diluting agents are often sortable by dairy heifers, but previous visual evidence has suggested that eastern gamagrass haylage may be a nonsortable alternative. Our objectives were (1) to compare the growth performance of dairy heifers offered a high-quality forage diet (control) with diets containing 1 of 3 diluting agents [eastern gamagrass haylage (EGH), chopped wheat straw (WS), or chopped corn fodder (CF)]; and (2) evaluate sorting behaviors of heifers offered these forage diets. Holstein heifers (n=128) were stratified (32 heifers/block) on the basis of initial body weight (heavy, 560 ± 27.7 kg; medium-heavy, 481 ± 17.7 kg; medium-light, 441 ± 22.0 kg; and light, 399 ± 14.4 kg), and then assigned to 1 of 16 identical research pens (4 pens/block; 8 heifers/pen), where each of the 4 research diets were assigned to 1 pen within each block. Diets were offered in a 118-d feeding trial with heifers crowded to 133% of capacity at the feed bunk. Inclusion of low-energy forages was effective in reducing both diet energy density and DMI. Concentrations of physically effective fiber (pef) particles did not change during the 24-h period following feeding for either the control or EGH diets; however, this response for pef particles masked the competing (and cancelling) responses for individual large and medium particles, which heifers sorted with discrimination and preference, respectively. Sorting against pef particles was detected for WS, and much more severely for the CF diet. Sorting of forage particles by heifers could not be related to heifer performance. Compared with control (1.16 kg/d), average daily gains (ADG) were reduced by dilution in all cases, but

The Evolution of Ribosomal DNA: Divergent Paralogues and Phylogenetic Implications

PubMed Central

Buckler-IV, E. S.; Ippolito, A.; Holtsford, T. P.

1997-01-01

Although nuclear ribosomal DNA (rDNA) repeats evolve together through concerted evolution, some genomes contain a considerable diversity of paralogous rDNA. This diversity includes not only multiple functional loci but also putative pseudogenes and recombinants. We examined the occurrence of divergent paralogues and recombinants in Gossypium, Nicotiana, Tripsacum, Winteraceae, and Zea ribosomal internal transcribed spacer (ITS) sequences. Some of the divergent paralogues are probably rDNA pseudogenes, since they have low predicted secondary structure stability, high substitution rates, and many deamination-driven substitutions at methylation sites. Under standard PCR conditions, the low stability paralogues amplified well, while many high-stability paralogues amplified poorly. Under highly denaturing PCR conditions (i.e., with dimethylsulfoxide), both low- and high-stability paralogues amplified well. We also found recombination between divergent paralogues. For phylogenetics, divergent ribosomal paralogues can aid in reconstructing ancestral states and thus serve as good outgroups. Divergent paralogues can also provide companion rDNA phylogenies. However, phylogeneticists must discriminate among families of divergent paralogues and recombinants or suffer from muddled and inaccurate organismal phylogenies. PMID:9055091

Megabase-Scale Inversion Polymorphism in the Wild Ancestor of Maize

PubMed Central

Fang, Zhou; Pyhäjärvi, Tanja; Weber, Allison L.; Dawe, R. Kelly; Glaubitz, Jeffrey C.; González, José de Jesus Sánchez; Ross-Ibarra, Claudia; Doebley, John; Morrell, Peter L.; Ross-Ibarra, Jeffrey

2012-01-01

Chromosomal inversions are thought to play a special role in local adaptation, through dramatic suppression of recombination, which favors the maintenance of locally adapted alleles. However, relatively few inversions have been characterized in population genomic data. On the basis of single-nucleotide polymorphism (SNP) genotyping across a large panel of Zea mays, we have identified an ∼50-Mb region on the short arm of chromosome 1 where patterns of polymorphism are highly consistent with a polymorphic paracentric inversion that captures >700 genes. Comparison to other taxa in Zea and Tripsacum suggests that the derived, inverted state is present only in the wild Z. mays subspecies parviglumis and mexicana and is completely absent in domesticated maize. Patterns of polymorphism suggest that the inversion is ancient and geographically widespread in parviglumis. Cytological screens find little evidence for inversion loops, suggesting that inversion heterozygotes may suffer few crossover-induced fitness consequences. The inversion polymorphism shows evidence of adaptive evolution, including a strong altitudinal cline, a statistical association with environmental variables and phenotypic traits, and a skewed haplotype frequency spectrum for inverted alleles. PMID:22542971

Screening level model for ecological risk assessment at EF-Site Los Alamos National Laboratory, New Mexico. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alldredge, A.W.; Kirchner, T.B.; McLendon, T.

1995-12-01

In response to a paucity of data on the chemical toxicity of uranium to plants, a factorial experiment employing five uranium concentrations (0, 50, 500, 5000, 25000 ppm) and three moisture regimes (low, medium, high) was performed using three native grasses. Buchloe dactyloides (buffalograss-mid/late seral), Schizachyrium scoparium (little bluestem-late seral), and Aristida longiseta (purple threeawn-early/mid seral) were grown in monocultures and every mixture of two species under all combinations of uranium and moisture levels. This design allows for the analysis of uranium effects, as well as possible compound effects due to moisture stress. Several measures of plant health and viabilitymore » were made, including: percent emergence, survivability of seedlings and mature plants, root and shoot biomass, and the number and mass of inflorescences. No significant differences between uranium levels were observed in terms of emergence and seedling survival. Effects are evident for plant biomass, fecundity, and long-term survivability.« less

Rhizosphere Colonization and Control of Meloidogyne spp. by Nematode-trapping Fungi

PubMed Central

Persson, Christina; Jansson, Hans-Börje

1999-01-01

The ability of nematode-trapping fungi to colonize the rhizosphere of crop plants has been suggested to be an important factor in biological control of root-infecting nematodes. In this study, rhizosphere colonization was evaluated for 38 isolates of nematode-trapping fungi representing 11 species. In an initial screen, Arthrobotrys dactyloides, A. superba, and Monacrosporium ellipsosporum were most frequently detected in the tomato rhizosphere. In subsequent pot experiments these fungi and the non-root colonizing M. geophyropagum were introduced to soil in a sodium alginate matrix, and further tested both for establishment in the tomato rhizosphere and suppression of root-knot nematodes. The knob-forming M. ellipsosporum showed a high capacity to colonize the rhizosphere both in the initial screen and the pot experiments, with more than twice as many fungal propagules in the rhizosphere as in the root-free soil. However, neither this fungus nor the other nematode-trapping fungi tested reduced nematode damage to tomato plants. PMID:19270886

Efficacy of a Simple Formulation Composed of Nematode-Trapping Fungi and Bidens pilosa var. radiata Scherff Aqueous Extracts (BPE) for Controlling the Southern Root-Knot Nematode

PubMed Central

Ajitomi, Atsushi; Taba, Satoshi; Ajitomi, Yoshino; Kinjo, Misa; Sekine, Ken-taro

2018-01-01

We tested a formulation composed of a mixture of Bidens pilosa var. radiata extract (BPE) and nematode-trapping fungi for its effects on Meloidogyne incognita. In earlier evaluations of the effects of plant extracts on the hyphal growth of 5 species of nematode-trapping fungi with different capture organs (traps), the growth of all species was slightly inhibited. However, an investigation on the number of capture organs and nematode-trapping rates revealed that Arthrobotrys dactyloides formed significantly more rings and nematode traps than those of the control. An evaluation of simple mixed formulations prepared using sodium alginate showed that nematodes were captured with all formulations tested. The simple mixed formulation showed a particularly high capture rate. Furthermore, in a pot test, although the effects of a single formulation made from the fungus or plant extract were acceptable, the efficacy of the simple mixed formulation against M. incognita root-knot formation was particularly high. PMID:29311429

In-vitro predatory activity of nematophagous fungi from Costa Rica with potential use for controlling sheep and goat parasitic nematodes.

PubMed

Soto-Barrientos, Natalia; de Oliveira, Jaqueline; Vega-Obando, Rommel; Montero-Caballero, Danilo; Vargas, Bernardo; Hernández-Gamboa, Jorge; Orozco-Solano, Claudio

2011-03-01

In tropical and subtropical regions of the world, parasitic diseases are a main cause of losses in livestock productivity. The increased acquired resistence to anthelmintics by gastrointestinal nematodes, requires biological control be considered as a potential feasible and effective alternative. The most effective natural soil enemies of nematodes are nematophagous fungi. In order to collect and identify predator nematophagous fungi (PNF), samples were obtained from 51 farms distributed throughout the seven provinces of Costa Rica. The origin samples included: soil from different crops (potatoes, tomatoes, bananas, ornamental plants, squash and coffee); animal feces (cattle, sheep, goat and horse); soil and fallen leaves from forest; and plants with signs of nematode infection. Each sample was processed using three techniques for the extraction of fungi from soil: sprinkling technique, soil dilution and humidity chamber. Twenty four strains of nematophagous fungi were found in 19 farms; 83.3% of the fungi were isolated by sprinkling technique. The following fungi were identified: Arthrobotrys oligospora (n = 13); Candelabrella musiformis (n = 9); and for the first time there was isolation of A. conoides (n = 1) and A. dactyloides (n = 1) in the country. Moreover, 16 strains from Trichoderma (n=13), Beauveria (n = 1), Clonostachys (n = 1) and Lecanicillium (n = 1) were obtained. In addition, pH of each possible fungal isolation source was measured, and it varied from 5.2 to 9.9, however PNF isolates fell within the range of 5.6 to 7.5. The PNF strains were cultivated in four different media for the production of chhlamydospores: potato dextrose agar (PDA); corn meal agar (CMA); malt extract agar (MEA) and potato carrot agar (PCA). Out of these cultures, 95.8% of the strains formed chlamydospores primarily in the PCA. Of these strains, the profilic spore producers were subjected to ruminant artificial gastrointestinal conditions. A total of 14 fungi were tested, out

Phytotoxicity of depleted uranium on three grasses characteristic of different successional stages

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, M.C.; McLendon, T.

1997-05-01

In response to a paucity of data on the chemical toxicity of uranium (U) to plants, a factorial experiment employing five U concentrations (0, 50, 500, 5000, 25,000 mg kg{sup -1}) and three moisture regimes (low, medium, and high) was performed using three native grasses. Buchloe dactyloides (buffalograss; mid/late-seral), Schizachyrium scoparium (little bluestem; late-seral), and Aristida purpurea (purple threeawn; early/mid-seral) were grown in monocultures and as a mixture of two species under all combinations of U and moisture levels. This design allowed for the analysis of U effects, as well as possible interactions with moisture stress. Several measures of plantmore » health and viability were made, including: percent emergence, plant survival, shoot biomass, and number and weight of inflorescences. Decreases in plant biomass, fecundity, and long-term survivability were observed only at the highest U level (25 000 mg kg{sup -1}). No significant differences (P < 0.05) between the U treatment levels were observed in terms of seedling emergence and survival. Drought stress also negatively impacted survival and biomass, but acted independently of U stress. 18 refs., 4 figs., 3 tabs.« less

Ground level air convection produces frost damage patterns in turfgrass

NASA Astrophysics Data System (ADS)

Ackerson, Bruce J.; Beier, Richard A.; Martin, Dennis L.

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass ( Cynodon species Rich.), zoysiagrass ( Zoysia species Willd.), and buffalograss [ Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

Ground level air convection produces frost damage patterns in turfgrass.

PubMed

Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

A maize map standard with sequenced core markers, grass genome reference points and 932 expressed sequence tagged sites (ESTs) in a 1736-locus map.

PubMed Central

Davis, G L; McMullen, M D; Baysdorfer, C; Musket, T; Grant, D; Staebell, M; Xu, G; Polacco, M; Koster, L; Melia-Hancock, S; Houchins, K; Chao, S; Coe, E H

1999-01-01

We have constructed a 1736-locus maize genome map containing1156 loci probed by cDNAs, 545 probed by random genomic clones, 16 by simple sequence repeats (SSRs), 14 by isozymes, and 5 by anonymous clones. Sequence information is available for 56% of the loci with 66% of the sequenced loci assigned functions. A total of 596 new ESTs were mapped from a B73 library of 5-wk-old shoots. The map contains 237 loci probed by barley, oat, wheat, rice, or tripsacum clones, which serve as grass genome reference points in comparisons between maize and other grass maps. Ninety core markers selected for low copy number, high polymorphism, and even spacing along the chromosome delineate the 100 bins on the map. The average bin size is 17 cM. Use of bin assignments enables comparison among different maize mapping populations and experiments including those involving cytogenetic stocks, mutants, or quantitative trait loci. Integration of nonmaize markers in the map extends the resources available for gene discovery beyond the boundaries of maize mapping information into the expanse of map, sequence, and phenotype information from other grass species. This map provides a foundation for numerous basic and applied investigations including studies of gene organization, gene and genome evolution, targeted cloning, and dissection of complex traits. PMID:10388831

Selective placement disposal of drilling fluids in west Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

McFarland, M.L.

1988-01-01

Burial of spent drilling fluids used in petroleum and natural gas exploration was evaluated as an alternative disposal technique for reducing surface soil contamination in western Texas. Simulated reserve pits were constructed to provide burial depths of 30, 90, and 150 cm below the surface, with orderly replacement of stockpiled subsoil and topsoil. Movement of soluble salts and heavy metals from drilling fluids into the overlying soil was monitored over a 20-month period. The effects of depth of drilling fluid burial on establishment, yields, and chemical composition of transplanted fourwing saltbush (Atriplex canescens (Pursh) Nutt.) and buffalograss (Buchloe dactyloides (Nutt.)more » Engelm.) were determined for two growing seasons. Sodium, Ca{sup +2}, and Cl{sup {minus}} were the dominant mobile ions, while migration of Mg{sup +2}, K{sup +}, and SO{sub 4}{sup {minus}2} was observed to a lesser degree. Exchangeable sodium percentages in the 15-cm zone immediately above drilling fluid ranged from 1.9 to 19.0 after 20 months. Total concentrations of Ba, Cr, Cu, Ni, and Zn were greater in drilling fluids than in native soil, but there was no evidence of migration of these metals into overlying soil.« less

Charadrius montanus: Montane, grassland, or bare-ground plover?

USGS Publications Warehouse

Knopf, Fritz L.; Miller, B.

1994-01-01

The Mountain Plover (Charadrius montanus) is an aridland member of the Charadriidae. This plover is generally considered an associate of the North American shortgrass prairie, which is dominated by blue grama (Bouteloua gracilis) and buffalo grass (Buchloe dactyloides; Graul 1975). The species breeds at many locations across the western Great Plains plus at isolated locales in western Colorado, Wyoming and New Mexico (Leachman and Osmundson 1990) and recently in eastern Utah (K.S. Day pers.comm.). Continental populations of the Mountain Plover declined 63% from 1966 to 1991 (Knopf 1994), with the historic and current breeding stronghold being the Pawnee National Grassland in Weld County, Colorado (Graul and Webster 1976). Currently, a second major breeding population of Mountain Plovers is on the Charles M. Russell National Wildlife Refuge, Phillips County, Montana. Unlike when found on the grassland landscape of Weld County, Mountain Plovers in Phillips County selectively nest in prairie dog (Cynomys spp.) towns (Knowles et al., 1982, Olson and Edge 1985) in vegetative settings that include prickly pear (Opunitia polyacantha), fringed sagewort (Arteminisia frigida), big sagebrush (A. tridentata), western wheatgrass (Agropyron smithii), and blue grama, Collectively, Weld and Phillips counties provide nesting habitat for approximately one-half of the continental population of Mountain Plovers,

Transcriptome Profiling of Buffalograss Challenged with the Leaf Spot Pathogen Curvularia inaequalis.

PubMed

Amaradasa, Bimal S; Amundsen, Keenan

2016-01-01

Buffalograss (Bouteloua dactyloides) is a low maintenance U. S. native turfgrass species with exceptional drought, heat, and cold tolerance. Leaf spot caused by Curvularia inaequalis negatively impacts buffalograss visual quality. Two leaf spot susceptible and two resistant buffalograss lines were challenged with C. inaequalis. Samples were collected from treated and untreated leaves when susceptible lines showed symptoms. Transcriptome sequencing was done and differentially expressed genes were identified. Approximately 27 million raw sequencing reads were produced per sample. More than 86% of the sequencing reads mapped to an existing buffalograss reference transcriptome. De novo assembly of unmapped reads was merged with the existing reference to produce a more complete transcriptome. There were 461 differentially expressed transcripts between the resistant and susceptible lines when challenged with the pathogen and 1552 in its absence. Previously characterized defense-related genes were identified among the differentially expressed transcripts. Twenty one resistant line transcripts were similar to genes regulating pattern triggered immunity and 20 transcripts were similar to genes regulating effector triggered immunity. There were also nine up-regulated transcripts in resistance lines which showed potential to initiate systemic acquired resistance (SAR) and three transcripts encoding pathogenesis-related proteins which are downstream products of SAR. This is the first study characterizing changes in the buffalograss transcriptome when challenged with C. inaequalis.

Screening of different sample types associated with sheep and cattle for the presence of nematophagous fungi in China.

PubMed

Cai, Kui-Zheng; Liu, Jun-Lin; Liu, Wei; Wang, Bo-Bo; Xu, Qiang; Sun, Long-Jie; Chen, Ming-Yue; Zhao, Ming-Wang; Wu, Jia-Yan; Li, Xiao-Shan; Yang, Jing; Wei, Shuan; Chen, Chun-Rong; Ma, Zhong-Ren; Xu, Chun-Lan; Wang, Feng; Hu, Qian-Lin; Fang, Wen-Xiu; Zheng, Tian-Hui; Wang, Yue-Ying; Zhu, Wen-Long; Li, Dan; Li, Qing; Zhang, Chao; Cai, Bing; Wang, Fan; Yang, Zai-Yun; Liu, Yan-Qiu

2016-03-01

A total of 1502 samples, including feces of sheep (793) and cattle (348), pasture soil (118), dung compost (147) and barn soil (96), were examined between October 2012 and August 2014 to discover potential strains of nematophagous fungi for the biological control of livestock-parasitic nematodes. These samples were collected from 87 sites located in 48 counties of 20 provinces (autonomous regions/municipalities) of China. Fungi were identified down to a species level. Four hundred and seventy-seven isolates, which were distributed in 8 genera and 28 taxa, were identified as nematophagous fungi. Nematode-trapping fungi included 17 species and one unidentified species of Arthrobotrys, two of Dactylella, Drechslerella dactyloides, and Duddingtonia flagrans. Five identified species and two unidentified species of endoparasitic fungi were isolated. The predominant species from all regions were Arthrobotrys oligospora, followed by Arthrobotrys musiformis, Arthrobotrys (Monacrosporium) thaumasiun, and Arthrobotrys (Monacrosporium) microscaphoides. Species with adhesive networks were the most frequently isolated. Among the endoparasitic fungi, Podocrella harposporifera (Harposporium anguillulae) was the most common species, followed by Harposporium lilliputanum and Harposporium arcuatum. Based on Shannon diversity index, the diversity levels of nematophagous fungi were relatively higher in samples associated with cattle, barn soil, and subtropical monsoon climate zone. Three species isolated from this study, namely, Duddingtonia flagrans, Arthrobotrys salina (Monacrosporium salinum), and Arthrobotrys oligospora var. sarmatica, are newly recorded in China, and 20 species (including one unidentified species) are newly recorded in sheep and cattle barn soils worldwide. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Comparison of Conservation Reserve Program Habitat Plantings with Respect to Arthropod Prey for Grassland Birds

USGS Publications Warehouse

McIntyre, N.E.; Thompson, Thomas R.

2003-01-01

The Conservation Reserve Program (CRP) was designed to reduce soil erosion and curb agricultural overproduction by converting highly erodible agricultural land to various forms of perennial habitat. It has had an incidental benefit of providing habitat for wildlife and has been beneficial in reversing population declines of several grassland bird species. However, the mechanisms behind these reversals remain unknown. One such mechanism may be differences in food availability on CRP vs. non-CRP land or between different types of CRP. The influence of CRP habitat type on the abundance of arthropod prey used by grassland birds has not been previously explored. We compared the abundance and diversity of arthropods among four CRP habitat types in Texas [replicated plots of exotic lovegrass (Eragrostis curvula), Old World bluestem (Bothriochloa ischaemum), mixed native grasses with buffalograss (Buchloe?? dactyloides) and mixed native grasses without buffalograss] and native shortgrass prairie. Attention was focused on adult and juvenile spiders (Order Araneae), beetles (Coleoptera), orthopterans (Orthroptera: grasshoppers and crickets) and lepidopterans (Lepidoptera: butterflies and moths), as these taxa are the primary prey items of grassland birds during the breeding season. Arthropod diversity and abundance were higher on indigenous prairie compared to CRP, reflecting differences in vegetative diversity and structure, but there were no differences in arthropod richness or abundance among CRP types. These results indicate that, although CRP is not equivalent to native prairie in terms of vegetation or arthropod diversity, CRP lands do support arthropod prey for grassland birds. More direct assays of the survivorship and fitness of birds on CRP compared to native shortgrass prairie are clearly warranted.

Interspecific and host-related gene expression patterns in nematode-trapping fungi.

PubMed

Andersson, Karl-Magnus; Kumar, Dharmendra; Bentzer, Johan; Friman, Eva; Ahrén, Dag; Tunlid, Anders

2014-11-11

Nematode-trapping fungi are soil-living fungi that capture and kill nematodes using special hyphal structures called traps. They display a large diversity of trapping mechanisms and differ in their host preferences. To provide insights into the genetic basis for this variation, we compared the transcriptome expressed by three species of nematode-trapping fungi (Arthrobotrys oligospora, Monacrosporium cionopagum and Arthrobotrys dactyloides, which use adhesive nets, adhesive branches or constricting rings, respectively, to trap nematodes) during infection of two different plant-pathogenic nematode hosts (the root knot nematode Meloidogyne hapla and the sugar beet cyst nematode Heterodera schachtii). The divergence in gene expression between the fungi was significantly larger than that related to the nematode species being infected. Transcripts predicted to encode secreted proteins and proteins with unknown function (orphans) were overrepresented among the highly expressed transcripts in all fungi. Genes that were highly expressed in all fungi encoded endopeptidases, such as subtilisins and aspartic proteases; cell-surface proteins containing the carbohydrate-binding domain WSC; stress response proteins; membrane transporters; transcription factors; and transcripts containing the Ricin-B lectin domain. Differentially expressed transcripts among the fungal species encoded various lectins, such as the fungal fruit-body lectin and the D-mannose binding lectin; transcription factors; cell-signaling components; proteins containing a WSC domain; and proteins containing a DUF3129 domain. A small set of transcripts were differentially expressed in infections of different host nematodes, including peptidases, WSC domain proteins, tyrosinases, and small secreted proteins with unknown function. This is the first study on the variation of infection-related gene expression patterns in nematode-trapping fungi infecting different host species. A better understanding of these

Root development during soil genesis: effects of root-root interactions, mycorrhizae, and substrate

NASA Astrophysics Data System (ADS)

Salinas, A.; Zaharescu, D. G.

2015-12-01

A major driver of soil formation is the colonization and transformation of rock by plants and associated microbiota. In turn, substrate chemical composition can also influence the capacity for plant colonization and development. In order to better define these relationships, a mesocosm study was set up to analyze the effect mycorrhizal fungi, plant density and rock have on root development, and to determine the effect of root morphology on weathering and soil formation. We hypothesized that plant-plant and plant-fungi interactions have a stronger influence on root architecture and rock weathering than the substrate composition alone. Buffalo grass (Bouteloua dactyloides) was grown in a controlled environment in columns filled with either granular granite, schist, rhyolite or basalt. Each substrate was given two different treatments, including grass-microbes and grass-microbes-mycorrhizae and incubated for 120, 240, and 480 days. Columns were then extracted and analyzed for root morphology, fine fraction, and pore water major element content. Preliminary results showed that plants produced more biomass in rhyolite, followed by schist, basalt, and granite, indicating that substrate composition is an important driver of root development. In support of our hypothesis, mycorrhizae was a strong driver of root development by stimulating length growth, biomass production, and branching. However, average root length and branching also appeared to decrease in response to high plant density, though this trend was only present among roots with mycorrhizal fungi. Interestingly, fine fraction production was negatively correlated with average root thickness and volume. There is also slight evidence indicating that fine fraction production is more related to substrate composition than root morphology, though this data needs to be further analyzed. Our hope is that the results of this study can one day be applied to agricultural research in order to promote the production of crops

Spatial relationships between entomopathogenic nematodes and nematophagous fungi in Florida citrus orchards.

PubMed

Pathak, Ekta; Campos-Herrera, Raquel; El-Borai, Fahiem E; Duncan, Larry W

2017-03-01

Relationships between entomopathogenic nematodes (EPNs), nematophagous fungi (NF) and soil physical and chemical properties were studied in a survey of 53 citrus orchards in central ridge and flatwoods ecoregions of Florida. Seven species of NF associated with nematodes were quantified directly using a real time qPCR assay. All nematophagous fungi studied except Arthrobotrys musiformis and Hirsutella rhossiliensis were frequently detected (24-56%) in both regions. Paecilomyces lilacinus and Gamsylella gephyropagumwere encountered more frequently in the flatwoods (P=0.03) and on the ridge (P=0.02), respectively. Redundancy analysis revealed seven abiotic and biotic factors as significantly related to the NF occurrence. Multiple regression of fungi on these variables explained 78%, 66%, 48%, 36%, 23% and 4% of the variation in Catenaria sp., A. musiformis, A. dactyloides, P. lilacinus, A. oligospora and G. gepharopagum, respectively. When the data from citrus were pooled with those reported previously from natural areas and subjected to principle component analysis, the first two principle components explained 43% of the variation in NF communities. The surveys (citrus vs natural areas) were discriminated by PC2 (P<0.001) and the ecoregion by PC1 (P<0.002), and all but one NF species were related (P<0.01) to one or both components. NF communities tended to have more species and greater diversity in the flatwoods, where EPN richness and diversity were the least. However, the strength of associations between individual EPN and NF species as measured by SADIE reflected the associations between each species and ground water depth, suggesting that ecoregion preferences affected the species associations. Within each ecoregion, significant relationships between the individual NF and EPN species measured by stepwise regression tended to be positive. The results did not support the hypothesis that NF modulate the spatial patterns of EPN species between or within these two

Grassland bird associations with introduced and native grass Conservation Reserve Program fields in the Southern High Plains

USGS Publications Warehouse

Thompson, Thomas R.; Boal, Clint W.; Lucia, Duane

2009-01-01

We examined relative abundances of grassland birds among Conservation Reserve Program (CRP) fields seeded with 2 monocultures of introduced grass species and 2 mixes of native grasses in the Southern High Plains of Texas. We assessed bird compositions among these 4 cover types and between the cover types pooled into categories of introduced and native fields. Breeding season bird diversity and total abundance did not differ among cover types or between introduced and native fields. Grasshopper Sparrows (Ammodramus savannarum), Cassin's Sparrows (Aimophila cassinii), and Western Meadowlarks (Sturnella neglecta) accounted for more than 90% of breeding season detections. Grasshopper Sparrows were the most abundant and found in all cover types. Cassin's Sparrows were 38% to 170% more abundant among the native seed mix without buffalograss (Buchloë dactyloides) compared to 3 other cover types. Although this association was statistically lost when cover types were pooled into introduced or native fields (U = 93.5, P = 0.91), the species was still 50% more abundant among native CRP than introduced CRP fields. Meadowlarks occurred ubiquitously but at very low numbers during the breeding season. During winter, avian abundance was 44% greater among native CRP than introduced CRP fields. Meadowlarks, Homed Larks (Eremophila alpestris), and Savannah Sparrows (Passerculus sandwichensis) accounted for 94% of all winter detections. Meadowlarks occurred ubiquitously, but Horned Larks and Savannah Sparrows were 157% and 96% more abundant, respectively, among native CRP than introduced CRP fields. Our data suggest that monocultures of introduced grasses may benefit some bird species but also that native seed mixes may have a more positive influence through increased diversity and abundance of grassland birds. However, pooling cover types into the broader categories of introduced or native grasses may dampen or occlude biologically meaningful results. It may be prudent to avoid

Role of plant-rock interactions in the N cycle of oligotrophic environments

NASA Astrophysics Data System (ADS)

Gaddis, E. E.; Zaharescu, D. G.; Dontsova, K.; Chorover, J.; Galey, M.; Huxman, T. E.

2013-12-01

The vital role of nitrogen--an abundant, but inaccessible building block for growth--in plants is well known. At the same time, plants and microorganisms are driving forces for accumulation of available N in the soils as they form. A deep understanding of N cycle initiation, progression, and link to ecological systems and their development is therefore necessary. A mesocosm experiment was set up with the goal of exploring the role of interactions between four rock types and biota on N fate in oligotrophic environments. Basalt, rhyolite, granite, and schist were used with 6 treatments: abiotic control; microbes only; grass and microbes; pine and microbes; grass, microbes, and mycorrhizal fungi; and pine, microbes, and mycorrhizal fungi. Pinus ponderosa and Buchloe dactyloides were seeded on the different rock media and maintained with purified air and water but no nutrient additions for 8 month. Throughout the experiment leachate solution was collected and its chemical composition characterized, including organic and inorganic C and N. In addition, plant roots were scanned and their images analyzed to quantify their morphological features. Root parameters included measurements of length, surface area, diameter, volume, the number of tips, forks and links, altitude, and overall plant biomass. Over the 8 month period, there was sustained vegetation growth on all rocks without N addition. A high C:N ratio was seen across all substrates, indicating N deficiency. A strong relationship was observed between total N removal in soil leachate and a number of plant parameters, including plant biomass, total surface area of the roots, sum of the root tips, and total root volume. These relationships were the strongest in basalt, where the pines had higher root surface area than grasses and this was accompanied by higher total N in leachate. There was also a positive correlation between total N removal and the total biomass, total N and the sum of the root tips, and total N and

Establishment, drought tolerance and recovery, and canopy analysis of turfgrasses in the transition zone

NASA Astrophysics Data System (ADS)

Goldsby, Anthony Lee

Increasing water scarcity may result in greater irrigation restrictions for turfgrass. Drought tolerance and recovery of Kentucky bluegrasses ( Poa. pratensis L.) (KBG) were evaluated during and after 88 and 60 day dry downs in 2010 and 2011, respectively, under a rainout shelter. Changes in green coverage were evaluated with digital images. Green coverage declined slowest during dry downs and increased fastest during recoveries in the cultivar 'Apollo', indicating it had superior drought tolerance. Electrolyte leakage, photosynthesis, and leaf water potential were evaluated in 7 KBG cultivars during and after the dry downs. Soil moisture at 5 and 20 cm was measured. There were generally no differences in physiological parameters among cultivars during or after dry down. The highest reduction in soil moisture at 5 and 20 cm was in Apollo, suggesting it had a better developed root system for mining water from the profile during drought. Weed prevention and turfgrass establishment of 'Legacy' buffalograss (Buchloe dactyloides [Nutt.] Engelm.) and 'Chisholm' zoysiagrass (Zoysia japonica Steud.) grown on turf reinforcement mats (TRM) was evaluated. 'Chisholm' zoysiagrass stolons grew under the TRM; as such, use of TRM for this cultivar is not practical. Buffalograss had 90% or greater coverage when established on TRM in 2010 and 65% or greater coverage in 2011; coverage was similar to that in oxadiazon-treated plots at the end of each year. 'Legacy' buffalograss plugs were established on TRM over plastic for 3 weeks, stored in TRM under tree shade for 7, 14, or 21 days, and evaluated for establishment after storage. In 2010, plugs on mats stored for 7 days had similar coverage to the control, but in 2011 displayed similar coverage to plugs stored on TRM for 14 or 21 day treatments. Green leaf are index (LAI) is an important indicator of turfgrass performance, but its measurement is time consuming and destructive. Measurements using hyperspectral radiometry were