The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
John W Forster - One of the best experts on this subject based on the ideXlab platform.
-
Phylogenomics of Fescue grass-derived fungal endophytes based on selected nuclear genes and the mitochondrial gene complement
BMC Evolutionary Biology, 2013Co-Authors: Piyumi N. Ekanayake, Maia Andrea Rabinovich, John W Forster, Kathryn M. Guthridge, German Spangenberg, Tim SawbridgeAbstract:Background Tall Fescue and meadow Fescue are important as temperate pasture grasses, forming mutualistic associations with asexual Neotyphodium endophytes. The most frequently identified endophyte of Continental allohexaploid tall Fescue is Neotyphodium coenophialum, while representatives of two other taxa (FaTG-2 and FaTG-3) have been described as colonising decaploid and Mediterranean hexaploid tall Fescue, respectively. In addition, a recent study identified two other putatively novel endophyte taxa from Mediterranean hexaploid and decaploid tall Fescue accessions, which were designated as uncharacterised Neotyphodium species (UNS) and FaTG-3-like respectively. In contrast, diploid meadow Fescue mainly forms associations with the endophyte taxon Neotyphodium uncinatum, although a second endophyte taxon, termed N. siegelii, has also been described.
-
molecular characterisation and interpretation of genetic diversity within globally distributed germplasm collections of tall Fescue festuca arundinacea schreb and meadow Fescue f pratensis huds
Theoretical and Applied Genetics, 2012Co-Authors: John W Forster, Melanie L Hand, Noel O I CoganAbstract:Allohexaploid tall Fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceum [Schreb.] Darbysh.) is an agriculturally important grass cultivated for pasture and turf world-wide. Genetic improvement of tall Fescue could benefit from the use of non-domesticated germplasm to diversify breeding populations through the incorporation of novel and superior allele content. However, such potential germplasm must first be characterised, as three major morphotypes (Continental, Mediterranean and rhizomatous) with varying degrees of hybrid interfertility are commonly described within this species. As hexaploid tall Fescue is also a member of a polyploid species complex that contains tetraploid, octoploid and decaploid taxa, it is also possible that germplasm collections may have inadvertently sampled some of these sub-species. In this study, 1,040 accessions from the publicly available United States Department of Agriculture tall Fescue and meadow Fescue germplasm collections were investigated. Sequence of the chloroplast genome-located matK gene and the nuclear ribosomal DNA internal transcribed spacer (rDNA ITS) permitted attribution of accessions to the three previously known morphotypes and also revealed the presence of tall Fescue sub-species of varying ploidy levels, as well as other closely related species. The majority of accessions were, however, identified as Continental hexaploid tall Fescue. Analysis using 34 simple sequence repeat markers was able to further investigate the level of genetic diversity within each hexaploid tall Fescue morphotype group. At least two genetically distinct sub-groups of Continental hexaploid tall Fescue were identified which are probably associated with palaeogeographic range expansion of this morphotype. This work has comprehensively characterised a large and complex germplasm collection and has identified genetically diverse accessions which may potentially contribute valuable alleles at agronomic loci for tall Fescue cultivar improvement programs.
-
evolutionary history of tall Fescue morphotypes inferred from molecular phylogenetics of the lolium festuca species complex
BMC Evolutionary Biology, 2010Co-Authors: Melanie L Hand, Noel O I Cogan, Alan V Stewart, John W ForsterAbstract:The agriculturally important pasture grass tall Fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.) is an outbreeding allohexaploid, that may be more accurately described as a species complex consisting of three major (Continental, Mediterranean and rhizomatous) morphotypes. Observation of hybrid infertility in some crossing combinations between morphotypes suggests the possibility of independent origins from different diploid progenitors. This study aims to clarify the evolutionary relationships between each tall Fescue morphotype through phylogenetic analysis using two low-copy nuclear genes (encoding plastid acetyl-CoA carboxylase [Acc1] and centroradialis [CEN]), the nuclear ribosomal DNA internal transcribed spacer (rDNA ITS) and the chloroplast DNA (cpDNA) genome-located matK gene. Other taxa within the closely related Lolium-Festuca species complex were also included in the study, to increase understanding of evolutionary processes in a taxonomic group characterised by multiple inter-specific hybridisation events. Putative homoeologous sequences from both nuclear genes were obtained from each polyploid species and compared to counterparts from 15 diploid taxa. Phylogenetic reconstruction confirmed F. pratensis and F. arundinacea var. glaucescens as probable progenitors to Continental tall Fescue, and these species are also likely to be ancestral to the rhizomatous morphotype. However, these two morphotypes are sufficiently distinct to be located in separate clades based on the ITS-derived data set. All four of the generated data sets suggest independent evolution of the Mediterranean and Continental morphotypes, with minimal affinity between cognate sequence haplotypes. No obvious candidate progenitor species for Mediterranean tall Fescues were identified, and only two putative sub-genome-specific haplotypes were identified for this morphotype. This study describes the first phylogenetic analysis of the Festuca genus to include representatives of each tall Fescue morphotype, and to use low copy nuclear gene-derived sequences to identify putative progenitors of the polyploid species. The demonstration of distinct tall Fescue lineages has implications for both taxonomy and molecular breeding strategies, and may facilitate the generation of morphotype and/or sub-genome-specific molecular markers.
Melanie L Hand - One of the best experts on this subject based on the ideXlab platform.
-
molecular characterisation and interpretation of genetic diversity within globally distributed germplasm collections of tall Fescue festuca arundinacea schreb and meadow Fescue f pratensis huds
Theoretical and Applied Genetics, 2012Co-Authors: John W Forster, Melanie L Hand, Noel O I CoganAbstract:Allohexaploid tall Fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceum [Schreb.] Darbysh.) is an agriculturally important grass cultivated for pasture and turf world-wide. Genetic improvement of tall Fescue could benefit from the use of non-domesticated germplasm to diversify breeding populations through the incorporation of novel and superior allele content. However, such potential germplasm must first be characterised, as three major morphotypes (Continental, Mediterranean and rhizomatous) with varying degrees of hybrid interfertility are commonly described within this species. As hexaploid tall Fescue is also a member of a polyploid species complex that contains tetraploid, octoploid and decaploid taxa, it is also possible that germplasm collections may have inadvertently sampled some of these sub-species. In this study, 1,040 accessions from the publicly available United States Department of Agriculture tall Fescue and meadow Fescue germplasm collections were investigated. Sequence of the chloroplast genome-located matK gene and the nuclear ribosomal DNA internal transcribed spacer (rDNA ITS) permitted attribution of accessions to the three previously known morphotypes and also revealed the presence of tall Fescue sub-species of varying ploidy levels, as well as other closely related species. The majority of accessions were, however, identified as Continental hexaploid tall Fescue. Analysis using 34 simple sequence repeat markers was able to further investigate the level of genetic diversity within each hexaploid tall Fescue morphotype group. At least two genetically distinct sub-groups of Continental hexaploid tall Fescue were identified which are probably associated with palaeogeographic range expansion of this morphotype. This work has comprehensively characterised a large and complex germplasm collection and has identified genetically diverse accessions which may potentially contribute valuable alleles at agronomic loci for tall Fescue cultivar improvement programs.
-
evolutionary history of tall Fescue morphotypes inferred from molecular phylogenetics of the lolium festuca species complex
BMC Evolutionary Biology, 2010Co-Authors: Melanie L Hand, Noel O I Cogan, Alan V Stewart, John W ForsterAbstract:The agriculturally important pasture grass tall Fescue (Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh.) is an outbreeding allohexaploid, that may be more accurately described as a species complex consisting of three major (Continental, Mediterranean and rhizomatous) morphotypes. Observation of hybrid infertility in some crossing combinations between morphotypes suggests the possibility of independent origins from different diploid progenitors. This study aims to clarify the evolutionary relationships between each tall Fescue morphotype through phylogenetic analysis using two low-copy nuclear genes (encoding plastid acetyl-CoA carboxylase [Acc1] and centroradialis [CEN]), the nuclear ribosomal DNA internal transcribed spacer (rDNA ITS) and the chloroplast DNA (cpDNA) genome-located matK gene. Other taxa within the closely related Lolium-Festuca species complex were also included in the study, to increase understanding of evolutionary processes in a taxonomic group characterised by multiple inter-specific hybridisation events. Putative homoeologous sequences from both nuclear genes were obtained from each polyploid species and compared to counterparts from 15 diploid taxa. Phylogenetic reconstruction confirmed F. pratensis and F. arundinacea var. glaucescens as probable progenitors to Continental tall Fescue, and these species are also likely to be ancestral to the rhizomatous morphotype. However, these two morphotypes are sufficiently distinct to be located in separate clades based on the ITS-derived data set. All four of the generated data sets suggest independent evolution of the Mediterranean and Continental morphotypes, with minimal affinity between cognate sequence haplotypes. No obvious candidate progenitor species for Mediterranean tall Fescues were identified, and only two putative sub-genome-specific haplotypes were identified for this morphotype. This study describes the first phylogenetic analysis of the Festuca genus to include representatives of each tall Fescue morphotype, and to use low copy nuclear gene-derived sequences to identify putative progenitors of the polyploid species. The demonstration of distinct tall Fescue lineages has implications for both taxonomy and molecular breeding strategies, and may facilitate the generation of morphotype and/or sub-genome-specific molecular markers.
Jane P. Breen - One of the best experts on this subject based on the ideXlab platform.
-
Enhanced resistance to fall armyworm (Lepidoptera: Noctudiae) in Acremonium endophyte-infected turfgrasses
Journal of Economic Entomology, 1993Co-Authors: Jane P. BreenAbstract:Variation in resistance to insects in Acremonium endophyte-infected turfgrasses was studied using fall armyworms, Spodoptera frugiperda (J. E. Smith), and southern armyworms, Spodoptera eridania (Cramer). Third instars were fed one of three to four genotypes each of five turfgrass species. Development on Acremonium-infected grasses was compared with development on genetically identical endophyte-free controls. No differences in consumption, weight, survival, or developmental time were detected in fall armyworms fed tall Fescue, Festuca arundinacea Schreb., infected with Acremonium coenophialum Morgan-Jones & Gams compared with endophyte-free tall Fescue. Fall armyworm development was affected to different degrees in larvae fed four genotypes of perennial ryegrass, Lolium perenne L., infected with Acremonium lolii Latch Christensen & Samuels. Fall armyworms fed hard Fescue, Festuca longifolia Thuill, and Chewings Fescue, Festuca rubra L. subsp. commutata Gaud, infected with Acremonium spp. showed dramatic reductions in larval weight, consumption, and survival relative to endophyte-free controls. Larvae that fed on infected grasses did not survive to pupation. However, development of fall armyworms fed blue Fescue, Festuca glauca Lam., infected with Acremonium spp. did not differ from that of those feeding on endophyte-free blue Fescue. Endophyte concentration within blue Fescue was less than in the hard and Chewings Fescues. In contrast to fall armyworms, southern armyworms preferred and had improved development on endophyte-infected tall Fescue. These results indicate that endophyte-enhanced resistance varies among and within species of grasses and endophytes. Researchers need to be aware of the potential of endophytes for breeding purposes and as sources of variation in natural populations.
-
Importance of Acremonium endophytes in turf-grass breeding and management
Agriculture Ecosystems & Environment, 1993Co-Authors: C. R. Funk, Richard H. White, Jane P. BreenAbstract:Abstract The development and use of genetically improved turf-grasses containing useful endophytes is of great value in efforts to enhance the environment, reduce maintenance cost, and conserve and improve precious soil and water resources. Acremonium endophyte-infected (E+) turg-grasses have frequently shown dramatic enhancement of resistance to many foliage-feeding insect pests. Modest improvements in resistance to root-feeding white grubs and some nematodes have been reported. Improvements in stress tolerance and modifications in water relations have been observed under certain conditions. Acremonium endophytes cause modifications to physiological mechanisms of adaptation of the host that result in superior performance of some turf-grass genotypes during moisture deficits. An understanding of the role of endophytes in modifying host plant performance makes turf-grass breeding and evaluation much more efficient. During 1990, an estimated 6000 tonnes of seed of elite, E+ containing perennial ryegrasses, Lolium perenne L., was produced and utilized throughout the world. Endophyte-enhanced ryegrass cultivars include ‘Advent’, ‘Assure’, ‘Dandy’, ‘Dasher II’, ‘Gettysburg’, ‘Pinnacle’, ‘Repell’, ‘SR 4200’, ‘Seville’, and ‘Sherwood’. Acremonium endophytes have been incorporated into ‘Reliant’ and ‘SR 3000’ hard Fescue, Festuca longifolia Thuill, ‘SR 5000’ and ‘Jamestown II’ Chewings Fescue, Festuca rubra L. subsp. commutata Gaud., as well as elite germplasm of these species. Lower-growing, turf-type tall Fescues, Festuca arundinacea Schreb., are being developed with high infection levels of useful Acremonium endophytes. Efforts are being made to find or develop and use desirable endophytes in Kentucky bluegrass, Poa pratensis L., strong creeping red Fescue, F. rubra L. subsp. rubra, blue Fescue, Festuca glauca Lam., and various bentgrasses, Agrostis spp. The discovery and/or development of superior genetic strains of Acremonium endophytes will make endophyte-enhanced turf-grass performance of even greater significance. There is also the potential to discover, genetically modify, and use other species of fungal and bacterial endophytes with the ability to improve turf-grass performance.
Christopher L Schardl - One of the best experts on this subject based on the ideXlab platform.
-
evolutionary diversification of fungal endophytes of tall Fescue grass by hybridization with epichloe species
Proceedings of the National Academy of Sciences of the United States of America, 1994Co-Authors: Hueifung Tsai, Chuck Staben, M. R. Siegel, G C M Latch, Michael J. Christensen, Christopher L SchardlAbstract:Abstract The mutualistic associations of tall Fescue (Festuca arundinacea) with seed-borne fungal symbionts (endophytes) are important for fitness of the grass host and its survival under biotic and abiotic stress. The tall Fescue endophytes are asexual relatives of biological species (mating populations) of genus Epichloe (Clavicipitaceae), sexual fungi that cause grass choke disease. Isozyme studies have suggested considerable genetic diversity among endophytes of tall Fescue. Phylogenetic relationships among seven isolates from tall Fescue, three from meadow Fescue (a probable ancestor of tall Fescue), and nine Epichloe isolates from other host species were investigated by comparing sequences of noncoding segments of the beta-tubulin (tub2) and rRNA (rrn) genes. Whereas each Epichloe isolate and meadow Fescue endophyte had only a single tub2 gene, most tall Fescue endophytes had two or three distinct tub2 copies. Phylogenetic analysis of tub2 sequences indicated that the presence of multiple copies in the tall Fescue endophytes was a consequence of hybridization with Epichloe species. At least three hybridization events account for the distribution and relationships of tub2 genes. These results suggest that interspecific hybridization is the major cause of genetic diversification of the tall Fescue endophytes.
Eric Watkins - One of the best experts on this subject based on the ideXlab platform.
-
towards improved molecular identification tools in fine Fescue festuca l poaceae turfgrasses nuclear genome size ploidy and chloroplast genome sequencing
Frontiers in Genetics, 2019Co-Authors: Yinjie Qiu, Cory D Hirsch, Ya Yang, Eric WatkinsAbstract:Fine Fescues (Festuca L., Poaceae) are turfgrass species that perform well in low-input environments. Based on morphological characteristics, the most commonly-utilized fine Fescues are divided into five taxa: three are subspecies within F. rubra L. and the remaining two are treated as species within the F. ovina L. complex. Morphologically, these five taxa are very similar, and both identification and classification of fine Fescues remain challenging. In an effort to develop classification methods for Fescues, we used flow cytometry to estimate genome size and sequenced the chloroplast genome of all five taxa. Fine Fescue chloroplast genome sizes ranged from 133,331 to 133,841 bp and contained 113-114 genes. Phylogenetic reconstruction using whole plastid genome sequences agreed with previous work based on morphology. Comparative genomics suggested unique repeat signatures for each fine Fescue taxon and could potentially be used for marker development for taxon identification.
-
towards improved molecular identification tools in fine Fescue festuca l poaceae turfgrasses nuclear genome size ploidy and chloroplast genome sequencing
bioRxiv, 2019Co-Authors: Yinjie Qiu, Cory D Hirsch, Ya Yang, Eric WatkinsAbstract:Abstract Fine Fescues (Festuca L., Poaceae) are turfgrass species that perform well in low-input environments. Based on morphological characteristics, the most commonly-utilized fine Fescues are divided into five taxa: three are subspecies within F. rubra L. and the remaining two are treated as species within the F. ovina L. complex. Morphologically, these five taxa are very similar, both identification and classification of fine Fescues remain challenging. In an effort to develop identification methods for Fescues, we used flow cytometry to estimate genome size, ploidy level, and sequenced the chloroplast genome of all five taxa. Fine Fescue chloroplast genome sizes ranged from 133,331 to 133,841 bp and contained 113 to 114 genes. Phylogenetic relationship reconstruction using whole chloroplast genome sequences agreed with previous work based on morphology. Comparative genomics suggested unique repeat signatures for each fine Fescue taxon that could potentially be used for marker development for taxon identification.
-
chloroplast genome sequencing and comparative analysis for fine Fescue festuca l poaceae turfgrasses
bioRxiv, 2019Co-Authors: Yinjie Qiu, Cory D Hirsch, Ya Yang, Eric WatkinsAbstract:Abstract Fine Fescues (Festuca L., Poaceae) are turfgrass species that perform well in low-input environments. Based on morphological characteristics, the most commonly-utilized fine Fescues are divided into five taxa: three are subspecies within F. rubra L. and the remaining two are treated as species within the F. ovina L. complex. Morphologically, these five taxa are very similar, and both identification and classification of fine Fescues remain challenging. In an effort to develop identification methods for Fescues, we used flow cytometry to estimate genome size, and sequenced the chloroplast genome of all five taxa. Fine Fescue chloroplast genome sizes ranged from 133,331 to 133,842 bp and contained 113 to 114 genes. Phylogenetic reconstruction using whole chloroplast genome sequences agreed with previous work based on morphology. Comparative genomics suggested unique repeat signatures for each fine Fescue taxon that could potentially be used for marker development for taxon identification.