title: Transcriptome responses in alfalfa associated with tolerance to intensive animal grazing.
abstract: Tolerance of alfalfa (Medicago sativa L.) to animal grazing varies widely within the species. However, the molecular mechanisms influencing the grazing tolerant phenotype remain uncharacterized. The objective of this study was to identify genes and pathways that control grazing response in alfalfa. We analyzed whole-plant de novo transcriptomes from grazing tolerant and intolerant populations of M. sativa ssp. falcata subjected to grazing by sheep. Among the Gene Ontology terms which were identified as grazing responsive in the tolerant plants and differentially enriched between the tolerant and intolerant populations (both grazed), most were associated with the ribosome and translation-related activities, cell wall processes, and response to oxygen levels. Twenty-one grazing responsive pathways were identified that also exhibited differential expression between the tolerant and intolerant populations. These pathways were associated with secondary metabolite production, primary carbohydrate metabolic pathways, shikimate derivative dependent pathways, ribosomal subunit composition, hormone signaling, wound response, cell wall formation, and anti-oxidant defense. Sequence polymorphisms were detected among several differentially expressed homologous transcripts between the tolerant and intolerant populations. These differentially responsive genes and pathways constitute potential response mechanisms for grazing tolerance in alfalfa. They also provide potential targets for molecular breeding efforts to develop grazing-tolerant cultivars of alfalfa.
authors.affiliation: College of Ecology and Environmental Science, Inner Mongolia Agricultural University, Hohhot, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Ecology and Environmental Science, Inner Mongolia Agricultural University, Hohhot, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Ray
authors.affiliation: Department of Computer Science, New Mexico State University, Las Cruces, NM, USA.
authors.forename: Mingzhou
authors.initials: M
authors.lastname: Song
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D002473:Cell Wall / Q000378:metabolism; D019295:Computational Biology / Q000379:methods; D004734:Energy Metabolism; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D059647:Gene-Environment Interaction; D060434:Herbivory; D000455:Medicago sativa / Q000235:genetics* / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D017382:Reactive Oxygen Species / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012641:Selection, Genetic; D015398:Signal Transduction; D059467:Transcriptome
chemical_list: D017382:Reactive Oxygen Species