title: System responses to long-term drought and re-watering of two contrasting alfalfa varieties.
abstract: Systems analysis of two alfalfa varieties, Wisfal (Medicago sativa ssp. falcata var. Wisfal) and Chilean (M. sativa ssp. sativa var. Chilean), with contrasting tolerance/sensitivity to drought revealed common and divergent responses to drought stress. At a qualitative level, molecular, biochemical, and physiological responses to drought stress were similar in the two varieties, indicating that they employ the same strategies to cope with drought. However, quantitative differences in responses at all levels were revealed that may contribute to greater drought tolerance in Wisfal. These included lower stomatal density and conductance in Wisfal; delayed leaf senescence compared with Chilean; greater root growth following a drought episode, and greater accumulation of osmolytes, including raffinose and galactinol, and flavonoid antioxidants in roots and/or shoots of Wisfal. Genes encoding transcription factors and other regulatory proteins, and genes involved in the biosynthesis of osmolytes and (iso)flavonoids were differentially regulated between the two varieties and represent potential targets for improving drought tolerance in alfalfa in the future.
authors.affiliation: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Kang
authors.forename: Yuanhong
authors.initials: Y
authors.lastname: Han
authors.forename: Ivone
authors.initials: I
authors.lastname: Torres-Jerez
authors.forename: Mingyi
authors.initials: M
authors.lastname: Wang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Tang
authors.forename: Maria
authors.initials: M
authors.lastname: Monteros
authors.forename: Michael
authors.initials: M
authors.lastname: Udvardi
mesh_terms: D000064:Acclimatization; D000975:Antioxidants / Q000378:metabolism; D004187:Disaccharides / Q000378:metabolism; D055864:Droughts; D005419:Flavonoids / Q000096:biosynthesis; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005809:Genes, Regulator; D000455:Medicago sativa / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000378:metabolism* / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology; D011887:Raffinose / Q000378:metabolism; D013045:Species Specificity; D013312:Stress, Physiological; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014867:Water / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D004187:Disaccharides; D005419:Flavonoids; D014157:Transcription Factors; D014867:Water; C013536:6 beta-galactinol; D011887:Raffinose