title: Variable salinity responses of 12 alfalfa genotypes and comparative expression analyses of salt-response genes.
abstract: Twelve alfalfa genotypes that were selected for biomass under salinity, differences in Na and Cl concentrations in shoots and K/Na ratio were evaluated in this long-term salinity experiment. The selected plants were cloned to reduce genetic variability within each genotype. Salt tolerance (ST) index of the genotypes ranged from 0.39 to 1. The most salt-tolerant genotypes SISA14-1 (G03) and AZ-90ST (G10), the top performers for biomass, exhibited the least effect on shoot number and height. SISA14-1 (G03) accumulated low Na and Cl under salinity. Most genotypes exhibited a net reduction in shoot Ca, Mg, P, Fe, and Cu, while Mn and Zn increased under salinity. Salinity reduced foliar area and stomatal conductance; while net photosynthetic rate and transpiration were not affected. Interestingly, salinity increased chlorophyll and antioxidant capacity in most genotypes; however neither parameter correlated well to ST index. Salt-tolerant genotypes showed upregulation of the SOS1, SOS2, SOS3, HKT1, AKT1, NHX1, P5CS1, HSP90.7, HSP81.2, HSP71.1, HSPC025, OTS1, SGF29 and SAL1 genes. Gene expression analyses allowed us to classify genotypes based on their ability to regulate different components of the salt tolerance mechanism. Pyramiding different components of the salt tolerance mechanism may lead to superior salt-tolerant alfalfa genotypes.
authors.affiliation: USDA-ARS US Salinity Lab, 450 W Big Springs Road, Riverside, CA 92507, USA.
authors.forename: Devinder
authors.initials: D
authors.lastname: Sandhu
authors.affiliation: USDA-ARS US Salinity Lab, 450 W Big Springs Road, Riverside, CA 92507, USA.|INTA-Estación Experimental Agropecuaria Santiago del Estero, Jujuy 850, Santiago del Estero 4200, Argentina.
authors.forename: Monica V
authors.initials: MV
authors.lastname: Cornacchione
authors.affiliation: USDA-ARS US Salinity Lab, 450 W Big Springs Road, Riverside, CA 92507, USA.
authors.forename: Jorge F S
authors.initials: JF
authors.lastname: Ferreira
authors.affiliation: USDA-ARS US Salinity Lab, 450 W Big Springs Road, Riverside, CA 92507, USA.
authors.forename: Donald L
authors.initials: DL
authors.lastname: Suarez
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D018533:Biomass; D002712:Chlorides / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D005838:Genotype; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D000455:Medicago sativa / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D054712:Salinity; D015398:Signal Transduction / Q000235:genetics; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D012987:Soil / Q000737:chemistry; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002712:Chlorides; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D012987:Soil; D002734:Chlorophyll; D012965:Sodium Chloride; D012964:Sodium; D013482:Superoxide Dismutase