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.

Varietal differences in physiological and biochemical responses to salinity stress in six finger millet plants

“…We found out that Under higher high hypertonic potential, the reduction in the germination rate was less for the salinity-tolerant variety (GBK043094), compared with most salt sensitive variety (GBK043050). Our finding was in accordance to previous work in lettuce (Ahmed et al, 2019), alfalfa (Sandhu et al, 2017) and wheat (Tounsi et al, 2017) under saline conditions. In addition, a high degree of shoot growth depression in seedlings grown under salinity stress was clearly noticeable, more in the salt-sensitive varieties, which displayed reduced leaf area, leaf chlorosis, leaf burns and plant death, symptoms associated with plant toxicity.…”

“…It has been established that Na + and K + have similar cellular effects despite the fact Na + inhibits K + absorption through binding and obstructing to its transport system (Flowers and Yeo (1986). Many studies have reported that plants growing under high NaCl concentrations have low ratios of K + /Na + ratio caused by deficiency of intracellular K + (Dugasa et al, 2018; Cirillo et al, 2018; Sandhu et al, 2017; Sarabi et al, 2017). The same phenomenon was also observed in this study, where increment of NaCl concentration decreased the leaf K + /Na + ratios.…”

Morphological, Physiological, and Genetic Responses to Salt Stress in Alfalfa: A Review

“…Though a reduction in growth rate and shoot mass were common, high genetic diversity existed among alfalfa populations under salt stress [16,35,48], suggesting an adequate genetic variation for further selection for improved salt tolerance. Lei et al [49] compared the performance of seven alfalfa cultivars under NaCl stress and found that the growth rate of salt-tolerant cultivars was less affected by a high salt stress of~50 dS m −1 .…”

Evaluation of Different Fall Dormancy-Rating Alfalfa Cultivars for Forage Yield in a Semiarid Environment

“…Moreover, Arshad et al [27] and Lei et al [28] reported that drought tolerance in alfalfa is a key challenge in improving its productivity. Forage yield of alfalfa could be tremendously affected by salinity [29][30][31][32][33]. Li and Su [34] reported alfalfa annual forage yield as function of irrigation amount and which varied from 11.7 to 18.6 Mg ha −1 in China with increasing trend in seasonal irrigation [35,36].…”