책임운영기관 농촌진흥청 국립축산과학원 (로고)

Accumulation of high sodium (Na+) leads to disruption of metabolic processes, decline plant growth and productivity. Therefore, current studies were undertaken to clarify how several Na+/H+ exchanger, Na+/K+ transporter genes contribute to Na+ homeostasis, and substantial involvement of lignin biosynthesis genes in salt tolerance in alfalfa that is poorly understood. This study illustrates the mechanisms underlying the differential salt tolerance in alfalfa. High Na+ exhibited a substantial reduction of morpho-physiological indices, and induced of oxidative stress indicators in Xingjiang Daye (XJD; sensitive), while Zhongmu (ZM; tolerant) remained unaffected. Excess Na+ increased in root and shoot in XJD, whereas ZM showed less amount of Na+ in roots and shoots than XJD, leading to a higher K+/(K++Na+) ratio under saline conditions. ZM exhibited a significant high expression of SOS1 (salt overly sensitive 1), NHX1 (sodium/hydrogen exchanger 1) and HKT1 (high affinity potassium transporter 1), which lead to enhance K+ accumulation and high Na+ extrusion from the cells compared to XJD. Salt adapted ZM showed an increased lignin content than sensitive XJD cultivar. As a consequence, several lignin biosynthesis related genes including 4CL2, CCoAOMT, COMT, CCR, C4H, PAL1 and PRX1 exhibited higher mRNA level in salt tolerant ZM compared to XJD. Moreover, high salt level indicated an increase in antioxidant enzymes (CAT, SOD, APX, and GR) in root of ZM giving defense to oxidative damages, while high Na+ possibly triggered oxidative damages in XJD. This study illustrates the ion exchangers, transporter and/or antiporters, and lignin genes involving mechanistic insights of differential salt tolerance in alfalfa.