Expression of a vacuolar Na+/H+ antiporter from Lotus tenuis improved salt tolerance of transgenic Arabidopsis thaliana at germination stage.

AFFINITO, AGOSTINA; MACIEL, M; ROLDÁN, L; AGUILÁ, J; DEL VAS, M; DIAZ PALEO, A

Santa Fé

Otro; XXXIII Argentinian meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología Vegetal

Lotus tenuis is a perennial forage legume that is naturalized in the Flooding Pampa region of Argentina. Even when it is considered a salt-tolerant species, the mechanisms underlying this trait are not fully understood. Intracellular compartmentation of Na+ into vacuoles by NHX antiporters is an important and well-known strategy to reduce ion toxicity during salt stress. To study the contribution of Lotus tenuis NHX1 antiporter to salinity tolerance, the LtNHX1 coding region was cloned into pEarleyGate203 vector downstream of the CaMV35S promoter. The recombinant plasmid was introduced into Agrobacterium tumefaciens GV3101, and a transgenic Arabidopsis thaliana line was obtained by Agrobacterium-mediated transformation using the floral dip method. The expression of the transgene was confirmed by RT-PCR analysis. Seeds of wild-type (Col-0) and T3 generation of the transgenic line (P8-68) were sown on MS media containing 0 (control), 50, 100 and 150 mM NaCl. Germination speed was estimated by using a modification of the Timson Index: GI = G/t where G is the percentage of seeds germinated at 5-day intervals and t is the total germination period (25 days). Two-way ANOVA and DGC multiple-comparisons method were performed. Compared to wild-type, P8-68 displayed less sensitivity under salt stress, with higher index of germination speed and a higher percentage of seed germination after 25 days. In addition, under 50 and 100 mM NaCl, GI of P8-68 was not significantly reduced compared to control conditions. These results suggest that the constitutive expression of LtNHX1 contributes to enhance salt tolerance at germination stage.