Na+ transporter HKT1;2 reduces flower Na+ content and considerably mitigates the decline in tomato fruit yields under saline conditions
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AuthorRomero-Aranda, María R.; González-Fernández, Paloma; Pérez-Tienda, Jacob R.; López-Díaz, María R.; Espinosa, Jesús; Granum, Espen; Traverso, Jose A.; Pineda, Benito; Garcia-Sogo, Begona; Moreno, Vicente; Asins, María J.; Belver, Andres
Cita bibliográficaRomero-Aranda, M. R., Fernández, P. G., López-Tienda, J. R., López-Diaz, M. R., Espinosa, J., Granum, E., ... & Asins, M. J. (2020). Na+ transporter HKT1; 2 reduces flower Na+ content and considerably mitigates the decline in tomato fruit yields under saline conditions. Plant Physiology and Biochemistry. 154, 341-352.
Genes encoding HKT1-like Na+ transporters play a key role in the salinity tolerance mechanism in Arabidopsis and other plant species by retrieving Na+ from the xylem of different organs and tissues. In this study, we investigated the role of two HKT1;2 allelic variants in tomato salt tolerance in relation to vegetative growth and fruit yield in plants subjected to salt treatment in a commercial greenhouse under real production conditions. We used two near-isogenic lines (NILs), homozygous for either the Solanum lycopersicum (NIL17) or S. cheesmaniae (NIL14) allele, at HKT1;2 loci and their respective RNAi-Sl/ScHKT1;2 lines. The results obtained show that both ScHKT1;2- and SlHKT1;2-silenced lines display hypersensitivity to salinity associated with an altered leaf Na+/K+ ratio, thus confirming that HKT1;2 plays an important role in Na+ homeostasis and salinity tolerance in tomato. Both silenced lines also showed Na+ over-accumulation and a slight, but significant, reduction in K+ content in the flower tissues of salt-treated plants and consequently a higher Na+/K+ ratio as compared to the respective unsilenced lines. This altered Na+/K+ ratio in flower tissues is associated with a sharp reduction in fruit yield, measured as total fresh weight and number of fruits, in both silenced lines under salinity conditions. Our findings demonstrate that Na+ transporter HKT1;2 protects the flower against Na+ toxicity and mitigates the reduction in tomato fruit yield under salinity conditions.