A novel function of the tomato CALCINEURIN‐B LIKE 10 gene as a root‐located negative regulator of salt stress

Abstract

Climate change exacerbates abiotic stresses like salinization, negatively impacting crop yield, so development of strategies, like using salt‐tolerant rootstocks, is crucial. The CALCINEURIN B‐LIKE 10 (SlCBL10) gene has been previously identified as a positive regulator of salt tolerance in the tomato shoot. Here, we report a different function of SlCBL10 in tomato shoot and root, as disruption of SlCBL10 only induced salt sensitivity when it was used in the scion but not in the rootstock. The use of SlCBL10 silencing rootstocks (Slcbl10 mutant and RNAi line) improved salt tolerance on the basis of fruit yield. These changes were associated with improved Na+ and K+ homoeostasis, as SlCBL10 silencing reduced the Na+ content and increased the K+ content under salinity, not only in the rootstock but also in the shoot. Improvement of Na+ homoeostasis in Slcbl10 rootstock seems to be mainly due to induction of SlSOS1 expression, while the higher K+ accumulation in roots seems to be mainly determined by expression of LKT1 transporter and SlSKOR channel. These findings demonstrate that SlCBL10 is a negative regulator of salt tolerance in the root, so the use of downregulated SlCBL10 rootstocks may provide a suitable strategy to increase tomato fruit production under salinity.

Meta-QTL and Candidate Gene Analyses of Agronomic Salt Tolerance and Related Traits in an RIL Population Derived from Solanum pimpinellifolium

“…In this sense, the expression level of genes involved in Na + extrusion, Na + compartmentation, K + nutrition, cell expansion and division, osmotic adjustment, reactive oxygen species scavenging, and chemical and phytohormone signaling (Ca 2+ , abscisic acid, auxin, etc. ), relevant for salt tolerance, depends not only on the wild accession but also on the plant organ [ 18 , 19 ]. Moreover, in the case of crop plants, it is ultimately the yield under salinity that determines whether a gene (or a given set of linked genes) is of agronomic importance.…”