Salt Tolerance Diversity in Citrus Rootstocks Agrees with Genotypic Diversity at the Quantitative Trait Locus.

Background/objective: Salinity is a growing problem affecting a large portion of global agricultural land, particularly in areas where water resources are scarce. The objective of this study was to provide physiological and molecular information on salt-tolerant citrus rootstocks to mitigate the detrimental effects of salinity on citriculture.

Methods: Ten accessions belonging to eight species and four to Raf.

HKT1;1 and HKT1;2 Na Transporters from Play Different Roles in the Plant Na Distribution under Salinity.

Salt tolerance is a target trait in plant science and tomato breeding programs. Wild tomato accessions have been often explored for this purpose. Since shoot Na/K is a key component of salt tolerance, RNAi-mediated knockdown isogenic lines obtained for alleles encoding both class I Na transporters HKT1;1 and HKT1;2 were used to investigate the silencing effects on the Na and K contents of the xylem sap, and source and sink organs of the scion, and their contribution to salt tolerance in all 16 rootstock/scion combinations of non-silenced and silenced lines, under two salinity treatments.

Role of Na transporters HKT1;1 and HKT1;2 in tomato salt tolerance. I. Function loss of cheesmaniae alleles in roots and aerial parts.

We analyzed the physiological impact of function loss on cheesmaniae alleles at the HKT1;1 and HKT1;2 loci in the roots and aerial parts of tomato plants in order to determine the relative contributions of each locus in the different tissues to plant Na/K homeostasis and subsequently to tomato salt tolerance. We generated different reciprocal rootstock/scion combinations with non-silenced, single RNAi-silenced lines for ScHKT1;1 and ScHKT1;2, as well as a silenced line at both loci from a near isogenic line (NIL14), homozygous for the Solanum cheesmaniae haplotype containing both HKT1 loci and subjected to salinity under natural greenhouse conditions. Our results show that salt treatment reduced vegetative growth and altered the Na/K ratio in leaves and flowers; negatively affecting fruit production, particularly in graft combinations containing single silenced ScHKT1;2- and double silenced ScHKT1;1/ScHKT1;2 lines when used as scion.