Genetic analysis of Na+ and K+ concentrations in leaf and stem as physiological components of salt tolerance in Tomato

Abstract

The sodium and potassium concentrations in leaf and stem have been genetically studied as physiological components of the vegetative and reproductive development in two populations of F(8) lines, derived from a salt sensitive genotype of Solanum lycopersicum cv. Cerasiforme, as female parent, and two salt tolerant lines, as male parents, from S. pimpinellifolium, the P population (142 lines), and S. cheesmaniae, the C population (116 lines). Genetic parameters of ten traits under salinity and five of them under control conditions were studied by ANOVA, correlation, principal component and QTL analysis to understand the global response of the plant. Two linkage maps including some tomato flowering time and salt tolerance candidate genes encoding for SlSOS1, SlSOS2, SlSOS3, LeNHX1, LeNHX3, were used for the QTL detection. Thirteen and 20 QTLs were detected under salinity in the P and C populations, respectively, and four under control conditions. Highly significant and contributing QTLs (over 40%) for the concentrations of Na(+) and K(+) in stems and leaves have been detected on chromosome 7 in both the populations. This is the only genomic position where the concentration QTLs for both the cations locate together. The proportion of QTLs significantly affected by salinity was larger in the P population (64.3%, including all QTLs detected under control) than in the C population (21.4%), where the estimated genetic component of variance was larger for most traits. A highly significant association between the leaf area and fruit yield under salinity was found only in the C population, which is supported by the location of QTLs for these traits in a common region of chromososome C1. As far as breeding for salt tolerance is concerned, only two sodium QTLs (lnc1.1 and lnc8.1) map in genomic regions of C1 and C8 where fruit yield QTLs are also located but in both the cases the profitable allele corresponds to the salt sensitive, cultivated species. One of those QTLs, lnc1.1 might involve LeNHX3.

Relationship between survival and yield related traits in Solanum pimpinellifolium under salt stress

“…Based on QTL analysis of physiological and yield traits of two segregating populations derived from a salt-sensitive S. lycopersicum var. cerasiforme genotype and one salt-tolerant male line each of S. pimpinellifolium and S. cheesmaniae, Villalta et al (2008) observed that fruit yield was not strongly associated with any physiological or vegetative trait under salinity. Only two sodium QTLs could be mapped in genomic regions of chromosome C1 and C8 where fruit yield QTLs were also located, but in both cases the beneficial allele corresponded to the salt-sensitive, cultivated S. lycopersicum var.…”

“…Salt tolerance traits have been introgressed successfully into commercial tomato varieties from the wild tomato species S. cheesmaniae and S. pennellii through backcrossing or recurrent selection methods (Shannon 1997). Although S. pimpinellifolium is the closest relative of cultivated tomato and several accessions already have been identified and characterized for salt tolerance (Bolarín et al 1991;Cuartero et al 1992;Hassan et al 1990;Villalta et al 2008) the use of this species in breeding programs for salt tolerance is still largely untapped. Salt tolerance of crops is often expressed as relative yield depression for a defined level of soluble salts in the soil solution compared with yields under nonsaline conditions (Bernstein et al 1974).…”

Combined biotic and abiotic stress resistance in tomato

“…However previous studies have as well identified a non-significant correlation of Na ? accumulation with salt stress tolerance in tomato (Rao et al 2013;Villalta et al 2008). In fact, Na ?…”

Mapping QTLs with epistatic effects and QTL × treatment interactions for salt tolerance at seedling stage of wheat

“…Marker-assisted selection (MAS) based on QTL analysis can greatly facilitate crop improvement (Tuberosa and Salvi 2007). Many QTLs for salt tolerance have already been detected in barley (Hordeum vulgare L.) (Mano and Takeda 1997), rice (Oryza sativa L.) (Gong et al 1999;Lee et al 2006;Lin et al 2004;Prasad et al 2000;Takehisa et al 2004), tomato (Solanum lycopersicum L.) (Foolad 1999;Foolad and Chen 1999;Foolad et al 2001;Villalta et al 2008) and arabidopsis (Arabidopsis thaliana L.) (Quesada et al 2002).…”