QTL mapping by whole genome re-sequencing and analysis of candidate genes for salt tolerance in linseed (Linum usitatissmum L.)

Soil salinization is detrimental to the growth and development of flax and ultimately leads to a decrease in yield. However, the molecular mechanism of linseed response to salt stress is still unclear. In this study, a salt-tolerant (ST) linseed variety STS and a salt-sensitive (SS) variety DYM were selected as experiment materials. Bulk segregation analysis and whole-genome resequencing technologies were performed to map salt tolerance quantitative trait loci (QTL). A total of 38,625 QTL loci were identified. Fifteen genes (which were not annotated in the reference genome) were identified within a 2.597 ​Mb region in chromosome 1. Two salt tolerance candidate genes Lus.o.m.scaffold91.141 and Lus.o.m. Scaffold1.14 encoding WD40 and cytochrome P450 were identified by predicting protein functions. Previous studies showed that WD40 and cytochrome P450 could significantly improve plant salt stress tolerance. In this paper, results showed that Lus.o.m.scaffold91.141 and Lus.o.m. Scaffold1.14 might be involved in response to salt stress in lineseed. The fine mapping and functional analysis of these genes provide a molecular breeding basis for the genetic improvement of high salt-tolerant linseed varieties.