Genetic mapping of a lobed-leaf gene associated with salt tolerance in Brassica napus L.

Lobed leaf is a common trait, which is related with photosynthesis and plant stress resistance in crops. In order to fine map and isolate the lobed-leaf gene in Brassica napus, an F2:3 population derived from 2205 (salt tolerance) and 1423 (salt sensitive) was constructed, and the quantitative trait locus (QTL) technology was adopted to identify the QTLs related to lobed leaf formation. As a result, one major QTL was identified on LG10, and two intron polymorphic (IP) markers and one sequence characterized amplified region (SCAR) marker were successfully developed in QTL region. The lobed-leaf gene was mapped to a region from 15.701 to 15.817 M on A10. In light of annotations of the genes in candidate region, a leaf morphological development related gene, Bra009510, was primary identified as the candidate gene. The full length of the candidate gene was 1390 bp containing three exons and two introns in the two parents. The open reading frame (ORF) was 693 bp and encoded a protein of 229 amino acids. Eight amino acid differences between the two parents in CDS (coding sequences) region were identified. qRT-PCR analysis showed that the expression of the candidate gene was significantly different between the two parents under salt stress. These results showed that the candidate gene might be related to leaf morphological development and abiotic stresses. Our study will lay a solid foundation for studying lobed leaf mechanism in B. napus L.