Fine Mapping and Characterization of a Major Gene Responsible for Chlorophyll Biosynthesis in L.

Rapeseed ( L.) is mainly used for oil production and industrial purposes. A high photosynthetic efficiency is the premise of a high yield capable of meeting people's various demands. Chlorophyll-deficient mutants are ideal materials for studying chlorophyll biosynthesis and photosynthesis. In a previous study, we obtained the mutant for leaf yellowing throughout the growth period by ethyl methanesulfonate mutagenesis of . A genetic analysis showed that the chlorophyll-deficient phenotype was controlled by one incompletely dominant gene, which was mapped on chromosome A03 by a quantitative trait loci sequencing analysis and designated as in this study. We constructed an F population containing 5256 individuals to clone . Finally, was fine-mapped to a 304.7 kb interval of the 'ZS11' genome containing 58 annotated genes. Functional annotation, transcriptome, and sequence variation analyses confirmed that , a homolog of , was the most likely candidate gene. encodes the H subunit of Mg-chelatase. A sequence analysis revealed a single-nucleotide polymorphism (SNP), causing an amino-acid substitution from glutamic acid to lysine (Glu1349Lys). In addition, the molecular marker BnaYL1 was developed based on the SNP of , which perfectly cosegregated with the chlorophyll-deficient phenotype in two different F populations. Our results provide insight into the molecular mechanism underlying chlorophyll synthesis in .