Identification and fine mapping of a candidate gene for oil yellow leaf 2 conferring yellow leaf phenotype in maize

Leaf colour is an important agronomic trait for studying molecular mechanisms in chlorophyll biosynthesis and chloroplast development. Here, a novel mutant oil yellow leaf 2 (Oy2) with a typical yellow leaf phenotype at the seedling stage was identified from the mutant population derived from the maize inbred line RP125. Compared with wild type, Oy2 mutant displays decreased chlorophyll content, reduced photosynthetic capacity and impaired chloroplast structure, which is likely controlled by a single recessive gene. The Oy2 locus was then delimited into a 117 kb region on chromosome 5 harbouring four genes, amongst which the gene Zm00001d013013, encoding a magnesium chelatase subunit D, was identified as the only candidate gene associated with Oy2 mutant phenotype. Moreover, the expression levels of candidate gene Oy2 and genes associated with chlorophyll biosynthesis and photosynthesis were tested by RNA‐seq and qRT‐PCR, implying that the causal gene Oy2 playing a critical role in chlorophyll synthesis. Taken together, we propose that the causal gene Oy2 highly associated with the yellow leaf phenotype may be helpful in elucidating photosynthetic pigments biosynthesis and chloroplast development in maize.