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.

中文翻译：

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玉米油黄叶2型表型候选基因的鉴定和精细定位

叶色是研究叶绿素生物合成和叶绿体发育的分子机制的重要农艺性状。在此，从玉米自交系RP125衍生的突变群体中鉴定出了在苗期具有典型黄叶表型的新型突变油黄叶2（Oy 2）。与野生型相比，Oy2突变体显示叶绿素含量降低，光合能力降低和叶绿体结构受损，这很可能受单个隐性基因控制。然后将Oy2基因座界定为5号染色体上117 kb的区域，该区域包含4个基因，其中基因Zm00001d013013，编码镁螯合酶亚基D，被确定为与Oy2突变表型相关的唯一候选基因。此外，通过RNA-seq和qRT-PCR检测了候选基因Oy2以及与叶绿素生物合成和光合作用相关的基因的表达水平，这表明因果基因Oy2在叶绿素合成中起关键作用。两者合计，我们建议与黄叶表型高度相关的因果基因Oy2可能有助于阐明玉米中光合色素的生物合成和叶绿体的发育。