Zhao Yonghui, Huang Shengnan, Zhang Meidi, Zhang Yun, Feng Hui
Department of Horticulture, Shenyang Agricultural University, Shenyang, China.
Front Plant Sci. 2021 Aug 12;12:699308. doi: 10.3389/fpls.2021.699308. eCollection 2021.
Leaves are the main organ for photosynthesis, and variations in leaf color affect photosynthesis and plant biomass formation. We created two similar whole-plant pale green mutants ( and ) from the double haploid (DH) Chinese cabbage line "FT" through ethyl methanesulfonate (EMS) mutagenesis of seeds. Photosynthetic pigment contents and net photosynthetic rates were significantly lower in the mutants than in the wild-type "FT," and the chloroplast thylakoid endomembrane system was poor. Genetic analysis showed that the mutated phenotypes of and were caused by a single nuclear gene. Allelism tests showed that and were alleles. We mapped to a 64.25 kb region on chromosome A10, using BSR-Seq and map-based cloning of 979 F recessive individuals. Whole-genome re-sequencing revealed a single nucleotide polymorphism (SNP) transition from guanine to adenosine on in , causing an amino acid shift from glycine to glutamic acid (G to E); in addition, in was found to have a single nucleotide substitution from guanine to adenosine, causing an amino acid change from E to lysine (K). is a homolog of the () gene that encodes 3,8-divinyl protochlorophyllide a 8-vinyl reductase, which is a key enzyme in chlorophyll biosynthesis. Enzyme activity assay and chlorophyll composition analysis demonstrated that impaired DVR had partial loss of function. These results provide a basis to understand chlorophyll metabolism and explore the mechanism of a pale green phenotype in Chinese cabbage.
叶片是光合作用的主要器官，叶片颜色的变化会影响光合作用和植物生物量的形成。我们通过对双单倍体（DH）大白菜品系“FT”的种子进行甲磺酸乙酯（EMS）诱变，创建了两个相似的全株淡绿色突变体（和）。突变体的光合色素含量和净光合速率显著低于野生型“FT”，叶绿体类囊体内膜系统较差。遗传分析表明，和的突变表型由单个核基因引起。等位性测试表明，和是等位基因。我们利用BSR-Seq和对979个F隐性个体进行图位克隆，将定位到A10染色体上一个64.25 kb的区域。全基因组重测序显示，中的发生了从鸟嘌呤到腺苷的单核苷酸多态性（SNP）转换，导致氨基酸从甘氨酸转变为谷氨酸（G到E）；此外，发现中的有一个从鸟嘌呤到腺苷的单核苷酸替换，导致氨基酸从E变为赖氨酸（K）。是编码3,8-二乙烯基原叶绿素酸a 8-乙烯基还原酶的（）基因的同源物，该酶是叶绿素生物合成中的关键酶。酶活性测定和叶绿素组成分析表明，受损的DVR功能部分丧失。这些结果为理解叶绿素代谢和探究大白菜淡绿色表型的机制提供了依据。
