Defect in Brnym1, a magnesium-dechelatase protein, causes a stay-green phenotype in an EMS-mutagenized Chinese cabbage (Brassica campestris L. ssp. pekinensis) line
Defect in Brnym1, a magnesium-dechelatase protein, causes a stay-green phenotype in an EMS-mutagenized Chinese cabbage (Brassica campestris L. ssp. pekinensis) line
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DOI：
10.1038/s41438-019-0223-6
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发表时间：
2020-01
影响因子：
8.7
通讯作者：
Nan Wang;Yun Zhang;Shengnan Huang;Zhiyong Liu;Chengyu Li;H. Feng
中科院分区：
文献类型：
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作者：
Nan Wang;Yun Zhang;Shengnan Huang;Zhiyong Liu;Chengyu Li;H. Feng
叶色是大白菜育种的重要目标性状。叶片变黄可能会降低作物的商业价值和营养价值。一些具有“保绿”特性的植物在衰老期间甚至在死亡后仍能保持叶片的绿色。保绿大白菜可能是未来育种项目的重点，因为它可以提高作物质量和产量，并延长货架期。从甲烷磺酸乙酯(EMS)诱变的大白菜中鉴定出一个新的保绿突变体nym1(Nym1)。该突变体具有保绿特性，叶片衰老过程中的叶绿素含量高于野生型。突变大白菜的持绿性状受隐性基因Brnym1控制。MutMap和KASP分析表明，Brnym1(BraA03g050600.C3c)编码一个镁脱氢酶(SGR蛋白)，这可能是大白菜突变的致病基因。Brnym1基因第三外显子的非同义单核苷酸碱基替换(G到A)导致了镁脱氢酶高度保守区域的氨基酸从L到F的替换。异位过表达表明，野生型大白菜的BrNYM1基因与拟南芥SGR缺陷的保绿突变体nye1-1互补。与野生型相比，突变体nym1的镁脱氢酶活性显著下调。在衰老后期，Brnym1在突变体中相对上调，Brnym1定位于叶绿体。这些结果表明，Brnym1(BraA03g050600.C3c)是导致大白菜保绿突变的原因基因，在大白菜遗传改良中可能具有特殊意义。
Leaf color is an important target trait in Chinese cabbage breeding programs. Leaf yellowing may reduce crop commercial and nutritional values. Some plants with the “stay-green” trait maintain leaf greenness during senescence and even after death. Stay-green Chinese cabbage may be a focal point of future breeding projects because it could improve crop quality and yield and prolong shelf life. A new stay-green mutant, non-yellowing mutant 1 (nym1), was identified in Chinese cabbage derived from an ethyl methane sulfonate (EMS)-mutagenized population. The mutant had stay-green characteristics and a higher chlorophyll content than the wild-type during leaf senescence. The stay-green trait in the mutant Chinese cabbage was controlled by the recessive gene Brnym1. MutMap and KASP analyses showed that Brnym1 (BraA03g050600. 3C) encodes an mg-dechelatase (SGR protein), which might be the causal gene of the mutation in Chinese cabbage. A nonsynonymous single nucleotide base substitution (G to A) in the third exon of Brnym1 caused an amino acid substitution from L to F in the highly conserved domain of the magnesium-dechelatase. Ectopic overexpression showed that the BrNYM1 gene of wild-type Chinese cabbage complemented the SGR-defective stay-green mutant nye1-1 of Arabidopsis. The magnesium-dechelatase activity in the nym1 mutant was significantly downregulated compared to that in the wild type. Brnym1 was relatively upregulated in the mutant during late senescence, and BrNYM1 was localized to the chloroplasts. These results indicate that Brnym1 (BraA03g050600. 3C) is the causal gene of the stay-green mutation and could be of particular significance in the genetic improvement of Chinese cabbage.