Identification and characterization of the rice pre-harvest sprouting mutants involved in molybdenum cofactor biosynthesis
Identification and characterization of the rice pre-harvest sprouting mutants involved in molybdenum cofactor biosynthesis
复制标题
参与钼辅因子生物合成的水稻收获前发芽突变体的鉴定和表征
DOI：
10.1111/nph.15607
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发表时间：
2019-04-01
期刊：
影响因子：
9.4
通讯作者：
Fang, Jun
中科院分区：
文献类型：
--
作者：
Liu, Xin;Wang, Jing;Fang, Jun
在谷类作物中，种子成熟期缺乏ABA会导致收获前发芽（PHS），而ABA的生物合成需要钼辅助因子（MoCo）。本研究对两个水稻小灵通突变体F254和F5-1进行了鉴定。除小叶片外，这些突变体还表现出叶片扭曲、细长等多效表型，在幼苗发育到四片或五片叶片时死亡。基于图谱的克隆显示，编码MoaE和MoeA的OsCNX6和OsCNX1分别与F254和F5-1突变体同源。遗传互补表明，OsCNX6不仅恢复了cnx6突变体的小PHS和幼苗致死表型，而且恢复了moco依赖酶的活性，如黄嘌呤脱氢酶（XDH）、醛氧化酶（AO）、硝酸盐还原酶（NR）和亚硫酸盐氧化酶（SO）。定量逆转录酶PCR和RNA原位杂交结果显示，OsCNX6在胚芽成熟过程中在种子中大量表达。此外，OsCNX6过表达植株可以显著提高moco依赖性酶的活性，提高渗透和盐胁迫的耐受性，且无不良表型。综上所述，OsCNX6参与了MoCo的生物合成，对水稻发育，特别是种子休眠和萌发至关重要，OsCNX6可能是提高水稻非生物胁迫耐受性的有效靶点。
In cereal crops, ABA deficiency during seed maturation phase causes pre-harvest sprouting (PHS), and molybdenum cofactor (MoCo) is required for ABA biosynthesis. Here, two rice PHS mutants F254 and F5-1 were characterized. In addition to the PHS, these mutants showed pleiotropic phenotypes such as twisting and slender leaves, and then died when the seedling developed to four or five leaves. Map-based cloning showed that OsCNX6 and OsCNX1 encoding homologs of MoaE and MoeA were responsible for F254 and F5-1 mutants, respectively. Genetic complementation indicated that OsCNX6 not only rescued the PHS and seedling lethal phenotype of the cnx6 mutant, but also recovered the MoCo-dependent enzyme activities such as xanthine dehydrogenase (XDH), aldehyde oxidase (AO), nitrate reductase (NR) and sulfite oxidase (SO). Expression pattern showed that OsCNX6 was richly expressed in seed during embryo maturation by quantitative reverse transcriptase PCR and RNA in situ hybridization. Furthermore, the OsCNX6 overexpression plants can significantly enhance the MoCo-dependent enzyme activities, and improved the osmotic and salt stress tolerance without unfavorable phenotypes. Collectively, these data indicated that OsCNX6 participated in MoCo biosynthesis, and is essential for rice development, especially for seed dormancy and germination, and OsCNX6 could be an effective target for improving abiotic stress tolerance in rice.