College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
Biochem Biophys Res Commun. 2021 Apr 9;548:189-195. doi: 10.1016/j.bbrc.2021.02.047. Epub 2021 Feb 26.
Abscisic acid (ABA) regulates many aspects of plant growth and development and the responses to abiotic stresses. Arabidopsis aldehyde oxidase 3 (AAO3) catalyzes the final step of ABA biosynthesis. We cloned and functionally characterized a novel aldehyde oxidase gene, OsAO3, the rice homolog of AAO3. OsAO3 was expressed in germinated seeds, roots, leaves, and floral organs, particularly in vascular tissues and guard cells, and its expression was significantly induced by exogenous ABA and mannitol. Mutation and overexpression of OsAO3 decreased and increased ABA levels, respectively, in seedling shoots and roots under both normal and drought stress conditions. The osao3 mutant exhibited earlier seed germination, increased seedling growth, and decreased drought tolerance compared to the wild-type, OsAO3-overexpressing lines exhibited the opposite phenotype. Mutation and overexpression of OsAO3 increased and decreased grain yield, respectively, by affecting panicle number per plant, spikelet number per panicle, and spikelet fertility. Thus, OsAO3 may participate in ABA biosynthesis, and is essential for regulation of seed germination, seedling growth, grain yield, and drought tolerance in rice.
脱落酸（ABA）调节植物生长发育和非生物胁迫响应的许多方面。拟南芥醛氧化酶 3（AAO3）催化 ABA 生物合成的最后一步。我们克隆并功能表征了一个新的醛氧化酶基因 OsAO3，它是 AAO3 的水稻同源物。OsAO3 在萌发的种子、根、叶和花器官中表达，特别是在维管束组织和保卫细胞中，其表达在外源 ABA 和甘露醇的诱导下显著增加。OsAO3 的突变和过表达分别降低和增加了正常和干旱胁迫条件下幼苗地上部和根部的 ABA 水平。与野生型相比，osao3 突变体的种子萌发更早，幼苗生长更快，耐旱性降低，而 OsAO3 过表达系则表现出相反的表型。OsAO3 的突变和过表达分别增加和减少了粒产量，这主要是通过影响每株穗数、每穗小穗数和小穗育性来实现的。因此，OsAO3 可能参与 ABA 生物合成，对于调节水稻种子萌发、幼苗生长、粒产量和耐旱性是必需的。
