Wang Xuemin, Wang Zan, Dong Jie, Wang Meizhen, Gao Hongwen
Institute of Animal Science, Chinese Academy of Agricultural Science, 2-Yuan-Ming-Yuan West Rd., Haidian district, Beijing 100193, P R China.
Genes Genet Syst. 2009 Dec;84(6):397-405. doi: 10.1266/ggs.84.397.
Abscisic acid (ABA) regulates plant adaptive responses to various environmental stresses. Oxidative cleavage of cis-epoxycarotenoids catalyzed by 9-cis-epoxycarotenoid dioxygenase (NCED) is the main regulatory step in the biosynthesis of ABA in higher plants. Using RACE technology, a full-length cDNA-encoding NCED gene was isolated and characterized from the leaves of Caragana korshinskii (Peashrub). The 2442-bp full-length CkNCED1 had a 1818-bp ORF, which encodes a peptide of 605 amino acids. The deduced amino acid sequence of CkNCED1 protein shared high identity with other NCEDs. Southern blot analysis revealed that the gene CkNCED1 was a single copy in the genome of C. korshinskii. When C. korshinskii plants were exposed to a water deficit, ABA accumulation was followed by large increases in CkNCED1 mRNA in leaves and stems, but only a moderate increase in the roots. Conversely, rehydration of stressed leaves caused a rapid decrease in CkNCED1 mRNA and ABA levels. RT-PCR and Quantitative real-time PCR analysis showed that salt stress rapidly induced the strong expression of CkNCED1 in leaves and roots of C. korshinskii, as well as ABA accumulation. The expression of CkNCED1 and ABA accumulation was also induced by cold stress and the application of exogenous ABA. Taken together, these results suggest that CkNCED1 likely plays a primary role in the biosynthesis of ABA in C. korshinskii.
脱落酸（ABA）调控植物对各种环境胁迫的适应性反应。由9-顺式环氧类胡萝卜素双加氧酶（NCED）催化的顺式环氧类胡萝卜素的氧化裂解是高等植物中ABA生物合成的主要调控步骤。利用RACE技术，从柠条锦鸡儿（柠条）叶片中分离并鉴定了一个编码NCED基因的全长cDNA。2442bp的全长CkNCED1具有一个1818bp的开放阅读框，编码一个605个氨基酸的肽段。CkNCED1蛋白推导的氨基酸序列与其他NCEDs具有高度同源性。Southern杂交分析表明，基因CkNCED1在柠条锦鸡儿基因组中为单拷贝。当柠条锦鸡儿植株遭受水分亏缺时，ABA积累伴随着叶片和茎中CkNCED1 mRNA的大幅增加，但根中仅适度增加。相反，对受胁迫叶片进行复水会导致CkNCED1 mRNA和ABA水平迅速下降。RT-PCR和实时定量PCR分析表明，盐胁迫迅速诱导柠条锦鸡儿叶片和根中CkNCED1的强烈表达以及ABA积累。冷胁迫和外源ABA处理也诱导了CkNCED1的表达和ABA积累。综上所述，这些结果表明CkNCED1可能在柠条锦鸡儿ABA生物合成中起主要作用。
