Natural Variation in 9-Cis-Epoxycartenoid Dioxygenase 3 and ABA Accumulation
Natural Variation in 9-Cis-Epoxycartenoid Dioxygenase 3 and ABA Accumulation
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DOI：
10.1104/pp.18.01185
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发表时间：
2019-04-01
期刊：
影响因子：
7.4
通讯作者：
Verslues, Paul E.
中科院分区：
文献类型：
--
作者：
Kalladan, Rajesh;Lasky, Jesse R.;Verslues, Paul E.
应激激素脱落酸 (ABA) 对于抗旱至关重要；然而，控制 ABA 水平的机制尚不清楚。在低水势条件下，拟南芥 (Arabidopsis thaliana) 种质 Shandara (Sha) 的 ABA 积累量少于 Landsbergectera (Ler) 或 Columbia。对 Ler X Sha 重组自交系群体的分析揭示了 ABA 积累的单一主效数量性状位点，其中包括 9-顺式环氧类胡萝卜素双加氧酶 3 (NCED3) 作为候选基因。 NCED3 编码应激诱导的 ABA 合成的限速酶。互补实验表明 Sha 具有功能降低的 NCED3 等位基因。与Ler相比，Sha没有降低NCED3基因表达或蛋白质水平，但在NCED3内有四个氨基酸取代。 Sha 与 Ler 的不同之处在于 NCED3 的表观分子量，表明叶绿体中 NCED3 蛋白水解过程发生了改变。定点诱变表明，271 位氨基酸的取代对于改变 NCED3 分子质量模式至关重要，而其他 Sha NCED3 多态性也与 ABA 积累减少有关。 Sha 的类囊体结合 NCED3 水平没有降低，但基质 NCED3 的表观分子质量与 Ler 不同。由于 Sha 在 ABA 合成中对 NCED3 功能至关重要的已知因素（表达、叶绿体输入和类囊体结合）并未受损，因此 Ler 和 Sha NCED3 之间的差异可能会影响 NCED3 活性或影响 NCED3 功能的其他因素。这些结果确定了 NCED3 上功能上重要的位点，并表明叶绿体中 NCED3 翻译后调节的复杂模式。
The stress hormone abscisic acid (ABA) is critical for drought resistance; however, mechanisms controlling ABA levels are unclear. At low water potential, ABA accumulation in the Arabidopsis (Arabidopsis thaliana) accession Shandara (Sha) was less than that in Landsberg erecta (Ler) or Columbia. Analysis of a Ler X Sha recombinant inbred line population revealed a single major-effect quantitative trait locus for ABA accumulation, which included 9-cis-epoxycarotenoid dioxygenase3 (NCED3) as a candidate gene. NCED3 encodes a rate-limiting enzyme for stress-induced ABA synthesis. Complementation experiments indicated that Sha has a reduced-function NCED3 allele. Compared with Ler, Sha did not have reduced NCED3 gene expression or protein level but did have four amino acid substitutions within NCED3. Sha differed from Ler in the apparent molecular mass of NCED3, indicative of altered NCED3 proteolytic processing in the chloroplast. Site-directed mutagenesis demonstrated that substitution at amino acid 271 was critical for the altered NCED3 molecular mass pattern, while the other Sha NCED3 polymorphisms were also involved in the reduced ABA accumulation. Sha did not have a reduced level of thylakoid-bound NCED3 but did differ from Ler in the apparent molecular mass of stromal NCED3. As Sha was not impaired in known factors critical for NCED3 function in ABA synthesis (expression, chloroplast import, and thylakoid binding), the differences between Ler and Sha NCED3 may affect NCED3 activity or other factors influencing NCED3 function. These results identify functionally important sites on NCED3 and indicate a complex pattern of NCED3 posttranslational regulation in the chloroplast.