Gene expression of monodehydroascorbate reductase and dehydroascorbate reductase during fruit ripening and in response to environmental stresses in acerola (Malpighia glabra)
Gene expression of monodehydroascorbate reductase and dehydroascorbate reductase during fruit ripening and in response to environmental stresses in acerola (Malpighia glabra)
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DOI：
10.1016/j.jplph.2010.09.003
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发表时间：
2011-04-15
影响因子：
4.3
通讯作者：
Esaka, Muneharu
中科院分区：
文献类型：
--
作者：
Eltelib, Hani A.;Badejo, Adebanjo A.;Esaka, Muneharu
针叶树（Malpighia glabra）是一种外来水果，因其富含抗坏血酸（阿萨）而被广泛栽培。调节阿萨代谢的分子机制尚未确定。单脱氢抗坏血酸还原酶（MDHAR）和脱氢抗坏血酸还原酶（达尔）是抗坏血酸-谷胱甘肽循环的关键酶，其维持还原的抗坏血酸池并充当重要的抗氧化剂。采用RT-PCR和RACE技术从针叶树中分离出编码MDHAR和达尔的cDNA。系统发育树将针叶树MDHAR和DHAR与其他植物胞质MDHAR和DHAR相关联。这两个基因的表达与它们的酶活性相关，并在果实成熟过程中受到差异调节。有趣的是，MDHAR的表达只在过熟的果实中检测到，而达尔的转录水平在果实成熟的中期达到最高。在黑暗条件下，有一个急剧和显着的下降，总的和减少抗坏血酸含量，伴随着减少的转录水平和酶活性的两个基因在针叶树叶片。MDHAR和达尔的转录和酶活性显着上调针叶在寒冷和盐胁迫条件下，表明这两个基因的表达在这些压力下的转录调控。(C)2010年Elsevier GmbH。All rights reserved.
Acerola (Malpighia glabra) is an exotic fruit cultivated primarily for its abundant ascorbic acid (AsA) content. The molecular mechanisms that regulate the metabolism of AsA in acerola have yet to be defined. Monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) are key enzymes of the ascorbate-glutathione cycle that maintain reduced pools of ascorbic acid and serve as important antioxidants. cDNAs encoding MDHAR and DHAR were isolated from acerola using RT-PCR and RACE. Phylogenetic trees associated acerola MDHAR and DHAR with other plant cytosolic MDHARs and DHARs. Expressions of the two genes correlated with their enzymatic activities and were differentially regulated during fruit ripening. Interestingly, MDHAR expression was only detected in overripe fruits, whereas the transcript level of DHAR was highest at the intermediate stage of fruit ripening. Under dark conditions, there was a sharp and significant decline in the total and reduced ascorbate contents, accompanied by a decrease in the level of transcripts and enzyme activities of the two genes in acerola leaves. MDHAR and DHAR transcripts and enzyme activities were significantly up-regulated in the leaves of acerola under cold and salt stress conditions, indicating that expression of both genes are transcriptionally regulated under these stresses. (C) 2010 Elsevier GmbH. All rights reserved.