Ascorbic acid formation and profiling of genes expressed in its synthesis and recycling in apple leaves of different ages
Ascorbic acid formation and profiling of genes expressed in its synthesis and recycling in apple leaves of different ages
复制标题
不同龄苹果叶中抗坏血酸的形成及其合成和回收中表达的基因分析
DOI：
10.1016/j.plaphy.2010.01.015
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发表时间：
2010-04-01
影响因子：
6.5
通讯作者：
Liu, Jun
中科院分区：
文献类型：
--
作者：
Li, Mingjun;Ma, Fengwang;Liu, Jun
抗坏血酸（AsA）作为一种独特的抗氧化剂和酶辅助因子，在植物中具有多种作用。然而，对叶片中AsA的积累和调控机制的研究非常有限。本研究测定了苹果（Malus domestica Borkh）不同年龄叶片中AsA积累水平，分析了l -半乳糖途径合成和再循环相关基因的表达模式及酶活性。AsA含量随叶片发育而增加，在20 d龄叶片中含量最高。这一水平在成熟叶中一直保持到衰老叶中下降。与幼叶和衰老叶相比，成熟叶的AsA合成能力较强，l -半乳糖脱氢酶和l -半乳糖-1,4-内酯脱氢酶的表达量和活性均较高。AsA合成相关基因的mRNA表达量在20日龄叶片中也最高，但gdp -甘露糖-3′，5′-外聚酶和l -半乳糖-1-磷酸磷酸酶的表达量在20日龄前达到最高水平。上述结果表明，AsA在苹果叶片中的积累主要发生在幼叶到成熟叶的过渡阶段，合成和循环速率较高，l -半乳糖-1-磷酸磷酸酶可能通过l -半乳糖途径调控AsA的生物合成。(c) 2010 Elsevier Masson SAS。版权所有。
Ascorbic acid (AsA), as a unique antioxidant and enzyme cofactor, has multiple roles in plants. However, there is very limited information on the mechanism of AsA accumulation and controlling in leaves. In this study, we determined AsA accumulation levels, analyzed expression patterns of the genes involved in synthesizing via L-galactose pathway and recycling as well as enzyme activities in apple (Malus domestica Borkh) leaves with different age. AsA content was found to increase with leaf development, reaching the highest level in 20-day-old leaves. This level was maintained in mature leaves until the dropping in senescent leaves. Comparing with young and senescent leaves, mature leaves had higher capability for AsA synthesis with high expression levels and activity of L-galactose dehydrogenase and L-galactono-1,4-lactone dehydrogenase. The mRNA expression of genes involved in AsA synthesis also showed highest abundance in 20-day-old leaves, though GDP-mannose-3',5'-epimerase and L-galactose-1-phosphate phosphatase expression reached the highest levels before 20 days old. These results suggest that AsA accumulation in apple leaves mainly occurs during the transition phase from young to mature leaves with high rates of synthesis and recycling, and that L-galactose-1-phosphate phosphatase could play an important role in regulating AsA biosynthesis via the L-galactose pathway. (c) 2010 Elsevier Masson SAS. All rights reserved.