水分胁迫下纽荷尔脐橙和山下红温州蜜柑脱落酸合成及关键酶基因表达研究

ABA production and expression analysis of its key genes in Newhall navel orange and Satsuma mandarin under water stress

【目的】研究水分胁迫对柑橘叶片相关生理特征、脱落酸合成及关键酶基因表达的影响。【方法】采用2 a生盆栽苗,研究水分胁迫条件对枳砧山下红温州蜜柑和纽荷尔脐橙叶片叶绿素,脯氨酸,脱落酸(ABA)含量及ABA合成关键酶基因的影响。【结果】结果表明,与对照相比,水分胁迫下纽荷尔脐橙和山下红温州蜜柑叶绿素含量显著降低,并伴随着不同程度的叶片黄化;随着水分胁迫程度的加剧,纽荷尔脐橙和山下红温州蜜柑叶片中的脯氨酸、可溶性糖和ABA含量均增加;对ABA合成途径中玉米黄质环氧化酶基因(CitZEP)和9-顺势类氧胡萝卜素双加氧酶基因(CitNCED)进行表达模式分析表明,CitNCED表达量随着水分胁迫程度加剧逐渐增加,而CitZEP表达量在胁迫初期增加,胁迫到一定程度时表达量降低。【结论】随着水分胁迫程度的增加,脯氨酸、可溶性糖和ABA含量增加,叶绿素含量降低,CitNCED可能是柑橘体内ABA生物合成过程中的关键酶之一。

[Objective]The object of this paper is to investigate the effects of water stress on some physio- logical characteristic, the biosynthesis of ABA and the expression of key genes of citrus. [Method]The ef- fect of water stress on content of chlorophyll, ABA, proline, soluble sugar and the key genes expression during ABA biosynthesis were studied using two-year Newhall navel orange and Satsuma mandarin as ma- terials. [Result]The results showed that water stress significantly decreased leaf chlorophyll content of Newhall navel orange and Satsuma mandarin showing obvious yellowing leaf. Content of ABA, soluble sugar and proline were increased with water stress in leaves of both cultivars. The expression of CitZEP gene and CitNCED gene which were involved in ABA biosynthesis showed much difference, expression level of CitNCED in leaf was gradually increased with water stress exacerbation, while the expression level of CitZEP was increased at the early stage and then decreased. [Conclusion]It suggested that the content of proline, soluble sugar and ABA increased under water stress in leaves of both citrus cultivars, while the content of chlorophyll decreased; CitNCED gene was one of the important genes in regulating ABA biosynthesis of citrus.