Light effect on carotenoids production and expression of carotenogenesis genes in citrus callus of four genotypes
Light effect on carotenoids production and expression of carotenogenesis genes in citrus callus of four genotypes
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光对四种基因型柑橘愈伤组织类胡萝卜素产生及胡萝卜素生成基因表达的影响
DOI：
10.1007/s11738-011-0793-x
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发表时间：
2011-11-01
影响因子：
2.6
通讯作者：
Deng, Xiuxin
中科院分区：
文献类型：
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作者：
Gao, Huijun;Xu, Juan;Deng, Xiuxin
由于其理论上相同的遗传背景，柑橘愈伤组织和其他植物组织在类胡萝卜素合成的调控方面可能存在一些共同机制。因此，为了进一步了解柑橘中类胡萝卜素生物合成的光调控机制，研究了四种柑橘基因型的愈伤组织在光照或黑暗处理下的类胡萝卜素及其合成相关基因的表达情况。结果表明，作为对白光的响应，红马叙葡萄柚（Citrus paradisi Macf.）愈伤组织中的类胡萝卜素生物合成受到阻碍，而塔罗科血橙（C. sinensis (L.) Osbeck）的愈伤组织对光敏感，平均类胡萝卜素积累量增加了55%以上。在检测到的类胡萝卜素中，胡萝卜素的生物合成似乎比叶黄素更敏感。对编码八氢番茄红素合酶（PSY）、八氢番茄红素脱氢酶（PDS）、ζ -胡萝卜素脱氢酶（ZDS）、类胡萝卜素异构酶（CRTISO）等八个类胡萝卜素合成相关基因的表达情况进行了研究。结果显示，PSY在两种甜橙的愈伤组织中上调表达，在茂谷柑（C. reticulata x C. sinensis）的愈伤组织中下调表达。这三种基因型的生化数据强调了PSY是类胡萝卜素合成中的一个限速基因。然而，在红马叙葡萄柚的愈伤组织中，PDS和ZDS可能是限速基因，它们的转录本明显受到光的抑制，导致β -胡萝卜素和总类胡萝卜素含量显著下降，而这与PSY的转录水平无关。CRTISO的表达受光诱导，特别是在茂谷柑的愈伤组织中，其表达量增加了近12倍。总之，光调控柑橘愈伤组织中几个类胡萝卜素合成相关基因的表达，但不一定导致类胡萝卜素产量的显著变化。
Due to their theoretically identical genetic background, citrus callus and other plant tissues may share some mechanisms in the regulation of carotenogenesis. Thus, in order to gain further information on light regulation of carotenoids biosynthesis in citrus, the carotenoids and expression profiles of carotenogenesis in calluses of four citrus genotypes treated with light or dark were investigated. As a response to white light, results showed that carotenoids biosynthesis in callus of Red Marsh grapefruit (Citrus paradisiMacf.) was hampered, whereas callus of Tarocco blood orange (C. sinensis(L.) Osbeck) was sensitive to light by accumulating over 55% more carotenoids on average. Among the detected carotenoids, the biosynthesis of carotenes seemed to be more sensitive than that of xanthophylls. Expression profiles of eight carotenogenesis genes encoding phytoene synthase (PSY), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), carotenoids isomerase (CRTISO) etc. were investigated. Results revealed thatPSYwas up regulated in calluses of two sweet oranges, and down regulated in callus of Murcott tangor (C. reticulata×C. sinensis). Biochemical data in the three genotypes emphasized thePSYas a rate-limiting gene in the carotenogenesis. However, in the callus of Red Marsh grapefruit,PDSandZDSmight be the rate-limiting genes, and their transcripts were apparently inhibited by light, led to significant decreases in contents of β-carotene and total carotenoids irrelevant to transcription levels ofPSY. Expression ofCRTISOwas light-induced, especially in the callus of Murcott tangor, and increased by nearly 12-fold. In conclusion, light regulates the expression of several carotenogenesis genes in citrus callus, but may not necessarily result in significant changes in carotenoids production.