Virus-induced silencing of Comt, pAmt and Kas genes results in a reduction of capsaicinoid accumulation in chili pepper fruits
Virus-induced silencing of Comt, pAmt and Kas genes results in a reduction of capsaicinoid accumulation in chili pepper fruits
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DOI：
10.1007/s00425-007-0651-7
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发表时间：
2008-02-01
期刊：
影响因子：
4.3
通讯作者：
Ochoa-Alejo, Neftali
中科院分区：
文献类型：
--
作者：
del Rosario Abraham-Juarez, Ma;del Carmen Rocha-Granados, Ma;Ochoa-Alejo, Neftali
辣椒素是辣椒属植物辣椒果实具有辛辣味道的原因。辣椒素是通过苯丙烷和支链脂肪酸两种途径生物合成的。将在辣辣椒胎盘组织中差异表达的COMT(编码咖啡酸O-甲基转移酶)、PAMT(可能的氨基转移酶)和KAS(β-酮酰基-[酰基载体蛋白]合酶)基因片段分别插入到辣椒黄脉病毒(PHYVV)衍生载体中，通过病毒诱导的基因沉默来确定这些基因是否参与辣椒素的生物合成。相应的mRNA水平的降低以及相关siRNAs的存在证实了这三个基因的沉默。接种PHYVV：：COMT和PHYVV：：KAS的植株有明显的形态变化，而接种PHYVV：：PAMT的植株没有明显的变化。另一方面，结果在所有情况下都是正常的。对胎盘组织的生化分析表明，确实，这三个基因的独立沉默导致了果实中辣椒素含量的急剧下降，表明这些基因参与了辣椒素的生物合成。使用这种方法，可以高效地生产出无辛辣的辣椒。
Capsaicinoids are responsible for the pungent taste of chili pepper fruits of Capsicum species. Capsaicinoids are biosynthesized through both the phenylpropanoid and the branched-fatty acids pathways. Fragments of Comt (encoding a caffeic acid O-methyltransferase), pAmt (a putative aminotransferase), and Kas (a beta-keto-acyl-[acyl-carrier-protein] synthase) genes, that are differentially expressed in placenta tissue of pungent chili pepper, were individually inserted into a Pepper huasteco yellow veins virus (PHYVV)-derived vector to determine, by virus-induced gene silencing, irrespective of whether these genes are involved in the biosynthesis of capsaicinoids. Reduction of the respective mRNA levels as well as the presence of related siRNAs confirmed the silencing of these three genes. Morphological alterations were evident in plants inoculated with PHYVV::Comt and PHYVV::Kas constructs; however, plants inoculated with PHYVV::pAmt showed no evident alterations. On the other hand, fruit setting was normal in all cases. Biochemical analysis of placenta tissues showed that, indeed, independent silencing of all three genes led to a dramatic reduction in capsaicinoid content in the fruits demonstrating the participation of these genes in capsaicinoid biosynthesis. Using this approach it was possible to generate non-pungent chili peppers at high efficiency.