Difference in capsaicinoid biosynthesis gene expression in the pericarp reveals elevation of capsaicinoid contents in chili peppers (Capsicum chinense)
Difference in capsaicinoid biosynthesis gene expression in the pericarp reveals elevation of capsaicinoid contents in chili peppers (Capsicum chinense)
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DOI：
10.1007/s00299-016-2078-8
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发表时间：
2016-11
影响因子：
6.2
通讯作者：
Yoshiyuki Tanaka;Fumihiro Nakashima;Erasmus Kirii;T. Goto;Y. Yoshida;K. Yasuba
中科院分区：
文献类型：
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作者：
Yoshiyuki Tanaka;Fumihiro Nakashima;Erasmus Kirii;T. Goto;Y. Yoshida;K. Yasuba
本研究揭示了辣椒果皮组织中多个类辣椒素生物合成基因的上调表达导致辣椒果实中总辣椒素含量的升高。摘要辣椒素是辣椒果实中特有的具有保健功能的化合物。高辣椒素水平是决定辣椒商品品质和促进健康特性的主要参数之一。为了研究其高含量的机制，我们将一种极辛辣的品种“特立尼达莫鲁加蝎子黄”（MY）与其他不同辛辣程度的品种（Fushimi-amanaga、Takanotsume、Red Habanero）进行了比较。MY果实的辣椒素浓度（23.9 mg/g DW）明显高于其他辛辣品种，包括“红哈瓦那”（HB）果实（14.3 mg/g DW）。对比分析表明，两种品种在胎盘隔中积累的辣椒素含量相似，但HB果皮中的辣椒素含量（1.8 mg/g DW）明显低于胎盘隔中的辣椒素含量（69.1 mg/g DW）。在HB果实中的辣椒素浓度依赖于胎盘隔，在其他资料报道。因此，尽管胎盘中隔组织含有较高的辣椒素浓度，但果皮和种子中的辣椒素浓度降低了其总含量。而MY果皮则表现出较高的浓度（23.2 mg/g DW）。qRT-PCR分析结果显示，辣椒素类生物合成途径基因Pun1、pAMT、KAS和bcat在辣椒品种胎盘隔中表达强烈上调。这些基因仅在MY果皮中表达，而在其他刺激性品种的果皮中几乎没有检测到。综上所述，这些基因不仅在胎盘隔中表达上调，而且在果皮中表达上调，对辣椒素在整个果实中的积累起重要作用。
Key messageThis research reveals that the up-regulated expression of multiple capsaicinoid biosynthetic genes in pericarp tissue leads to the elevation of total capsaicinoid content in chili pepper fruit.AbstractCapsaicinoids are health-functional compounds that are produced uniquely in chili pepper fruits. A high capsaicinoid level is one of the major parameters determining the commercial quality and health-promoting properties of chili peppers. To investigate the mechanisms responsible for its high contents, we compared an extremely pungent cultivar ‘Trinidad Moruga Scorpion Yellow’ (MY) with other cultivars of different pungency levels (Fushimi-amanaga, Takanotsume, Red Habanero). Capsaicinoid concentrations were markedly higher in MY fruit (23.9 mg/g DW) than in other pungent cultivars including ‘Red Habanero’ (HB) fruit (14.3 mg/g DW). Comparative analysis of MY and HB reveals that both cultivars accumulated similar capsaicinoid concentrations in the placental septum, with that in the HB pericarp (1.8 mg/g DW) being markedly lower than that in the placental septum (69.1 mg/g DW). The capsaicinoid concentration in HB fruit is dependent on the placental septum, as reported in other accessions. Therefore, even though placental septum tissue contains high capsaicinoid concentrations, those in the pericarp and seeds attenuated its total content. In contrast, the MY pericarp exhibited a markedly higher concentration (23.2 mg/g DW). A qRT-PCR analysis revealed that multiple capsaicinoid biosynthetic pathway genes (Pun1,pAMT,KAS, andBCAT) were strongly up-regulated in placental septum of pungent cultivars. The genes were expressed exclusively in the MY pericarp, but were barely detected in the pericarps of other pungent cultivars. Collectively, the present study indicates that the up-regulated expression of these genes not only in placental septum but also in pericarp plays an important role in driving capsaicinoid accumulation in the whole fruit.