Capsaicinoid biosynthesis in the pericarp of chili pepper fruits is associated with a placental septum-like transcriptome profile and tissue structure
Capsaicinoid biosynthesis in the pericarp of chili pepper fruits is associated with a placental septum-like transcriptome profile and tissue structure
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DOI：
10.1007/s00299-021-02750-0
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发表时间：
2021-07-14
影响因子：
6.2
通讯作者：
Doi, Motoaki
中科院分区：
文献类型：
--
作者：
Tanaka, Yoshiyuki;Watachi, Mayuko;Doi, Motoaki
辣椒果实果皮中CAP生物合成在胎座隔膜和果皮中的边界不明确。辣椒素是辣椒果实中的一种辛辣成分。一般来说，CAP的生物合成仅限于果实的胎座隔膜，但据报道，其生物合成甚至发生在一些极辛辣品种的果皮中，导致总含量大幅增加。为了研究CAP在果皮中生物合成的机制，对在果皮中产生CAP的品种（MY）和不产生CAP的品种（HB）进行了比较转录组分析。RNA-seq结果显示，与HB果皮相比，MY果皮中有2264个基因差异表达。主成分分析和GO富集分析表明，MY果皮的基因表达谱比HB果皮更像胎盘隔膜。CAP生物合成相关基因在MY果皮和胎座隔膜中的表达在果实发育过程中发生协调变化。在包括HB在内的大多数辣椒材料中，产生CAP的细长表皮细胞仅分布于胎盘隔膜中，胎盘隔膜与果皮之间的形态界限清晰。在一些极辛辣的品种如MY中，细长的表皮细胞分布在胎盘隔膜到果皮区域，并且果皮在形态上类似于胎盘隔膜，例如缺乏大的表皮下细胞和在实质组织中的丰富空间。我们的数据表明，CAP的生物合成在果皮中发生了一个模糊的边界在胎盘隔膜和果皮。这些结果有助于进一步提高辣椒果实CAP产量。
Key message CAP biosynthesis in the pericarp of chili pepper fruits occurs with an ambiguous boundary in the placental septum and pericarp. Capsaicinoid (CAP) is a pungent ingredient of chili pepper fruits. Generally, CAP biosynthesis is limited to the placental septum of fruits, but it has been reported that its biosynthesis occurs even in the pericarp of some extremely pungent varieties, resulting in a substantial increase in total content. To examine the mechanism of CAP biosynthesis in the pericarp, comparative transcriptome analysis of a variety that produces CAP in the pericarp (MY) and a variety that does not (HB) was carried out. RNA-seq revealed that 2264 genes were differentially expressed in the MY pericarp compared with the HB pericarp. PCA analysis and GO enrichment analysis indicated that the MY pericarp has a gene expression profile more like placental septum than the HB pericarp. The gene expression of CAP biosynthesis-related genes in the MY pericarp changed coordinately with the placental septum during fruit development. In most Capsicum accessions including HB, the distribution of slender epidermal cells producing CAP was limited to the placental septum, and the morphological boundary between the placental septum and pericarp was clear. In some extremely pungent varieties such as MY, slender epidermal cells ranged from the placental septum to the pericarp region, and the pericarp was morphologically similar to the placental septum, such as the absence of large sub-epidermal cells and abundant spaces in the parenchymal tissue. Our data suggest that CAP biosynthesis in the pericarp occurred with an ambiguous boundary in the placental septum and pericarp. These findings contribute to further enhancement of CAP production in chili pepper fruits.