黄瓜CsCYP90基因的鉴定及其对果实糖和多酚代谢的影响

Identification of the cucumber CsCYP90 gene and its effects on fruit sugar and polyphenol metabolism

摘要:

黄瓜果实代谢及品质受到多个基因家族调控，细胞色素P450家族基因CsCYP90对黄瓜果实品质的影响还未见报道。为了深入探究CsCYP90基因在黄瓜果实品质形成中的具体功能，并解析其潜在的代谢调控机制，本研究克隆了黄瓜CsCYP90 (CsaV3_1G007770)基因，发现其在果实中表达量最高；系统进化分析表明其与甜瓜亲缘关系较近，且属同一个CYP90亚分支。通过构建CsCYP90转基因载体获得过表达黄瓜株系，进行代谢组测序和生理指标测定分析发现，该基因过表达能够显著影响谷氨酰胺、一磷酸腺苷、异麦芽糖等多种代谢物在果实中的积累，主要富集在氨基酸生物合成、戊糖磷酸途径、淀粉和蔗糖代谢、苯丙烷类生物合成等多种生物途径，从而造成过表达黄瓜株系果实中可溶性糖含量的提升、单宁含量的下降，在一定程度上提升了果实的品质。本研究揭示了CsCYP90基因在黄瓜果实代谢调控与品质形成中的关键作用，为黄瓜品质改良提供了新的基因靶点与理论依据。

Abstract:

The metabolism and quality of cucumber (Cucumis sativus) fruits are modulated by various gene families. Nevertheless, the role of the cytochrome P450 family gene CsCYP90 in cucumber fruit quality remains largely unreported. To conduct an in-depth investigation into the specific function of the CsCYP90 gene in the formation of cucumber fruit quality and analyze its underlying metabolic regulatory mechanism, we cloned CsCYP90 (CsaV3_1G007770) from cucumber and discovered that it had the highest expression level in fruits. Phylogenetic analysis revealed a close evolutionary relationship with melon, placing it within the same CYP90 subclade. Transgenic vectors harboring CsCYP90 were constructed to generate overexpression lines, followed by metabolomic sequencing and physiological assays. Overexpression of CsCYP90 significantly altered the accumulation of various metabolites, including glutamine, adenosine monophosphate, and isomaltose, and enriched multiple biological pathways such as amino acid biosynthesis, pentose phosphate pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. These changes result in elevated soluble sugar content and reduced tannin levels in transgenic fruits, improving the overall fruit quality. This study reveals the key role of the CsCYP90 gene in the metabolic regulation and quality formation of cucumber fruits, providing a novel gene target and theoretical basis for cucumber quality improvement.