Brassinosteroids (BRs) are phytohormones that regulate numerous processes including fruit ripening. In this study, persimmon (Diospyros kaki L.) fruits were treated with 24-epibrassinolide (EBR) or brassinazole (Brz, a BR biosynthesis inhibitor) and then stored at ambient temperature. The results show that endogenous BR contents gradually increased during persimmon fruit ripening. EBR treatment significantly increased both the content of water-soluble pectin and the activities of polygalacturonase, pectate lyase, and endo-1,4-beta-glucanase but significantly reduced the content of acid-soluble pectin and cellulose, resulting in rapid fruit softening. The EBR treatment also promoted ethylene production and respiration rate. In contrast, Brz treatment delayed persimmon fruit ripening. qRT-PCR analysis showed that DkPG1, DkPL1, DkPE2, DkEGase1, DkACO2, DkACS1, and DkACS2 were up-regulated (especially a 38-fold increase in DkEGase1) in the fruit of the EBR-treated group. These results suggest that BRs are involved in persimmon fruit ripening by influencing cell-wall-degrading enzymes and ethylene biosynthesis.

中文翻译：

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在柿子（油菜素内酯的作用柿L.）果实成熟

油菜素类固醇（BRs）是一种植物激素，可调节包括果实成熟在内的许多过程。在这项研究中，柿子（柿）L.）果实用24-表油菜素内酯（EBR）或油菜素唑（Brz，BR生物合成抑制剂）处理，然后在环境温度下保存。结果表明，柿果实成熟过程中内源BR含量逐渐增加。EBR处理显着增加了水溶性果胶的含量以及聚半乳糖醛酸酶，果胶酸裂合酶和1,4-β-葡聚糖内切酶的活性，但显着降低了酸溶性果胶和纤维素的含量，从而使果实快速软化。EBR处理还促进了乙烯的产生和呼吸速率。相反，Brz处理延迟了柿子果实的成熟。qRT-PCR分析显示DkPG1，DkPL1，DkPE2，DkEGase1，DkACO2EBR治疗组的果实中的DkACS1，DkACS1和DkACS2上调（尤其是DkEGase1增加38倍）。这些结果表明，BR通过影响细胞壁降解酶和乙烯的生物合成参与柿子果实的成熟。