Bud dormancy is a crucial process in the annual growth cycle of woody perennials. In Rosaceae fruit tree species, DORMANCY-ASSOCIATED MADS-box (DAM) transcription factor genes regulating bud dormancy have been identified, but their molecular roles in meristematic tissues have not been thoroughly characterized. In this study, molecular and physiological analyses of transgenic apple plants overexpressing the Japanese apricot DAM6 gene (PmDAM6) and Japanese apricot cultivars and F1 individuals with contrasting dormancy characteristics revealed the metabolic pathways controlled by PmDAM6. Our transcriptome analysis and transmission electron microscopy examination demonstrated that PmDAM6 promotes the accumulation of lipid bodies and inhibits cell division in the dormant vegetative meristem by down-regulating the expression of lipid catabolism genes (GDSL ESTERASE/LIPASE and OIL BODY LIPASE) and CYCLIN genes, respectively. Our findings also indicate PmDAM6 promotes abscisic acid (ABA) accumulation and decreases cytokinin (CTK) accumulation in vegetative buds by up-regulating the expression of the ABA biosynthesis gene ARABIDOPSIS ALDEHYDE OXIDASE and the CTK catabolism gene CYTOKININ DEHYDROGENASE, while also down-regulating the expression of the CTK biosynthesis genes ISOPENTENYL TRANSFERASE (IPT) and CYP735A. Additionally, PmDAM6 modulates gibberellin (GA) metabolism by up-regulating GA2-OXIDASE expression and down-regulating GA3-OXIDASE expression. Furthermore, PmDAM6 may also indirectly promote lipid accumulation and restrict cell division by limiting the accumulation of CTK and GA in buds. In conclusion, using our valuable genetic platform, we clarified how PmDAM6 modifies diverse cellular processes, including lipid catabolism, phytohormone (ABA, CTK, and GA) biosynthesis and catabolism, and cell division, in the dormant vegetative meristem.

中文翻译：

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梅DAM6对休眠营养分生组织脂体积累和植物激素代谢的调节作用

芽休眠是多年生木本植物年度生长周期中的一个关键过程。在蔷薇科果树物种中，调节芽休眠的休眠相关 MADS-box (DAM) 转录因子基因已被鉴定，但其在分生组织中的分子作用尚未得到彻底表征。在本研究中，对过表达日本杏 DAM6 基因 (PmDAM6) 的转基因苹果植物以及具有对比休眠特性的日本杏品种和 F1 个体进行分子和生理分析，揭示了 PmDAM6 控制的代谢途径。我们的转录组分析和透射电镜检查表明，PmDAM6 通过下调脂质分解代谢基因（GDSL ESTERASE/LIPASE 和 OIL BODY LIPASE）和 CYCLIN 基因的表达，促进休眠营养分生组织中脂质体的积累并抑制细胞分裂，分别。我们的研究结果还表明，PmDAM6 通过上调 ABA 生物合成基因拟南芥醛氧化酶和 CTK 分解代谢基因细胞分裂素脱氢酶的表达，同时下调CTK 生物合成基因异戊烯基转移酶 (IPT) 和 CYP735A 的表达。此外，PmDAM6 通过上调 GA2-OXIDASE 表达和下调 GA3-OXIDASE 表达来调节赤霉素 (GA) 代谢。此外，PmDAM6还可能通过限制芽中CTK和GA的积累来间接促进脂质积累并限制细胞分裂。总之，利用我们宝贵的遗传平台，我们阐明了 PmDAM6 如何改变休眠营养分生组织中的多种细胞过程，包括脂质分解代谢、植物激素（ABA、CTK 和 GA）生物合成和分解代谢以及细胞分裂。