A global overview of transcriptome dynamics during the late stage of flower bud development in Camellia oleifera

Camellia oleifera Abel., recognized as a significant oil plant, is of immense potential health and economic value. Due to the self-incompatibility of C. oleifera, pollination relies on cross-pollination from other flowers. Additionally, the asynchronous flowering periods of individual plants result in low fruit set and yield, which limits the broader cultivation and utilization of this species. The study investigated the dynamic changes and regulatory patterns of different tissues within flower buds from flower bud development to flowering, employing a multi-faceted approach that included cellular dissection, analysis of hormone content, and transcriptome analysis. This study demonstrates that ABA and SA, rather than GA₃, IAA, ZT, acts as potentially effective endogenous agents to promote flowering in the later stages of flower development, which is a critical period for the maturation of pollen and embryo sacs; while ZT plays a more significant role in the early stages of flower bud development. Transcriptome analysis indicated that C.oleifera primarily regulates the late stages of flower bud development via regulating genes involved in starch and sucrose metabolism in petals, monoterpene synthesis and ABC transporters in pistils and stamens. WGCNA identified four key modules associated with the development of stamens and pistils in the late stage of C.oleifera flower buds, and also screened out key core genes, including CoBMY7/8, CoTPP6/10, and CoG8H7/11, which are involved in the regulation of flowering time. These findings enhance our understanding of the developmental changes in stamens, pistils, and petals during the flower bud development of C. oleifera. Moreover, they provide a foundation for manipulating flowering time and improving fruit set by regulating the expression of key genes in future studies.