Transcriptome analysis reveals key genes involved in rhizome bud germination of Cephalostachyum pingbianense in four seasons

Cephalostachyum pingbianense is the only known bamboo species that can produce bamboo shoots in four seasons under natural conditions. Nevertheless, the regulatory mechanisms of shoot bud differentiation and development of that is still unknown. In this study, RNA sequencing and differentially expressed gene analysis were performed on dormant rhizome bud (DR), growing rhizome bud (GR) and germinative bud (GB) of C. pingbianense in each season. The results showed that rhizome bud germination of C. pingbianense was cooperatively regulated by multiple pathways such as carbohydrate metabolism, hormone signal transduction, cell wall biogenesis, temperature response, water metabolism and so on. Putative major regulatory genes of each season, such as HK and BGLU4 in spring, GUX2 and GH3 in winter, GPI and talA/talB in summer and autumn, were identified through protein-protein interaction network analyses. We propose that dynamic changes of phytohormones and the differential expression of these genes contribute to the rhizome bud germination of C. pingbianense in four seasons.

平边秆竹（Cephalostachyum pingbianense）是目前已知唯一可在自然条件下四季出笋的竹类物种。然而，其笋芽分化与发育的调控机制仍未明晰。本研究针对平边秆竹不同季节的休眠根茎芽（dormant rhizome bud，DR）、生长中根茎芽（growing rhizome bud，GR）及萌发芽（germinative bud，GB）开展了RNA测序（RNA sequencing）与差异表达基因分析。结果表明，平边秆竹的根茎芽萌发受碳水化合物代谢、激素信号转导、细胞壁生物发生、温度响应、水分代谢等多条通路协同调控。通过蛋白质相互作用网络（protein-protein interaction network）分析，本研究鉴定出各季节的潜在核心调控基因，其中春季为HK与BGLU4、冬季为GUX2与GH3、夏秋季节为GPI与talA/talB。本研究提出，植物激素的动态变化及这些基因的差异表达，共同促成了平边秆竹根茎芽的四季萌发。