屏边空竹四季发笋的生理生态机制

The germination of bamboo shoot buds is a key biological problem during its growth and development. It is also the foundation of bamboo resource cultivation and industry development. However, the current research is relatively weak, which focuses on bamboo shoot phenology and development process. All studied bamboo species have only single peak of shooting. On the other hand, the increasing of soil temperature and precipitation are generally considered as an ecological triggering factor for the germination of bamboo shoot buds. Cephalostachyum pingbianense is newly published and is endemic to Yunnan Province of China, with fine bamboo shoot products. This species is the only known bamboo which can produce bamboo shoot under natural conditions every season, with two peaks of bamboo shooting in spring and winter. Cephalostachyum pingbianense is of great value for the study on diversity of the germination of bamboo shooting. . This study intends to start from the key ecological factors, i.e., soil temperature and moisture, to explore the shooting mechanism of Cephalostachyum pingbianense. Meanwhile, dynamic Spatial-Temporal pattern of endogenous hormone will be analyzed by the mean of the content determination and transcriptome throughout the year. This study will help to explain the shooting mechanism of Cephalostachyum pingbianense, and to provide the scientific data for a comprehensive understanding of the physiological and ecological mechanism of bamboo shoot bud germination. At the same time, this study will also help to provide a theoretical basis for developing a high-yielded management technology, and for promoting popularization and cultivation of this bamboo species. Lastly, our study is of important significance for developing fresh bamboo shoots supply throughout the year.

竹子地下茎的笋芽萌发是其生长发育过程中的关键生物学问题之一，也是竹资源培育和产业发展的基础，目前的研究较薄弱，集中于竹子的发笋物候和笋-幼竹发育过程，且均为在春季或夏季具有单一出笋峰值的竹种。土壤温度升高和降水量增加一般被认为是竹子笋芽萌发的生态启动因子。屏边空竹是新近发表的、特产于云南的优良笋用竹，为目前已知在自然条件下唯一能够四季产笋，且在春、冬两季具有两个出笋峰值的竹种，对于研究笋芽萌发习性的多样性具有重要价值。. 本研究拟从竹林土壤温度、水分等关键生态因子入手，结合各季节笋芽休眠期和萌发期的内源激素含量以及在转录组水平上的时空变化规律，探讨屏边空竹周年发笋的机制。研究将有助于深入了解其终年发笋的机制，为全面认识竹子笋芽萌发的生理生态机制提供科学资料；同时也可为制定科学的竹林丰产经营技术，推广该种极具特色的竹子资源提供理论依据，对于发展周年鲜笋供应的竹笋产业具有特殊意义。

屏边空竹（Cephalostachyum pingbianense）是目前已知唯一能够在自然条件下四季出笋的我国特有珍稀笋用竹种，对于研究竹类发笋机制多样性具有重要意义。本项目通过结合土壤、降水等生态因子调查，以及笋芽萌发过程的激素含量测定、转录组分析，揭示了屏边空竹周年发笋的生态生理调控机制。. 研究结果显示屏边空竹具有四季出笋的习性，且各季节出笋量与气温、土壤温度、土壤湿度、降雨量显著正相关。不同气象因子对各季节出笋的影响滞后期为15~60d。笋芽萌发过程中IAA和ABA的含量较高，ZR和GA3的含量较低。夏季和秋季的笋芽中IAA、ZR和GA3含量高于春季和冬季，而ABA含量表现为春季和冬季较高。笋芽中较高的IAA、ZR含量和较低的ABA含量可能促进其休眠至萌发阶段的转变。在笋芽萌发过程中，与激素和碳水化合物代谢相关基因（如春季的HK和BGLU4，冬季的IDH和GH3，夏秋季的GPI和talA/talB）在基因调控网络中处于中枢地位。另外，出笋量还与土壤速效磷和速效氮含量、PH存在显著正相关关系。多种参与碳、氮循环的微生物类群(如Bradyrhizobium和Trichoderma)与出笋量显著正相关，且在各季节根际土壤和根内微生物群落中占优势地位。土壤酸化与磷缺乏可能是限制屏边空竹分布区域的重要土壤属性。. 基于以上结果，我们提出了屏边空竹四季发笋的机制假说：由于优越的水热条件（月平均降水量22mm-116mm，土壤体积含水量33%-41%，月平均土温9.5℃-17.8℃），屏边空竹的笋芽萌发没有受到由于土壤低温和水分缺乏引起的生态休眠的限制；笋芽中较高的IAA、ZR含量和较低的ABA含量可能促进其休眠至萌发阶段的转变；在笋芽萌发过程中，与激素和碳水化合物代谢相关基因在基因调控网络中处于中枢地位；根际和根内微生物促进了水分和养分的供给。以上因素维持了其周年发笋。. 研究成果不仅促进了对于竹子笋芽萌发机制多样性的深入理解，而且还为制定科学的竹林丰产稳产技术措施，全面有效地保护和推广该种质资源奠定了基础。

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