咖啡花芽内休眠解除过程中激素变化及相关差异表达基因筛选

There is a period of dormancy from coffee flower bud formation to flowering. The amount of time required for the dormancy release is different among the flower buds, which leads to the poor synchronization of coffee flowering and fruit maturity. This has become a big problem in coffee production. It has been confirmed that water stress is essential for the release of coffee flower bud endo-dormancy, and water stress imposed separately either on the roots or the leaves can break the endo-dormancy, which means roots and leaves may play an important part in the process of endo-dormancy release. In addition, hormones have also been proved to be involved in coffee flower bud endo-dormancy release. Based on above, two ways of endo-dormancy breaking will be separately set up through imposing a water stress only on the roots or the leaves. The dynamic changes of hormones and gene expression in roots - flower buds, leaves – flower buds during the two ways of endo-dormancy breaking will be analyzed, and so does the correlation between them. Those genes expressed in a similar way between the two ways of endo-dormancy breaking will be screened. In order to explore the mechanism of the coffee flower buds endo-dormancy, the qRT-PCR analysis of the screened genes will be conducted. This research will provide theory basis for the synchronization of coffee flowering.

咖啡从花芽形成到开花，中间需经历一段时间上不等的休眠期，休眠解除时间不同步是导致咖啡开花不同步的主要原因，进而影响果实成熟一致性，由此带来的采果效率低下已经成为咖啡产业面临的突出问题。已经证实，水分胁迫是解除咖啡花芽内休眠的必要条件，且无论是根系还是枝条，都可以通过独立感受水分胁迫而使花芽内休眠解除，暗示了根系和枝叶在其中的重要作用。另外，研究表明，激素对咖啡花芽休眠解除具有重要影响。针对此，本项目拟通过分别单独对根系及枝叶进行水分胁迫处理，建立两种不同的咖啡花芽内休眠解除途径，以此为基础，对比分析这两种途径在花芽内休眠解除过程中不同阶段，激素及相关基因表达在根系-花芽、叶片-花芽间的动态变化及相关性，在此基础上寻找共性的激素变化规律及相关差异表达基因，并通过分析相关基因表达模式与激素在内休眠解除进程中的动态规律，探讨咖啡花芽内休眠解除相关机理，为咖啡花期同步化调控提供理论基础。

咖啡花芽休眠解除不同步是导致咖啡开花及果实成熟不同步的主要原因，解析咖啡花芽休眠解除相关机理对于咖啡花、果期调控具有重要实际生产意义。本项目通过对水分胁迫诱导咖啡花芽休眠解除过程中内源激素动态变化及基因差异表达分析，探讨ABA等内源激素在咖啡花芽休眠解除中的作用，筛选咖啡花芽休眠解除相关基因。GA3和IAA在咖啡花芽内休眠解除进程中逐渐升高，表明GA3和IAA对咖啡花芽内休眠解除具有促进作用；ABA对休眠解除具有抑制作用，咖啡花芽内休眠解除期间花芽游离态ABA含量有一个短暂的下降过程，花芽游离态ABA含量的下降可能是开启咖啡花芽内休眠解除的信号。对咖啡花芽休眠解除过程中处于内休眠期、内休眠解除期、内休眠解除完成期、生态休眠解除完成期、花芽萌发期5个关键节点花芽样本进行表达谱分析。随着休眠解除进程的深入，基因上调和下调表达不断加强，中粒种咖啡水分胁迫处理初期差异表达基因仅为81个，其中大部分为下调表达；花芽内休眠完全解除时，差异表达基因数量增加到218个，且上调表达的基因快速增加；生态休眠解除期，差异表达基因数量增加至837个，其中上调表达基因多于下调表达基因；至花芽萌发期，差异表达基因数量进一步增加至1271个。通过差异表达基因KEGG富集分析,共检测到与激素代谢通路相关的差异表达基因17个：PP2C、SnRK2、ABF、PYR/PYL、ETR、EBF1/2、ERF1/2、EIN3、AUX1、SAUR、B-ARR、AUX/LAA、GH3、GID1、PR-1、TGA、NPR1，主要涉及脱落酸、乙烯、赤霉素、生长素及水杨酸等激素信号转导，在咖啡花芽休眠解除过程中可能起重要调控作用。研究结果对于咖啡花期同步化调控，降低咖啡采收成本具有一定理论指导意义。