The role of cytokinin and CKX genes in regulating seed yield in barley and oilseed rape

由于世界人口的迅速增长，稳定或提高农业植物的产量是非常重要的。作物产量的调控是一个复杂的过程，涉及许多基因，其中大部分是未知的。CKX基因已被证明在单子房和双子房的产量控制中起作用。这些基因编码蛋白质，催化植物激素细胞分裂素的分解。本文旨在更详细地研究CKX基因在大麦（Hordeum vulgare L.）和油菜（Brassica napus L.）中的作用。项目第一部分拟研究与水稻著名产量基因OsCKX2相关的两个基因HvCKX2.1和HvCKX2.2在大麦产量形成中的作用。本文重点研究通过基因组编辑产生的Hvckx2.1和Hvckx2.2对应的单、双突变体的分子和表型特征。突变体生殖发育和产量形成将在温室和田间进行分析，重点是穗和种子的发育。研究的第二种作物是油菜，这是欧洲最重要的油料作物。申请人的研究小组已经发现了两个CKX基因在控制汇强度中起关键作用，这对高产很重要。BnCKX3和BnCKX5同时失活导致细胞分裂素含量升高，从而激活花序分生组织和其他生殖组织。这导致形成更多的花，更多的豆荚和更多的胚珠，最终获得更高的种子产量。在拟建的项目中，将研究特定的油菜籽突变体Bnckx3,5的种子含油量高的原因。进一步分析了6个BnCKX3和BnCKX5等位基因对温室和田间产量形成的贡献。在油菜和拟南芥中研究了额外产量基因的影响，特别是增加了来源的形成。最后，通过大麦和油菜的野生、陆地和育种系的基因组数据，探讨了CKX基因在驯化过程中的选择。

Due to the rapidly growing world population, stabilizing or increasing the yields of agricultural plants is of great importance. Regulation of crop yield is a complex process involving numerous genes, most of which are unknown. CKX genes have been shown to play a role in yield control in monocots and dicots. These genes code for proteins, which catalyze the breakdown of the plant hormone cytokinin. It is the aim of this proposal to investigate the role of certain CKX genes in barley (Hordeum vulgare L.) and oilseed rape (Brassica napus L.) in more detail. The first part of the project proposes to investigate the role of two genes, HvCKX2.1 and HvCKX2.2, which are related to the well-known yield gene OsCKX2 of rice, in yield formation in barley. Here, the focus is on the molecular and phenotypic characterization of corresponding Hvckx2.1 and Hvckx2.2 single and double mutants generated by genome editing. Mutant reproductive development and yield formation will be analyzed in the greenhouse and in the field, with a focus on spike and seed development. The second crop studied is oilseed rape, the most important oil crop in Europe. The applicant's research group has discovered two CKX genes that play a key role in controlling sink strength, which is important for high yields. The simultaneous inactivation of BnCKX3 and BnCKX5 leads to a higher cytokinin content and thereby to an activation of the inflorescence meristem and other reproductive tissues. This results in the formation of more flowers, more pods with more ovules, and ultimately a higher seed yield. In the proposed project, the reasons for a high oil content in the seeds of a specific Bnckx3,5 rapeseed mutant are to be investigated. Furthermore, the contribution of each of the six BnCKX3 and BnCKX5 alleles to yield formation in the greenhouse and in the field is analyzed. The effect of additional yield genes, which in particular increase source formation, is examined in oilseed rape and comparatively in Arabidopsis. Last but not least, the selection of CKX genes during domestication is explored in genomic data from wild, land and breeding lines of barley and oilseed rape.