拟南芥黄嘌呤脱氢酶XDH1/2调控极核融合的机理研究

In the female gametophyte development, the fusion of polar nuclei marks the development and maturation of central cells. The fusion of polar nuclei can affect the development and maturation of central cells and lead to seed development defects, but the regulation mechanism of polar nuclear is still unknown. Our previous studies found that XDH1/2 expressed in inner integuments specifically, the mutants showed that the polar nucleus was not fused, and the female gametophyte development stagnates in the FG5, leading to the abortion of the ovule. These results indicate that XDH1/2 could produce some signal in the sporophyte tissues to regulated the development of female gametophyte. Here, we will apply the techniques of cell biology, molecular genetics, biochemistry and transcriptome to study the function of XDH1/2 in polar nucleus fusion. We aim to explore the signaling molecules produced by XDH1/2 to clarity the mechanism underlies the fusion of polar nucleus. Our findings will provide important theoretical basis for study of the regulation mechanism of central cell development.

植物雌配子体发育过程中，极核的融合标志着中央细胞的发育成熟。极核不能融合，则会影响中央细胞的发育成熟，导致种子发育缺陷。然而，调控极核融合的机理至今仍不清楚。本项目前期研究发现黄嘌呤脱氢酶XDH1/2功能缺失突变体中，极核不能融合，雌配子体发育停滞在FG5时期，导致胚珠败育；而XDH1/2表达模式分析表明该基因在雌配子体发育早期的内珠被中特异表达，暗示着XDH1/2在孢子体组织中可能会产生某种信号来调控配子体的发育。本项目将在此基础上，采用细胞生物学、分子遗传学、生物化学和转录组学等方法，来探究XDH1/2基因在中央细胞极核融合过程中的生物学功能，挖掘XDH1/2调控中央细胞极核融合的信号分子，为中央细胞发育的调控机理解析提供重要的理论依据。

植物雌配子体发育过程中，极核的融合标志着中央细胞的发育成熟。极核不能融合或胚囊退化，会直接影响中央细胞和胚囊的发育成熟，最终导致种子发育缺陷。然而，调控极核融合和胚囊退化的机理尚不清楚。本项目发现黄嘌呤脱氢酶XDH1/2功能缺失突变体中，极核不能融合，雌配子体发育停滞在FG5时期，胚囊退化，导致胚珠败育；而XDH1/2表达模式分析表明该基因在雌配子体发育早期的内珠被中特异表达，暗示着XDH1/2在孢子体组织中可能会产生某种信号来调控配子体的发育。我们采用细胞生物学、分子遗传学和LC-MS等方法，进一步研究发现次黄嘌呤和黄嘌呤过度积累导致细胞质体pH碱化，细胞酸碱失衡，最终导致极核不能融合和胚囊退化。本研究系统研究了XDH1/2通过调节细胞pH稳态进而调控雌配子体发育的分子机制，为雌配子体发育的调控机理解析提供重要的理论依据。本项目原目标全部完成。共发表第二标注SCI论文4篇，分别为：International Journal of Molecular Sciences 1篇，Tropical Plant Biology 1篇，BMC Genomics 1篇，Peer J 1篇。

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