DUF784基因在花粉管导向中的功能分析

Functional Analysis of DUF784 Genes in Micropylar Pollen Tube Guidance

花粉管导向是高等植物完成双受精过程的重要环节,是受多重信号调控的复杂过程.最近的研究揭示,配子体阶段花粉管导向的诱导信号分子是一类具多态性的富含半胱氨酸的防卫素类似蛋白,如来自玉米的ZmEA1和蓝猪耳草中的LUREs在吸引花粉管进入珠孔起重要作用.但是拟南芥及其它植物中此类信号未知.转录组学分析表明,一组DUF784基因可能在花粉管导向中起到重要作用.通过RNAi技术降低一组DUF784基因的表达,分析发现在RNAi转基因植株中,出现胚珠败育现象,花粉管导向出现异常,一部分花粉管不能进入珠孔.另外,用MYB98基因的启动子携带1个DUF基因的编码区,然后转化ccg突变体,发现ccg转基因株系中胚胎败育率下降,即DUF基因能部分互补ccg突变体的表型;从这两方面证实了DUF784基因在花粉管定向导入过程中的作用.

Pollen tube guidance is the key step in double fertilization of plant,which is a complex process regulated by multi-level signals.The attractants from female gametophyte is one kind of cystine-rich defensin-like protein with polymorphism,such as ZmEA1 from maize and LUREs from T.fournieri.But the attractants from other plants,such as rice and Arabidopsis were not identified until now.Transcriptomics analysis showed that a group of DUF784 genes in Arabidopsis might play an important role in pollen tube guidance.We decreased the expression level of a group of DUF784 genes by RNAi.In these RNAi transgenic lines,we found that some ovules were aborted in silique.Phenotypic analysis showed defect in pollen tube guidance,some pollen tubes failed to entry into micropyle.Simultaneously we cloned CDS sequence of several DUF784 genes and put it downstream of MYB98 promoter in pCAMBIA1300 vector.Then we use this construct to transform ccg mutant.In ccg transgenic lines,ovule abortion ratio decreased and KanR segregation ratio increased.Both of these results indicated that DUF784 genes play an important role in pollen tube guidance.