Key Laboratory of Forest Silviculture and Conservation of the Ministry of Education, Beijing Forestry University, Beijing 100083, PR China.
J Exp Bot. 2011 Oct;62(14):4805-17. doi: 10.1093/jxb/err120. Epub 2011 Jul 22.
The HAP complex occurs in many eukaryotic organisms and is involved in multiple physiological processes. Here it was found that in Picea wilsonii, HAP5 (PwHAP5), a putative CCAAT-binding transcription factor gene, is involved in pollen tube development and control of tube orientation. Quantitative real-time reverse transcription-PCR showed that PwHAP5 transcripts were expressed strongly in germinating pollen and could be induced by Ca(2+). Overexpression of PwHAP5 in pollen altered pollen tube orientation, whereas the tube with PwHAP5RNAi showed normal growth without diminishing pollen tube growth. Furthermore, PwFKBP12, which encodes an FK506-binding protein (FKBP) was screened and a bimolecular fluorescence complementation assay performed to confirm the interaction of PwHAP5 and PwFKBP12 in vivo. Transient expression of PwFKBP12 in pollen showed normal pollen tube growth, whereas the tube with PwFKBP12RNAi bent. The phenotype of overexpression of HAP5 on pollen tube was restored by FKBP12. Altogether, our study supported the role of HAP5 in pollen tube development and orientation regulation and identified FKBP12 as a novel partner to interact with HAP5 involved in the process.
HAP 复合体存在于许多真核生物中，参与多种生理过程。在这里发现，在白皮松中，HAP5（PwHAP5），一个假定的 CCAAT 结合转录因子基因，参与花粉管发育和管取向控制。定量实时反转录-PCR 显示，PwHAP5 转录本在萌发花粉中强烈表达，并可被 Ca(2+)诱导。花粉中 PwHAP5 的过表达改变了花粉管的取向，而 PwHAP5RNAi 的管则正常生长，花粉管生长没有减弱。此外，筛选出编码 FK506 结合蛋白（FKBP）的 PwFKBP12，并进行双分子荧光互补测定以确认 PwHAP5 和 PwFKBP12 在体内的相互作用。PwFKBP12 在花粉中的瞬时表达显示花粉管正常生长，而 PwFKBP12RNAi 的管弯曲。FKBP12 恢复了 HAP5 对花粉管的过表达表型。总之，我们的研究支持 HAP5 在花粉管发育和取向调控中的作用，并确定 FKBP12 是参与该过程的与 HAP5 相互作用的新伙伴。
