张绍铃课题组成果登权威期刊 破解新基因功能

　　

以在校博士生王春雷为第一作者、张绍铃教授为通讯作者、南京农业大学为第一知识产权单位、题目为《S-RNase triggers mitochondrial alteration and DNA degradation in the incompatible pollen tube of Pyrus pyrifolia in vitro》（doi: 10.1111/j.1365-313X.2008.03681.x）的研究论文在世界著名杂志《The Plant Journal》（影响因子6.751）上发表。该论文主要通过建立自交不亲和性反应离体系统，研究了S-RNase对不亲和花粉管线粒体和核DNA的影响，推测S-RNase激发了不亲和花粉管发生程序性死亡。该研究成果在国际上是首次报道。张绍铃教授课题组长期从事梨研究，这是继去年在《New Phytologist》（影响因子5.249）发表的题目为《Identification of hyperpolarization-activated calcium channels in apical pollen tubes of Pyrus pyrifolia》（2007,174（3）:524-536）论文之后的又一篇高水平研究论文。

 

   梨和大多数植物一样靠授粉繁衍后代，从而在进化过程中发展了抑制“近亲繁殖”的生殖机制，其中最重要的就是自交不亲和性，即能够特异性地识别并拒绝自花或亲缘关系很近的花粉，而田间自花授粉则不结实。  

据论文第一作者、南京农业大学在校博士生王春雷介绍，梨是亚洲及我国主栽果树之一，是典型的自花授粉不结实性果树，田间自花授粉坐果率极低。因此在生产上需要合理配置授粉树或进行人工辅助授粉。但人工授粉需要花费很多劳力，同时也常因授粉树配置不当，花期不良，气象条件影响，昆虫传粉或人工授粉不及时等原因造成减产。  

提高梨的产量和品质，需要掌握梨自花授粉不结实的原因。张绍铃教授领导的南京农大梨工程中心经多年研究，成功从梨花花柱分离出控制自花授粉不结实性的基因的产物“S-RNase”，并在实验室建立了一套梨“近亲繁殖”不结实反应系统———自交不亲和性反应离体系统。利用这个系统，在新近的研究中进一步解释了“S-RNase”能够抑制梨“近亲繁殖”的原因：“S-RNase”进入梨花花粉管，降解了亲缘关系较近的花粉管中的核糖核酸，使蛋白质合成受阻，同时伴随花粉管线粒体和核DNA变化，引起花粉管发生程序性死亡。他说，梨自花授粉不结实花粉管停止生长的死亡过程属于程序性死亡，这对最终了解自花授粉不结实的机制具有重大意义。

 

原文检索：S-RNase triggers mitochondrial alteration and DNA degradation in the incompatible pollen tube of Pyrus pyrifolia in vitro

 

【Abstract】

Pear (Pyrus pyrifolia L.) has a S-RNase-based gametophytic self-incompatibility (SI) mechanism, and S-RNase has also been implicated in the rejection of self-pollen and genetically identical pollen. No studies, however, have examined the extent of organelle alterations during the SI response in Pyrus pyrifolia. Consequently, this study focused on the alterations to mitochondria and nuclear DNA in incompatible pollen tubes of the pear. Methylthiazolyldiphenyl-tetrazolium bromide was used to evaluate the viability of pollen tubes under S-RNase challenge. The results showed that the viability of the control and compatible pollen tubes decreased slightly, but that of the incompatible pollen and pollen tubes began to decline at 30 min. The mitochondrial membrane potential (Δψmit) was also tested with rhodamine 123 30 min after SI challenge, and was shown to have collapsed in the incompatible pollen tubes after exposure to S-RNase. Western blotting 2 h after SI challenge confirmed that the Δψmit collapse induced leakage of cytochrome c into the cytosol. Swollen mitochondria were detected by transmission electron microscopy as early as 1 h after SI challenge and the degradation of nuclear DNA was observed by both 4,6-diamidino-2-phenylindole and transferase-mediated dUTP nick-end labeling. These diagnostic features of programmed cell death (PCD) suggested that PCD may specifically occur in incompatible pollen tubes.