在中国大豆品种上创建ALSV诱导的基因沉默体系

Establishment of ALSV-Induced Gene Silencing in Chinese Soybean Cultivars

【目的】在中国大豆品种上建立以苹果潜隐球形病毒(apple latent spherical virus,ALSV)为载体的基因沉默体系,为中国大豆品种的基因功能和遗传育种提供一种简便、省时、易操作的技术体系。【方法】构建以农杆菌介导接种的ALSV病毒侵染性克隆载体。从大豆品种威廉姆斯82(Williams 82)中特异扩增327 bp的八氢番茄红素脱氢酶(GmPDS)基因cDNA片段,插入病毒载体pALSV2。通过农杆菌浸润法将病毒载体导入模式植物本氏烟(Nicotiana benthamiana),17 d后富集病毒粒子,摩擦接种大豆第一轮真叶,以接种病毒空载作为对照组,持续观察测试大豆植株系统叶表型,并结合逆转录-聚合酶链式反应(RT-PCR)或荧光定量PCR(qRT-PCR)检测ALSV衣壳蛋白基因(CP)和GmPDS的表达水平。【结果】ALSV﹕GmPDS接种大豆品种威廉姆斯82和南农1138-2,20 d后,前者系统叶未见白化表型,而后者系统叶出现明显的白化表型;qRT-PCR检测结果表明,发生白化的南农1138-2植株中GmPDS的表达水平显著降低,未出现白化表型的威廉姆斯82中GmPDS的表达水平没有出现显著变化。在此基础上,采用相同的方法,测试了ALSV在其他9种大豆品种中诱导GmPDS的沉默效率,发现在南农47、安豆203、祥斗4号、中黄13、山宁29、齐黄34等大豆品种上接种ALSV﹕GmPDS后植株系统叶均产生白化表型,而菏豆12、中黄311和山宁16等3个品种的GmPDS均不能诱导有效沉默。【结论】构建了农杆菌介导的ALSV病毒载体,利用本氏烟扩繁富集ALSV病毒,将提纯的病毒粒体摩擦接种大豆真叶,在多个中国大豆品种上成功建立了基因沉默体系。

【Objective】 The establishment of apple latent spherical virus(ALSV)-induced gene silencing on domestic soybean cultivars will offer a simple, time-saving and operable system for gene function and genetic breeding of soybean cultivars in China.【Method】The infectious clones of ALSV which was used to infect plant through Agro-infiltration was constructed. A 327 bp cDNA fragment of phytoene desaturase(Gm PDS) cDNA was amplified from soybean cultivar Williams 82 and inserted into the pALSV2vector. The pALSV1 and pALSV2-Gm PDS were used to co-infect Nicotiana benthamiana plant through Agro-infiltration, and the ALSV virus particle was purified from systemic infected leaves of N. benthamiana plants at 17 days post infiltration(dpi). The purified virions were mechanically inoculated onto the first-round true leaves of soybean and photobleaching phenotype on the upper non-inoculated leaves was monitored from 10 to 30 dpi. Using the empty ALSV vector as a control, the gene expression levels of ALSV coat protein(CP) gene and Gm PDS in ALSV:GmPDS infected soybean were examined by RT-PCR and quantitative RT-PCR analysis, respectively. 【Result】At 20 dpi, soybean cultivar Nannong 1138-2 inoculated with ALSV:GmPDS showed photobleaching phenotype in the systemic infected leaves, however Williams 82 did not show gene silencing phenotype of PDS in the systemic infected leaves. The results of qRT-PCR confirmed that the RNA expression level of GmPDS in Nannong 1138-2 was significantly reduced but ALSV:Gm PDS was unable to silence PDS in Williams 82. By using the same method, the gene silencing efficiency of other 9 domestic soybean cultivars mediated by ALSV:Gm PDS was examined. Soybean cultivars including Nannong 47, Andou 203,Xiangdou 4, Zhonghuang 13, Shanning 29 and Qihuang 34 all displayed photobleaching phenotype in plant systemic infected leaves after inoculation with ALSV:GmPDS, while GmPDS was not silenced in Hedou 12, Zhonghuang 311 and Shanning 16.【Conclusion】In this study, an Agrobacterium-mediated ALSV viral VIGS vector was constructed. ALSV virions was propagated and purified from N. benthamiana plant. The purified virions were rub inoculated onto the first-round true leaves of soybean. Finally, an efficient gene silencing system was established on a number of domestic soybean cultivars in China.