Dai Shunhong, Wei Xiaoping, Alfonso Antonio A, Pei Liping, Duque Ulysses G, Zhang Zhihong, Babb Gina M, Beachy Roger N
Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA.
Proc Natl Acad Sci U S A. 2008 Dec 30;105(52):21012-6. doi: 10.1073/pnas.0810303105. Epub 2008 Dec 22.
Rice tungro disease (RTD) is a significant yield constraint in rice-growing areas of South and Southeast Asia. Disease symptoms are caused largely by infection by the rice tungro bacilliform virus (RTBV). Two host transcription factors, RF2a and RF2b, regulate expression of the RTBV promoter and are important for plant development. Expression of a dominant negative mutant of these factors in transgenic rice resulted in phenotypes that mimic the symptoms of RTD, whereas overexpression of RF2a and RF2b had essentially no impact on plant development. Conversely, lines with elevated expression of RF2a or RF2b showed weak or no symptoms of infection after Agrobacterium inoculation of RTBV, whereas control plants showed severe stunting and leaf discoloration. Furthermore, transgenic plants exhibited reduced accumulation of RTBV RNA and viral DNA compared with nontransgenic plants. Similar results were obtained in studies after virus inoculation by green leafhoppers. Gaining disease resistance by elevating the expression of host regulators provides another strategy against RTD and may have implications for other pararetrovirus infections.
水稻东格鲁病（RTD）是南亚和东南亚水稻种植区产量的一个重要限制因素。该病症状主要由水稻东格鲁杆状病毒（RTBV）感染引起。两个宿主转录因子RF2a和RF2b调节RTBV启动子的表达，对植物发育很重要。在转基因水稻中表达这些因子的显性负突变体导致了模拟RTD症状的表型，而RF2a和RF2b的过表达对植物发育基本没有影响。相反，RF2a或RF2b表达升高的株系在经农杆菌接种RTBV后表现出轻微或没有感染症状，而对照植株则表现出严重矮化和叶片变色。此外，与非转基因植物相比，转基因植物中RTBV RNA和病毒DNA的积累减少。通过绿叶蝉接种病毒后的研究也得到了类似结果。通过提高宿主调节因子的表达来获得抗病性为防治RTD提供了另一种策略，可能对其他副逆转录病毒感染也有意义。
