Jan F J, Pang S Z, Fagoaga C, Gonsalves D
Department of Plant Pathology, Cornell University, NYSAES, Geneva, NY 14456, USA.
Transgenic Res. 1999 Jun;8(3):203-13. doi: 10.1023/a:1008915007271.
The coat protein (CP) gene of turnip mosaic potyvirus isolate ESC8 (TuMV-ESC8) was cloned and sequenced. Comparisons of the 867-nucleotide (nt) CP region with those of 11 TuMV isolates showed 86.7-89.3% nucleotide identity and 92.4-95.5% amino acid identity. The CP gene was cloned into a plant expression vector and transformed into Nicotiana benthamiana plants via Agrobacterium tumefaciens-mediated leaf disk transformation. Progeny from R0 lines was screened for resistance to TuMV-ESC8. Five of 29 tested lines showed TuMV protection in more than 50% of their progeny. Interestingly, some of the resistant plants transformed with the CP gene of TuMV displayed mild mosaicism in the new growing leaves at the later stages of evaluation; but these mosaic symptoms disappeared when the leaves were fully expanded. Collective data from steady-state RNA analysis and nuclear run-on assay of a line showed that the resistance was RNA-mediated through the post-transcriptional gene silencing mechanism.
克隆并测序了芜菁花叶马铃薯Y病毒分离株ESC8（TuMV-ESC8）的外壳蛋白（CP）基因。将该867个核苷酸（nt）的CP区域与11个TuMV分离株的相应区域进行比较，结果显示核苷酸同一性为86.7-89.3%，氨基酸同一性为92.4-95.5%。将CP基因克隆到植物表达载体中，并通过根癌农杆菌介导的叶盘转化法转化到本氏烟草植株中。对R0代植株的后代进行了对TuMV-ESC8抗性的筛选。在29个测试株系中，有5个株系在其50%以上的后代中表现出对TuMV的抗性。有趣的是，一些用TuMV的CP基因转化的抗性植株在评估后期新长出的叶片中表现出轻度花叶病症状；但当叶片完全展开时，这些花叶症状消失。对一个株系的稳态RNA分析和核转录分析的综合数据表明，这种抗性是通过转录后基因沉默机制由RNA介导的。
