Tsai C H, Dreher T W
Department of Agricultural Chemistry, Oregon State University, Corvallis 97331.
Mol Plant Microbe Interact. 1993 May-Jun;6(3):268-73. doi: 10.1094/mpmi-6-268.
Turnip yellow mosaic virus is a positive-strand RNA virus that produces light green or yellow-green mosaic symptoms in Chinese cabbage plants. We have characterized a strain that produces nearly uniform yellow-green chlorosis in systemically infected Chinese cabbage leaves. The increased symptom severity is due to the single nucleotide substitution U1888-->C, which results in a tyrosine to histidine substitution in the movement protein encoded by ORF-69. Coding by the overlapping ORF-206 is not affected. The mutation results in fourfold higher accumulations of viral products in systemically infected Chinese cabbage leaves but does not affect viral replication in isolated protoplasts. These results suggest that the increased viral yield and symptom severity result from improved viral spread in the host plant. These effects were specific to Chinese cabbage, since neither viral yield nor symptoms in turnips were affected by the U1888-->C mutation.
芜菁黄花叶病毒是一种正链RNA病毒，可在大白菜植株上产生浅绿或黄绿相间的花叶症状。我们鉴定了一个毒株，它在系统感染的大白菜叶片中产生近乎均匀的黄绿褪绿症状。症状严重程度增加是由于单核苷酸替换U1888→C，这导致由ORF-69编码的运动蛋白中酪氨酸被组氨酸取代。由重叠的ORF-206编码不受影响。该突变导致系统感染的大白菜叶片中病毒产物积累增加四倍，但不影响分离原生质体中的病毒复制。这些结果表明，病毒产量增加和症状严重程度增加是由于病毒在宿主植物中传播改善所致。这些效应是大白菜特有的，因为U1888→C突变既不影响芜菁中的病毒产量，也不影响其症状。
