A potential pathogenicity determinant and its critical amino acid (aa) sequences of mulberry crinkle leaf virus (MCLV) were determined through expression of MCLV genes in Nicotiana benthamiana using a potato virus X (PVX) vector. Among six genes encoded by MCLV, expression of only V3 resulted in a severe downward-leaf-curling symptom in newly emerging leaves of N. benthamiana plants, which suggested that the V3 protein is a pathogenicity determinant of MCLV. Analyses of truncation mutations indicated that the 94 residues at the N terminus of V3 are sufficient to maintain the function of the pathogenicity determinant V3 in N. benthamiana.

中文翻译：

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桑树皱叶病毒编码的V3蛋白在本氏烟草中起致病作用

桑树皱叶病毒（MCLV）的潜在致病性决定因素及其关键氨基酸（aa）序列是通过使用马铃薯X病毒（PVX）载体在本氏烟草中表达MCLV基因来确定的。在MCLV编码的六个基因中，仅V3的表达导致本生烟草新近出现的叶子中出现严重的下叶卷曲症状，这表明V3蛋白是MCLV的致病性决定因素。截短突变的分析表明，V3的N末端的94个残基足以维持本氏烟草的致病性决定因子V3的功能。