大麦黄花叶病毒抗性突破株系的分子变异

通过大麦黄花叶病毒 (Ba YMV)抗性突破株系的核酸 RNA1全序列分析并与野生株系比较表明 ,抗性突破株系在病毒复制酶或转运蛋白区域 (6K2 )和核酸 RNA复制酶区域 (NIb)存在二个变异位点 .在这二个位点上抗性突破株系核酸分子编码的氨基酸分别为脯氨酸 (Pro)和苏氨酸 (Thr) ,而野生株系分别为缬氨酸(Val)和丙氨酸 (Ala) .对该两种酶蛋白质二级结构分析显示 ,氨基酸的变异可能导致了蛋白质的结构、功能与性质的改变 ,并且此种变异与抗 Ba YMV冬大麦中抗性基因 ym4的功能丧失有关 ,同时也说明了大麦品种田间致病性的差异与病毒核酸分子中的点突变关系密切 .

Molecular characterization of resistance-breaking strain of barley yellow mosaic bymovirus genus

Amongst isolates representing common and resistance\|breaking the two BaYMV strains reported from Britain, nucleotide sequencing of almost the whole of RNA1 of one common strain and two resistance\|breaking strain isolates identified two positions where there were consistent strain\|related differences. These resulted in amino acid differences of Valine (CS)\|Proline (RB) at amino acid 1155 in the 6K2 region encoding virus replicase or long distance movement protein, and Alanine (CS)\|Threonine (RB) at amino acid 1766 in the NIb region encoding virus RNA dependant RNA polymerase. Secondary structure predictions suggest that these changes could affect the properties of these proteins. It seems probable that one or both are involved in overcoming \%ym4\% gene resistance in winter barley and differences in pathogenicity among barley varieties are associated with only minor changes in molecular sequence of virus.