根据致病性差异，我国大麦黄花叶病毒（ＢａＹＭＶ）存在若干不同株系，血清学和核酸杂交等技术不能区分这些株系。但还由于致病性不同，各株系的核酸序列间必定存在差异。最近建立的单链构象多态性。聚合酶链反应（ＳＳＣＰ－ＰＣＲ）技术能灵敏而有效地诊断和区分核酸序列间的差异，从而进一步证实我国ＢａＹＭＶ不同株系的分化。

everal strains of barley yellow mosaic virus(BaYMV),each distinct from those recognisedin Japan and Europe,have been identified in China based upon the response of foriegn barley cul-tivars.These strains are identical in serological properties and can not be distinguished by ELISA and Western blot;They are also probably high homlogous and can not be distinguished by North-ern blot analysis and reverse transcriptase- polymorase chain reaction(RT-PCR).However,sincetheir pathogenicities are different,they must have some variations at nucleic acid level,Thesevariations can be detected by examining single-strand conformation polymorphisms of RT-PCRproducts,which further confirmed that different strains of the virus are presented in China.