SUMMARY

Barley yellow dwarf viruses (BYDVs) are economically important viruses that infect cereal crops worldwide, in-cluding wheat grown in China. These viruses include sev-eral members of the Luteoviridae and are transmitted only by aphids. In this study, BYDV isolates and their aphid vectors were collected from different regions of China and assayed. BYDV isolates from China were generally transmitted by more than one aphid species except for BYDV-RMV and a few BYDV-PAV. Seven vector trans-mission phenotypes (VTPs) were identified involving five serotypes; BYDV-GAV, BYDV-GPV and BYDV-PAV were predominant in China. Aphid clones differing in virus transmission abilities were occasionally observed for three laboratory-maintained species although they gener-ally showed similar virus transmission profiles. Degener-ate primers similar to Lu1 and Lu4 were designed to am-plify coat protein gene fragments from all in the virus col-lection. Serotypes could be distinguished after cleavage of the resulting PCR products with HinfI. Sequence varia-tions among Chinese BYDVs were also deduced from dif-ferences among their restriction patterns. To clarify this, intact coat protein genes of a few isolates were amplified with serotype-specific primers, cloned and sequenced. Similarity and genetic distance analyses confirmed that the three major Chinese BYDVs possess coat protein genes distinct from those of BYDV from other countries