COMPARISON OF WHEAT SPINDLE STREAK MOSAIC-VIRUS (WSSMV) AND BARLEY YELLOW MOSAIC-VIRUS (BAYMV) - 2 CLOSELY-RELATED BYMOVIRUSES

In order to better understand the evolutionary development that leads to different host ranges, we made a comparison of the closely related barley yellow mosaic bymovirus (BaYMV) and wheat spindle streak mosaic bymovirus (WSSMV). Using different methods both viruses were found to be closely related. Leaves of BaYMV-infected winter barley and WSSMV- infected wheat typically showed similar symptoms. Electron microscopy studies revealed that both viruses lead to formation of 2 types of cyt oplasmic inclusions bodies (Cl, 'pinwheel' structures; crystal-like re spectively membranous) in infected cells that showed structural differ ences. This close relationship is also reflected by the high degree of amino acid sequence homology (74% in CP-, 83% in Nlb-, 68% in Nla-reg ion). In spite of the remarkably high similarities both viruses have s eparate hosts. We demonstrated that, independently of the host range, a reliable distinction between WSSMV and BaYMV is possible using North ern blot hybridisation, reverse transcriptase-polymerase chain reactio n (RT-PCR) and Western blot analysis. Antisera raised against BaYMV pr oteins also detected WSSMV proteins in Western blot analyses. Even tho ugh corresponding proteins of both viruses were usually similar in siz e, the BaYMV-Cl antiserum cross-reacted with an additional protein abo ut 8 kDa larger in wheat extracts and the BaYMV 28 kDa antiserum detec ted a protein of about 30 kDa in wheat extracts.