Studies On The Variation Of Pennisetum Mosaic Virus

Fifteen infected samples collected from Xinzhou in Shanxi Province including whitegrass, sorghum and maize were detected and analyzed by bioassay, serology and molecular biological methods and techniques.ACP-ELISA showed that all the 15 isolates were serologically related to PenMV. Only one isolate—No. 10 was serologically related to both PenMV and SCMV-BJ. The 3' -NTR and C-terminal part of the CP gene were obtained from No. 10 isolate using primers specific for virus SCMV-BJ. The obtained sequence of No. 10 shared identities of 99.28% with that of SCMV-BJ, which confirmed that these two viruses coexisted in the infected leaves.Coat protein genes of the 15 isolates were cloned and their nucleotide sequences were analyzed, which showed that the CP gene of all these 15 isolates consisted of 909nt (including the stop codon) encoding 302 amino acid residues. The nucleotide sequence alignment showed that all the PenMV isolates (including PenMV-A, PenMV-B, PenMV-C) shared identities from 91.1% to 100%. Four isolates (Nos.1, 4,10,15) had the identity of 100%, and the same were No. 11 and No. 13.The motif (DAG) in the coat protein related to aphid transmission had mutated into DTG in these isolates except No.2 and No. 14.KITC and PTK motifs which are closely related to aphid transmission were examined to exhibit no mutations. The following aphid transmission experiments showed that No. 13 could not be aphid transmitted, whereas other isolates including No.1, No.7, No.9 and No. 15 presented drastically reduced rate of aphid transmission. The mutation from DAG to DTG resulted in low transmission efficiency, even loss of the transmission ability by aphid.