First report of Malvastrum yellow vein virus infecting Ageratum conyzoides

A virus isolate, Y206, was obtained from Ageratum conyzoides showing yellow vein symptoms from Baoshan in the Yunnan province of China. To identify possible begomoviruses, total DNA was extracted from the leaf sample. Degenerate primers, PA and PB, were designed to amplify part of the intergenic region and coat protein (CP) gene of DNA-A (Zhou et al., 2003a). An amplicon of approximately 500 bp was obtained, cloned and sequenced. Sequence comparisons showed an 88.3% nucleotide sequence identity with Malvastrum yellow vein virus-[Y47] (MYVV-[Y47]; Acc. No. AJ457824). Using the sequence obtained, overlapping primers E01 (5'-GAATTCCTCGACGAGAAAGA-3') and E02 (5'-GAATTCTTTATAGCTGCTAT-3') were designed and used to amplify a full length DNA-A from isolate Y206. The complete DNA-A sequence was determined to be 2739 nucleotides (Acc. No. AJ744881). A comparison with other begomoviruses showed that DNA-A of Y206 is closely related to MYVV-[Y47] with a 95.1% nucleotide sequence identity.

To ascertain whether a satellite molecule was associated with this virus isolate, a universal abutting primer pair (beta01/beta02) was employed to amplify the putative DNAβ (Zhou et al., 2003b). Using this primer set, an amplicon of approximately 1400 bp was obtained from isolate Y206. Sequence analysis revealed that DNAβ of Y206 (Acc. No. AJ744882) was 1337 nucleotides long and was most closely related to the DNAβ associated with MYVV-[Y47] (Acc. No. AJ421482), with a 95.4% nucleotide sequence identity.

The above sequence results confirmed that ageratum sample was infected with MYVV. MYVV has previously been reported infecting Malvastrum coromandelianum showing yellow vein symptoms in the Honghe of Yunnan province, China (Zhou et al., 2003a). This is the first report of MYVV infecting A. conyzoides.