Archivio Journal of Plant Pathology

Abstract:

Three Euphorbia pulcherrima (poinsettia, family Euphorbia) plants showing leaf curl and vein thickening symptoms were collected in Fujian Province, China, in 2006. Total DNA was extracted from each sample using a CTAB method. A fragment of approximately 500 bp was amplified by PCR in each sample, using the special degenerate primer pair PA/PB (Deng et al., 1994). PCR products were gel-purified, ligated into pMD18-T vector (Takara Biotechnology, China), and sequenced. Six clones from each sample were sequenced. Phylogenetic analysis of the 500 bp fragments showed that these sequences formed three distinct branches, and sequence alignment among each branches (63.3% to 73.6%) in one sample indicated that each sample might be mixed infected by three distinct viruses. FE01, FE02 and FE03 isolates representing each virus were further studied. To amplify the full-length DNA-A of the three isolates, three pairs of abutting primers (FE01-F 5’-CCTTAGCAAGTAGTTCATTCCG-3’/FE01-R 5’-GACATGTCTTTGTCAGTTAGTGG-3’, FE02-F 5’-CCACTCAGAACGCTCCCTCA-3’/FE02-R 5’-GTTCGTGGTAGGGACCACTT-3’, and FE03-F 5’-TGCGCGCTCATCGCTTAGT-3’/FE03-R 5’-ATTATATTGGTCGAGGGCCCAC-3’) were designed based on the obtained sequences, respectively. They were determined to be 2751 (FJ487911), 2754 (FJ495183) and 2733 (FJ495184) nucleotides, and had the typical genome organization of Old World monopartite begomoviruses, respectively. Sequence comparisons revealed that the three isolates were most closely related to those of Euphorbia leaf curl virus (ELCV, AJ558121), Ageratum yellow vein virus (AYVV, FJ869908) and Papaya leaf curl Guangdong virus (PaLCuGDV, FJ869907), with 92.8%, 99.8% and 99.1% sequence identity, respectively. The attempt to detect a DNA-B or a betasatellite component by using specific primers (Briddon et al., 2002; Rojas et al., 1993) was unsuccessful. To the best of our knowledge, this is the first report of AYVV and PaLCuGDV and mixed infection of three begomoviruses in poinsettia in China.