| Based on the survey of viruses infecting Araceae plants from in Zhejiang Province, Hunan Province, Hainan Province and other regions in China, pathogenic viruses of this family were detected and identified. Sequence similarity was compared between dasheen mosaic virus (DsMV) isolates of different origin. Virus-free seedlings were obtained for two important taros cultivar, Colocasia esculenta cv. Fenghuayunaitou and Wugengyu, respectively, through thermo-therapy and meristem-tip culture. Tissue culture seedlings were obtained for Pinellia cordata, with virus-free seeds as explant and cultured on MS medium supplemented with 2.0 mg/L 6-BA.DsMV is proved as the predominating virus-pathogen on aroid plants from Zhejiang Province and other regions in China. cDNA of DsMV RNA 3' end partial sequence and subgenomic RNA promoter region of cucumber mosaic virus (CMV) RNA3 were used as probes for detection of DsMV and CMV respectively. Total RNA extracted from field samples were used for RNA dot-hybridization. Combined with hybridization, virus purification and morphological observation were used. A total of 91 virus isolates were identified from 81 field samples collected from 16 Areaceae plants in Zhejiang Province, Hunan Province, Hainan Province and other regions in year 2001. Dasheen mosaic virus was identified from Aglaonema, Alocasia, Anthurium, Anadendum, Arisanema, Colocasia, Calla, Dieffenbachia, Epiprimmun, Monstera, Pinellia, Philodendron, Trphonium, Zantedeschia, and Epiprimmun, Calla, Trphonium are proved as new hosts of this virus. DsMV and CMV infection syndrome was firstly identified from Aglaonema, Alocasia, Colocasia, Calla, Epiprimmun and Philodendron. Of all the field samples, 85.18% were found being infected with DsMV, while 24.72% were found being infected complexly with DsMV and CMV. Only one sample was found being infectedwith CMV alone. Of Colocasia plants, 97.5% were found being infected with DsMV and 20% were found being infected complexly with CMV and DsMV. These results indicate that DsMV is the principal aroids-infecting virus, while DsMV and CMV infection syndrome is common in some areas. The occurrence ratio of DsMV and CMV infection syndrome varied largely on different origins. It takes 62.5% in Hainan Province, 41.7% in Hunan Province and 10.87% in Zhejiang Province from the field sampes examined.Molecular variation was presented obviously for 3' end partial sequence of DsMV.Three DsMV isolates DY1, DY2 isolated from Dongyang, Zhejiang and FH isolated from Hangzhou, Zhejiang were studied for sequence similarity analysis. Complementary DNAs for DsMV partial genomic RNAs were obtained and cloned with total RNAs being extracted from DsMV infected colocasia. The 3' terminal part of DsMV-DYl were composed of 1265 nt, including a coding region for coat protein (CP) of 1008 nt, coding 336 amino acids, followed by the 3' end untranslated region (3'-UTR) of 257 nt. The sequences of the 3' terminal part of DsMV-DY2 and FH were composed of 809 and 822 nt each, including a partial sequence of CP of 560 and 574 nt respectively, followed by the 3'-UTRof249and248nt.Nucleotide sequence and deduced amino acid sequence of CP and 3'-UTR between DsMV-DYl, DY2 and FH isolates were compared with those of documented references. Size of the CP and 3'-UTR of DsMV ranged from 939 to 1008 nt and 247 to 258 nt, respectively. Multiple alignments of these sequences showed that CP amino acid and 3'-UTR nucleotide sequence varied from 79% to 95% and 66% to 96%, respectively. In particular, DsMV-DYl possesses only 76-83% and 66-73% sequence similarity with those documented data for CP and 3'-UTR, while sequence identity of DsMV-DY2 and FH possess 89-91% and 87-95% similarity respectively with other isolates. The results indicated taht the aminoacid sequence and 3'-UTR nucleotide sequence identities varied largely. The phylogenetic tree analysis showed no relationship to geographical origin or host plant with the above data.Buds and shoot tips of field taro cultivars as explants were cultured, combined...
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