<p style="text-align:justify;"> <span><i><span style="font-family:""><span style="font-family:Verdana;">Citrus </span><span style="font-fa...<p style="text-align:justify;"> <span><i><span style="font-family:""><span style="font-family:Verdana;">Citrus </span><span style="font-family:Verdana;">tristeza</span><span style="font-family:Verdana;"> virus</span></span></i></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> (CTV) outbreaks have been reported in the main citrus growing region of Mexico in the past four years. Recently, in eastern Mexico (the major citrus-growing region in the country), severe CTV isolates have been detected. However, the molecular identity of </span><span style="font-family:Verdana;">observed</span><span style="font-family:Verdana;"> isolates remains unestablished. This research was undertaken to elucidate the molecular characterization of CTV populations spreading in this region and to compare it with </span><span style="font-family:Verdana;">phylogeny</span><span style="font-family:Verdana;"> of existing isolates. Genotyping of 32 collected isolates was performed using reverse-transcription polymerase chain reaction (RT-PCR) with sequence analysis of the coat protein (CP) gene, putatively associated with pathogenicity. This protein is a 25 kDa major capsid protein, which forms a long virion body coating 95% of the particle length. </span><span style="font-family:Verdana;">A comparative</span><span style="font-family:Verdana;"> sequence </span><span style="font-family:Verdana;">analys</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> was performed using CTV sequences from different geographical origins already published and deposited in the GenBank databases. Phylogenetic analysis showed that the degree of sequence divergence among isolates correlated with their pathogenicity. Based on the sequencing results, the collected isolates were categorizedn as mild or severe phylogenetic clusters展开更多
The presence and distribution of Citrus tristeza virus (CTV) strains on plants of four citrus species required analysis of plants showing small fruits, yellowing, and twig dieback. Typical citrus tristeza symptoms sho...The presence and distribution of Citrus tristeza virus (CTV) strains on plants of four citrus species required analysis of plants showing small fruits, yellowing, and twig dieback. Typical citrus tristeza symptoms showed in citrus plantations in Veracruz, Mexico, and caused gradual deterioration, low yield, and death of the plants. Seven citrus-growing municipalities in Central and Northern Veracruz presented the severe VT strain: the incidence in seven of the eight sampled municipalities ranged from 7% in Alamo to 50% in Tihuatlan. As for the T30 strain, its presence and distribution ranged from 17% in Tihuatlan to 83% in Cuitlahuac. Values for the T3 strain went from 20% in Castillo de Teayo to 50% in Papantla. In Tihuatlan, two samples were positive for the T36 strain. Only Citrus sinensis has historical recording infections by severe strains of CTV, unlike other important citrus species. The incidence of orchards quickly declining increases rapidly in Veracruz, the largest citrus producer in Mexico. It becomes critical as the predominant and sensitive rootstock is sour orange (Citrus aurantium). It is important to note that the specific primers used could not be identified in 29% of the samples, suggesting that they could be other than T30, T3, VT, and T36 strains.展开更多
文摘<p style="text-align:justify;"> <span><i><span style="font-family:""><span style="font-family:Verdana;">Citrus </span><span style="font-family:Verdana;">tristeza</span><span style="font-family:Verdana;"> virus</span></span></i></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> (CTV) outbreaks have been reported in the main citrus growing region of Mexico in the past four years. Recently, in eastern Mexico (the major citrus-growing region in the country), severe CTV isolates have been detected. However, the molecular identity of </span><span style="font-family:Verdana;">observed</span><span style="font-family:Verdana;"> isolates remains unestablished. This research was undertaken to elucidate the molecular characterization of CTV populations spreading in this region and to compare it with </span><span style="font-family:Verdana;">phylogeny</span><span style="font-family:Verdana;"> of existing isolates. Genotyping of 32 collected isolates was performed using reverse-transcription polymerase chain reaction (RT-PCR) with sequence analysis of the coat protein (CP) gene, putatively associated with pathogenicity. This protein is a 25 kDa major capsid protein, which forms a long virion body coating 95% of the particle length. </span><span style="font-family:Verdana;">A comparative</span><span style="font-family:Verdana;"> sequence </span><span style="font-family:Verdana;">analys</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> was performed using CTV sequences from different geographical origins already published and deposited in the GenBank databases. Phylogenetic analysis showed that the degree of sequence divergence among isolates correlated with their pathogenicity. Based on the sequencing results, the collected isolates were categorizedn as mild or severe phylogenetic clusters
文摘The presence and distribution of Citrus tristeza virus (CTV) strains on plants of four citrus species required analysis of plants showing small fruits, yellowing, and twig dieback. Typical citrus tristeza symptoms showed in citrus plantations in Veracruz, Mexico, and caused gradual deterioration, low yield, and death of the plants. Seven citrus-growing municipalities in Central and Northern Veracruz presented the severe VT strain: the incidence in seven of the eight sampled municipalities ranged from 7% in Alamo to 50% in Tihuatlan. As for the T30 strain, its presence and distribution ranged from 17% in Tihuatlan to 83% in Cuitlahuac. Values for the T3 strain went from 20% in Castillo de Teayo to 50% in Papantla. In Tihuatlan, two samples were positive for the T36 strain. Only Citrus sinensis has historical recording infections by severe strains of CTV, unlike other important citrus species. The incidence of orchards quickly declining increases rapidly in Veracruz, the largest citrus producer in Mexico. It becomes critical as the predominant and sensitive rootstock is sour orange (Citrus aurantium). It is important to note that the specific primers used could not be identified in 29% of the samples, suggesting that they could be other than T30, T3, VT, and T36 strains.
