Contribution of recombination and selection to molecular evolution of Citrus tristeza virus.
نویسندگان
چکیده
The genetic variation of Citrus tristeza virus (CTV) was analysed by comparing the predominant sequence variants in seven genomic regions (p33, p65, p61, p18, p13, p20 and p23) of 18 pathogenically distinct isolates from seven different countries. Analyses of the selective constraints acting on each codon suggest that most regions were under purifying selection. Phylogenetic analysis shows diverse patterns of molecular evolution for different genomic regions. A first clade composed of isolates that are genetically close to the reference mild isolates T385 or T30 was inferred from all genomic regions. A second clade, mostly comprising virulent isolates, was defined from regions p33, p65, p13 and p23. For regions p65, p61, p18, p13 and p23, a third clade that mostly included South American isolates could not be related to any reference genotype. Phylogenetic relationships among isolates did not reflect their geographical origin, suggesting significant gene flow between geographically distant areas. Incongruent phylogenetic trees for different genomic regions suggested recombination events, an extreme that was supported by several recombination-detecting methods. A phylogenetic network incorporating the effect of recombination showed an explosive radiation pattern for the evolution of some isolates and also grouped isolates by virulence. Taken together, the above results suggest that negative selection, gene flow, sequence recombination and virulence may be important factors driving CTV evolution.
منابع مشابه
Contribution of recombination and selection to 1 molecular evolution of Citrus tristeza virus 2 3
متن کامل
Citrus tristeza virus: Evolution of Complex and Varied Genotypic Groups
Amongst the Closteroviridae, Citrus tristeza virus (CTV) is almost unique in possessing a number of distinct and characterized strains, isolates of which produce a wide range of phenotype combinations among its different hosts. There is little understanding to connect genotypes to phenotypes, and to complicate matters more, these genotypes are found throughout the world as members of mixed popu...
متن کاملMild strain cross protection of tristeza: a review of research to protect against decline on sour orange in Florida
Tristeza, caused by Citrus tristeza virus (CTV), has long been present in Florida but outbreaks of decline on sour orange rootstock were occasional events until the late 1970s. Sour orange rootstock was valued for the high quality of fruit produced and was widely used because of its tolerance of citrus blight, a disease of unknown etiology. Research was directed towards the selection and screen...
متن کاملDevelopment of a Multiplex RT-PCR Assay for Detection of the Causal Agents of Citrus Tristeza and Cachexia Diseases with Coamplification of Plant mRNA as an Internal Control
Background and Aims: Plant certification programs need reliable, fast, cheap and sensitive methods for detection of systemic pathogens with special interest in virus and viroid detection. Reverse transcriptase-polymerase chain reaction (RT-PCR) has been documented as an alternative assay for certification of plant propagating materials. The main object of the present study was the optimization ...
متن کاملتولید کلون های عاری از ویروس ارقام نارنگی ساتسوما از تخمکهای نابارور
In order to produce Tristeza virus-free plants from Satsuma mandarin (Citrus unshiu) cultivars (Ishikawa, Sugiyama and Myogawa), unfertilized ovules of plants suspected of CTV (Citrus Tristeza virus), from Mazandaran Mahdasht orchard were cultured on 4 media. Embryogenesis of nucellus tissue of ovules from Ishikawa and Sugiyama cultivars on MS medium were 31% and 25% and on MT medium from Ishik...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of general virology
دوره 90 Pt 6 شماره
صفحات -
تاریخ انتشار 2009