On the evolution and molecular epidemiology of the potyvirus Papaya ringspot virus

Abstract

The potyvirus Papaya ringspot virus (PRSV) is found throughout the tropics and subtropics. Its P biotype is a devastating pathogen of papaya crops and its W biotype of cucurbits. PRSV-P is thought to arise by mutation from PRSV-W. However, the relative impact of mutation and movement on the structure of PRSV populations is not well characterized. To investigate this, we have determined the coat protein sequences of isolates of both biotypes of PRSV from Vietnam (50), Thailand (13), India (1) and the Philippines (1), and analysed them together with 28 PRSV sequences already published, so that we can better understand the molecular epidemiology and evolution of PRSV. In Thailand, variation was greater among PRSV-W isolates (mean nucleotide divergence 7n6 %) than PRSV-P isolates (mean 2n6 %), but in Vietnamese populations the P and W biotypes were more but similarly diverse. Phylogenetic analyses of PRSV also involving its closest known relative, Moroccan watermelon mosaic virus, indicate that PRSV may have originated in Asia, particularly in the Indian subcontinent, as PRSV populations there are most diverse and hence have probably been present longest. Our analyses show that mutation, together with local and longdistance movement, contributes to population variation, and also confirms an earlier conclusion that populations of the PRSV-P biotype have evolved on several occasions from PRSV-W populations.

Resistencia de Vasconcellea cauliflora al Virus de la mancha anular de la papaya-potyvirus (PRSV-P) y su introgresión en Carica papaya

“…De acuerdo con Bateson et al (2002), existe variabilidad en la secuencia nucleotídica del 12% entre regiones geográficas, tales como Asia, Australia y América del Norte. Además, se ha propuesto que Asia es su centro de origen y de ahí se propagó al resto del mundo.…”

“…According to Bateson et al (2002), there is 12% of variability in the nucleotidic sequence among geographic regions such as Asia, Australia and North America. It has also been suggested that it first appeared in Asia from where it spread to the rest of the world.…”

Inheritance of resistance to papaya ringspot virus-watermelon strain (PRSV-W) in 'Whitaker' summer squash line

“…Higher virus disease incidence is related to greater aphid populations (Bateson et al 2002). PRSV-W control is very difficult, and the method that has been widely used is the insecticide sprays to eliminate virus vectors.…”

Inheritance of resistance to the Papaya ringspot virus-watermelon strain (PRSV-W) from watermelon accession 'PI 595201'

“…The virus is transmitted in a non-persistent manner by numerous species of aphids, including Myzus persicae and Aphis spp. (Bateson et al 2002). It has become one of the most limiting pathogens to cucurbit crops in warm climate countries as Brazil, where aphids can easily survive throughout the year.…”