Genetic variability and evolutionary dynamics of atypical Papaya ringspot virus infecting Papaya

Papaya ringspot virus biotype-P is a detrimental pathogen of economically important papaya and cucurbits worldwide. The mutation prone feature of this virus perhaps accounts for its geographical dissemination. In this study, investigations of the atypical PRSV-P strain was conducted based on phylogenetic, recombination and genetic differentiation analyses considering of it’s likely spread across India and Bangladesh. Full length genomic sequences of 38 PRSV isolates and 35 CP gene sequences were subjected to recombination analysis. A total of 61 recombination events were detected in aligned complete PRSV genome sequences. 3 events were detected in complete genome of PRSV strain PK whereas one was in its CP gene sequence. The PRSV-PK appeared to be recombinant of a major parent from Bangladesh. However, the genetic differentiation based on full length genomic sequences revealed less frequent gene flow between virus PRSV-PK and the population from America, India, Colombia, other Asian Countries and Australia. Whereas, frequent gene flow exists between Pakistan and Bangladesh virus populations. These results provided evidence correlating geographical position and genetic distances. We speculate that the genetic variations and evolutionary dynamics of this virus may challenge the resistance developed in papaya against PRSV and give rise to virus lineage because of its atypical emergence where geographic spread is already occurring

The Prehistory of Potyviruses: Their Initial Radiation Was during the Dawn of Agriculture

Background: Potyviruses are found world wide, are spread by probing aphids and cause considerable crop damage. Potyvirus is one of the two largest plant virus genera and contains about 15% of all named plant virus species. When and why did the potyviruses become so numerous? Here we answer the first question and discuss the other. Methods and Findings: We have inferred the phylogenies of the partial coat protein gene sequences of about 50 potyviruses, and studied in detail the phylogenies of some using various methods and evolutionary models. Their phylogenies have been calibrated using historical isolation and outbreak events: the plum pox virus epidemic which swept through Europe in the 20th century, incursions of potyviruses into Australia after agriculture was established by European colonists, the likely transport of cowpea aphid-borne mosaic virus in cowpea seed from Africa to the Americas with the 16th century slave trade and the similar transport of papaya ringspot virus from India to the Americas. Conclusions/Significance: Our studies indicate that the partial coat protein genes of potyviruses have an evolutionary rate of about 1.1561024 nucleotide substitutions/site/year, and the initial radiation of the potyviruses occurred only about 6,600 years ago, and hence coincided with the dawn of agriculture. We discuss the ways in which agriculture may have triggered the prehistoric emergence of potyviruses and fostered their speciation

Virus de la mancha anular de la papaya (PRSV-p): Biología, epifitiología y diversidad genética como base para el manejo mediante técnicas biotecnológicas

Papaya ringspot virus constitutes, in many tropical and subtropical countries, the biggest obstacle in the production and responsible of considerable losses in papaya harvests. The way of transmission of this virus enables the success of treatments with insecticides. In addition, the presence of vector aphids during the year in the plantations constitutes an important way to spread the disease. Once the plantations are infected, there is not way to control this disease. Strategies using genetic engineering have been developed in several countries achieving good results. This implies biologic and molecular studies of possible PRSV isolates that can be present in a region or a country. In Cuba, investigations focused on the development of management strategies of this viral disease have been realized. The objective of this work was to state the main biological and epidemiology aspects of PRSV, with results in Cuba and the world, as a tool in the management by plant biotechnology techniques.Keywords: aphids, coat protein, PRSVEl Virus de la mancha anular de la papaya constituye en muchos países tropicales y subtropicales el mayor obstáculo en la producción de papaya y es responsable de pérdidas considerables en las cosechas. El modo de transmisión de este virus impide el éxito de los tratamientos con insecticidas. Además, la presencia de áfidos vectores durante todo el año en las plantaciones constituye una importante vía para la distribución de la enfermedad. Una vez infectadas las plantaciones no existe tratamiento eficaz para su control. En varios países se han desarrollado estrategias mediante la ingeniería genética, donde se ha logrado obtener buenos resultados, lo que implica el estudio biológico y molecular de los posibles aislados del PRSV que se pueden presentar en una región o país. En Cuba, se han realizado investigaciones encaminadas al desarrollo de estrategias para el manejo de esta enfermedad viral. Este trabajo tuvo como objetivo relacionar los principales aspectos biológicos y epifitiológicos del PRSV, con resultados de Cuba y el mundo, como herramienta para el manejo de esta enfermedad mediante el uso de la biotecnología vegetal.Palabras clave: áfidos, proteína de la cápsida, PRS

Coat protein sequence comparison of south Indian isolates of Papaya ringspot virus with other Indian subcontinent isolates

Papaya ringspot virus (PRSV) is an economically important pathogen causing the most devastating disease in papaya worldwide. Isolates of PRSV originating from different geographical regions in south India were collected and maintained on natural host papaya. The 3’ terminal region of about 1.7 kb comprising a part of the nuclear inclusion b (NIb) gene, complete coat protein (CP) gene and the 3’ untranslated region (3’UTR) of seven Papaya ringspot virus (PRSV) isolates from south India were cloned and sequenced. The CP nucleotide and deduced amino acid sequences of seven isolates were compared to each other and to sequences of 22 other PRSV isolates from different geographical locations in the Indian subcontinent. The sequence comparisons revealed greater sequence divergence (up to 18.4% and 15% at nucleotide and amino acid levels, respectively) within Indian PRSV populations. All south Indian isolates were clearly separated from isolates of other geographical regions and formed a major group in phylogenetic trees, and the clustering pattern of isolates did not correlate well with their geographical origins

When viruses play team sports : mixed infections in plants

Altres ajuts: Generalitat de Catalunya/CERCA ProgrammeThe pathological importance of mixed viral infections in plants might be underestimated except for a few well-characterized synergistic combinations in certain crops. Considering that the host ranges of many viruses often overlap and that most plant species can be infected by several unrelated viruses, it is not surprising to find more than one virus simultaneously in the same plant. Furthermore, dispersal of the majority of plant viruses relies on efficient transmission mechanisms mediated by vector organisms, mainly but not exclusively insects, which can contribute to the occurrence of multiple infections in the same plant. Recent work using different experimental approaches has shown that mixed viral infections can be remarkably frequent, up to the point that they could be considered the rule more than the exception. The purpose of this review is to describe the impact of multiple infections not only on the participating viruses themselves but also on their vectors and on the common host. From this standpoint, mixed infections arise as complex events that involve several cross-interacting players, and they consequently require a more general perspective than the analysis of single-virus/single-host approaches for a full understanding of their relevance

Characterization of unknown genetic modifications using high throughput sequencing and computational subtraction

<p>Abstract</p> <p>Background</p> <p>When generating a genetically modified organism (GMO), the primary goal is to give a target organism one or several novel traits by using biotechnology techniques. A GMO will differ from its parental strain in that its pool of transcripts will be altered. Currently, there are no methods that are reliably able to determine if an organism has been genetically altered if the nature of the modification is unknown.</p> <p>Results</p> <p>We show that the concept of computational subtraction can be used to identify transgenic cDNA sequences from genetically modified plants. Our datasets include 454-type sequences from a transgenic line of <it>Arabidopsis thaliana </it>and published EST datasets from commercially relevant species (rice and papaya).</p> <p>Conclusion</p> <p>We believe that computational subtraction represents a powerful new strategy for determining if an organism has been genetically modified as well as to define the nature of the modification. Fewer assumptions have to be made compared to methods currently in use and this is an advantage particularly when working with unknown GMOs.</p

Estrategias para la obtención de plantas transgénicas de papaya con resistencia al Virus de la mancha anular de la papaya (PRSV)

The papaya production acquires major economic importance all over the world every day. It is consumed as fresh fruit or processed to obtain other products in the pharmaceutical, cooking, and medical industries and in the brewing industry to obtain nonalcoholic drinks. Currently, Agricultural Science faces serious problems such as plant virus control, which form an important group of pathogenic organisms. To obtain resistance to the Papaya ringspot virus is an increasing interest area because main commercial varieties of papaya are susceptible to this disease. Genetic engineering has achieved important results aimed to solve this problem introducing new elements at the global strategic control. Our work summarizes the main strategies used to obtain resistance to Papaya ringspot virus during the last two decades.Keywords: Genetic transformation, PRSVLa producción de papaya (Carica papaya L.) cada día cobra mayor importancia económica a nivel mundial debido a que se puede consumir como fruta fresca o procesarse para obtener otros productos en el área farmacéutica, culinaria, médica, industria cervecera y bebidas no alcohólicas. Sin embargo, la agricultura se enfrenta a las series dificultades que supone el control de los virus que constituyen un importante grupo de organismos patógenos para este cultivo. La obtención de resistencia al Virus de la mancha anular de la papaya constituye un área de interés creciente pues las principales variedades comerciales de papaya son susceptibles a esta enfermedad. Con este objetivo, la Ingeniería Genética ha generado importantes resultados y al mismo tiempo, ha introducido elementos nuevos en el planteamiento estratégico global del control. Este trabajo resume las principales estrategias utilizadas para la obtención de resistencia al Virus de la mancha anular de la papaya durante las últimas dos décadas.Palabras clave: PRSV, transformación genétic

Citrus tristeza virus in Hawaii

This article describes the citrus tristeza virus in Hawai‘i, the pathogen, diseases and disease symptoms caused by the virus, insect vectors and transmission, diagnosis and detection, management, and quarantine, certification and suppression/eradication programs