Advances in Plant Virus Evolution: Translating Evolutionary Insights into Better Disease Management

Abstract

49Recent works in plant virus evolution are revealing that genetic structure and behavior of 50 virus and viroid populations can explain important pathogenic properties of these agents, such 51 as host resistance breakdown, disease severity, and host shifting among others. Genetic 52 variation is essential for the survival of organisms. The exploration of how these subcellular 53 parasites generate and maintain a certain frequency of mutations at the intra-and inter-host 54 levels is revealing novel molecular virus-plant interactions. They emphasize the role of host 55 environment in the dynamic genetic composition of virus populations. Functional genomics has 56 identified host factors that are transcriptionally altered after virus infections. The analyses of 57 these data by means of systems biology approaches are uncovering critical plant genes 58 specifically targeted by viruses during host adaptation. Also, a next-generation re-sequencing 59 approach of a whole virus genome is opening new avenues to study virus recombination and 60 the relationships between intra-host virus composition and pathogenesis. Altogether, the 61 analyzed data indicate that systematic disruption of some specific parameters of evolving virus 62 populations could lead to more efficient ways of disease prevention, eradication, or tolerable 63 virus-plant coexistence. 64 65 66 Acosta-Leal, R., Duffy, S., Xiong, Z., Hammond, R. W., and Elena, S. F. 2011. Advances in 67 plant virus evolution: Translating evolutionary insights into better disease management. 68 Phytopathology (accepted). 69 Acosta--Leal et al (2011). Mini--review in Phytopathology 4 70Viruses and viroids appear to be the fastest-evolving plant pathogens (39), and cause 71 tremendous economical crop losses annually. Some, such as the single-stranded DNA 72 begomoviruses, are emergent problems worldwide (117, 126). These subcellular pathogens 73 have higher mutation rates than, and distinct evolutionary dynamics from, bacterial and fungal 74 phytopathogens. Understanding their reproductive and transmission strategies -their biology, 75 ecology, and evolution -can lead to insights and interventions for effective crop disease 76 management. This review highlights how viruses and viroids achieve and maintain their unique 77 parasitic lifestyles and how evolutionary virology and systems biology approaches to virus-plant 78 interactions have implications for pathogen control. 79The ability of viruses and viroids to change, and to change rapidly, underlies many 80 disease management concerns. Excepting migration from distant locations and other countries, 81 variability in plant pathogen populations is the necessary initial step in adaptation to new plants 82 (host shifting), resistance breaking (RB), and changes in symptoms and virulence. Many times 83 the rise and fall of different genotypes in a population is due to the effects of natural selection: 84 variant genomes that generate more viable descendants become more frequent over time. This 85 process can be sped up ...

Diversity of Plant Virus Populations: A Valuable Tool for Epidemiological Studies

“…Mutation is the result of errors during the replication of a genome due to the misincorporation of nucleotides in the daughter strand that do not correspond to those present in the template [3][4][5]. Besides its relevance in evolution as the initial step for generation of variability in populations, the mutation process has significant practical implications in the design and assessment of virus diseases control strategies (antiviral therapies, vaccinations, etc.).…”

“…Observation of changes in the genetic structure of within-host populations that are associated to different degree of compatibility between the virus and the host provides insights into the host-adaptive process (reviewed in [3]). In compatible interactions of highly hostadapted viruses, negative selection tends to maintain virus population in equilibrium, resulting in a high stability of its genetic structure, as found in intra-host populations of Tobacco mild green mosaic virus and other plant viruses infecting their susceptible hosts.…”

“…In contrast, more variability was found in small intra-host populations of Beet necrotic yellow vein virus (BNYVV) in partially resistant plants, expected to be under virus-host adaptation, than in large BNYVV populations in susceptible plants. This contributes to explain the sudden stochastic diversification of BNYVV populations in sugar beet after the deployment of resistant plant genotypes in the field, and the higher diversity observed in populations of other plant viruses in their centers of origin, where they are in phase of adaptation to a new host [3]. Similarly, higher between-hosts diversities were found in host-adapting populations in virus' centers of origin (Wheat streak mosaic virus in North America; Rice yellow mottle virus, RYMV, in eastern Tanzania) or in virus emerging areas (resistance breaking variants of BNYVV in the Imperial Valley of California) than in well-adapted virus populations in other areas (other regions in Africa for RYMV or in USA for BYNVV, see references 3, 51, 114 and 130 in [3]).…”

“…Acosta-Leal [3] evaluated possible opportunities Genetic Diversityfor virus-disease control, as resistance genes, natural plant resistance mechanisms, control of coinfection dynamics, modeling virus robustness, etc. and discussed about research advances and needs in relation to a simple theoretical model, which states that an assembly of management measures should be addressed to altogether reduce the effective population size of virus populations, increase their genetic diversity and maximize bottleneck effects, so that a virus population could be gradually excluded from its hosts species.…”

Resposta de genótipos de citros à leprose e variabilidade genética da ORF p29 do vírus da leprose dos citros C (CiLV-C)

“…As doenças virais emergentes podem ser causadas pelo surgimento de uma nova espécie viral, por uma espécie viral de uma determinada cultura que está emergindo em outra totalmente distinta, ou vírus antigos que reemergem devido ao uso de cultivares antigos (HANSSEN et al, 2010). A emergência de novos vírus é frequentemente reportada (PADIDAM et al, 1999;DUFFY et al, 2009;HANSSEN et al, 2010;ZHANG;ZHANG et al, 2011;MELZER et al, 2012;JONES, 2011b No novo hospedeiro, aqueles variantes se adaptarão facilmente e aumentarão sua frequência (ACOSTA-LEAL et al, 2011). Aproximadamente 70% das mutações são deletérias e muitas vezes letais (SANJUÁN et al, 2004;CARRASCO et al, 2007;DOMINGO-CALAP et al, 2009).…”