Drought reduces transmission of Turnip yellows virus , an insect-vectored circulative virus

Application of a severe water deficit to Arabidopsis thaliana plants infected with a mutant of Turnip yellows virus (TuYV, Family Luteoviridae) triggers a significant alteration of several plant phenology traits and strongly reduces the transmission efficiency of the virus by aphids. Although virus accumulation in water-stressed plants was similar to that in plants grown under well-watered conditions, virus accumulation was reduced in aphids fed on plant under water deficit. These results suggest alteration of the aphid feeding behavior on plants under water deficit

The Genome Sequence of the Grape Phylloxera Provides Insights into the Evolution, Adaptation, and Invasion Routes of an Iconic Pest

Background: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Results: Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. Conclusions: The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture

Rapid transcriptional plasticity of duplicated gene clusters enables a clonally reproducing aphid to colonise diverse plant species

Background: The prevailing paradigm of host-parasite evolution is that arms races lead to increasing specialisation via genetic adaptation. Insect herbivores are no exception and the majority have evolved to colonise a small number of closely related host species. Remarkably, the green peach aphid, Myzus persicae, colonises plant species across 40 families and single M. persicae clonal lineages can colonise distantly related plants. This remarkable ability makes M. persicae a highly destructive pest of many important crop species. Results: To investigate the exceptional phenotypic plasticity of M. persicae, we sequenced the M. persicae genome and assessed how one clonal lineage responds to host plant species of different families. We show that genetically identical individuals are able to colonise distantly related host species through the differential regulation of genes belonging to aphid-expanded gene families. Multigene clusters collectively upregulate in single aphids within two days upon host switch. Furthermore, we demonstrate the functional significance of this rapid transcriptional change using RNA interference (RNAi)-mediated knock-down of genes belonging to the cathepsin B gene family. Knock-down of cathepsin B genes reduced aphid fitness, but only on the host that induced upregulation of these genes. Conclusions: Previous research has focused on the role of genetic adaptation of parasites to their hosts. Here we show that the generalist aphid pest M. persicae is able to colonise diverse host plant species in the absence of genetic specialisation. This is achieved through rapid transcriptional plasticity of genes that have duplicated during aphid evolution

Impact of Abiotic Stresses on Plant Virus Transmission by Aphids

Plants regularly encounter abiotic constraints, and plant response to stress has been a focus of research for decades. Given increasing global temperatures and elevated atmospheric CO 2 levels and the occurrence of water stress episodes driven by climate change, plant biochemistry, in particular, plant defence responses, may be altered significantly. Environmental factors also have a wider impact, shaping viral transmission processes that rely on a complex set of interactions between, at least, the pathogen, the vector, and the host plant. This review considers how abiotic stresses influence the transmission and spread of plant viruses by aphid vectors, mainly through changes in host physiology status, and summarizes the latest findings in this research field. The direct effects of climate change and severe weather events that impact the feeding behaviour of insect vectors as well as the major traits (e.g., within-host accumulation, disease severity and transmission) of viral plant pathogens are discussed. Finally, the intrinsic capacity of viruses to react to environmental cues in planta and how this may influence viral transmission efficiency is summarized. The clear interaction between biotic (virus) and abiotic stresses is a risk that must be accounted for when modelling virus epidemiology under scenarios of climate change

Drought alters epidemiological traits of phytoviruses

National audienc

Water deficit enhances the transmission of plant viruses by insect vectors_raw data.xlsx

Raw data supporting figures <br

Plant-virus-vector interactions under water deficit. Relationships between epidemiological traits of the Cauliflower mosaic virus and Arabidopsis thaliana growth-related traits under artificial drought

National audienc

Effet d'un stress hydrique sur l'épidémiologie d'un virus non circulant, le Cauliflower mosaic virus et adaptation des plantes à la sècheresse

National audienceLa production agricole et le fonctionnement des écosystèmes sontfréquemment contraints par des épisodes de sécheresse dont la fréquence e tla durée devraient augmenter sous l'influence des changements climatiques. Les recherches en agronomie doivent permettre de proposer une évolution des pratiques agricoles et de gestion durable des écosystèmes dans un contexte de limitation des ressources en eau. Les interactions entre les plantes, leur scortèges de pathogènes, de symbiotes, de vecteurs et de l'environnement abiotique sont encore trop peu intégrés à ces recherches. A ce jour, 900 phytovirus ont été décrits, infectant environ 70% des plantes et générant des pertes majeures de productivité. Outre l'impact négatif des virus sur leurs plantes hôtes, un aspect inattendu mais convergent de ces virus, émerge d'après la littérature et des résultats préliminaires effectués à BGPI (par Manuella VanMunster). Dans certains cas, une infection virale pourrait être bénéfique, en améliorant la tolérance des plantes à des stress abiotiques comme un déficiten eau. Dans d'autres cas, la transmission virale serait plus importante en contexte de sécheresse. Ces résultats pourraient être en lien avec la granderéactivité des phytovirus à percevoir et réagir (en termes d'efficacité de transmission et de virulence) en réponse à un déficit hydrique du sol. Les buts du projet sont d'évaluer les paramètres épidémiologiques (efficacitéde transmission, charge virale, virulence) et éco physiologiques de plantes infectées en conditions de stress hydrique sévère et d'analyser les effets délétères ou bénéfiques du CaMV dans ces conditions. Deux questions seront abordées : l'infection virale améliore-t-elle la tolérance des plantes à un stress hydrique sévère ? Quelles sont les conséquences d'un déficit hydrique sévère sur l'épidémiologie virale

From stylet to cuticle: Transcriptomics and genomics of aphid cuticular protein

International audienc