8 research outputs found
Manipulation of Plant Defense Responses by the Tomato Psyllid (Bactericerca cockerelli) and Its Associated Endosymbiont Candidatus Liberibacter Psyllaurous
Some plant pathogens form obligate relationships with their insect vector and are vertically transmitted via eggs analogous to insect endosymbionts. Whether insect endosymbionts manipulate plant defenses to benefit their insect host remains unclear. The tomato psyllid, Bactericerca cockerelli (Sulc), vectors the endosymbiont âCandidatus Liberibacter psyllaurousâ (Lps) during feeding on tomato (Solanum lycopersicum L.). Lps titer in psyllids varied relative to the psyllid developmental stage with younger psyllids harboring smaller Lps populations compared to older psyllids. In the present study, feeding by different life stages of B. cockerelli infected with Lps, resulted in distinct tomato transcript profiles. Feeding by young psyllid nymphs, with lower Lps levels, induced tomato genes regulated by jasmonic acid (JA) and salicylic acid (SA) (Allene oxide synthase, Proteinase inhibitor 2, Phenylalanine ammonia-lyase 5, Pathogenesis-related protein 1) compared to feeding by older nymphs and adults, where higher Lps titers were found. In addition, inoculation of Lps without insect hosts suppressed accumulation of these defense transcripts. Collectively, these data suggest that the endosymbiont-like pathogen Lps manipulates plant signaling and defensive responses to benefit themselves and the success of their obligate insect vector on their host plant
Improvement of the strategies to control yellow decline of lavander and lavandin
La lavande et le lavandin sont des cultures emblĂ©matiques de Haute Provence, victimes dâun dĂ©pĂ©rissement depuis quelques dĂ©cennies. Lâagent Ă©tiologique de ce dĂ©pĂ©rissement est le phytoplasme du stolbur, et le principal vecteur de ce phytoplasme est la cicadelle Hyalesthes obsoletus. Une technique de diagnostic sensible et fiable a Ă©tĂ© mise au point, et a permis de sĂ©curiser la certification du matĂ©riel vĂ©gĂ©tal produit selon le cahier des charges plants sains. Une Ă©tude Ă©pidĂ©miologique de grande envergure a montrĂ© que les parcelles Ă©taient infectĂ©es par 16 gĂ©notypes diffĂ©rents du phytoplasme du stolbur, et que la maladie se propageait surtout de lavande(in) Ă lavande(in), et de lavanderaies Ă lavanderaies. Enfin, lâĂ©tude du phĂ©nomĂšne de tolĂ©rance a montrĂ© que la sensibilitĂ© au dĂ©pĂ©rissement ne serait pas liĂ©e Ă la relation plante-phytoplasme, mais plus vraisemblablement Ă lâinteraction de la cicadelle avec les plantes. Cette cicadelle est prĂ©sente dans toutes les parcelles cultivĂ©es, mais Ă des effectifs trĂšs variables. Un gĂ©notypage AFLP a Ă©galement montrĂ© que la diversitĂ© gĂ©nĂ©tique des lavandes sauvages Ă©tait assez restreinte, et que la sĂ©lection gĂ©nĂ©tique effectuĂ©e par la filiĂšre lâavait trĂšs lĂ©gĂšrement rĂ©duite.Lavander and lavandin are symbolic crops in south-eastern France, in the region of Haute-Provence, but they have been affected by yellow decline for decades. The etiological agent which is involved in this decline is the stolbur phytoplasm, which is transmitted by the cixiidae Hyalesthes obsoletus. A reliable diagnosis has been developed, and permitted to secure the specification of phytosanitary certified material, according to the specifications âhealthy plantsâ. A large epidemiological survey identified 16 genotypes of the stolbur phytoplasm. The study demonstrated that the epidemics mainly propagated from lavander to lavander. Finally, the study of the mechanism of tolerance showed that lavander and lavandin susceptibility was not correlated with the relation plant - phytoplasm, but more likely with the interaction of the insect with the plant. The insect is present in all cultivated plots, but in very variable densities. AFLP genotyping has also shown that genetic diversity of wild lavanders was quite restricted, and that genetic selection reduced it only a little
Amélioration des stratégies de lutte contre le dépérissement de la lavande et du lavandin
Textes issus des travaux du programme Casdar "Innovation et Partenariat" de 2007 et prĂ©sentĂ©s lors d'un colloque le 4 dĂ©cembre 2012, sous l'Ă©gide du GIS Relance AgronomiqueNational audienceLavander and lavandin are symbolic crops in south-eastern France, in the region of Haute-Provence, but they have been affected by yellow decline for decades. The etiological agent which is involved in this decline is the stolbur phytoplasm, which is transmitted by the cixiidae Hyalesthes obsoletus. A reliable diagnosis has been developed, and permitted to secure the specification of phytosanitary certified material, according to the specifications âhealthy plantsâ. A large epidemiological survey identified 16 genotypes of the stolbur phytoplasm. The study demonstrated that the epidemics mainly propagated from lavander to lavander. Finally, the study of the mechanism of tolerance showed that lavander and lavandin susceptibility was not correlated with the relation plant - phytoplasm, but more likely with the interaction of the insect with the plant. The insect is present in all cultivated plots, but in very variable densities. AFLP genotyping has also shown that genetic diversity of wild lavanders was quite restricted, and that genetic selection reduced it only a little.La lavande et le lavandin sont des cultures emblĂ©matiques de Haute Provence, victimes dâun dĂ©pĂ©rissement depuis quelques dĂ©cennies. Lâagent Ă©tiologique de ce dĂ©pĂ©rissement est le phytoplasme du stolbur, et le principal vecteur de ce phytoplasme est la cicadelle Hyalesthes obsoletus. Une technique de diagnostic sensible et fiable a Ă©tĂ© mise au point, et a permis de sĂ©curiser la certification du matĂ©riel vĂ©gĂ©tal produit selon le cahier des charges plants sains. Une Ă©tude Ă©pidĂ©miologique de grande envergure a montrĂ© que les parcelles Ă©taient infectĂ©es par 16 gĂ©notypes diffĂ©rents du phytoplasme du stolbur, et que la maladie se propageait surtout de lavande(in) Ă lavande(in), et de lavanderaies Ă lavanderaies. Enfin, lâĂ©tude du phĂ©nomĂšne de tolĂ©rance a montrĂ© que la sensibilitĂ© au dĂ©pĂ©rissement ne serait pas liĂ©e Ă la relation plante-phytoplasme, mais plus vraisemblablement Ă lâinteraction de la cicadelle avec les plantes. Cette cicadelle est prĂ©sente dans toutes les parcelles cultivĂ©es, mais Ă des effectifs trĂšs variables. Un gĂ©notypage AFLP a Ă©galement montrĂ© que la diversitĂ© gĂ©nĂ©tique des lavandes sauvages Ă©tait assez restreinte, et que la sĂ©lection gĂ©nĂ©tique effectuĂ©e par la filiĂšre lâavait trĂšs lĂ©gĂšrement rĂ©duite