The recent emergence of several plant diseases caused by psyllid-borne bacterial pathogens worldwide (Candidatus Liberibacter spp.) has created renewed interest on the interaction between psyllids and bacteria.In spite of these efforts to understand psyllid association with bacteria,many aspects of their interactions remain poorly understood.As more organisms are studied,subtleties on the molecular interactions as well as on the effects of the bacteria on the psyllid host are being uncovered.Additionally,psyllid-borne bacterial phytopathogens can also affect the host plant,which in turn can impact psyllid physiology and behavior.Here,we review the current literature on different aspects of the influence of bacteria on multitrophic interactions among plants,psyllids,and pathogens.We then highlight gaps that need to be addressed to advance this field,which can have significant implications for controlling these newly emergent and other plant diseases.

Vector-borne plant diseases have significant ecological and economic impacts,affecting farm profitability and forest composition throughout the world.Bacterial vector-borne pathogens have evolved sophisticated strategies to interact with their hemipteran insect vectors and plant hosts.These pathogens reside in plant vascular tissue,and their study represents an excellent opportunity to uncover novel biological mechanisms regulating intracellular pathogenesis and to contribute to the control of some of the world's most invasive emerging diseases.In this perspective,we highlight recent advances and major unanswered questions in the realm of bacterial vector-borne disease,focusing on liberibacters,phytoplasmas,spiroplasmas,and Xylella fastidiosa.

Paulownias are among the fastest growing trees in the world,but they often suffer tremendous loss of wood production due to infection by Paulownia witches'broom(PaWB)phytoplasmas.In this study,we have sequenced and assembled a high-quality nuclear genome of Paulownia fortunei,a commonly cultivated paulownia species.The assembled genome of P.fortunei is 511.6 Mb in size,with 93.2％of its sequences anchored to 20 pseudo-chromosomes,and it contains 31 985 protein-coding genes.Phylogenomic analyses show that the family Paulownlaceae is sister to a clade composed of Phrymaceae and Orobanchaceae.Higher photosynthetic efficiency is achieved by integrating C3 photosynthesis and the crassulacean acid metabolism pathway,which may contribute to the extremely fast growth habit of paulownia trees.Comparative transcriptome analyses reveal modules related to cambial growth and development,photosynthesis,and defense responses.Additional genome sequencing of PaWB phytoplasma,combined with functional analyses,indicates that the effector PaWB-SAP54 interacts directly with Paulownia PfSPLa,which in turn causes the degradation of PfSPLa by the ubiquitin-mediated pathway and leads to the formation of witches'broom.Taken together,these results provide significant insights into the biology of paulownias and the regulatory mechanism for the formation of PaWB.

[目的]探索异沙叶蝉Psammotettix alienus ATP6蛋白对小麦蓝矮植原体(wheat blue dwarf phytoplasma,WBDp)传播效率的影响.[方法]将异沙叶蝉mRNA反转录合成cDNA,构建分离泛素酵母双杂交膜系统cDNA文库;用WBDp的虫传相关蛋白P2-4为诱饵,从异沙叶蝉cDNA文库杂交筛选互作蛋白;通过RNAi沉默ATP6基因,验证ATP6蛋白对异沙叶蝉3龄若虫传播WBDp的影响.[结果]构建了异沙叶蝉分离泛素酵母双杂交膜系统cDNA文库,用P2-4从cDNA文库中杂交筛选获得了ATP6等多种互作蛋白.RNAi结果发现沉默ATP6基因后异沙叶蝉3龄若虫的WBDp传播率比对照组显著下降了23.33％±3.33％,表明ATP6是异沙叶蝉参与WBDp传播的关键蛋白.[结论]明确了异沙叶蝉ATP6是参与WBDp传播的一个关键蛋白.为进一步探明异沙叶蝉传播WBDp的分子机制和植原体病害的田间防治提供了理论基础.