We have created an open access web portal with pathosystem-wide resources and bioinformatics tools for the host citrus, the vector Asian citrus psyllid (ACP) and multiple pathogens including Ca. Liberibacter asiaticus. To the best of our knowledge, this is the first example of a database to use the pathosystem as a holistic framework to understand an insect transmitted plant disease. This endeavor integrates and enables the analysis of data sets generated by the community to study the citrus greening disease complex. Users can submit relevant data sets to enable sharing and allow the community to better analyze their data within an integrated system. The portal contains a variety of tools for omics data. Metabolic pathway databases, CitrusCyc and DiaphorinaCyc provide organism specific pathways that can be used to mine metabolomics, transcriptomics and proteomics results to identify pathways and regulatory mechanism involved in disease response. Psyllid Expression Network (PEN) contains expression profiles of ACP genes from multiple life stages, tissues, conditions and hosts. Citrus Expression Network (CEN) contains public expression data from multiple tissues and conditions for various citrus hosts. All tools like Apollo/JBrowse, Biocyc, Blast, CEN and PEN connect to a central database containing gene models for citrus, ACP and multiple Liberibacter pathogens. The portal also includes electrical penetration graph (EPG) recordings of ACP feeding on citrus, information about citrus rootstock trials and metabolomics data in addition to traditional omics data types with a goal of combining and mining all information related to a pathosystem. The portal includes user-friendly manual curation tools to allow the research community to continuously improve this knowledge base as more experimental research is published. Bulk downloads are available for all genome and annotation datasets from the FTP site (ftp://ftp.citrusgreening.org). The portal can be accessed at https://citrusgreening.org/.

"Candidatus Liberibacter asiaticus" is the causative bacterium associated with 24 citrus greening disease. "Ca. L. asiaticus" is transmitted by Diaphorina citri more efficiently 25 when it is acquired by nymphs rather than adults. Why this occurs is not known. We compared 26 midguts of D. citri reared on healthy or "Ca. L. asiaticus"-infected citrus trees using quantitative 27 PCR, confocal microscopy, and mitochondrial superoxide staining for evidence of oxidative 28 stress. Consistent with its classification as propagative, "Ca. L. asiaticus" titers were higher in 29 adults as compared to nymphs. Our previous work showed that adult D. citri show basal levels of 30 karyorrhexis, (fragmentation of the nucleus), in midgut epithelial cells which is increased in 31 severity and frequency in response to "Ca. L. asiaticus". Here, we show that nymphs exhibit 32 lower levels of early-stage karyorrhexis as compared to adults and are refractory to the induction 33 of advanced karyorrhexis by "Ca. L. asiaticus" in the midgut epithelium. MitoSox Red staining 34showed that guts of infected adults, particularly males, experience oxidative stress in response to 35 "Ca. L. asiaticus." A positive correlation between the titers of "Ca. L. asiaticus" and the 36Wolbachia endosymbiont was observed in adult and nymph midguts, suggesting an interplay 37 between these bacteria during development. We hypothesize that the resistance of the nymph 38 midgut to late stage karyorrhexis through as yet unknown molecular mechanisms benefits "Ca. 39

No abstract