Zhang, Yi

Background New tick-borne pathogens are being discovered worldwide, and recognized tick-borne diseases are becoming increasingly diverse. Candidatus R. jingxinensis is endemic in Asia, but its potential to cause clinical infection in humans remains unclear. This study was designed to elucidate the prevalence and delineate the clinical profile of Candidatus Rickettsia jingxinensis infection in Liaoning Province, China. Methods The subjects of this study were suspected cases of tick-borne infectious diseases admitted to the First Affiliated Hospital of China Medical University or reported to the Liaoning Provincial Center for Disease Control and Prevention in 2018–2022. Epidemiological and clinical data were collected. Tick-borne pathogens were detected with a microfluidic chip detection system, and specific gene fragments of the screened pathogens were amplified, sequenced, and compared. Evolutionary and phylogenetic trees were constructed and analyzed. Results In total, 398 infected subjects from 14 cities were included in the study, and 255 tick-borne pathogens were detected. Among these, 11 subjects were found to be infected with Candidatus Rickettsia jingxinensis. This is the first time this strain has been shown to cause infection and illness in humans. The main clinical features of subjects infected with Candidatus R. jingxinensis included fever, fatigue, dizziness, headache, nausea, diarrhea, general pain or muscle and joint pain, reduced leukocytes and platelets, abnormal coagulation function and liver function. Conclusions This study documents the first human infections with Candidatus R. jingxinensis, confirms its prevalence in Liaoning Province, and delineates the primary clinical manifestations of the disease.

Long non-coding RNAs (lncRNAs) serve as crucial regulators in plant response to various diseases, while none have been systematically identified and characterized in response to citrus Huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) bacteria. Here, we comprehensively investigated the transcriptional and regulatory dynamics of the lncRNAs in response to CLas. Samples were collected from leaf midribs of CLas- and mock-inoculated HLB-tolerant rough lemon (Citrus jambhiri) and HLB-sensitive sweet orange (C. sinensis) at week 0, 7, 17, and 34 following inoculation using CLas+ budwood of three biological replicates in the greenhouse. A total of 8,742 lncRNAs, including 2,529 novel lncRNAs, were identified from RNA-seq data with rRNA-removed from strand-specific libraries. Genomic variation analyses of conserved lncRNAs from 38 citrus accessions showed that 26 single nucleotide polymorphisms (SNPs) were significantly correlated with HLB. In addition, lncRNA-mRNA weighted gene co-expression network analysis (WGCNA) showed a significant module correlated with CLas-inoculation in rough lemon. Notably, the most significant LNC_28805 and multiple co-expressed genes related to plant defense in the module were targeted by miRNA5021, suggesting that LNC28805 might compete with endogenous miR5021 to maintain the homeostasis of immune gene expression levels. Candidate WRKY33 and SYP121 genes targeted by miRNA5021 were identified as two key hub genes interacting with bacteria pathogen response genes based on the prediction of protein-protein interaction (PPI) network. These two genes were also found within HLB-associated QTL in linkage group 6. Overall, our findings provide a reference for a better understanding of the role of lncRNAs involved in citrus HLB regulation.

Huanglongbing (HLB) is a devastating citrus disease that has caused massive economic losses to the citrus industry worldwide. The disease is endemic in most citrus-producing areas of southern China, especially in the sweet orange orchards where soil acidification has intensified. In this work, we used lime as soil pH amendment to optimize soil pH and enhance the endurance capacity of citrus against Candidatus Liberibacter asiaticus (CLas). The results showed that regulation of soil acidity is effective to reduce the occurrence of new infections and mitigate disease severity in the presence of HLB disease. We also studied the associated molecular mechanism and found that acid soil improvement can (i) increase the root metabolic activity and up-regulate the expression of ion transporter-related genes in HLB-infected roots, (ii) alleviate the physiological disorders of sieve tube blockage of HLB-infected leaves, (iii) strengthen the citrus immune response by increasing the expression of genes involved in SAR and activating the salicylic acid signal pathway, (iv) up-regulate 55 proteins related to stress/defence response and secondary metabolism. This study contributes to a better understanding of the correlation between environment factors and HLB disease outbreaks and also suggests that acid soil improvement is of potential value for the management of HLB disease in southern China.