Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/9/2021
Publication Date: N/A
Technical Abstract: Citrus Huanglongbing (HLB, yellow shoot disease) is associated with an unculturable alpha- proteobacterium “Candidatus Liberibacter asiaticus” (CLas) which is transmitted by Asian citrus psyllid (ACP, Diaphorina citri) under field conditions. Recent research has shown that in ACP and citrus, there can be bacteria other than CLas present. Little is known about ACP- and citrus- associated bacteria in the HLB system. Such information is important in HLB management. Recent advancements in next-generation sequencing technology provide new opportunities to study HLB through genomic DNA sequence analyses (metagenomics). In this case study, HLB-related bacteria in ACP and citrus samples from southern California were analyzed. A metagenomic pipeline was developed. Using the pipeline, ten bacteria in ACP and citrus leaves were identified with high confidence based on the presence of full or partial genome sequences. These included Bradyrhizobium, Buchnera, Burkholderia, “Candidatus Profftella armature,” “Candidatus Carsonella ruddii,” CLas, Mesorhizobium, Paraburkholderia, Pseudomonas, and Wolbachia. Two of these bacteria, Bradyrhizobium and Mesorhizobium, were known to be phylogenetically related to CLas. These bacteria, if present in high concentration, could interfere with current 16S-rDNA-based PCR for CLas detection and result in a false positive result. Other bacteria, such as Burkholderia, Paraburkholderia, and Pseudomonas, could have potential for future HLB biological control research and management.