Diversity of “Candidatus Liberibacter asiaticus” strains in Texas revealed by prophage sequence analyses


Citation
De Leon et al. (2024). Plant Disease
Names (1)
Ca. Liberibacter asiaticus
Subjects
Agronomy and Crop Science Plant Science
Abstract
Prophages/phages are important components of the genome of ‘Candidatus Liberibacter asiaticus’ (CLas), an unculturable alphaproteobacterium associated with citrus Huanglongbing (HLB) disease. Phage variations have significant contributions to CLas strain diversity research, which provide critical information for HLB management. In this study, prophage variations among selected CLas strains from southern Texas were studied. The CLas strains were collected from three different CLas inhabitant environments: citrus leaf, citrus root, and Asian citrus psyllid (ACP), the vector of CLas. Regardless of the different habitats and time span, more than 80% of CLas strains consistently had both Type 1 and Type 2 prophages, the same prophage type profile as in CLas strains from Florida, but different to those reported in California and China. Further studies were performed on within prophage type diversity. Analyses on Type 1 specific PCR amplicon sequences (encoding an endolysin protein) revealed the presence of two groups: Type 1-A, clustered around prophage SC1 originated from Florida and Type 1-B, clustered with prophage P-SGCA5-1 detected in California. Type 1-B strains were mostly from ACP of nearby citrus orchards. On the other hand, analyses on Type 2 specific PCR amplicon sequences (encoding a putative hypothetical protein) showed a single group clustering around prophage SC2 originated from Florida, although a different Type 2 prophage has been reported in California. The presence of two distinct Type 1 prophage groups suggested the possibility of two different CLas introductions in southern Texas. Results from this study provides an initial baseline information on genomic and population diversity of CLas in Texas.
Authors
Publication date
2024-01-22
DOI
10.1094/pdis-09-23-1994-sr