Genetic Diversity of Candidatus Liberibacter asiaticus Based on Two Hypervariable Effector Genes in Thailand

Abstract

Huanglongbing (HLB), also known as citrus greening, is one of the most destructive diseases of citrus worldwide. HLB is associated with three species of ‘Candidatus Liberibacter’ with ‘Ca. L. asiaticus’ (Las) being the most widely distributed around the world, and the only species detected in Thailand. To understand the genetic diversity of Las bacteria in Thailand, we evaluated two closely-related effector genes, lasA I and lasA II, found within the Las prophages from 239 infected citrus and 55 infected psyllid samples collected from different provinces in Thailand. The results indicated that most of the Las-infected samples collected from Thailand contained at least one prophage sequence with 48.29% containing prophage 1 (FP1), 63.26% containing prophage 2 (FP2), and 19.38% containing both prophages. Interestingly, FP2 was found to be the predominant population in Las-infected citrus samples while Las-infected psyllids contained primarily FP1. The multiple banding patterns that resulted from amplification of lasA I imply extensive variation exists within the full and partial repeat sequence while the single band from lasA II indicates a low amount of variation within the repeat sequence. Phylogenetic analysis of Las-infected samples from 22 provinces in Thailand suggested that the bacterial pathogen may have been introduced to Thailand from China and the Philippines. This is the first report evaluating the genetic variation of a large population of Ca. L. asiaticus infected samples in Thailand using the two effector genes from Las prophage regions.

Diversity and characterization of Candidatus Liberibacter asiaticus strains causing huanglongbing disease in Iran, based on two prophage loci

“…Several previous studies have revealed the role of Ca. Liberibacter prophage as a virulence effector and in disease development (Fleites, Jain, Zhang, & Gabriel, 2014;Hao, Boyle, Zhou, & Duan, 2013;Jain, Fleites, & Gabriel, 2015;Puttamuk et al, 2014;Zhou, Powell, Li, Irey, & Duan, 2013). For instance, Jain et al (2015) confirmed the role of prophage-encoded peroxidase (SC2_gp095) as a predicted lysogenic conversion factor in suppressing plant defences, thereby suppressing host symptom development, a tactic used by most biotrophic plant pathogens.…”

“…Several previous studies have revealed the role of Ca. Liberibacter prophage as a virulence effector and in disease development (Fleites, Jain, Zhang, & Gabriel, ; Hao, Boyle, Zhou, & Duan, ; Jain, Fleites, & Gabriel, ; Puttamuk et al., ; Zhou, Powell, Li, Irey, & Duan, ). For instance, Jain et al.…”

“…It has been confirmed that a VTRN in the CLIBASIA _01645 locus of the CLas genome is a good marker for detecting CLas diversity among isolates from different countries (Chen et al., ; Katoh et al., ). Subsequently, the contribution of the prophages loci to the genetic diversity of CLas was investigated in several studies (Deng et al., ; Liu et al., , ; Puttamuk et al., , ; Tomimura et al., ; Villechanoux, Garnier, Laigret, Renaudin, & Bové, ; Wang, Zhou, Deng, Su, & Chen, ; Zhou et al., ).…”

Susceptibilities of Candidatus Liberibacter asiaticus‐infected and noninfected Diaphorina citri to entomopathogenic fungi and their detoxification enzyme activities under different temperatures

“…() reported positive correlation between temperature and synthetic insecticide susceptibility for Las‐uninfected D. citri . As the detection of Las infection has increased in Asia and some other parts of the world (Bove & Ayres, ; Chen et al., ; Islam et al., ; Morris, Erick, & Estes, ; Puttamuk et al., ; Wang et al., ), the proportion of Las‐infected psyllids is in some cases more than 95% (Coy & Stelinski, ). However Las‐infected psyllids were more susceptible to some synthetic insecticides than Las‐uninfected psyllids (Tiwari, Pelz‐Stelinski, & Stelinski, 2011).…”

New Insights into the Genetic Diversity of the Bacterial Plant Pathogen ‘Candidatus Liberibacter solanacearum’ as Revealed by a New Multilocus Sequence Analysis Scheme

“…The diversification of this species into different lineages could result from ecological adaptation, geographical structure or neutral processes (Haapalainen, 2014; Munyaneza, 2015). Genetic diversity investigations may provide an understanding of the population structure of a bacterial species and the evolutionary forces that led to its diversification (Puttamuk et al, 2014). For Lso, few studies have been attempted to investigate its population structure and genetic diversity, in particular due to its fastidious nature (Lin and Gudmestad, 2013).…”