title: 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, lasAI and lasAII, 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 lasAI imply extensive variation exists within the full and partial repeat sequence while the single band from lasAII 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.
authors.affiliation: Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand; U.S. Horticultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America.
authors.forename: Thamrongjet
authors.initials: T
authors.lastname: Puttamuk
authors.affiliation: U.S. Horticultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.
authors.forename: Niphone
authors.initials: N
authors.lastname: Thaveechai
authors.affiliation: Tropical Research and Education Center, University of Florida, Homestead, Florida, United States of America.
authors.forename: Shouan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: U.S. Horticultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America.
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Armstrong
authors.affiliation: U.S. Horticultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Fort Pierce, Florida, United States of America.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Duan
mesh_terms: D000818:Animals; D002957:Citrus / Q000382:microbiology; D005798:Genes, Bacterial / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006430:Hemiptera / Q000382:microbiology; D010802:Phylogeny; D012230:Rhizobiaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D013785:Thailand