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ARS Home » Pacific West Area » Riverside, California » National Clonal Germplasm Repository for Citrus » Research » Publications at this Location » Publication #321946
Title: Citrus huanglongbing (HLB) discoveries in California respective in 2015 and 2012 are different genotypes of candidatus liberibacter asiaticus (CLas) by double-locus genomic variations analysis

Author
item ZHONGE, YAN - Animal And Plant Health Inspection Service (APHIS)
item RASCOE, JOHN - Animal And Plant Health Inspection Service (APHIS)
item KUMAGAI, LUCITA - California Department Of Food And Agriculture
item Keremane, Manjunath
item NAKHLA, MARK - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2015
Publication Date: 3/1/2016
Citation: Zhonge, Y., Rascoe, J., Kumagai, L.B., Keremane, M.L., Nakhla, M.K. 2016. Citrus huanglongbing (HLB) discoveries in California respective in 2015 and 2012 are different genotypes of candidatus liberibacter asiaticus (CLas) by double-locus genomic variations analysis. Plant Disease. 100(3):647.

Interpretive Summary: Interpretive Summary: Following discovery of a single HLB infected citrus tree in 2012 from hacienda Heights, California, intensive follow up suppression and monitoring procedures are in place. With the recent discovery of ten more infected trees 15 miles north of the first find, the immediate concern was whether the new find resulted from the 2012 source tree, or it is from a new source. The molecular analysis presented in this study suggests that the two sources appear to have started from two separate introductions.

Technical Abstract: Technical Abstract: Huanglongbing (HLB), the most destructive citrus disease worldwide, has been recognized as a major threat to California’s billion-dollar citrus industry since its first report (CA HLB12) in 2012 (Kumagai et al. 2013). Ongoing statewide surveys to find and quickly remove initial residential HLB introductions became even more extensive after the first discovery. In June 2015, CDFA again detected several HLB cLas positive citrus plants (CA HLB15-1, 2, 3, [kumquat, Mexican lime, and mandarin respectively]) in neighboring Los Angeles residential blocks. Genomic variation analysis suggested that CA HLB12 and CA HLB15 introductions had distinct cLas evolutionarily divergent characters, implying their different origins of introduction into CA. Whether CA HLB15-1, 2 & 3 isolates represent an independent introduction into CA or resulted from local HLB spread relies on yet unclear mechanisms concerning how the DL genomic variations have evolved.