|Deng, X - SOUTH CHINA AGR. UNIV.|
|Li, H - SOUTH CHINA AGR. UNIV.|
Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2007
Publication Date: July 28, 2007
Citation: Deng, X., Chen, J., Li, H., Civerolo, E.L. 2007. Two rrn DNAs from periwinkle infected by Candidatus Liberibacter asiaticus. [abstract] Phytopathology. 97:S21 Technical Abstract: Huanglongbing (HLB, ex. greening,) is a highly destructive disease threatening citrus production worldwide. In southern China, HLB is currently believed to be caused by infection by Candidatus Liberibacter asiaticus. The pathogen is not culturable <i>in vitro</i>. We have been maintaining a strain of Ca. L. asiaticus in periwinkle transmitted from HLB citrus through dodder in China with increased titer. Bacterial DNA was isolated directly from plant tissue. Degenerate primers from the bacterial rrn operon were designed. Anchored by the previously defined 16S rDNA locus, Ca. L. asiaticus genomic sequences were sequestered through PCR in a manner of classical chromosomal walking. A 4,770 bp DNA sequence was cloned. Over 2,000 bp were new to the current Genbank database and located in the 23S rDNA locus. A primer set spanning the 16S-23S rDNA region was designed and amplified two DNA fragments (1,800 bp and 352 bp) from periwinkle and citrus samples infected by Ca. L. asiaticus, suggesting the possible presence of two non-identical rrn operons.