Abstract
Citrus greening disease caused by greening organisms (GOs; Liberobacter sp.) is one of the most destructive diseases of citrus in Thailand. We applied the PCR method to the detection of 16S rDNA fragments of GOs in leaves with seven kinds of symptoms, mottling (Type I), mild chlorosis with green veins (Type II), severe chlorosis with green veins (Type III), pale green color in young leaves (Type IV), vein yellowing (Type V), vein corking (Type VI) and unclear symptoms (Type VII) collected from GO-infected citrus trees in Thailand. The GO DNA was high in leaves with Types I, II, III, V and VI symptoms. We also detected GO DNA in an insect vector Diaphorina citri. Sequence analysis of the amplified 16S rDNA fragment of seven Thai isolates collected from six major citrus-producing areas revealed that the sequences of the 16S rDNA fragments of these isolates were the same and were very similar to that of the Indian isolate of L. asiaticum.
