Characterization of CVPD disease in citrus plant in Bali based on host, 16S rDNA polymorphism of the poathogen, and polymorphism of candidatus CVPDr gene

The main disease of citrus plants in the world as well as in Indonesia or especially in Bali is citrus vein phloem degeneration (CVPD) disease or citrus greening disease or huang long bing.  The pathogen of the disease is a Gram negative bacteria called Liberibacter asiaticus.  The bacteria spread in the phloem cells and resulted in nutrient deficiency and the symptom of chlorosis.

This study tried to analysis the 16S rDNA of the pathogen in 25 citrus plant species that were found in Bali.  The interesting results found  new strain of L. asiaticus in Katung Village, Kintamani, Bali and they were differ from other hosts and DNA sequence found in the Gene Bank.  In addition, we also found that different citrus plant host and strain of the pathogen gave the different symptom of nutrient deficiency such as deficiency of Mg or Mn, or Zn, Fe,  or others. 

Our previous study found a DNA fragment called CVPDr DNA fragment that seem to be a factor which play an important role in the resistant mechanism of citrus plant to CVPD disease. DNA polymorphism of 25 species of citrus plants were analysis and we found that the citrus plant which resistant or relatively resistant  to CVPD disease clustered in different group that differ to other susceptible citrus plants.  The whole DNA fragment of CVPDr as a gene, the role of the gene and the gene product are still under study.