Study of gene expression pattern in Citrus grandis plants infected by Candidatus Liberibacter asiaticus causal agent of citrus greening disease

Citrus greening has been reported from south of Iran in 2007. The molecular basis of compatibility and disease development in this system is poorly understood. We have carried out a cDNA-AFLP analysis to identify resistance genes of Citrus grandis and Candidatus Leiberibacter aciaticus susceptibility genes in late infection development stage. Selective amplifications with 10 primer combinations allowed the visualization of about 25 transcript-derived fragments (TDFs) in inoculated leaves, which were differentially expressed. We sequenced 16 fragments, which were identified as Citrus grandis transcripts after homology searching, while 5 were homologous to sequences in NCBI databases and were attributed to Candidatus Leiberibacter asiaticus. Many Citrus grandis genes spanning almost all functional categories were upregulated during infection. This study provides the first global catalogue of Citrus grandis and Candidatus Leiberibacter asiaticus genes expressed during inoculation, together with their functional annotations. This will help to elucidate the molecular basis of the resistance process and identify genes and chemicals that could help to inhibit the pathogen.