Cloning And Fuctional Study Of Pai2Gene Of Xanthomonas Oryzae

Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xooc) cause leaf blight and leaf streak on rice, respectively. In this study, we do the comparative genomic research on the three strains (PXO99A, KACC10331and MAFF311018) of Xoo and one strain (BLS256) of Xooc announced by the global genome and then get the specific genome of PXO99in Xoo. By comparison and analysis, we choose pai2gene as the candidate pathogenic gene, then do gene knockout and functional study of it.(Ⅰ) Based on the three Xoo strains and one Xooc strain announced by the global genome, we do comparative genomic research through the EDGAR1.2system and find that the core genome of Xoo contains3184genes while the core genome of Xoo and Xooc contains2925genes, so we find there are259specific genes in Xoo strains, compared to Xooc. These specific genes includes59hypothetical protein genes,67TPase genes,28phage-related protein genes and105other genes. Hypothetical proteins, TPases and phage-related proteins are not related to pathogenicity, accordding to the former references, so we confer some genes which are related to pathogenicity exist in the rest105genes. Such as pai2, it will come into the transcriptional regulatory protein through transcription, which has been reported to be involved in pathogenicity in many stains. What’s more, the gene pai2in three strains of Xoo all have two and they are continuous. However, there is only one pai2gene in Xooc. In this study, we name the two genes pai2of PXO99strain of Xoo respectively:pai2A and pai2B. We call them pai2and do directional knockout to gene pai2of PXO99altogether.(Ⅱ) A pai2homologue, designated pai2xoo, was cloned from Xoo PXO99through the GeneBank data base with degenerated primers by polymerase amplification reaction (PCR). We succeed in getting the insertion mutants of pai2in PXO99strain by means of homologous recombinationand with the confirmation of hybridization verified through PCR and Southern. With the method of shear-leaf inoculation, we inoculate the susceptible host IR24. It has been reported that the invasive power of mutants has decreased, although the degree is limited. We can speculate the gene pai2have positive influence on the invasive power.