GENOMIC VARIABILITY OF THE XANTHOMONAS PATHOVAR MANGIFERAEINDICAE, AGENT OF MANGO BACTERIAL BLACK SPOT

The genetic diversity of 138 strains of the Xanthomonas pathovar mangi feraeindicae, which were isolated from three different hosts (mango, a mbarella, and pepper tree) in 14 different countries, was assessed wit h restriction fragment length polymorphism markers. An analysis of pat terns obtained by hybridization with an hrp cluster probe from Xanthom onas oryzae pv. oryzae separated 11 of the strains from all of the oth er strains, which suggested that these 11 strains may not be Xanthomon as pv. mangiferaeindicae strains. Hybridization ,vith an avirulence ge ne from X. oryzae pv. oryzae and a repetitive DNA fragment from Xantho monas pv. mangiferaeindicae separated the remaining 127 strains into f our groups that were consistent with both geographic and host origins. The group with the greatest diversity consisted of strains from South east Asia, where mango originated. Other groups and subgroups containe d strains that were either from widely separated countries, which sugg ested that,vide dissemination from a single site occurred, or from loc alized areas, which suggested that evolution of separate lineages of s trains occurred. One group of strains contained only strains isolated from pepper trees in Reunion, indicating that pepper tree may not be a n alternate host for Xanthomonas pv. mangiferaeindicae strains.