RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSES OF IRANIAN STRAINS OF XANTHOMONAS-CAMPESTRIS FROM CEREALS AND GRASSES

Restriction fragment length polymorphism (RFLP) analyses of the genomi c DNA of 45 Xanthomonas campestris strains from cereals and grasses in Iran, and of 17 reference strains, were performed using two probes or iginating from X. campestris and including hrp genes. The Iranian stra ins studied belonged to three clearly distinct RFLP groups related to the grouping previously established on the basis of biochemical and ph ysiological characters and host range. RFLP group 1 encompassed all th e strains pathogenic to barley but not to the other plants tested (i.e ., wheat, rye, Bromus inermis, Lolium multiflorum, Agropyron elongatum , and oat). RFLP group 2 contained strains that are pathogenic to all the above mentioned plants except oat. One strain, which has the same host range as group 2, was classified as RFLP group 3. Reference strai ns were distributed over these three groups, independently of their ge ographical origin. Strains in groups 1 and 3 had highly conserved RFLP patterns. In contrast, group 2 strains were easily split into two RFL P subgroups, although they did not differ significantly for other char acters. The data suggest that RFLP analysis is a useful tool to distin guish among X. campestris strains causing bacterial leaf streak of cer eals.