VARIABILITY OF XANTHOMONAS-CAMPESTRIS PV VASCULATURE FROM SUGARCANE AND OTHER GRAMINEAE IN REUNION-ISLAND - CHARACTERIZATION OF A DIFFERENTXANTHOMONAD

Strains presumed to he of Xanthomonas campestris pv. vasculorum (Cobb. ) Dye, obtained from sugarcane and other gramineae in Reunion Island, were compared in terms of cult:ural aspects, pathogenic and physiologi cal reactions, fatty acid profiles and restriction fragment length pol ymorphism (RFLP) of genomic DNA. The strains could be divided into two separate groups (G1 and G2). The G1 strains were identical to strains described as X, campestris pv. vasculorum; they showed an important v ariability in their cultural characteristics and in their aggressivene ss. The G2 strains did not induce the usual symptoms of gumming diseas e on sugarcane cultivars infected under natural conditions or inoculat ed in the greenhouse. The G2 strains grew faster on agar medium, their colonies were more pigmented and less fluidal and had a different mor phology on agar slant. Unlike the G1 strains, G2 strains hydrolyzed st arch weakly and casein strongly; they utilized L-fucose and, to a less er extent, melibioze. The fatty acid and genomic DNA profiles differed between the groups. Differences seemed large enough to support separa tion of G1 and G2 strains into distinct taxonomic entities, namely G1 as Xanthomonas campestris pv. vasculorum and G2 as a different pathova r of X. campestris. The taxonomic position of G2 strains is discussed.