CHARACTERIZATION OF XANTHOMONAS CAMPESTRIS PV. VIGNICOLA TRAINS BY METABOLIC FINGERPRINTS (BIOLOG-SYSTEM)
GB KHATRI-CHHETRI1 and K WYDRA2 and K Rudolph11Institute of Plant Pathology and Plant Protection of the University, Gottingen, Germany; 2International Institute of Tropical Agriculture, PHMD, Cotonou, BeninBackground and objectives
Cowpea bacterial blight caused by Xanthomonas campestris pv. vignicola (Xcv) is common worldwide, whereas cowpea bacterial pustule is reported only from Nigeria and West Africa where mixed symptoms of blight and pustules are often observed. The pathovar vignaeunguiculatae proposed for pustule causing bacteria  has not been accepted internationally. For both bacterial variants differences in aggressiveness have been reported, but the existence of races has not been clearly established . It is still an open question, whether blight and pustule causing bacteria belong to the same pathovar vignicoia. Therefore, the objectives of this study were to characterize blight and pustule causing strains by analysing their capability to metabolize 95 organic substrates.
Materials and methods
Results and conclusions
A specific difference could be observed between strains according to geographic origin. Dextrin, glycogen and succinamic acid were not used by strains from Benin and Thailand, but were used by all the others, whereas N-acety]-D-glucosamine, malonic acid and L-proline were used only by strains from Benin and Thailand, The strains from Venezuela differed considerably in the metabolization of cis-aconitic acid and hydroxybutyric acid from the other strains.
Ninety-one per cent of the strains from Benin and Thailand (18% of all the strains) were identified as X. campestris pv. vignicola. None of the other strains was identified as Xcv. The Biolog data base identified 80% of the strains as X. campestris, however belonging to seven different pathovars. Twenty per cent were identified as Pseudomonas cissicola.
According to the variations in substrate utilization (but similarities within a group) the strains could be categorized into four groups: (1) Cameroon, Nigeria, Niger, Sudan and Uganda; (2) Benin and Thailand; (3) Venezuela and Brazil; and (4) Mozambique. The Biolog System revealed a considerable variation in metabolic fingerprints of the strains, which were more or less correlated with their origin and identification, but not to blight or pustule development and pathogenicity. It is concluded that the strains isolated from blight and pustules from West Africa belong to the same pv. vignicola.