Abstract:
The yearly losses incurred by bacterial blackspot disease are high. Often trees are
asymptomatic, with the pathogen either in the resident phase or latent stage of infection.
Detection of the pathogen in these asymptomatic trees is one of the most important
means of controlling the disease. Isolates which consistently differed in virulence were
isolated from symptomatic mango plants. These isolates could be categorised into four
groups based upon differences in virulence. Monoclonal antibodies (mAbs) were
successfully raised using separate and pooled isolates for immunisation. MAbsraised were
of the lgG class and reacted with a proteinaceous epitope. These monoclonal antibodies
could distinguish between different virulence groups of Xanthomonas campestris pv.
mangiferaeindicae by means of Western Blot analysis. These antibodies were used along
with a selective medium, BVGA for detection of epiphytic populations as well as latent
infections in mango. An enrichment step prior to the enzyme- linked immunosorbent assay
(ELISA) is important, since bacterial counts on trees with latent infections are too low to
result in a positive signal. These techniques in combination are thus useful for detection
and monitoring of the pathogen, which may play an important role in controlling the
spread of the disease.
