Abstract:
Carrot production in Sri Lanka faces severe
post-harvest losses due to bacterial soft rot. The quality
deterioration of vegetables owing to typical bacterial soft
rot can greatly affect the market value and consumer
preference. Although the carrot soft rot causing bacteria
occur all over the world, and are well-studied and characterized,
the scarcity of data on the precise identification
of the causal agents of the disease in Sri Lanka acts as a
great barrier in managing such post-harvest losses. In an
attempt to bridge this knowledge gap, we have isolated
potential causative agents of bacterial soft rot from diseased
carrot samples collected from Gampaha district,
Sri Lanka.All the seven bacterial isolateswere confirmed
for their ability to exhibit pectolysis, and vegetable disk
assays were used to evaluate the pathogenicity of bacterial
isolates. The pathogenicity assays showed that these
isolates have the ability to infect not only carrot, but also
potato, radish, beetroot and Napa cabbage, suggesting
their possible broad host range. The ITS–PCR RELP
profiles of the pectobacterial isolates and hierarchical
clustering of the resulting profiles have placed the strains
isolated in this study into four groups. The 16S rRNA
gene sequencing and subsequent analyses aided in identifying
isolates as Pectobacterium carotovorum (C1B5,
C2B6, C2B7 and C2B8), P. aroidearum (C1B3 and
C1B4), and P. polaris (C3B9). The study indicated the
possibility of different Pectobacterium spp. being involved
in causing carrot soft rot in the area, emphasizing
the need to carry out an island-wide, comprehensive
analysis to understand the distribution of the pathogen,
which could be used in implementing successful disease
management strategies.
