| Popis: |
Mango bacterial black spot (MBBS) caused by Xanthomonas pv. mangiferaeindicae, (Xm) has a high incidence in several tropical countries (Asia, East Africa). Most commercial cultivars are highly susceptible to MBBS and infections can result in drastic reductions of crop yield, loss of fruit quality and induction of severe defoliation, especially when storms or hurricanes are involved. Lesions develop mainly on leaves, twigs and fruit. Leaf and twig lesions constitute the most important inoculum source. A single leaf lesion contains 106-107 cfu lesion-1 throughout the growing season. Survival in soil is limited and populations surviving in plant debris are of little significance for new grove infections. The pathogen can survive as an epiphyte, although the epidemiological significance of the epiphytic inoculum is presently unknown. Short distance spread in nurseries mainly occurs through rain and irrigation splashing, whereas short or medium distance spread within or among groves mainly occurs through wind-driven rains and grove maintenance operations; long distance spread occurs mainly through plant material exchanges [3, 4]. Information brought by “classical” ecology and epidemiology programs can be efficiently complemented by those obtained from genetic analyses of bacterial strains. The combination of both approaches, often qualified as “molecular epidemiology”, integrate the genetic diversity of the bacterial inoculum, which is no longer regarded as homogenous, but rather as a mixture of interacting subpopulations. In this study, we evaluated the usefulness of an insertion sequence cloned from Xm as a tool for epidemiological typing. |
