Characterization of Fusarium wilt resistant somaclonal variants of banana cv. Rasthali by cDNA-RAPD.

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), is counted among the most destructive diseases of crop plants in India. In the absence of any credible control measure to manage this disease, development of resistant cultivars is the best option. Somaclonal variations arising out of long term in vitro culture of plant tissues is an important source of genetic variability and the selection of somaclones having desired characteristics is a promising strategy to develop plants with improved characters. In the present study, we isolated a group of somaclonal variants of banana cv. Rasthali which showed efficient resistance towards Foc race 1 infection in repeated bioassays. cDNA-RAPD methodology using 96 decamer primers was used to characterize these somaclonal variants. Among the four differentially amplified bands obtained, one mapping to the coding region of a lipoxygenase gene was confirmed to be down regulated in the somaclones as compared to controls by real-time quantitative RT-PCR. Our results correlated well with earlier studies with lipoxygenase mutants in maize wherein reduced expression of lipoxygenase led to enhanced resistance towards Fusarium infection.