Identification of molecular marker for resistance against Fusarium oxysporum f. sp. ricini in Ricinus communis (Castor)

Ricinus communis (castor), a member of Euphorbiaceae, is an important oleaginous plant from both an economical and medicinal point of view. The oil, which is obtained from castor seeds, has excellent medicinal and industrial uses. India is one of the foremost countries that leads in the production and export of castor oil and its derivatives. Fusarium wilt caused by Fusarium oxysporum f.sp. ricini is one of the most important diseases from an economical point of view as it has destroyed 80% of the crops in the endemic areas. Use of cultural practices and use of resistant cultivars can be combined to reduce economic losses due to the fungus. This study correlates two bioassays for testing Fusarium wilt disease in Ricinus communis carried out at field level and laboratory level. After the discrimination of wilt resistant and wilt susceptible varieties based on bioassay method, plants were further characterized at a molecular level by investigation of the presence of Resistant (R) gene as well as SSR markers. SSR markers showed a high degree of polymorphism and clear differentiation between resistant and susceptible cultivars and based on the amplification pattern of R gene, a 1 kb amplification product was obtained from both resistant and susceptible varieties. This clearly shows that in susceptible plants the R genes are non functional as reported in Arabidopsis thaliana [1].

Reference: Quirino BF, Genger R, et al. (2004) Physiological and Mol Plant Path, 65: 257–267.