Attempts to induce mutants resistant or tolerant to golden mosaic virus in dry beans (Phaseolus vulgaris)

The golden mosaic of dry beans (Phaseolus vulgaris L.) that is present in the tropical parts of the American continent has become a major hindrance for the cultivation of this food legume of great importance to many Latin America countries. Good control measures are not known and bean germ plasm resistant or tolerant to this virus disease is not yet available. Attempts to induce bean mutants with this desirable characteristic were made using gamma radiation and chemical mutagen. Some M2 plants from one progeny of the cultivar Carioca treated with 0.48% ethyl methane sulphonate (EMS), 6 hours of treatment at 200C, showed milder symptoms than the control progenies, and at the same time they showed a tendency to recover. This mutant is being tested under field conditions and used in crosses with other bean types that show a certain degree of tolerance, aiming at adding the favourable characters of both parents. Seeds of the hybrids, as well as those of the parent types, are also being further submitted to mutagenic treatments in order to obtain still better mutants that will be satisfactory for direct or indirect control of bean golden mosaic. (author)