The induction of genetic variability, in relation to blast resistance, using tissue culture as a tool, constitutes one of the alternatives for obtaining novel resistance gene sources. The objective of this study was to increase the frequency of variants using immature panicles as explant from the F1 plants of crosses involving susceptible and moderately blast resistant sources as parents. Somaclones of rice derived from F1 plants of the crosses Bluebelle/Araguaia and Maratelli/Basmati-370 were assessed in advanced generations for blast resistance and some agronomic characters. In the greenhouse inoculation tests, all somaclones of both crosses in R4 generation exhibited a high degree of blast resistance to pathotypes IB-1 and IB-9. Some of them remained resistant in the R5 generation under a high disease pressure. In the field evaluation of R5 and R6 generations somaclones showed a high frequency of variation for blast resistance, plant height, grain weight, grain type and yield. Two somaclones derived from the crosses Bluebelle/Araguaia and 31 somaclones developed from the cross between cultivars Maratelli/Basmati-370 were identified as novel blast resistant sources which can be utilized in the irrigated rice breeding program.
Oryza sativa; Pyricularia grisea; tissue culture; genetic variation; blast resistance
