Variation for rice blast resistance in early somaclonal generations derived from immature panicles

Abstract

Somaclones derived from immature panicles of the rice cultivars Bluebelle and Maratelli susceptible to blast and their F₁'s from crosses with resistant donors (Araguaia, Basmati-370 and Ramtulasi) were compared in the R₂ (plants from self-pollinated seed from primary R₁ regenerants) and R₃ generations in the greenhouse and field for blast resistance. In the greenhouse the R₂ plants and R₃ lines were inoculated with the races IB-1 and IB-9 of Pyricularia grisea. The frequency of plants resistant to both races ranged from 16 to 42% in the F₁ derived somaclones, whereas no resistant plant was recovered from the susceptible parents when inoculated with IB-1. The means of the leaf blast rating of R₂ and R₃ populations of F₁'s were significantly lower than those derived from susceptible parents. Similar results were obtained in field trials. However, the performance of the F₁ derived somaclones varied depending on the resistant donor parent. In field trials, the mean visual ratings for leaf blast of regenerants from F₁ derived R₂ and R₃ populations were significantly lower than those regenerants derived from the parental genotypes Maratelli and Basmati-370.