Partial resistance to blast in somaclones of rice cultivar CICA-8

Abstract

The development of rice blast resistance sources is a basic requirement for rice (Oryza sativa) breeding. The main objective of this investigation was to evaluate somaclones of rice cultivar CICA-8, developed from callus cultures of immature panicles for blast resistance. Rice blast in 39 somaclones was assessed in the advanced generations from R5 to R7, in the blast nursery under natural conditions of infection and in greenhouse inoculation tests, using five isolates pertaining to four pathotypes (ID-14, II-1, IB-1 and IB-45) of Pyricularia grisea. In the rice blast nursery, somaclones exhibited differences in disease reactions. In inoculation tests, somaclones showed differential interaction between isolates of the pathogen and genotypes. Two isolates highly virulent to five somaclones including CICA-8 and CO 39 were selected to determine the partial resistance. There was no significant interaction between isolates and somaclones for partial resistance index, determined based on leaf lesion number per cm². Four somaclones showed significantly higher degree of partial resistance when compared with the parent cultivar CICA-8.