Molecular profiling of some blast resistance genes and analysis of physiological variability in rice plants produced by anther culture and hybridization

Abstract

For genetic improvement of rice plants against blast fungus disease caused by Magnaporthe oryzae, eight rice genotypes including four Egyptian and four foreign genotypes which represented a broad range of variation for blast resistance and other several traits were used in this study through line X tester mating design to produce F1 hybrids used as source of anther culture. Results of analysis of variance showed highly significant differences for all studied traits indicating overall genetic variations among parents and hybrids suggested that specific combining ability referred heavily to the expression of studied traits. Data of anther culture experiment for parents (8 parents) and hybrids (15 crosses) showed highly significant differences for all studied traits which illustrate genetic variations through the used materials. The highest callus induction percentage was found for CR7 (18.3%) and P6 (14.0%) while, the lowest callus induction percentage was found for CR5 (2.0%) and CR1 (4.0%). On the other hand, nine out of 15 hybrids recorded regeneration percentage more than the highest parental genotypes. Anther culture-derived plants and their parental genotypes were evaluated for blast disease resistance according to artificial infection with 10 blast races. The results showed that resistance percentage varied between 10% and 100%. While all anther culture-derived plants showed high level of resistance (100%) against all tested blast races. For enzyme activities for catalase, peroxidase and polyphenol oxidase in anther culture-drived plants and their parent, results showed that line TC9 derived from CR9 gave the highest value for catalase activity (301). Also, CR11 and P4 recorded the high level of peroxidase and polyphenol oxidase activities, respectively. Moreover, genetic diversity among anther culture-derived plants and their parental genotypes using five SSR primers related to Pi5(t), Pikh, Pi-b, Pi-1 and Pi-ta blast resistance genes showed heterozygous bands in all tested genotypes. The highest PIC value recorded for RM 247 and RM 206 markers which had PIC values of 0.778 and 0.761, respectively. Out of the used five SSR markers, RM 247 was the most informative marker with amplicon size ranged from 134 to 242 bp. These markers are therefore useful markers for studying polymorphism concerning blast resistance in rice and hence can be used in the marker-assisted selection for blast resistance. While development of resistant genotypes is the most effective way to control rice blast disease, anther culture technique used in this study helpful in production of resistant double haploid plants used in rice preeding programe in Egypt.