Performance of different rice genotypes against blast pathogen through linked molecular markers

In order to study the function of blast resistance gene and estimate resistance scale to Pyricularia grisea Sacc., the cause of Rice Blast Disease in rice, we evaluated 58 rice genotypes for phenotypic and molecular assessment. Phenotypic tests were conducted in a blast upland nursery and also in the greenhouse by using specific races of blast IA-82 and IA-90 in the greenhouse and local races for the nursery. The traits assessed consisted of infection type (IT), percent diseased leaf area (DLA) (in both nursery and greenhouse), and lesion number (LN), lesion size (LS, mm2) only in greenhouse conditions. Molecular assessment was done by using three STS, JJ80, JJ81, and JJ113, and four microsatellite markers, RM224, RM277, RM463, and RM179 which are linked to resistance genes on rice chromosomes. Genotypes had different reactions against blast races in the phenotypic part of experiment. Consequently, all genotypes were divided into three groups with high, intermediate, and susceptible resistance. Our results indicated that partial resistant genotypes are preferable for achieving durable control. Eventually, the association test between molecular data and phenotypic results showed that there is a significant level for some of the SSR markers. This means there is at least one race-specific resistance gene in the genetic sources of these genotypes that bring about resistance functions to the blast races. These results demonstrated the existence of functional resistance genes in Iranian rice genotypes. Thus, these functional genes are responsible for some parts of resistance that have been measured in phenotypic tests. Our results could be useful for breeding programs to make some modifications in the rice germplasm and would also be applicable for the marker-assisted selection process.