Study on blast resistance in experimental aromatic hybrids rice (Oryza sativa L.) using morpho-molecular markers

Abstract

Rice Blast caused by Magnaporthe oryzae is the major biotic stress causing substantial yield loss in every year worldwide. For this, 11 experimental hybrids together with their 7 parents were screened for blast resistance in the field of Bangladesh Jute Research Institute, Nashipur, Dinajpur. The experiment was conducted in a Randomized Complete Block Design with three replications during June to November 2022. The molecular detection of resistance was done in parallel of phenotyping at the laboratory of Department of Genetics and Plant Breeding, Hajee Mohammad Danesh Science and Technology University, Dinajpur. In field, the data were collected on 1000 grain weight (g), disease severity percentage (%), leaf spots per plant (mm) and yield per plant (g). The analysis of variance revealed significant differences among the genotypes for all the traits. The highest mean value for 1000 grain weight 29.45g was found in MR-506 genotype. The highest percent leaf blast severity (46.00) was found in BRRI dhan 34 genotype. The highest size of the spots 14.76 9 (mm) was revealed in BRRI dhan34 genotype. Simple correlation coefficient among four important characters viz. 1000 grain weight, % severity, leaf spot and yield per plant were analyzed for 18 rice genotypes. 1000 grain weight had significant positive correlation with yield per plant (0.16). The regression coefficient between yield per plant and the other traits viz. 1000 grain weight, disease severity percentage and leaf spot per plant were analyzed. From this, a linear relationship was found between yield per plant and 1000 grain weight. In this study, principle component analysis confirmed the existence of high diversity in rice genotypes. All the characters have their own contribution in a variance degree for the variance observed in every component and the character variation was explained in several PCs. The first two axes of a PCA biplot summarizing the relationships between the variables and the genotypes explained 58.2% of the total variance by PC1 and 41.8% of the variance by PC2. The genotypes KR-501, KB-502, RH-504, RB-505, RS-508 and MB-5011 found far away from the centroid of the cluster and favored the trait performances In the study, PCR-based simple sequence repeat (SSR) markers have been studied to screen and identify different blast resistance genes. Determination of PCR results for 5 blast resistance genes viz Pi-9, Pi-1, Pi-5(t), Pi-b, and Pi-33 were determined by visualization of RM 541, RM 21, RM 224, RM 208 and RM 72 chromosome amplicons on near 158 bp, 157 bp, 157 bp, 173 bp, and 166 bp of positive fragments, respectively. All the 18 aromatic rice genotypes were evaluated individually through molecular and morphologically in this study and identified 55 alleles. Three (3) experimental hybrids viz. KR-501, BM-503 and RB-505 had maximum five (5) blast resistance genes, while five (5) parental genotypes and experimental hybrids genotypes namely Multioverian, Munni, KB-502, MR-506 and SB-507 had four (4) blast resistance genes. In the study, a clear co-segregation was revealed by the resistant genes Pi-9, Pi-1, Pi-5(t), Pi-b, and Pi-33 in experimental hybrids as KR-501, MR 506, MS-501, RH-504 and RB-505 from their parents. Therefore, these experimental F1‘s should be utilized for development of blast resistant aromatic hybrids in Bangladesh.