Leveraging genetic diversity of aromatic rice landraces in Odisha for sustainable rice blast resistance

Abstract

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most destructive diseases affecting rice, leading to significant global yield losses. Investigation on genetic diversity and population structure of 108 aromatic rice (Oryza sativa L.) landraces from Odisha, India were made using a set of 20 major blast resistance (R) genes. Phenotypic evaluation classified these landraces into resistant (17 landraces), moderately resistant (17 landraces), and susceptible (74 landraces) groups based on their disease response. The frequency of the 20 R genes across the landraces varied widely, ranging from 2.78 % to 100 %, with each landrace carrying 7 to 18 positive R-gene alleles. In population structure analysis, two sub-populations (K = 2) were found with considerable admixture. Principal coordinate analysis (PCoA) further demonstrated distinct clustering patterns, separating the resistant and moderately resistant landraces. Molecular variance analysis (AMOVA) indicated that the majority of genetic diversity (57 %) was found within populations, while a smaller proportion (6 %) occurred between populations. Among the eight significant markers identified, YL155/YL87 (Pita gene, R² = 7.8 %), Pita3 (R² = 5.1 %), and Pikh (Pi54 gene, R² = 4.0 %) exhibited the strongest associations with blast resistance, highlighting their potential for marker-assisted selection in breeding programs.