Molecular Analysis of Indian Rice Germplasm Accessions with Resistance to Blast Pathogen

Abstract

The present study was needed to understand the genetic constitution of indigenous rice (Oryza sativa L.) germplasm with respect to their resistance towards the blast pathogen Magnaporthe oryzae. Specifically, the objective was to identify landrace(s) of rice for the presence of effective rice blast resistance (R) gene(s) that can be employed in breeding programs for Eastern India. A set of 47 landraces that consistently showed resistant reaction to blast disease (Magnaporthe oryzae) in multi-season evaluations in outdoor blast nurseries at Hazaribag, Jharkhand, was probed for the presence of known R genes. Seven DNA-based single nucleotide polymorphism (SNP) markers, namely, z56592, zt56591, k39512, k3957, Pita3, PB8, and Pb28, were used to determine the presence of eight major R genes, Piz, Piz-t, Pik, Pik-p, Pita, Pita-2, Pi2, and Pib, in the rice accessions from North East and Eastern India. Among the 47 accessions, only one was positive for Piz, three for Piz-t, and six for Pi2. Three accessions were positive for Pik gene and 21 for Pik-p gene. One accession, 333039, was positive for both Pik and Pik-p genes. Out of 47, 16 accessions possessed the two closely linked Pita and Pita-2 genes. The Pib gene was commonly detected, with 45 out of 47 accessions amplifying the marker Pb28, whereas Piz, Piz-t, Pik, and Pi2 were less common. Many accessions carried multiple genes; one accession, 352766, amplified the markers for as many as six genes, viz., Pib, Piz-t, Pi2, Pik-p, Pita, and Pita-2. Because this core set of accessions was consistently resistant to blast in outdoor blast nurseries and had the added advantage of local adaptation, knowledge of their genetic constitution with respect to the detected R genes and availability of robust markers would be useful for resistance breeding programs.