Abstract
North-East (NE) India, the probable origin of rice has diverse genetic resources. Many rice landraces of NE India were not yet characterized for blast resistance. A set of 232 landraces of NE India, were screened for field resistance at two different hotspots of rice blast, viz., IIRR-UBN, Hyderabad and ICAR-NEH, Manipur in two consecutive seasons. The phenotypic evaluation as well as gene profiling for 12 major blast resistance genes (Pitp, Pi33, Pi54, Pib, Pi20, Pi38, Pita2, Pi1, Piz, Pi9, Pizt, and Pi40) with linked as well as gene-specific markers, identified 84 resistant landraces possessing different gene(s) either in singly or in combinations and also identified seven resistant landraces which do not have the tested genes, indicating the valuable genetic resources for blast resistance. To understand the molecular diversity existing in the population, distance and model based analysis were performed using 120 SSR markers. Results of both analyses are highly correlated by forming two distinct subgroups and the existence of high diversity (24.9% among the subgroups; 75.1% among individuals of each subgroup) was observed. To practically utilize the diversity in the breeding program, a robust core set having an efficiency index of 0.82 which consists of 33 landraces were identified through data of molecular, blast phenotyping, and important agro-morphological traits. The association of eight novel SSR markers for important agronomic traits which includes leaf and neck blast resistance was determined using genome-wide association analysis. The current study focuses on identifying novel resources having field resistance to blast as well as markers which can be explored in rice improvement programs. It also entails the development of a core set which can aid in representing the entire diversity for efficiently harnessing its properties to broaden the gene pool of rice.
Highlights
Rice is a major staple crop in the world and demand for rice is increasing every year (Ray et al, 2013)
Neck blast is becoming more problematic than the leaf blast at several locations in India (Aglawe et al, 2017; Laha, 2017) so, it has become imperative in breeding programs to choose the accession having resistance for two phases of blast resistance (Abhijeet et al, 2013)
The premise of collecting, analyzing and characterizing unexplored NE landraces is for identification of donors containing multiple blast resistance genes which can be readily used in the breeding programs
Summary
Rice is a major staple crop in the world and demand for rice is increasing every year (Ray et al, 2013). Biotic stresses continue to be the constraint in rice production and becoming severe in the climate change regime. One of the most identifiable major biotic stresses is the blast disease caused by Magnaporthe oryzae. It infects rice leaves, nodes, color, and panicles at different stages of crop growth decreasing the overall yield. In India, neck blast is becoming severe in many agro-ecological zones and causing more threats to the rice production (Laha, 2017). Identification of durable resistance sources and resistance genes is a continuous process in rice improvement programs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
