Abstract
Rice blast disease caused by Magnaporthe oryzae is one of the most destructive disease causing huge losses to rice yield in different parts of the world. Therefore, an attempt has been made to find out the resistance by screening and studying the genetic diversity of eighty released rice varieties by National Rice Research Institute, Cuttack (NRVs) using molecular markers linked to twelve major blast resistance (R) genes viz Pib, Piz, Piz-t, Pik, Pik-p, Pikm Pik-h, Pita/Pita-2, Pi2, Pi9, Pi1 and Pi5. Out of which, nineteen varieties (23.75%) showed resistance, twenty one were moderately resistant (26.25%) while remaining forty varieties (50%) showed susceptible in uniform blast nursery. Rice varieties possessing blast resistance genes varied from four to twelve and the frequencies of the resistance genes ranged from 0 to 100%. The cluster analysis grouped the eighty NRVs into two major clusters at 63% level of genetic similarity coefficient. The PIC value for seventeen markers varied from 0 to 0.37 at an average of 0.20. Out of seventeen markers, only five markers, 195R-1, Pi9-i, Pita3, YL155/YL87 and 40N23r corresponded to three broad spectrum R genes viz. Pi9, Pita/Pita2 and Pi5 were found to be significantly associated with the blast disease with explaining phenotypic variance from 3.5% to 7.7%. The population structure analysis and PCoA divided the entire 80 NRVs into two sub-groups. The outcome of this study would help to formulate strategies for improving rice blast resistance through genetic studies, plant-pathogen interaction, identification of novel R genes, development of new resistant varieties through marker-assisted breeding for improving rice blast resistance in India and worldwide.
Highlights
Rice (Oryza sativa L.) is the staple food for more than half of the world’s population and provide more than 19% of the calories consumed by the world population [1]
Phenotyping of NRVs against leaf blast and molecular screening and genetic diversity for major blast resistance genes will help in rational use of these varieties
The present study provided an overview of the genetic diversity of the eighty rice varieties for leaf blast resistance
Summary
Rice (Oryza sativa L.) is the staple food for more than half of the world’s population and provide more than 19% of the calories consumed by the world population [1]. It is predicted that the world population will exceed 8 billion people by 2025 and to meet these global food demands, the production of grain needs to increase up to 50% more by the year 2025 [2]. A rigorous yield loss that has affected the rice cultivation is accounted to biotic and abiotic stresses. Major resistance genes against rice blast [3]. The emergence of new races with the changing climate are the major issues that address the requirement for sustainable crop development and resistance to biotic stresses. With the advances made in the area of molecular markers, the tracking of the genes for resistance is possible by following the path of markers that are linked/tagged to each gene for resistance, making simple for the identification of plants containing more genes
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