Mapping quantitative trait loci and biochemical analysis of sheath blight resistance in rice (Oryza sativa L.)
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Date
2023
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Punjab Agricultural University
Abstract
Sheath blight caused by Rhizoctonia solani Kühn, is one of the most prevalent diseases of rice in South East Asia. Use of resistant sources is an eco- and farmer friendly and more economically approach to mitigate yield losses due to this disease. The aim of the present study was to identify potential quantitative trait loci (QTLs) linked with resistance to sheath blight and associated with temporal spike in defense related enzymes as well as histopathological patterns during infection process of R. solani. Next generation sequencing (NGS) assisted bulk segregant analysis (BSA) was integrated with R package i.e. QTLseqr to map QTLs associated with sheath blight resistance in F3 mapping population derived from the cross between susceptible rice cultivar PR121 and resistant parent ShB1. The five QTLs namely qShB1, qShB3, qShB5.1, qShB5.2 and qShB6 were identified on chromosome 1, 3, 5 and 6, respectively. Activity of defense related enzymes such as phenylalanine ammonia lyase, polyphenol oxidase and peroxidase were estimated in parental lines along with three sets of progeny lines which showed significantly high activity in resistant parent as compared to the susceptible parent after R. solani inoculation. The moderately resistant (MR) lines expressed maximum enzyme activity than the highly susceptible (HS) lines. The pathogen R. solani exhibited more profuse and dense hyphal growth with close contact to surface grooves, lobate appressoria-like structures, higher number of microsclerotial development and longer lesion length on HS line as compared to the MR line. The present results provided better understanding of host-pathogen interaction and novel QTLs identified may be used in rice breeding program for the development of durable resistance to sheath blight in rice cultivars.
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Thesiya Mayur Rajeshbhai (2023). Mapping quantitative trait loci and biochemical analysis of sheath blight resistance in rice (Oryza sativa L.) (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.