Characterization of the major sheath blight resistant QTL qShB9-2 on rice chromosome 9

Authors: Jia, Yulin; WANG, G. - The Ohio State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/18/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Sheath blight disease caused by the soil borne necrotrophic pathogen Rhizoctonia solani is a major threat to rice production in the USA. The disease is managed by the use of fungicide. Because major resistance (R) genes to R. solani are lacking, minor R genes or QTLs have been identified and used in rice breeding programs. Among the over dozens of QTLs, qShB9-2 located on chromosome 9 contributes to 25% phenotypic variation. The role of qShB9-2 in resisting sheath blight disease was verified by repeated phenotyping of 77 recombinant inbred lines with and without qShB9-2 under greenhouse and field conditions. Within the qShB9-2 region, we found one ATP-binding cassette (ABC) transporter gene family encoding pleiotropic drug resistance-like ABC transporters. The gene specific high-resolution melting (HRM) DNA marker derived from OsABC9 was developed and the existence of an HRM marker for the resistant allele correlated well with the resistant phenotype, suggesting that OsABC9 is a promising candidate for sheath blight resistance. To validate the functional role of OsABC9, we analyzed DNA sequences of OsABC9 in both susceptible variety Nipponbare and resistant variety Jasmine 85. Two polymorphic nucleotides that altere amino acids in Jasmine 85 were identified and were used to for designing guide RNAs for single-base editing using CRISPR-Cas9. At the same time, two overexpression contructs of OsABC9 were generated for transformation in Nipponbare. Transgenic lines containing these constructs will be developed and evaluated for resistant function of the ABC transporter in response to R. solani.