Dissection of the Genetic Basis for Total γ-Oryzanol and Its Components in Whole Grain Brown Rice through Genome-Wide Association Study

Antioxidants detain the onset and progression of several noncommunicable diseases. γ-oryzanol (GOZ), a major antioxidant in rice grain, is a mixture of steryl esters of ferulic acid and caffeic acid. The present study was conducted with the objective of assessing the natural genetic variation for GOZ and its components in Indian rice cultivars and further identify the genomic regions associated with it. A panel of 174 Indian rice accessions depicted significant genetic variation for GOZ concentration, which ranged from 78.96 to 765.43 mg kg^-1 of brown rice. 24-Methylenecycloartanyl ferulate was the major constituent (23.99-317.82 mg kg^-1), followed by campesteryl ferulate (13.86-117.56 mg kg^-1) and cycloartenyl ferulate (7.18-207.50 mg kg^-1). Further, a genome-wide association study (GWAS) conducted using 32,712 single nucleotide polymorphism (SNP) markers with BLINK and FarmCPU models identified 19 significant marker-trait associations (MTAs) for GOZ and its components. These significant MTAs could explain the phenotypic variation ranging from 0.001 to 48.875% and have enormous potential in marker-assisted breeding programs aiming at the development of nutrient-dense rice varieties.