Analysis and comparison of the γ-oryzanol content based on phylogenetic groups in Korean landraces of rice (Oryza sativa L.)

Brown rice contains beneficial phytonutrients such as antioxidants, anthocyanins and oryzanol, and oryzanol is one of the major components. However, the information of oryzanol contents and genetic data are limited in Korean rice landraces to use the genetic resources. This study was conducted to investigate varietal differences of the oryzanol content and analyze the genetic diversity using SSR marker about 196 Korean rice landraces. Among tested germplasm, the total γ-oryzanol values showed the high variation ranged from 9.8 to 55.9 mg 100g-1 and an average content value was 27.2 mg 100g-1. Particularly, IT007903, IT007714, IT006622 and IT006125 accessions were showed γ-oryzanol contents higher than 50mg 100g-1. The 24-methylene cycloartenyl ferulate was the most prevalent with an average value of 29.9% among the total γ-oryzanol components, and followed by cycloartenyl ferulate (26.7%). Genetic diversity among 196 landrace accessions was evaluated based on 46 SSR markers carrying total 396 alleles. The mean values of observed (HO) and expected heterozygosities (HE) were 0.009 and 0.497, respectively, indicating a considerable amount of polymorphism within this collection. A genetic distance-based phylogeny grouped into seven clusters with genetic distance (GD) value was 0.6. According to the phylogenetic analysis, roughly 7 clusters were divergent, and the γ-oryzanol content values showed statistical differences by the four groups (P<0.001). These traits of the selected accession would be helped broadening for parent materials selection to improve the γ-oryzanol content through the rice breeding.