Analysis of genetic diversity and trait correlations among Korean landrace rice (Oryza sativa L.)

This study analyzed 394 Korean rice landrace accessions, including 93 waxy varieties, for polymorphisms using 29 simple sequence repeat (SSR) markers. In total, 381 alleles served as raw data for estimating the genetic diversity (GD) and population structure. The number of alleles per locus ranged from 3 to 44 (average = 13.14). The expected heterozygosity and polymorphism information content (PIC) ranged from 0.0341 to 0.9358 (mean = 0.5623) and from 0.0783 to 0.9367 (mean = 0.5839), respectively. The mean GDs in waxy, low amylose content, intermediate amylose content, and high amylose content (HAC) varieties were 0.6014, 0.5922, 0.5858, and 0.7232, respectively, whereas the mean PIC values for each SSR locus were 0.5701, 0.5594, 0.5550, and 0.6926, respectively. HAC varieties had the highest GD and PIC. Consistent with clustering by genetic distances, a model-based structural analysis revealed 3 subpopulations. Analysis of molecular variance revealed that the between-population component of genetic variance was 22.35%, and that of the within-population component was 77.65%. Significant correlations were observed between eating quality and protein content (r = -0.262), K+ (r = -0.655), Mg2+ (r = -0.680), 1000-GW (r = 0.159), and amylose content (r = -0.134). The overall F-ST value was 0.2235, indicating moderate differentiation among the groups. Analysis of variance of the 3 genetic groups (mean of 9 phenotypic and 5 physicochemical traits) by the Duncan multiple range test showed significant differences in 10 traits. This preliminary study represents a first step toward more efficient conservation and greater utilization of rice landraces to broaden the genetic bases of commercially grown varieties.