Importance of epistasis as the genetic basis of heterosis in an elite rice hybrid

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 17; pp. 9226 - 9231
• Main Authors: Yu, S.B, Li, J.X, Xu, C.G, Tan, Y.F, Gao, Y.J, Li, X.H, Zhang, Q.F, Saghai Maroof, M.A
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 19.08.1997; National Acad Sciences; The National Academy of Sciences of the USA
• Subjects: Biological Sciences; CARACTERES DE RENDIMIENTO; CARTE GENETIQUE; CHROMOSOME MAPS; Chromosomes; COMPOSANTE DE RENDEMENT; CROP YIELD; DIGENIC INTERACTIONS BETWEEN LOCI; DOMINANT GENES; Epistasis; FRUCTIFICACION; FRUCTIFICATION; FRUITING; GENE DOMINANT; GENE INTERACTION; GENES DOMINANTES; GENETIC EFFECTS; GENETIC INHERITANCE; Genetic loci; GENETIC MAPPING; GENETIC MAPS; GENETIC MARKERS; GENETICA; GENETICS; GENETIQUE; Genotypes; GRAINS PER PANICLE; HEREDITE; HERENCIA GENETICA; HETEROCIGOTOS; HETEROSIS; HETEROZYGOSITY; HETEROZYGOTE; HETEROZYGOTES; HIBRIDOS; HIGH YIELDING VARIETIES; HYBRIDE; Hybridity; HYBRIDS; INTERACCION DE GENES; INTERACTION GENIQUE; LINKAGE MAPS; LOCI; LOCUS; MAPAS GENETICOS; MARCADORES GENETICOS; MARQUEUR GENETIQUE; MOLECULAR MAPPING; ORYZA SATIVA; OVERDOMINANCE; Panicles; Phenotypic traits; Quantitative trait loci; QUANTITATIVE TRAITS; RENDEMENT DES CULTURES; RENDIMIENTO DE CULTIVOS; SEED SET; VARIEDADES DE ALTO RENDIMIENTO; VARIETE A HAUT RENDEMENT; VIGOR HIBRIDO; VIGUEUR HYBRIDE; YIELD COMPONENTS
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.17.9226

The genetic basis of heterosis was investigated in all elite rice hybrid by using a molecular linkage map with 150 segregating loci covering the entire rice genome. Data for yield and three traits that were components of yield were collected over 2 years from replicated field trials of 250 F2:3 families. Genotypic variations explained from about 50% to more than 80% of the total variation. Interactions between genotypes and years were small compared with the main effects. A total of 32 quantitative trait loci (QTLs) were detected for the four traits; 12 were observed in both years and the remaining 20 were detected in only one year. Overdominance was observed for most of the QTLs for yield and also for a few QTLs for the component traits. Correlations between marker heterozygosity and trait expression were low, indicating that the overall heterozygosity made little contribution to heterosis. Digenic interactions, including additive by additive, additive by dominance, and dominance by dominance, were frequent and widespread in this population. The interactions involved large numbers of marker loci, most of which individually were not detectable on single-locus basis; many interactions among loci were detected in both years. The results provide strong evidence that epistasis plays a major role as the genetic basis of heterosis