A New Statistical Model for Dissecting the Genetic Basis of Heterosis through Multiple Interval Mapping (MIM) in Design III Populations

• Activity Number: 421
• Type: Contributed
• Date/Time: Wednesday, August 9, 2006 : 10:30 AM to 12:20 PM
• Sponsor: Biometrics Section
• Author(s): Antonio A. F. Garcia*+ and Zhao-Bang Zeng
• Companies: Escola Superior de Agricultura "Luis de Queiroz" and Bioinformatics Research Center
• Keywords: hybrid vigor ; QTL ; plant breeding ; marker assisted selection

Abstract

Heterosis is a phenomenon in which hybrids have superior performance over their parents. Its causes are still not solved. Populations obtained through Design III with molecular markers have been used to study heterosis, but only in the framework of single marker analysis. To study the genetic basis of heterosis, we developed a Multiple Interval Mapping model for Design III, based on the genetic expectations of contrasts between marker genotypes. Our model allows estimation of genomic position, effects and interaction of QTL, and has more statistical power than the current ones. We applied our model to a maize data set and found 11 QTL and some digenic epistatic interactions, explaining about 80% of the phenotypic variation. The results suggested that dominance is the major cause of heterosis in maize. Additive by additive epistasis is responsible for a small fraction of this phenomenon.