Abstract
Heterosis (hybrid vigor) is often observed in F 1 individuals obtained from distantly related parents and it exhibits superior characteristics in various aspects of growth and environmental responses. The molecular basis of heterosis has been explained with either additive or synergistic expression of genes peculiar to each parent. However, many different organisms show the hybrid vigor in the basic activity of cells and individuals including growth rate and body size, therefore, there can be a biologically common mechanism of heterosis. To elucidate this hypothesis, we characterized the growth of F 1 rice seedlings obtained by crossing between a japonica (Nipponbare) and an indica (Kasalath) rice under a model environment using an automated growth monitoring system. Heterosis was observed in the growth rate of the third leaf and it was specifically reduced on application of an inhibitor for histone deacetylases that affect global chromatin structures.
