Evaluating the utility of Arabidopsis thaliana as a model for understanding heterosis in hybrid crops

Despite the phenomenon of heterosis having been used to improve crop productivity for almost a century, there is little understanding of the molecular mechanisms involved. Heterosis has been described recently in the widely used plant model Arabidopsis thaliana. To assess the opportunity afforded by this system, we have developed, through pollination to a male sterile female parent (Ler ms1), a range of hybrids of A. thaliana accessions. We tested this method of hybrid production in A. thaliana by comparing seed produced by natural pollination and hand pollination of emasculated plants. Our results demonstrate that using male sterile lines, which more closely represent methods used for hybrid crop production, circumvents the problems associated with the analysis of hybrids produced from emasculated plants. We identified hybrid combinations exhibiting mid-parent heterosis for vegetative fresh weight ranging from -9 to 103% and characterised heterosis in the reciprocal hybrids of one strongly heterotic combination. We found no evidence of a relationship between the extent of genetic relatedness of A. thaliana accessions and the strength of heterosis exhibited by their hybrids.