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Heterosis in the frost tolerance of crosses between different Arabidopsis thalianaaccessions.

The term heterosis, or hybrid vigor, describes the phenomenon of improved physiological performance of most hybrids in comparison to their parents. The effect decreases with increasing homozygosity in the next generations. Although heterosis has been known for decades, the genetical and molecular background remain still unknown.

We performed several reciprocal crosses of Arabidopsis thaliana accessions originating from different climatic regions and found significant heterotic effects in the freezing tolerance before and after cold acclimation at 4 °C. In addition we tested the accumulation of four soluble carbohydrates and proline which are known to play a role in the protection of plant cells against freezing damage. Again we found significant heterosis in many hybrids under both conditions. For further investigation eight crosses were chosen to compare the freezing tolerance, sugar and proline content of F1 and F2 plants, both non-acclimated and acclimated.

Furthermore, metabolite profiling was conducted to analyse the differential behaviour of the hybrids and parental lines under both treatments. As expected, clear differences could be shown between control and cold treated plants. We are currently using bioinformatic approaches to identify metabolites that are related to hybrid vigour. A parallel transcript profiling is in progress. Combined with the metabolite analysis this will lead to a better understanding of the molecular determinants of heterosis in plant freezing tolerance and cold acclimation.

Korn, M.; Hincha, D.K.; Heyer, A. 2007. Heterosis in the frost tolerance of crosses between different Arabidopsis thaliana accessions. Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology 146, S153-S153.