Estimation of the genetic components of heterosis by means of new experimental design and integrated data analysis with special focus on epistasis

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Heterosis is of fundamental importance in plant breeding, yet its underlying causes are still unknown. We tested several hybrids of Arabidopsis and found substantial (smaller than 50%) heterosis for biomass yield in this model species for plant genomic research. In agreement with other groups participating in this program, we chose the cross Col-O x C24 as a model for heterosis research. Our goal is to map and characterize QTL contributing to heterosis in this hybrid by using a triple testcross (TTC) design. A total of 1.200 testcross progenies and their 400 parental RILs will be evaluated in a huge greenhouse experiment with 80.000 plants for biomass yield and growth rates. In parallel, the quantitative genetic theory, statistical analysis, and software tools for QTL mapping with a TTC design will be worked out and tested with simulated and experimental data. Interesting QTL regions will be subject to fine-mapping approaches in a 2nd experiment using TTC of NILs carrying one or two target regions. Integrated bioinformatic analyses of data from various biological levels (e.g., mRNA and protein expression data) will be performed together with other groups by adopting various strategies of data mining. Altogether, this research promises a major contribution to reveal the genetic and molecular basis of heterosis.