Comparative analysis of the metabolic complement of hybrids and inbred lines (corn) and its suitability for predicting hybrid compatibility

Hybrid vigour or heterosis is a central concept in plant breeding. Despite the agronomical importance of heterosis, its underlying molecular mechanisms remain elusive. Starting from the notion that hybrid vigour should be founded in metabolism we performed a comparative analysis of the metabolome of six parental maize inbred lines and their corresponding fourteen hybrids.

The metabolic profile of each hybrid line when compared to the corresponding inbred lines is distinct and reciprocal hybrids can be easily separated. With respect to metabolite level inheritance all patterns (i.e. dominant, over dominant and additive) are observed with no specific overrepresentation. Comparison of all hybrids against all inbred lines reveals that metabolite levels in the group of hybrids display a lower variance as compared to the inbred lines suggesting the existence of an “optimal state” which might be obtained via additive, dominant, or over dominant combination of parental levels thus explaining the observation that all patterns of inheritance are observed. Reconstructed metabolic networks display a higher network density in most hybrids as compared to the corresponding inbred lines suggesting a tighter control of metabolism. Deviations from the “optimal state“ correlate negatively with biomass which might be helpful for the development of predictors of hybrid performance based on parental line characteristics.

References

Lisec, J., Romisch-Margl, L., Nikoloski, Z., Piepho, H.P., Giavalisco, P., Selbig, J., Gierl, A. & Willmitzer, L. Corn hybrids display lower metabolite variability and complex metabolite inheritance patterns. Plant Journal 68, 326-336 (2011).