Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 28 juin 2018
Salle Bibliothèque IBIP (Bâtiment 7) à 14h
Non-linear phenotypic relationships explain the emergence of heterosis in Arabidopsis thaliana
Heterosis describes the phenotypic superiority of hybrids over their parents in traits related to performance such as growth rate and reproductive success. Understanding and predicting heterosis is crucial for evolutionary biology, as well as for plant and animal breeding. Empirical data in various species have shown that a range of genetic and molecular mechanisms are likely to explain heterosis, making it difficult to predict its emergence from parental genotypes alone. Moreover, the physiological bases of heterosis remain a mystery. In this study, we evaluated a model of physiological dominance proposed by Sewall Wright to explain non-additivity in metabolic fluxes at the cellular level. We used 450 hybrids derived from crosses among inbred natural accessions of Arabidopsis thaliana to test Wright’s model for two traits at the whole-plant level: growth rate and fruit number. We found that allometric relationships constrain trait variation similarly in hybrids and inbred accessions. These allometric relationships behaved predictably, in a non-linear manner, explaining up to 75% of heterosis amplitude, while genetic distance among parents at best explained 7%. Thus, our findings validated Wright’s model of physiological dominance on plant performance, and suggest that the emergence of heterosis is an intrinsic property of non-linear relationships between traits. Furthermore, our study highlights the potential of a geometric approach of phenotypic relationships for predicting heterosis of two major components of crop productivity and yield.
Contact : Florent Pantin