Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, 78026 Versailles, France, INRA, UMR 547 PIAF, F-63100 Clermont Fd Cedex 01, France, Clermont Université, Université Blaise Pascal, UMR 547 PIAF, BP 10448, F-63000 Clermont-Ferrand, France, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.