Breeding for stem cell wall digestibility in alfalfa

The extensive genetic variability for cell wall (CW) digestibility in alfalfa (Medicago sativa L.) can be exploited for genetic improvement (Duceppe et al., 2012). However, one of the limitations is the availability of screening techniques for identification of superior genotypes.A screening approach was developed to identify genotypes with high CW digestibility using enzyme-release glucose (ERG), i.e. glucose released from CW following enzymatic hydrolysis (Bertrand et al., 2014; Duceppe et al., 2012). Using this screening method, our objectives were to evaluate:
the direct effect of a divergent phenotypic selection on stem ERG in alfalfa
the indirect effects of this selection on plant biomass and stem water soluble carbohydrate concentration (WSC).
Alfalfa stem CW digestibility, based on stem ERG concentration, can be increased by genetic selection. The increase in ERG with two cycles of selection (ERG+2) had no negative effect on plant biomass and stem WSC concentration. Phenotypic selection based on stem ERG concentration is a very promising approach to improve alfalfa stem CW digestibility without reducing plant biomass and stem WSC concentration.