Prospects for Hybrid Breeding in Bioenergy Grasses

Biofuels obtained from biomass have the potential to replace a substantial fraction of petroleum-based hydrocarbons that contribute to carbon emissions and are limited in supply. With the ultimate goal to maximize biomass yield for biofuel production, this review aims to evaluate prospects of different hybrid breeding schemes to optimally exploit heterosis for biomass yield in perennial ryegrass (Lolium perenne L.) and switchgrass (Panicum virgatum), two perennial model grass species for bioenergy production. Starting with a careful evaluation of current population and synthetic breeding methods, we address crucial topics to implement hybrid breeding, such as the availability and development of heterotic groups, as well as biological mechanisms for hybridization control such as self-incompatibility (SI) and male sterility (MS). Finally, we present potential hybrid breeding schemes based on SI and MS for the two bioenergy grass species, and discuss how molecular tools and synteny can be used to transfer relevant information for genes controlling these biological mechanisms across grass species.