Genetic resources of energy crops: Biological systems to combat climate change

Bioenergy crop plants that function as solar energy collectors and thermo-chemical energy storage systems are the basis for biological systems that are expected to contribute to renewable energy production, help stabilize the rising levels of green house gases (GHG), and mitigate the risk of global climate change (GCC). Wide genetic resource bases, especially of wild and semidomesticated perennial grasses and woody species of starch-, oil, and lingocellulose-producing plants, are available to select, breed, genetically-modify, and develop environmentally-friendly bioenergy crops. Plant species, with fast growth, tolerance to biotic and abiotic stresses, and low requirements for biological, chemical or physical pretreatments, are being evaluated as potential bioenergy crops. Currently, bioenergy systems based on traditional sources and first generation bioenergy crops, are not sustainable and their exploitation may contribute to environmental degradation. New genetic resources and technological breakthroughs are being employed to develop dedicated bioenergy crops (DECs) with better GHG profiles and with a suite of eco-physiological traits to maximize radiation interception, water- (WUE) and nutrient-use efficiencies (NUE), improved lingocellulosic accessibility to enzymatic degradation, and to confer environmental sustainability. Large-scale bioenergy crop plantations pose both opportunities and challenges, and will inevitably compete with food crops for land, water, nutrient resources and other inputs; whereas, biodiversity consequences of increased biofuel production will most likely result in habitat loss, increased and enhanced dispersion of invasive species, and pollution. Recent genetic modifications and breeding efforts of bioenergy crops aim at improving biomass yield, quality, and conversion efficiency. Improvements in composition and structure of bio-chemicals in bioenergy crops will enable the production of more energy per ton of biomass and will improve its caloric value, GHG profile, and GCC mitigation potential.