Technical and biotechnology innovations in perennial lignocellulosic crops for the production of bioenergy, green building and furniture panels

Bioeconomy is the knowledge-based production and utilization of biological resources to provide products, processes and services in all sectors of trade and industry within the framework of a sustainable economic system. Based on this ambitious definition, it follows that bioeconomy growth will require a sufficient supply of sustainably produced biomass (Scarlat et al., 2015). Sustainable biomass, produced in quantity and quality, for specific end–uses is thus the core issue of the bioeconomy. Initially, food crops (i.e., maize, sugarbeet, rapeseed, sugarcane, among others) have been used as biomass source to produce energy and biofuels. These are known as first generation feedstock, that led to food versus fuel debates, land use change scenarios and other environmental concerns. The promotion of advanced biofuels from non-food, cellulosic material (second generation), including non-edible perennial grasses, is expected to play an important role in the bioeconomy beyond 2020, minimizing the competition with food crops and on land use changes. Most promising perennial grasses (Arundo donax, Miscanthus spp., Panicun virgatum and Saccharum spontaneum, in this study) are still undomesticated types with specific traits of resistance and phenotypic plasticity and the ability to thrive under unfavourable biophysical conditions typically encountered in marginal lands (Cosentino et al., 2014; Cosentino et al., 2015; Alexopoulou et al., 2015). Growing a bioenergy crop in marginal lands, unsuitable for food crops, has been proposed as a viable alternative to avoid land-use competition for food production and security, land-based greenhouse gas emission emissions and biodiversity loss.
The scientific community has recognized several sustainable advantages of perennial grasses as biomass crops: reduced soil tillage, long productive cycle (10-25 years), low fertilizers requirements, efficient use of resources, little or any herbicide and pesticide application. Taken together, an overall sustainability of the cultivation phase is achieved. In addition, the biomass composition made up by cellulose, hemicellulose and lignin, makes these crops suitable for thermochemical and biochemical processes for energy application, and other alternative uses towards the bio-based economy. In the biofuel context, the European Directive 2015/1513 considers the energy content of the second generation biofuels twice as high as the first generation one. Perennial grasses as Panicum virgatum, Miscanthus spp. and Arundo donax from which advanced biofuels can be produced are already in the “white-list”.
Besides being largely undomesticated, many perennial grass species including Arundo donax, Saccharum spontaneum and Miscanthus x giganteus propagate vegetatively and suffer of extremely reduced genetic diversity. In this context, formal genetic improvement based on cross and selection is totally precluded. In order to circumvent this constraint a strategy based on mutagenesis followed by clonal selection was recently proposed and applied in Arundo by one partner of this proposal (Valli et al. 2017). In Saccharum there are no evidence of breeding strategies to date. On the other hand, genotypes within the three species groups of Miscanthus: sinensis, sacchariflorus and floridulus can inter-hybridise (Clifton-Brown et al., 2017). Certain combinations result in strong heterosis effects enhancing key traits such as net photosynthesis and biomass yield. The Aberystwith University have partnered with the University of Catania for the past 8 years on a succession of breeding projects with industrial investment. In 2016, more than 2 million seeds were produced from an interspecific crossing experiment (Hasting A, et al., 2017).
This circumstance might open a new dimension for biomass yield and quality improvements; besides this, a lot still remains to optimize the cultivation, logistic and bioconversion phases of these relatively new crops.
To this end, the present proposal attempts to overcome specific bottlenecks related to the bioenergy chain involving lignocellulosic perennial grasses (Miscanthus spp. Arundo donax, Panicum virgatum, Saccharum spontaneum spp. aegyptiacum, in this study), such as: innovative propagation methods – WP1 (Cavallaro et al., 2014; Scordia et al., 2015; Clifton-Brown et al., 2017), strategy based on mutagenesis followed by clonal selection – WP2 (Valli et al., 2017), testing under abiotic stresses that characterize marginal lands in Mediterranean area (i.e., drought, salinity and contaminated stress condition) - WP3, advanced biofuels production (i.e., second generation bioethanol and methane production via biochemical routes) and non-energy applications – WP4, and multi-criteria evaluation of the sustainability of the entire value chain by taking into account technological, environmental, economic and socio-economic aspects (WP5).