Physiological and Molecular Analysis of Drought Stress Responses in Miscanthus: Identifying Important Traits for Biofuel Production from Analysis of Networks

Miscanthus is a genus of C4 perennial grasses of great interest for the production of biorenewable energy and chemicals because of high biomass potential even in temperate regions. Yield is strongly linked to water availability and many sites across Europe where irradiation and temperature are favourable for Miscanthus cultivation have limited water supply. The aim of the research is to investigate in detail the response of diverse genotypes to reduced water availability, including the hybrid M. x giganteus that is grown for the majority of the crop and two exemplar genotypes from each of the species groups, M. sacchariflorus and M. sinensis, that hybridized to form M. x giganteus.

The five Miscanthus genotypes were subjected to two treatments, well-watered and mild drought, for 32 days under glasshouse conditions. Morphological and physiological measurements were made including growth rate, photosynthetic performance and water use efficiency. Plants were sampled at two time points to identify early and late responses to drought. Analyses included RNA sequencing for gene expression profiling and for compositional analysis of biomass (lignin, cellulose). The glasshouse measurements showed treatment affects differed between genotypes. From 116343 identified genes, 1219 were differentially expressed between control and drought treatments across all genotypes. Additionally 61 genes were found to be differentially expressed between the genotypes under drought compared to controlled conditions.

By comparing molecular, physiological and compositional responses to mild drought, we hope to identify pathways responsible for drought resistance and sensitivity and improve selections for plants with good biomass production under water stress.