Revealing the molecular and physiological responses to water deficit in the bioenergy crop Miscanthus x giganteus

Abstract

High yielding perennial biomass crops of the species Miscanthus are widely recognized as one of the most promising lignocellulosic feedstocks for the production of bioenergy and bioproducts. Cultivated Miscanthus comprises primarily of a single clone, Miscanthus x giganteus, which is high yielding and expresses a desirable combination of many traits present in the two parental species; however, responds poorly to low water availability. Despite this, there is little knowledge of the mechanisms involved in the drought response and recovery. This work forms the first major steps in the dissection of the drought response in M. x giganteus. To identify the physiological basis of the response to water stress in M. x giganteus the physiological responses to water-deficit stress where characterised in multiple pot experiments. Withholding water resulted in marked changes in plant physiology with growth-associated traits among the first affected. A reduction in photosynthetic performance was among the second set of changes observed; indicated by a decrease in stomatal conductance followed by decreases in chlorophyll fluorescence and chlorophyll content. Metabolite profiling and RNA-seq analysis were integrated and indicated changes in metabolites and genes associated with drought including involvement in proline, hormone and fatty acid biosynthesis, as well photosynthesis and respiration. Determining the ability of the plants to regrow after a period of water deficit has enabled tentative identification of the critical drought point from which the rhizome can no longer recover and has provided further insight into the balance between withstanding water deficit and biomass accumulation. The study has provided valuable insights into the temporal aspects of drought-induced responses of M. x giganteus. The outcomes in terms of drought-induced physiological changes and recovery, accompanied by a metabolomics and RNA-seq investigation, provide a platform for identifying targets for improved drought-tolerance of the Miscanthus bioenergy crop and possibly other plants beyond perennial biomass crops.

Date of Award	2015
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Maurice Bosch (Supervisor) & Paul Robson (Supervisor)