AUTHOR=Ings Jennifer , Mur Luis A., Robson Paul R., Bosch Maurice 

TITLE=Physiological and growth responses to water deficit in the bioenergy crop Miscanthus x giganteus

JOURNAL=Frontiers in Plant Science

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2013.00468

DOI=10.3389/fpls.2013.00468

ISSN=1664-462X

ABSTRACT=<p>High yielding perennial biomass crops of the species <italic>Miscanthus</italic> are widely recognized as one of the most promising lignocellulosic feedstocks for the production of bioenergy and bioproducts. <italic>Miscanthus</italic> is a C<sub>4</sub> grass and thus has relatively high water use efficiency. Cultivated <italic>Miscanthus</italic> comprises primarily of a single clone, <italic>Miscanthus</italic> x <italic>giganteus</italic>, a sterile hybrid between <italic>M. sacchariflorus</italic> and <italic>M. sinensis</italic>. <italic>M.</italic> x <italic>giganteus</italic> is high yielding and expresses desirable combinations of many traits present in the two parental species types; however, it responds poorly to low water availability. To identify the physiological basis of the response to water stress in <italic>M.</italic> x <italic>giganteus</italic> and to identify potential targets for breeding improvements we characterized the physiological responses to water-deficit stress in a pot experiment. The experiment has provided valuable insights into the temporal aspects of drought-induced responses of <italic>M.</italic> x <italic>giganteus</italic>. Withholding water resulted in marked changes in plant physiology with growth-associated traits among the first affected, the most rapid response being a decline in the rate of stem elongation. 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. Measures reflecting the plant water status were among the last affected by the drought treatment. Metabolite analysis indicated that proline was a drought stress marker in <italic>M.</italic> x <italic>giganteus</italic>, metabolites in the proline synthesis pathway were more abundant when stomatal conductance decreased and dry weight accumulation ceased. The outcomes of this study in terms of drought-induced physiological changes, accompanied by a proof-of-concept metabolomics investigation, provide a platform for identifying targets for improved drought-tolerance of the <italic>Miscanthus</italic> bioenergy crop.</p>