Abstract
BackgroundMiscanthus is a commercial lignocellulosic biomass crop owing to its high biomass productivity, resilience and photosynthetic capacity at low temperature. These qualities make Miscanthus a particularly good candidate for temperate marginal land, where yields can be limited by insufficient or excessive water supply. Differences in response to water stress have been observed among Miscanthus species, which correlated to origin. In this study, we compared the physiological and molecular responses among Miscanthus species under excessive (flooded) and insufficient (drought) water supply in glasshouse conditions.ResultsA significant biomass loss was observed under drought conditions in all genotypes. M. x giganteus showed a lower reduction in biomass yield under drought conditions compared to the control than the other species. Under flooded conditions, biomass yield was as good as or better than control conditions in all species. 4389 of the 67,789 genes (6.4%) in the reference genome were differentially expressed during drought among four Miscanthus genotypes from different species. We observed the same biological processes were regulated across Miscanthus species during drought stress despite the DEGs being not similar. Upregulated differentially expressed genes were significantly involved in sucrose and starch metabolism, redox, and water and glycerol homeostasis and channel activity. Multiple copies of the starch metabolic enzymes BAM and waxy GBSS-I were strongly up-regulated in drought stress in all Miscanthus genotypes, and 12 aquaporins (PIP1, PIP2 and NIP2) were also up-regulated in drought stress across genotypes.ConclusionsDifferent phenotypic responses were observed during drought stress among Miscanthus genotypes from different species, supporting differences in genetic adaption. The low number of DEGs and higher biomass yield in flooded conditions supported Miscanthus use in flooded land. The molecular processes regulated during drought were shared among Miscanthus species and consistent with functional categories known to be critical during drought stress in model organisms. However, differences in the regulated genes, likely associated with ploidy and heterosis, highlighted the value of exploring its diversity for breeding.
Highlights
Miscanthus is a commercial lignocellulosic biomass crop owing to its high biomass productivity, resilience and photosynthetic capacity at low temperature
Responses of each genotype were evaluated in terms of electrolyte leakage, relative water content (RWC) at two time points, and fresh and dry biomass weight (Fig. 1; Additional file 1: Figure S1: fresh and dry biomass by genotype with non-log transformed data)
When comparing drought, flooded and control conditions, high mean electrolyte leakage was recorded for Msac-G1, Msin-G2, Mxg-G5 and Hyb-G6 under flooded conditions, indicating stress induced by excess water
Summary
Miscanthus is a commercial lignocellulosic biomass crop owing to its high biomass productivity, resilience and photosynthetic capacity at low temperature. These qualities make Miscanthus a good candidate for temperate marginal land, where yields can be limited by insufficient or excessive water supply. De Vega et al Biotechnol Biofuels (2021) 14:60 related, perennial, and able to grow on marginal lands, having high biomass yield, low chemical and mechanical input requirement, and enhanced water-use efficiency and high carbon storage capacity [2,3,4]. Because of its high biomass yield and high lignocellulose content, Miscanthus spp. are presently commercially used as feedstock for bioenergy production [7,8,9,10]. A study on its biofuel capacity showed that Miscanthus was more efficient in ethanol production per hectare than switchgrass and corn [15]
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