Developmentally-specific physiological and metabolic responses support drought resilience in switchgrass and constrains biofuel yield

Basyal, B.; Li, X.; Pargulski, V.; Fu, X.; Nightingale, N.; Overmyer, K.; Coon, J.; Zhang, Y.; Benucci, G. M. N.; Last, R.; Sato, T.; Walker, B.

doi:10.1101/2025.05.29.656847

bioRxiv · 10.1101/2025.05.29.656847

Developmentally-specific physiological and metabolic responses support drought resilience in switchgrass and constrains biofuel yield

Basyal, B.·Li, X.·Pargulski, V.·Fu, X.·Nightingale, N.·Overmyer, K.·Coon, J.·Zhang, Y.·Benucci, G. M. N.·Last, R.·Sato, T.·Walker, B.

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Abstract

Switchgrass (Panicum virgatum) is a promising bioenergy crop due in part to its resilience to drought stress. However, the significance of drought timing remains poorly understood, both from a plant biology perspective and its impact on downstream biofuel production. This study determines the developmental stage-specific physiological and metabolic responses of switchgrass to drought stress and its implications for biofuel production using a custom-built programmable irrigation system. Vegetative, flowering, and senescence-stage drought significantly reduced CO2 assimilation, and stomatal conductance without affecting biomass yield. Metabolic profiling revealed significant accumulation of glucose, fructose, quinic acid, shikimate and GABA during vegetative-stage drought, while flowering and senescence stages exhibited limited metabolic changes. Similarly, specialized metabolites also displayed distinct developmental patterns, with vegetative-stage drought driving the most pronounced metabolic alterations. Thermochemically-treated and hydrolyzed switchgrass biomass from vegetative-stage drought showed elevated lignocellulose-derived compounds and saponins with the latter most positively correlating with fermentation lag times. Conversely, senescence-stage drought enhanced ethanol yields while lowering saponin levels in the hydrolysates. While vegetative-stage drought enhanced physiological resilience, it compromises downstream biofuel production by introducing fermentation inhibitors, particularly saponins.

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Basyal, B., Li, X., Pargulski, V., Fu, X., Nightingale, N., Overmyer, K., Coon, J., Zhang, Y., Benucci, G. M. N., Last, R., Sato, T., Walker, B.. 2025-06-01. Developmentally-specific physiological and metabolic responses support drought resilience in switchgrass and constrains biofuel yield. https://doi.org/10.1101/2025.05.29.656847

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