Biomechanical properties of Bioenergy Sorghum: Changes in Gene Expression Due to Mechanical Stimulation
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Bioenergy sorghum, a relatively new type of sorghum, has emerged as a potential source for biofuel owing to its large amount of biomass. This sorghum grows relatively tall (3-5 m) but commonly breaks and topples under wind, rain, hail or other mechanical stresses. A promising approach to reduce breakage is to develop new mechanically robust sorghum varieties. To do this will require a fundamental understanding of the biomechanical properties of stalks and identifying the genetic and environmental influences that produce stronger plants. Experiments have shown that mechanically stimulating the plants during growth can significantly change the physical and biomechanical characteristics of sorghum stems. This occurs because the mechanical load changes the growth of the cells in the plant stem. This mechanical stimulation causes adaptive growth that improves the mechanical properties of the stalk. This research will accelerate the development of new fuel-rich and mechanically robust varieties of sorghum, thereby leading to significant increases in food, feed, and biomass productivity. This project will provide undergraduate and graduate students with interdisciplinary professional and technical training. The team will also participate in a summer research experience for teacher (RET) program and summer camps to disseminate the study of biomechanics and genetics/epigenetics of sorghum to high school teachers and students.To accomplish these goals, this study will integrate experimental and computational studies of structural morphologies, biomechanical properties, physiology, and genetics/epigenetics of bioenergy sorghum stalks, to provide a fundamental explanation of stalk lodging (breaking) and to guide development of new lodging-resistant sorghum. The intellectual significance of this work resides in addressing the following fundamental topics: 1) uncovering the thigmomorphogenic response (response to mechanical stimulation) in tuning the biomechanical properties of bioenergy sorghum stalks, including investigating epigenetic changes, gene expression, and hormonal responses associated with the mechanical properties of stalks; 2) revealing the impact of the viscoelastic responses of stalks and their constituents (sclerenchymatous tissue and parenchymatous tissue with different cell wall structures) on stem lodging; and 3) providing structure-property-genetic/epigenetic relationships for stalks with superior biomechanical properties. Knowledge gained from this study will likely be transferable to other grasses, thereby extending the impact of the project.This award reflects NSF''s statutory mission and has been deemed worthy of support through evaluation using the Foundation''s intellectual merit and broader impacts review criteria.