Terahertz spectroscopy and imaging as a tool to unlock physiological and molecular mechanisms for drought resistance of agaves.

This article summarizes the findings of two of our own contributions and presents additional measurements that make us reach a conjecture about the physiological and molecular mechanisms that confer agaves their extraordinary capacity to withstand drought conditions. In these studies, we used terahertz (THz) spectroscopy and imaging to investigate the water retention mechanisms of agaves as well as the hydration dynamics of agave fructans, which are a peculiar type of carbohydrate produced by these plants. THz imaging was applied to map water distribution across different tissue regions, revealing a highly hydrated region in the core of the leaves and a less hydrated layer in the outside. Additionally, THz spectroscopy was used to study the hydration behavior of agave fructans in aqueous solutions. The hydration number and absorption coefficient increased nonlinearly with decreasing solute concentrations, reflecting the formation of complex hydration layers around these carbohydrates with an outstandingly large number of water molecules (∼320), which is 2 to 4 times larger than that of other carbohydrates such as inulin or maltodextrin. The findings underscore the importance of fructans in stabilizing membranes and enhancing drought tolerance by managing water at both tissue and molecular levels. This study demonstrates the versatility of THz technologies in plant science, offering a comprehensive approach to understanding water retention and hydration dynamics, with potential applications in improving agricultural practices for water-scarce environments.