Postharvest water loss-induced transcriptomic reprogramming modulates non-structural carbohydrate remobilization in Quercus texana kernels

Abstract

Quercus texana Buckley (Nuttall oak) acorns contain up to 46 % carbohydrates, making them a potential high-quality starch-based or sugar-based raw material for the production of food, feeds, value-added biochemicals, biomaterials, biofuels, and bioenergy. Natural air drying is a commonly used and economically friendly postharvest processing method of Nuttall oak acorns. However, the physiological changes and molecular mechanisms underlying postharvest dehydration in Nuttall oak kernels remain poorly understood. Here, we conducted a comprehensive analysis of physiological, transcriptomic, and metabolomic changes of postharvest Nuttall oak kernels. A general increase in soluble sugar, starch, and total non-structural carbohydrate (NSC) contents was observed, along with a fluctuating reduction in starch allocation ratios during postharvest natural dehydration. A time-course and comparative transcriptomics and metabolomics analysis revealed dramatic alterations in gene expression and metabolite accumulation induced by water loss, and multiple carbohydrate metabolism and energy production-related pathways and TF genes were involved in this process, including “Starch and sucrose metabolism”, “Glycolysis/Gluconeogenesis”, and “Citrate cycle”. Notably, postharvest water loss-triggered transcriptomic reprogramming modulated metabolomic landscape remodeling, especially NSC remobilization in Nuttall oak kernels. Overall, these results implied that postharvest natural water loss-induced transcriptomic reprogramming modulated NSC remobilization in Nuttall oak kernels. Hopefully, our present findings will provide valuable insights into the molecular and metabolic mechanism governing NSC in Nuttall oak kernels during postharvest. Additionally, this research may serve as a reference for postharvest preservation of Nuttall oak acorns and even genetic and bioengineering improvements.