Dual Role of Phenolic Bioactives in Improving Functional Health Benefits and Abiotic Stress Resilience in Barley

Food insecurity, climate change, and public health challenges are interconnected and pressing issues facing humanity in the 21st century. Therefore, it is imperative to address key obstacles underlying food and nutritional insecurity by developing strategies to concurrently improve the nutritional benefits and environmental stress resilience of food crops. The metabolic and physiological roles of plant-derived phenolic compounds are particularly relevant in addressing these challenges. Phenolic compounds are an integral part of plant adaptive defense responses against biotic and abiotic stresses. When consumed as part of diet, certain phenolic compounds from plant-based foods also provide wider protection against metabolic breakdowns and related health risks associated with non-communicable chronic diseases (NCDs). Therefore, the central theme of this dissertation is to delineate the dual protective roles of phenolic compounds in improving crop stress resilience and their human health protective functions, specifically antioxidant and anti-hyperglycemic benefits supporting management of early stages of type 2 diabetes. Barley was used as a model crop; initially several malting barley samples were screened based on their phenolic-linked antioxidant and anti-hyperglycemic functions using in vitro assay models. Following metabolically driven screening, novel bioprocessed elicitor treatments such as marine protein hydrolysates and chitosan oligosaccharides were used as seed and foliar treatments to improve type 2 diabetes supporting dietary functions through upregulation of proline-associated pentose phosphate pathway (PAPPP), which is linked to the biosynthesis of phenolic metabolites. Improvement of phenolic biosynthesis and type 2 diabetes related benefits were observed in grains and sprouts with targeted elicitor treatments. Further, elicitor treatments were also found to positively improve PAPPP-linked metabolic responses under abiotic stresses, such as high soil salinity and water logging stress. From a human health perspective, food barley tea and coffee were found to have significant phenolic-linked antioxidant, and anti-hyperglycemic benefits. Additionally, integrated bioprocessing strategy by combining sprouting with mixed Kefir culture-mediated fermentation was found to improve phenolic-linked antioxidant, anti-hyperglycemic, and human gut health benefits relevant functionalities in pigmented and unpigmented food barley substrates. Therefore, these metabolically driven strategies can be targeted to screen both abiotic stress resilience and human health protective functions in malting and food barley varieties