Metabolic stimulation of phenolic biosynthesis and antioxidant enzyme response in dark germinated barley (Hordeum vulgare L.) sprouts using bioprocessed elicitors.

Sprouting and seed elicitor treatments stimulate the biosynthesis of health relevant phenolic bioactives in plants partly by upregulating proline-associated pentose phosphate pathway (PAPPP). This study investigated the upregulation of PAPPP-linked and antioxidant enzyme associated metabolic responses in elicitor-treated barley (Hordeum vulgare L.) sprouts previously established with stimulation of health relevant phenolic bioactives. Barley seeds were treated with bioprocessed elicitors marine protein hydrolysates (GroPro®, GP) and soluble chitosan oligosaccharide and germinated under dark conditions. Upregulation of PAPPP and subsequent stimulation of phenolic biosynthesis and antioxidant enzyme responses were monitored at day 2, 4, and 6 of sprouting. High PAPPP-linked antioxidant enzyme responses were observed at early stages of germination with selected doses of GP treatments, especially in cv. Pinnacle. Total soluble phenolic content remained at higher level, while guaiacol peroxidase activity increased over the course of sprouting indicating increased phenolic polymerization to support structural needs of sprouts.