Sorbitol immersion accelerates the deposition of suberin polyphenolic and lignin at wounds of potato tubers by activating phenylpropanoid metabolism

Abstract

Sorbitol is the primary product of photosynthesis and sugar metabolism in plants. However, the mechanism by which sorbitol treatment affects potato tuber wound healing remains unclear. This study showed that sorbitol treatment reduced weight loss and disease index (inoculated with Fusarium sulphureum) of tubers during healing. Sorbitol also facilitated the accumulation of suberin polyphenolic (SPP) and lignin at the wounded sites. Sorbitol treatment activated the activities of phenylalanine ammonia-lyase (PAL), 4-coumaryl-CoA ligase (4CL), cinnamic acid-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD), and increased the levels of individual phenolic acids and lignin monomers. In addition, sorbitol treatment increased the H2O2 level and peroxidase (POD) activity. It was suggested that sorbitol treatment could activate phenylpropanoid metabolism, and promote SPP and lignin deposition at the wound sites of potato tubers.