Ca2+ Applications Affect the Phenylpropanoid Metabolism in Potato Tubers Induced by T-2 Toxin

The dry rot of potato caused by Fusarium sulphureum is the main postharvest disease that causes serious economic loss and leads to mycotoxin contamination. Therefore, it is necessary to find a strategy to increase the plant's resistance against disease. T-2 toxin at low concentration can act as an elicitor to induce resistance against disease. Calcium ion plays a vital role in induced resistance by responding the environmental stress in plant. In this study, the effect of Ca2+ on the development of dry rot, weight loss rate, the suberin polyphenolic (SPP) and suberin polyaliphatic (SPA) accumulation and their participation in phenylpropanoid metabolism were investigated in treated potato. The results showed that lesion diameter and weight loss rate significantly increased after ethylenebis (oxyethylenenitrilo) tetraacetic acid (EGTA) treatment, but the addition of exogenous Ca2+ noticeably inhibited the increase. The accumulations of SPP and SPA, enzymatic activities, gene expressions, as well as the contents of total phenols and lignin and their major substrates involved in phenylpropanoid metabolism were decreased after EGTA treatment, these indicators were recovered after the addition of exogenous Ca2+. Therefore, the results suggested that Ca2+ treatment induced resistance against dry rot, inhibited weight loss rate and accelerated the accumulation of SPP and SPA by activating phenylpropanoid metabolism in treated potato.