Influence of light-enhanced glycoalkaloids on resistance of potato tubers to Fusarium sulphureum and Fusarium solani var. coeruleum

Abstract

Increases in resistance to Fusarium sulphureum and Fusarium solani vat. coeruleum were determined in seed tubers of cultivars Desiree, Pentland Hawk and Kerr's Pink with light-enhanced glycoalkaloids. Glycoalkaloid concentration in the tubers ranged from 78-0 to 885.9 mg kg-1 fresh weight. Exposure of tubers to light prior to inoculation decreased fungal invasion, the greater reductions generally reflecting longer light exposure periods. In most cases, no direct relationship between resistance and glycoalkaloid concentrations was recorded for F. sulphureum. Surface infection indices and reduced depth of rot caused by F. solani vat. coeruleum were closely correlated with tuber glycoalkaloid content. No significant effects on spore length and width were recorded. Exposure to light of seed tubers that are not destined for human or animal consumption could provide a pretreatment to reduce fungal invasion by F. sulphureum and F. solani vat. coeruleum.