Mango resistance against Ceratocystis fimbriata is impaired by local starch mobilization

Mango wilt, caused by Ceratocystis fimbriata, is one of the most serious diseases affecting mango production worldwide. Considering the great variation in the basal level of wilt resistance among mango cultivars, this study aimed to assess changes in photosynthesis and the role played by the carbon metabolism on two mango cultivars with contrasting responses to C. fimbriata infection. Assessment of disease and plant physiology variables was performed over 21 days. The response of the mango cultivars against fungal infection was associated with an increase on the mobilization of starch from the leaf tissue around the infection sites on stems. Plants of cv. Uba were less susceptible to mango wilt and, presumably, better capable of mobilizing reserves for the production of defense compounds, which prevented colonization of the stem inner tissues and the consequent disruption of xylem hydraulic conductivity and leaf photosynthesis. On the other hand, the inability in mobilizing and targeting carbon for the production of defense-related compounds should have accounted for the higher susceptibility of cv. Palmer to C. fimbriata infection.