Evaluation of the chitinase activity in papaya fruit at different phenological stages as a possible biomarker for the detection of Colletotrichum gloeosporioides infection

Worldwide, papaya is a highly consumed fruit; however, they are very susceptible to the attack of the fungus Colletotrichum gloeosporioides. The fungal cell wall has mostly chitin, which is degraded by the chitinases enzymes that are synthesized as part of the plant's defence system. For diagnose a fungal disease, it is necessary to find a biological indicator as well-referred to as biomarkers which in turn could be detected through biosensors. Until now, there was no information about the activity of the chitinases in inoculated and stored papaya, at different phenological stages (preharvest stage) of the fruit and during storage (postharvest stage). The results showed higher activity of the enzyme in those stages close to the harvest period (c.a. 42 and 113 IU mg⁻¹ protein) and lower activity (0 IU mg⁻¹ protein) at the senescence stage during postharvest; meanwhile, in papayas artificially inoculated with C. gloeosporioides, at both the pre and postharvest stages, the chitinolytic activity increased, although, decreased as storage days progressed. Based on these results, chitinase activity in papaya could act as an indicator of the fungal growth for further use in the design of a biosensor for the detection of this fungus.