Bio-control activity of Pichia anomala supplemented with chitosan against Penicillium expansum in postharvest grapes and its possible inhibition mechanism

Blue mold decay caused by Penicillium expansum is one of the recently identified diseases of grapes (Vitis vinifera). The increasing concern about the use of chemical substances and pesticides in postharvest fruit pushes the trends of research toward bio-control strategies which are more sustainable and eco-friendly. This study determined the bio-control efficacy of Pichia anomala alone and supplemented with 1% chitosan in the grapes against blue mold disease. The result showed that chitosan (1%) better induced the bio-control efficacy of P. anomala. P. anomala supplemented with 1% w/v chitosan significantly reduced the disease incidence, lesion diameter and natural decay of grapes without affecting the fruit quality compared to the control. In addition it enhanced the activities of disease defence related enzymes like ascorbate peroxidase (APX) and chitinase (CHI); and decreased the formation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) which are responsible for fruits deterioration. The scanned electron microscope (SEM) concisely illustrates how the high denser yeast cells on the wounds reduced the growth of P. expansum mycelia. So it can be concluded that, P. anomala alone or P. anomala supplemented with 1% w/v chitosan can be presented as a potential bio-control alternative against the postharvest blue mold of grapes.