Selecting Antagonistic Yeast for Postharvest Biocontrol of Colletotrichum gloeosporioides in Papaya Fruit and Possible Mechanisms Involved

Hamizah Hassan,Erneeza Mohd Hata,Nor Elliza Tajidin,Siti Fairuz Yusoff,Mahmud Tengku Muda Mohamed

doi:10.3390/agronomy11040760

Hamizah Hassan, Erneeza Mohd Hata + Show 3 more

Open Access

https://doi.org/10.3390/agronomy11040760

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Abstract

Colletotrichum gloeosporioides causes anthracnose disease in papaya fruit resulting in tremendous economic loss due to its latent infection. This study aimed to evaluate the biocontrol activity of antagonistic yeasts against C. gloeosporioides in papaya and determine the possible mechanism involved. One hundred and ten yeast strains were isolated from different parts of the papaya plant. Among them, only five strains, namely F001, F006, L003, FL013 and LP010, showed more than 55% radial growth inhibition of C. gloeosporioides. These five potent yeast strains were further evaluated in vitro and in vivo. The results indicated that strain F001 had the strongest biocontrol activity based on spore germination and fungal growth inhibition. In vivo, the strain F001 caused 66.7% and 25% reductions in disease incidence and severity, respectively. Based on molecular identification, the strain F001 was confirmed as Trichosporon asahii. Despite there was no significant induction of defense enzyme activities found on the treated fruits, SEM observation showed direct attachment of T. asahii with the fungal hyphae and interfere in their establishment to the fruit surface. Based on these findings, the antagonistic yeast T. asahii strain F001 may be used as a potential natural biological control agent against anthracnose disease in papaya fruit.

Highlights

Anthracnose in papaya fruit is a devastating postharvest disease caused by Colletotrichum gloeosporioides where losses can be up to 62%, with disease incidence ranging from 90–98% in Malaysia [1]
A total of 110 yeasts strains were isolated from the leaves, petioles, and fruit surfaces of randomly selected papaya plants based on different colony colors, sizes and shapes
Out of the 25 yeast strains selected, only five isolates, namely, F001, F006, L003, FL013 and LP010, had more than 55% inhibitory effects compared to the control (0%)

Summary

Introduction

Anthracnose in papaya fruit is a devastating postharvest disease caused by Colletotrichum gloeosporioides where losses can be up to 62%, with disease incidence ranging from 90–98% in Malaysia [1]. The fungus infection generally starts during the flowering stage and remains dormant until postharvest when it becomes favorable for colonization on the fruit tissue. Postharvest infections may occur due to inoculum availability in the processing environment, and situation becomes worse when the fruit is subjected to considerable amount of wounding after harvest [2]. Synthetic fungicides are commonly used to protect perishable fruit and vegetable from postharvest fungal diseases due to their efficacy and convenience [3,4]. Prolonged use of registered chemicals fungicides result in declination in efficacy because of increasing pathogen-resistance [5,6]

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