Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)

Papaya (Carica papaya L.) contain high nutritive value and very susceptible to postharvest decay. Major postharvest disease related to papaya fruit is anthracnose, caused by Colletotrichum gloeosporioides. Postharvest fungicide treatments are very popular for the disease control due to it fast and b...

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Main Author:	Hassan, Hamizah
Format:	Thesis
Language:	English
Published:	2017
Subjects:	Fruit - Postharvest diseases and injuries Papaya
Online Access:	http://psasir.upm.edu.my/id/eprint/70395/1/FP%202017%2034%20IR.pdf
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spelling	my-upm-ir.703952019-08-16T07:34:58Z Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.) 2017-07 Hassan, Hamizah Papaya (Carica papaya L.) contain high nutritive value and very susceptible to postharvest decay. Major postharvest disease related to papaya fruit is anthracnose, caused by Colletotrichum gloeosporioides. Postharvest fungicide treatments are very popular for the disease control due to it fast and broad spectrum effects. However, withdrawal of a few commercial fungicides due to its negative effects on human, environment and produce increased public concerns and demands to other safer alternatives of control measures. Among all, biological control using microorganism to fight against host pathogens provides a positive results. However, limited studies done in Malaysia regarding the use of yeast as biocontrol agent for postharvest disease. Thus, this study was carried out with aim to develop a locally isolated, yeast antagonist agent for controlling anthracnose disease on papaya. In the first experiment, isolation of natural yeast on papaya plant was carried out. A total of 110 yeasts were isolated and tested for their antagonist activity against C. gloeosporioides. After a series of initial screening tests for antagonism, two yeasts, namely F001 and FL013 showed higher antagonistic activity against the pathogen were selected. Both F001 and FL013 showed better antagonist activity when concentration of yeast cells were increased from 5 x 104 to 5 x 108 cells mL-1 in fungal spore germination test. Both yeasts also showed their ability to work well in cold storage condition and significantly inhibited the mycelial growth up to 70% using FL013 dipping treatment. However, only F001 has the ability to produce diffusible antifungal compounds which caused total suppression (100%) on the fungal growth. Thus, by referring to previous results, only F001 was identified and used in next experiments. Yeast F001, identified as Trichosporon asahii, also exhibited direct attachment on pathogen to control fungal hyphae growth and able to colonize well on papaya peel. In the next experiment, suitable additives for combining with T. asahii to improve antagonist activity of the yeast was investigated. Results showed that combination of T. asahii with calcium chloride able to totally suppress the pathogen growth in in vitro test. For in vivo test, combination of T. asahii with calcium chloride at 2.5% (w/v) caused reduction in disease severity until 83% as compare to control fruit. This treatment combination was chosen and used in the subsequent studies. Next, effect of utilizing this treatment combination on disease incidence, disease severity, total phenolic, total flavonoid and antioxidant activity were evaluated. Results showed that T. asahii with 2.5% calcium chloride coating on ‘Solo’ papaya was capable to reduce disease severity but not able to significantly increase the activity of those phytochemicals. The treatment also showed that no interaction effect with storage day on defense-related enzyme, including polyphenol oxidase, phenylalanine ammonia lyase and catalase activity. However, treatment application on the fruit did not influence the quality and storability of papaya after stored at 12 °C for 28 days. Fruit - Postharvest diseases and injuries Papaya 2017-07 Thesis http://psasir.upm.edu.my/id/eprint/70395/ http://psasir.upm.edu.my/id/eprint/70395/1/FP%202017%2034%20IR.pdf text en public doctoral Universiti Putra Malaysia Fruit - Postharvest diseases and injuries Papaya
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English
topic	Fruit - Postharvest diseases and injuries Papaya
spellingShingle	Fruit - Postharvest diseases and injuries Papaya Hassan, Hamizah Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
description	Papaya (Carica papaya L.) contain high nutritive value and very susceptible to postharvest decay. Major postharvest disease related to papaya fruit is anthracnose, caused by Colletotrichum gloeosporioides. Postharvest fungicide treatments are very popular for the disease control due to it fast and broad spectrum effects. However, withdrawal of a few commercial fungicides due to its negative effects on human, environment and produce increased public concerns and demands to other safer alternatives of control measures. Among all, biological control using microorganism to fight against host pathogens provides a positive results. However, limited studies done in Malaysia regarding the use of yeast as biocontrol agent for postharvest disease. Thus, this study was carried out with aim to develop a locally isolated, yeast antagonist agent for controlling anthracnose disease on papaya. In the first experiment, isolation of natural yeast on papaya plant was carried out. A total of 110 yeasts were isolated and tested for their antagonist activity against C. gloeosporioides. After a series of initial screening tests for antagonism, two yeasts, namely F001 and FL013 showed higher antagonistic activity against the pathogen were selected. Both F001 and FL013 showed better antagonist activity when concentration of yeast cells were increased from 5 x 104 to 5 x 108 cells mL-1 in fungal spore germination test. Both yeasts also showed their ability to work well in cold storage condition and significantly inhibited the mycelial growth up to 70% using FL013 dipping treatment. However, only F001 has the ability to produce diffusible antifungal compounds which caused total suppression (100%) on the fungal growth. Thus, by referring to previous results, only F001 was identified and used in next experiments. Yeast F001, identified as Trichosporon asahii, also exhibited direct attachment on pathogen to control fungal hyphae growth and able to colonize well on papaya peel. In the next experiment, suitable additives for combining with T. asahii to improve antagonist activity of the yeast was investigated. Results showed that combination of T. asahii with calcium chloride able to totally suppress the pathogen growth in in vitro test. For in vivo test, combination of T. asahii with calcium chloride at 2.5% (w/v) caused reduction in disease severity until 83% as compare to control fruit. This treatment combination was chosen and used in the subsequent studies. Next, effect of utilizing this treatment combination on disease incidence, disease severity, total phenolic, total flavonoid and antioxidant activity were evaluated. Results showed that T. asahii with 2.5% calcium chloride coating on ‘Solo’ papaya was capable to reduce disease severity but not able to significantly increase the activity of those phytochemicals. The treatment also showed that no interaction effect with storage day on defense-related enzyme, including polyphenol oxidase, phenylalanine ammonia lyase and catalase activity. However, treatment application on the fruit did not influence the quality and storability of papaya after stored at 12 °C for 28 days.
format	Thesis
qualification_level	Doctorate
author	Hassan, Hamizah
author_facet	Hassan, Hamizah
author_sort	Hassan, Hamizah
title	Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
title_short	Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
title_full	Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
title_fullStr	Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
title_full_unstemmed	Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)
title_sort	antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (carica papaya l.)
granting_institution	Universiti Putra Malaysia
publishDate	2017
url	http://psasir.upm.edu.my/id/eprint/70395/1/FP%202017%2034%20IR.pdf
_version_	1747812829304455168

Antagonist yeast for biocontrol of postharvest anthracnose disease on papaya (Carica papaya L.)

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