~ 2302 ~ Journal of Pharmacognosy and Phytochemistry 2019; 8(3): 2302-2306 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2019; 8(3): 2302-2306 Received: 01-03-2019 Accepted: 03-04-2019 M Nandhini Department of Plant Pathology, Agricultural College and Research Institute, Madurai, Tamil Nadu, India S Harish Department of Plant Pathology, Agricultural College and Research Institute, Madurai, Tamil Nadu, India A Beaulah Department of Horticulture, Agricultural College and Research Institute, Madurai, Tamil Nadu, India K Eraivan Arutkani Aiyanathan Agricultural College and Research Institute, Killikulam, Tamil Nadu, India Correspondence S Harish Department of Plant Pathology, Agricultural College and Research Institute, Madurai, Tamil Nadu, India Antagonistic activity of epiphytic yeast against grapes mold caused by Rhizopus sp. M Nandhini, S Harish, A Beaulah and K Eraivan Arutkani Aiyanathan Abstract Post-harvest losses due to plant pathogens is a major problem in grapes which causes huge economic losses to the farmers in terms of quality and quantity. Yeast are unicellular organisms which exist on the fructosphere of crops and protects the plant from pathogens. In this study, yeast species has been exploited against Rhizopus sp. infecting grapes during the post-harvest stage. Thirty-three epiphytic yeasts on the surface of grapes were isolated from Madurai and Erode districts of Tamil Nadu and tested against Rhizopus sp. The results revealed that the yeast isolate, YCSL2 exhibited maximum inhibitory effect of 30.33% and 24.44% in dual culture and volatile compounds assay respectively over the control under in vitro. Similarly, wound site colonization of yeast against Rhizopus sp. recorded maximum inhibitory effect of 71.11% against the control under in vivo. Thus, the yeast species identified in this study can be used for the biological management of post-harvest pathogens in grapes. Keywords: Grapes, post-harvest pathogen, Rhizopus sp., volatile compounds, wound site colonization Introduction Grapes is one of the important fruit crops which is cultivated throughout the world for consumption and industrial purpose. Grapes cultivation is mainly affected by various biotic and abiotic stresses among which post-harvest pathogens cause huge economic loss. Post- harvest diseases of grapes mainly occur by high water content and sugar content in the fruit. Among post-harvest pathogens, Rhizopus mold caused by Rhizopus sp. occur at harvesting stage and storage condition. Rhizopus sp. quickly spread to entire areas of the fruit under favourable condition which leads to heavy economic losses. Grapes is also considered as a heavy pesticide utilizing crop and consuming the raw product will affect the human health. Based on public health concern and to avoid the fungicide resistance in pathogen, an alternative method for chemical management is the need of the day (Saravanakumar et al., 2008) [15] . During the last decades, beneficial microorganisms with antimicrobial properties have been isolated and utilized for the management of major diseases in horticultural crops (Kloepper et al., 1980) [7] . In some cases, plant and animal derived products was used as a biocontrol agent (Pal and Gardener, 2006) [12] . Biological control is a very useful approach for managing post- harvest diseases in grapes (Bleve et al., 2006) [3] . Yeasts are unicellular fungi that are found on/in the surface of fruits and are considered as a healthier biological control agent in post- harvest disease management, when compared to chemical fungicide (Kurtzman et al., 2011) [8] . Various groups throughout the world have utilized yeast strains for the management of post- harvest diseases of fruit crops (Saravanakumar et al., 2008) [16] . Yeast does not require luxurious components for their growth and require simple nutrient of dextrose, peptone etc. (Adel, 2004) [1] . Considerable progress has been made in understanding the action of yeast strains against pathogenic fungi (Spadaro and Droby, 2016) [17] . Other reports point to competition for space and nutrients and/or antibiosis by the protectant microorganisms as a major mechanism in disease control (Wilson and Wisniewski, 1989) [19] . In this paper, we have tested the efficacy of epiphytic yeast from the surface of grapes against Rhizopus sp. of grapes under laboratory condition. Materials and Methods Isolation of yeast from the fructosphere of grapes For yeast suspension preparation, ten grams of grapes were transferred to a beaker containing 100 ml of distilled water and shaked vigorously for 5-10 mins. Yeast extract peptone dextrose agar (YPD) (yeast extract powder-10g/lit, peptone-20g/lit, dextrose-20/lit and agar-20g/lit) media amended with streptomycin was prepared and sterilized. Serial dilution upto 10 -6 of the suspension was carried out and poured into the plates.