Abstract
This study aimed to control the common fungi causing post-harvest black rot of Taify table grape (Vitis vinefra L.) and to induce resistance against black Aspergilli. Six fungal genera belonging to Aspergillus, Penicillium, Trichoderma, Mucor, Rhizopus and Botrytis were isolated from contaminated grape samples, with different frequencies. The predominant fungal species belonged to the genus Aspergillus and the isolation frequency ranged between 2.40-18.66%. The most predominant black Aspergilli were identified to the molecular level based on 18S-rRNA, ITS1 and 5.8S-rRNA gene sequence as A. niger BAVSH1, A. parasiticus BAVSH4 and A. tubingensis BAVSH5. Forty one bacterial isolates were obtained from soil, meswak and the surface of grape fruits, and screened for antagonistic activity. In vitro dual microbial culture showed variable % inhibition of fungal growth values. Out of the active antagonistic bacteria, five epiphytic from grape fruits and one from meswak, being the most antagonistic were identified to the molecular level based on 16S rRNA gene sequence as Pseudomonas aeruginosa EBMSH1, P. aeruginosa EBVSH13, P. aeruginosa EBVSH14, P. aeruginosa EBVHSH17, Bacillus vallismortis EBHVSH28 and B. amyloliquefaciens EBHVSH29. The ability of living cells or crude cell extracts of the best three latter antagonistic bacteria to induce the resistance in pre-wounded and intact- flooded grape fruits against black Aspergillus rot disease progress were demonstrated. Higher reduction or complete absence of disease incidence% and lesion diameter were obtained in intact, pre-wounded and living bacteria treated fruits than untreated control. This was clearer in flooding treatments with crude cell extract and living bacteria, compared to some of the wounded and induced by living bacteria and no treated control.