IN VITRO SCREENING OF SIDEROPHORE-PRODUCERS FROM UPLAND RICE ROOT ENDOPHYTIC BACTERIA FOR ANTAGONISTIC ACTIVITIES AGAINST FUSARIUM OXYSPORUM, AND XANTHOMONAS ORYZEA PV. ORYZAE

Rice is a staple crop for a large part of the world population including Vietnam. Although it’s export is ranged of second place over the world just after Thailand, rice production in Vietnam is challenging by various issues. The most significant is application of agrochemicals, which are not eco-friendly, leading to side effects on the ecosystem and human health. Endophytic bacteria (EB) possess different beneficial traits such as Plant Growth Promoting (PGP) and antagonistic activities against plant pathogens. In this study, a collection of 150 EB strains have been isolated from upland rice roots grown on the mountain-farm in the Tung village, Nam Co commune, Mu Cang Chai district, Yen Bai province, Vietnam. 119/150 isolates showed sideropho reproduction ability including 12 isolates showed the halo orange zone surrounding colonies of 1 – 10 mm in diameter (Dh), considering them as low level of siderophore production, 80 strains exhibited the moderate activity, Dh of 11 – 30 mm and 27 strains showed strong/high activity, Dh more than 30 mm. All 119 endophytic bacterial isolates were screened for antifungal activity against Fusarium oxysporum (Fo), and antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo). Of them, thirty isolates showed either antifungal or antibacterial or both activities. Indeed, five isolates showed antifungal activity; fifteen isolates exhibited the antibacterial activity. Especially, ten isolates named NC88, NC89, NC126, NC129, NC130, NC131, NC134, NC152, NC153, and NC156 showed antimicrobial activity against both tested pathogens. These results are the starting-up for further investigation in planta under conditions of net house and field trial in order to reveal the potential strains for the development of bioinoculants toward to control the diseases caused by Fo and Xoo.