Possible Control of Potato Common Scab with Indigenous Nonpathogenic Species of Streptomyces in Egypt

Document Type : Original Article

Authors

Bacterial Diseases Research Department, Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt.

Abstract

The potato common scab disease became a major threat for potato raised in light soil(s) in Egypt. In the present work, eight out of twenty-five isolates of Streptomyces recovered from four locations and rhizosphere soil of three different crops showed antagonistic potential against Streptomyces scabies. The partial 16S rRNA gene sequences of five of these eight isolates showed 99.13 to 99.67 % similarity with Streptomyces rochei strain NRRL B-1559.The other three isolates showed 99.73, 99.60, and100 % similarity with Streptomyces geysiriensis strain NRRL_B-12102, Streptomyces tunisiensis strain CN-207, and Streptomyces djakartensis strain NBRC 15409, respectively. The partial 16S rRNA gene sequences of the eight antagonistic isolates have been deposited in the GenBank of the National Center for Biotechnology Information (NCBI) under the accession numbers MT878417, MT878546, MT878545, MT878152, MT878547, MT878450, MT878478, and MT878497. The inhibition zones of the growth of Streptomyces scabies by the eight selected antagonistic isolates of Streptomyces were variably from 32.7 to 66.7 mm. Application of Streptomyces geysiriensis 7AS_GP8, Streptomyces tunisiensis 8AS_BNM2, Streptomyces djakartensis 4AS_MO2, and Streptomyces rochei 5AS_MO3 in pots experiment significantly decreased scab index from 68.6 % in control treatment to 39.1, 47.7, 25.3, and 31.7 %, respectively. Streptomyces djakartensis 4AS_MO2 gave the pronounced decrease (63.1%) in disease followed by Streptomyces rochei 5AS_MO3 (53.8 %), Streptomyces geysiriensis 7AS_GP8 (42.9 %), and Streptomyces tunisiensis 8AS_BNM2 (30.4%), respectively. Streptomyces djakartensis 4AS_MO2 and Streptomyces rochei 5AS_MO3 provided promising results as potential biocontrol agents against Streptomyces scabies. Further field studies may be advised.

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