Efficiency of phenotypic methods and rep-PCR in the geographical separation of causal agent of mushroom brown spot, Pseudomonas tolaasii, in Fars province

Subject Areas : دو فصلنامه تحقیقات بیماریهای گیاهی

Gilda Najafi Pour ¹ , Kavous Ayaz Pour ²

1 - plant protection, Islamic Azad University, Jahrom Branch
2 - plant protection department, Islamic Azad University, Jahrom Branch

Received: 2024-02-27 Accepted : 2024-06-12 Published : 2024-05-21

Keywords: Fars province, Rep-PCR, Pseudomonas tolaasii, brown blotch, phenotypic and genotypic characteristics,

Abstract :

Brown Blotch in mushroom, caused by Pseudomonas tolaasii can be seen in many mushroom farms. This disease causes dark brown or chocolate spots on the cap and base, eventually reducing the quality and quantity of mushrooms produced. During 2017- 2018, samples were collected and transported in plastic bags to the laboratory. A total of 100 gram-negative isolates were initially identified as Pseudomonas tolaasii on nutrient agar. All isolates were studied for physiological, biochemical, and nutritional characterization, as well as for the presence of the tolaasin gene using specific primers, PT1D1 and PT1A. All strains were rod-shaped, Gram-negative, obligate aerobic, were positive for oxidase, and arginine dehydrolase. This isolates produced fluorescent pigment on KB medium. Levan production, hydrolyze starch were positive and tobacco hypersensitive reaction (HR) was assessed negative in all isolates. In this study rep-PCR method was used for evaluating of geographical diversity of P. tolaasii. Three primers, consist of BOX, ERIC, and REP primers, were used. The results showed that using these primers, the isolates from different regions of Fars province were divided into six or seven distinct groups. Clusters created based on geographical distribution showed relative similarity among the isolates. rep-PCR results revealed that both REP, ERIC, and BOX primers individually were largely acceptable, and isolates from different places were separated according to geographical area. Comparisons between groups were also made based on a pathogenicity test on mushroom’s cap, and clusters created by the rep-PCR showed synchronization based on pathogenicity.