The Potential of Serratia marcescens: An Indigenous Strain Isolated from Date Palm Compost as Biocontrol Agent of Rhizoctonia solani on Potato

Rabeb El Khaldi

doi:10.4172/2157-7471.1000s3-006

Abstract

Rhizoctonia solani, associated with stem canker and black scurf diseases of potato, was one of the most destructive pathogens in Tunisia and elsewhere. A bacterial strain was isolated from date palm compost, identified as Serratia marcescens using amplification and sequencing of the 16SrRNA in combination with biochemical characterization. The antifungal properties against R. solani AG3 strain were assessed on potato. Mycelial growth inhibition of the pathogen was evaluated after 6 days of incubation at 28°C in the presence of the bacterium and its cell-free culture filtrates. The application of bacterial suspension adjusted to 108CFU/ml as pre-planting treatment of potato seeds tubers cv. Nicola reduced the incidence and severity of diseases under greenhouses conditions. In pot experiments, no stem canker was detected and the percentage of progeny tubers showing symptoms of black scurf was significantly reduced With S. marcescencs treatment (36.47%) as compared to the controls. Results of this study suggest also that S. marcescencs was an effective biocontrol agent against black scurf and stem canker of potato since severity was reduced up to 49.31% and 83.16% respectively. Therefore, the bacterium could be considered as promising alternative to chemical products.

Highlights

The widespread soil-borne pathogen Rhizoctonia solani is the causal agent of Rhizoctonia disease complex in potato (Solanum tuberosum L.) resulting in two different appearances of the disease, namely stem canker and black scurf which lead to tuber yield reductions and losses in tuber quality [1]
The objective of this research was to evaluate the potential of using a strain of S. marcescens isolated from date palm compost as biological control agent to reduce the impact of stem canker and black scurf caused by R. solani in potato
Fungal growth and sclerotial germination of R. solani AG3 strain were inhibited in the presence of the bacterium and its cell free culture filtrates in vitro

Summary

Introduction

The widespread soil-borne pathogen Rhizoctonia solani is the causal agent of Rhizoctonia disease complex in potato (Solanum tuberosum L.) resulting in two different appearances of the disease, namely stem canker and black scurf which lead to tuber yield reductions and losses in tuber quality [1].Stem canker consists of brown and black sunken stem lesions which involve the reduction of nutrient in the whole plant as a result losses of yield, whereas black scurf is revealed by the formation of brown or black sclerotia on tuber surfaces, which may affect their quality and marketability [2,3,4].R. solani perpetuates in soil and tubers in the form of sclerotia. The widespread soil-borne pathogen Rhizoctonia solani is the causal agent of Rhizoctonia disease complex in potato (Solanum tuberosum L.) resulting in two different appearances of the disease, namely stem canker and black scurf which lead to tuber yield reductions and losses in tuber quality [1]. Stem canker consists of brown and black sunken stem lesions which involve the reduction of nutrient in the whole plant as a result losses of yield, whereas black scurf is revealed by the formation of brown or black sclerotia on tuber surfaces, which may affect their quality and marketability [2,3,4]. Control measures through cultural practices and chemical fungicides are used but they are not completely effective and Rhizoctonia disease remains a persistent problem. In addition chemical treatments are becoming increasingly difficult due to concerns about health and environmental hazards

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