Purpureocillium sp.: A potential antagonist against different phytopathogens

Introduction

Biological control agents developed on the basis of mycelium and spores from fungi belonging to the genus Purpureocillium Pers. Ex Fr., under phylum Ascomycota, Class Eurotiomycetes Order Eurotioales has gained immense importance since last four to five decades due to its biological control ability against the nematodes and other soil-borne pathogens (Anusha, 2014) [1] . Ability of biocontrol agent to capture nematodes depends on development of structures by the fungal mycelia. The predacious fungus forms hyphal structures, such as adhesive hyphal nets, knobs, branches and constricting or non constricting rings and in which nematodes are captured mechanically or through adhesion. Fungal hypha then penetrates into the nematode and utilizes its content as a food. The nematode parasitic fungi on the other hand infect nematodes with their spores which either adhere to the surface of nematodes or are swallowed by them. Ultimately the result of nematode infection in any way is always the death of the host. Purpureocillium sp. a saprophytic soil fungus has drawn the attentions of many researchers due to its promising effect in parasitizing and controlling the population of phytonematodes and other soil borne pathogens. These species can grow at a wide range of temperatures from 8 °C to 30 °C with optimal growth in the range of 20° to 25 °C. It has a wide pH tolerance and can grow on a variety of substrates. Purpureocillium sp. has shown promising results as a bio control agent to control the growth of destructive root knot nematodes and other soil-borne pathogens (Anusha, 2014) [1] .

Materials and Methods

1. Fusarium oxysporum (Wilt of banana), 2. Pythium aphanidermatum (Damping off of tomato), 3. Sclerotium rolfsii (Stem rot of Indian bean), 4. Fusarium moniliformae (Wilt of sugarcane), 5. Macrophomina phaseolina (Charcoal rot of groundnut), 6. Fusarium oxysporum f. sp. vasinfectum (Wilt of cotton)

The above cultures were obtained from the Department of Plant Pathology, N. M. College of Agriculture, Navsari Agricultural University, Navsari (Gujarat) and maintained on PDA medium. The methodology for testing against the phytopathogens was followed as given by Pau et al., 2012 [4] .

Dual culture technique (For fungal pathogens)

For interaction of each pathogen against Purpureocillium sp. sterilized Petri plates (9cm) were used. An autoclaved melted PDA was spread to make a thin PDA film in the Petri plates. After solidification of PDA in Petri plate, the 5mm discs of one week old growing colonies were cut from the margin of each pathogen and Purpureocillium sp. was placed on the opposite sides of the Petri plate 4cm apart on the PDA medium and was incubated at 25 ± 2ºC temperature. After seven days the mycelium growth of test pathogens in treated and control plates was recorded. Per cent growth inhibition (PGI) of pathogens was calculated by using the following formula given by Pau et al., (2012) [4] .

Where, PGI = Per cent Growth Inhibition DC = Average diameter of colony in control set DT = Average diameter of colony in treated set

Results and Discussion Dual culture technique (For Fungal Pathogens)

The most potent Purpureocillium sp. isolate i.e. Siker (P-3) isolate of Tapi district was tested for its antagonistic effect against the different soil-borne pathogens viz., 1. Fusarium oxysporum (Wilt of banana), 2. Pythium aphanidermatum (Damping off of tomato) 3. Sclerotium rolfsii (Stem rot of Indian bean), 4. Fusarium moniliformae (Wilt of sugarcane), 5. Macrophomina phaseolina (Charcoal rot of groundnut), 6. Fusarium oxysporum f. sp. vasinfectum (Wilt of cotton) Purpureocillium sp. isolate showed significant inhibition against all the pathogens. The maximum per cent growth inhibition was recorded in Pythium aphanidermatum (77.78%), which was followed by Fusarium moniliformae (68.23%) and least per cent growth inhibition was recorded in case of Sclerotium rolfsii (58.89%) (Table 1 and Fig. 1). Similar findings were shown by the research workers Hashem (2004) [2] isolated 31 fungal species from the soybean roots. The most dominant species were Aspergillus flavus Link., F. oxysporum Schlecht., F. solani Sacc., Macrophomina phaseolina (Tassi) Goid and Rhizoctonia solani J.G. Kuhn. Pathogenicity tests proved the ability of M. phaseolina and R. solani to infect soybean root and produce the symptoms of damping off and root rot diseases. The efficacy of T. harzianum, Epicoccum nigrum Link. and P. lilacinus was evaluated against pathogenic fungi. Biocontrol fungi significantly suppressed M. phaseolina and R. solani under in vitro and in vivo. E. nigrum and P. lilacinus suppressed the growth of the pathogens by producing an inhibition zone. Perveen et al. (2015) [5]

References

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2. Hashem M. Biological control of two phytopathogenic fungal species isolated from the rhizoplane of soybean (Glycine max). Czech Mycology. 2004;56(3-4):223238.
3. Patel N, Ruwali P, Sandipan P, Patel RK, Patel PS, Sharma C, et al. Evaluation of different fungicides against Corynespora cassiicola causing Corynespora leaf spot disease of cotton under in vitro condition. Progressive Research. 2024;19(Special-1):227-231.
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5. Perveen Z, Ramzan N, Noreen N, Rajpuit AQ, Shahzad S. In vitro evaluation of biocontrol potential of Paecilomyces species against Sclerotium rolfsii and Pythium aphanidermatum. International Journal of Biology and Biotechnology. 2015;12(3):407-411.