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Finotin: a promising new biopesticide

A very diluted amount of the purified protein was applied to the white round filter papers. Its antifungal activity against the fungal pathogen Rhizoctonia solani, in the centre of the petri dish, is clear (CIAT)
A very diluted amount of the purified protein was applied to the white round filter papers. Its antifungal activity against the fungal pathogen Rhizoctonia solani, in the centre of the petri dish, is clear
CIAT

A plant protein that has broad biocidal properties against insect pests as well as fungal and bacterial pathogens could be the next best thing in crop disease and pest control. The scientists who have extracted what they have named 'finotin' from seeds of the tropical forage legume Clitoria ternatea think that this could become a cheap and easy pest and disease control option for farmers.

The trend for harnessing nature to solve health problems has good logic behind it, and this is especially true for plant health. 'Artificial' pesticides, currently the mainstay of disease and pest control in the field and in storage, are increasingly associated with negative impacts to both human health and the environment. So the rise of biopesticides, a safer alternative based on naturally produced defensive compounds, is gaining momentum.

A fine time ahead for finotin

"We believe natural plant and microbial compounds will play a major role in pest and disease control in both developed and developing countries," says Segenet Kelemu, a plant pathologist at the Colombia-based International Center for Tropical Agriculture (CIAT) who is leading the work on finotin. "We are particularly excited about the potential of finotin for use by resource-poor farmers."

Finotin follows on the heels of several fungus- and virus-based biopesticides that have been developed and in some cases commercialised for use in the field. Probably the best known are those derived from the bacterium Bacillus thuringiensis (Bt), which are now widely used around the world. Bt preparations are usually sprayed directly onto plants to protect them against a variety of insect pests, but the genes encoding the pesticidal proteins have also been successfully transferred into plant species such as maize, providing protection without the need for spraying.

Finotin differs in that it is a protein-based biopesticide with a wide-spectrum of activity. "What is great about this protein is that it is effective against insects, a wide range of fungal pathogens, and some bacterial pathogens," says Kelemu. Her recently published research demonstrates these effects in laboratory experiments with pathogens of beans, rice, and some tropical forage and fruit species. Insecticidal effects on storage pests were also shown, and the team are optimistic that finotin has potential for use both in the field and post-harvest.

The next set of experiments looked at simple, low-tech ways to extract and apply the compound under greenhouse and field conditions. Seeds were ground, and the extract sprayed onto tomato plants that were naturally infected with various pathogens. The results were clear: the treated plants had fewer symptoms, greater biomass and produced more tomatoes than the control plants. A second experiment on beans was also successful.

Natural and local

Tomato plant 2 sprayed with finotin extract showing fewer symptoms of pathogen attack than control plant 1 (CIAT)
Tomato plant 2 sprayed with finotin extract showing fewer symptoms of pathogen attack than control plant 1
CIAT

Kelemu's vision is for resource-poor farmers to grow Clitoria ternatea in their fields, collect the seeds, extract the protein and apply it to their crop plants. Her demonstration of the crude extract's potency, along with its heat-stable nature, support the feasibility of this scenario.

Another option is commercialisation of the biopesticide by local producers. "The large markets, mainly based on Bt, are dominated by multinationals," says Kelemu. "We think there is considerable scope for small local producers to target regional and niche markets. We are currently collaborating with a small Colombian company, and hope to develop appropriate formulations of finotin for sale to farmers."

As with any new product, further research and development are needed to ensure its ultimate success. Farmers will be involved in identifying formulation and application strategies that work for them, while close collaboration between producers, scientists and the private sector will be important. The CIAT group will use their experience with three other biopesticides - Biocanii, Biorhizium and Biovirus - which have been successfully developed and are now commercially available from the Colombian company Biotropical S.A.

The finotin team also believe that, like Bt, their biocidal protein might have biotechnological applications. They are currently working on cloning the finotin gene. Once this has been done, they hope to produce transgenic plants that resist pests and diseases; or alternatively, transgenic endophytic bacteria or fungi containing the finotin gene, which could 'infect' plants and so deliver the biocidal protein. The latter route has several advantages, not least that it is less controversial because the plant genome remains unmodified.

Finotin holds great promise as an environmentally friendly and affordable way to defeat crop pests and diseases. This work could be an important step towards sustainable crop management based on the exploitation of natural plant defences.

Written by: Anne Moorhead

Date published: January 2006

 

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