Aflatoxin in Food: What Role for Biotechnology? - OFAB

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of the efficacy and mode of action of putative pathway-blocking compounds (e.g. Tex6 100 kDa protein) Plants natural products effect Regulation of the genes clusters during invasion of the plant host is also investigated using a genomics approach. This approach is based on the fact that certain plant-derived natural products apparently have regulatory effects on aflatoxin biosynthesis. Successful inhibition of aflatoxin elaboration therefore, may require not only the action of antifungal compounds, but of compounds that block biosynthesis of toxins as well. Enhancement of host resistance to aflatoxin contamination of maize Host resistance is the most widely explored strategy for eliminating aflatoxin contamination by Aspergillus flavus. Breeding strategies for developing resistant maize germplasm have been enhanced by developing new screening tools for field inoculation and for laboratory screening Resistance-associated proteins Restriction Fragment Length Polymorphism (RFLP) analysis of maize populations has highlighted the possibility that different resistance traits can be successfully pyramided into agronomically useful germplasm, while proteomics has impacted the identification of proteins associated with resistance-associated proteins (RAPs) Development of resistant germplasm Control of aflatoxin contamination of maize will likely be dependent upon the development and introduction into the commercial market, of germplasm, resistant to the growth of aflatoxigenic species, and/or biosynthesis of toxins by these species The identification of chromosomal regions as well as proteins and their corresponding genes associated with resistance, and the subsequent confirmation of their role in resistance using biotechnological tools available such as RFLP analysis or RNAi should provide an efficient means for the development of this germplasm. However, to derive commercial benefit from this resistance and develop lines that can aid growers, markers need to be identified to facilitate the transfer of resistance into commercially useful genetic backgrounds without transfer of unwanted traits. Limiting the growth of aflatoxigenic fungi might at times not be enough to maintain Aflatoxins at “acceptable” levels in maize crops. Therefore, the identification of compounds that block aflatoxin biosynthesis may represent the “magic bullet” needed to insure resistance. Thus, the identification of resistance traits in maize can, through marker-assisted breeding, facilitate a more rapid development of resistant, commercially-useful germplasm. Conclusion Dr Maina concluded by saying that Biotechnology tools have provided researchers with a rapid and effective method for identification of genes potentially involved in aflatoxin formation and infection of crops by A. flavus 4
In addition, with the availability of the A. oryzae whole genome sequence a close relative of A. flavus, which is used in industrial fermentation for enzyme production without producing Aflatoxins, and of A. fumigatus, a human pathogen and a non-aflatoxin producer will be very helpful to identify genes specifically used by A. flavus for aflatoxin formation, for fungal invasion of crops and for fungal survival in the field through comparative genomics. He was of the opinion therefore that using close relatives of a.flavus could help in mitigating Aflatoxin danger. He urged everybody to join hands and provide solutions to our families, societies and country. He suggested that the Kenya Bureau of Standards (KEBS), Kenya Plant Health Inspectorate Services (KEPHIS) and other regulatory agencies could use indigenous verities and explore if they can provide tools to induce resistance. Open discussions Comments: 1. Thank you for your good and timely presentation. I am from East African Grain Council (EAGC). Recently I attended a meeting where one of the recommendations was to form a national working group among those involved in fighting Aflatoxin. We took this resolution because we noticed that there are a number of disjointed efforts to tackle the problem. In order to achieve a concerted effort, I am encouraging you to get in touch with that committee because what is presented here is one option among many. A larger consortium of researchers can contribute mote to find solutions. 2. At the World Food Program we believe that scientists should join efforts. Reports have confirmed that there exist several approaches to fight Aflatoxin. It would be useful for scientists to link up and see what is being done and the various possibilities. Questions: 1. Question: Thank you for a good presentation. My question is not directly related to it but I would like to know why it is taking too long to get drought resistant maize Answer: I would say that researchers have done much work not only for drought resistant maize but in other crops also. However, that is not enough. For example, to complete an invention every scientist needs a policy so that what he invents is protected. The NBA regulations which will cater for that need are not yet out. 2. Question: How are you positioned to link up with others who are fighting the same problem Answer: I agree that we have to join efforts. JKUAT institution policy states that we have to link up with other research programs in order to get sustained support from the institution. From our side, we were tasked to come up with a policy document that brings together actors and restructures efforts towards fighting Aflatoxin. 3. Question: In Kenya it has been reported historically that he Aflatoxin is concentrated in Ukambani (Eastern province). Does it have anything to do with the soil What is the reason I would suggest that scientists link up with extension services to find a solution for the area. 5
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Aflatoxin in Food: What Role for Biotechnology? - OFAB

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