The control of biotic diseases in agriculture - particularly of those caused by fungi and bacteria- has produced an excessive use of chemically-synthesized products (agrochemicals), which, despite their important contribution to the increase of agricultural productivity, have considerable disadvantages, especially regarding the health of the people who apply these products and in environmental terms, since they contaminate soils and groundwater layers. On the other hand, the use of pesticide-free agricultural products has increased in recent years, requiring quality foods, free of toxic components. Alongside this, legislation (especially in developed nations) increasingly limits the use of pesticides on products for human consumption. A more sustainable alternative is the biological control of phytopathogenic fungi and bacteria with the use of their enemies/antagonists, which are considered biological control agents (BCA). In this field, I highlight the recent review by Lahlali et al. (2022) which describes extensively diverse aspects referring to the biological control of phytopathogens, including an analysis of the action mechanisms used by beneficial microorganisms for controlling the phytopathogens and the reduction of the losses caused by them, as well as the potential and limitations of this technology. This review paper also analyzes the reality that has characterized this field: an extensive scientific literature in which numerous isolations of microorganisms with antagonistic potential have been evaluated and reported, though showing that relatively few products have reached the market. An example of this has been pointed out by Córdova-Albores and collaborators (2021), who have shown the need for a greater biodiversity of biopesticides registered in COFEPRIS (Spanish acronym for the Federal Commission for the Protection against Sanitary Risk) and sold in Mexico. Lahlali et al. (2022) analyze the causes for this situation and conclude that researchers ignore or have not considered what is really needed for a product to be able to reach farmers and which has to do with aspects that go far beyond the evaluation of the biological effectiveness of a particular BCA. Nationally, Serrano-Carreón and Rincón-Enríquez (2021) have edited a special number of the dissemination journal “Biotecnología en Movimiento” around the situation of the biological control of pests and diseases in Mexico and in which some experiences with a potential for application are told.
The concept of microbial antagonism has been known in microbiology since the 19th century; nevertheless, the first product registered in the U.S. Food and Drug Administration (FDA) as a biological control agent for agriculture was the bacterial strain Agrobacterium radiobacter 84, in 1979 (Lahlali et al., 2022). A decade later, the same agency approved the use of the fungus Trichoderma harzianum to control plant diseases (Lahlali et al., 2022). To date, the FDA has issued registrations for 14 different bacteria and 12 fungi as BCAs (Lahlali et al., 2022), the most common of which are the bacteria of the Bacillus genus and the fungi of the Trichoderma genus. As pointed out by Köhl et al. (2011), most of the work on the isolation and characterization of antagonistic microorganisms have concentrated on the biological effectiveness (whether in vitro or in planta) as their main selection criterion. It is common to find the following phrase in articles frequently published in plant pathology, microbiology or biotechnology journals:
“Strain “XX”, isolated from “BB” and identified as “YY,” displays a high percentage of biocontrol over “ZZ” and “QQ,” and may therefore be a candidate for the control of these phytopathogens, which would represent an agroecological alternative for the control of “WW” in the region of “FF,” since it is a native strain that may have greater possibilities of adaptability and success, in comparison with the currently available commercial strains.”
Although it sounds obvious, it does not seem evident for most researchers that the effectiveness of a particular microbial isolation is not the only requirement to become a “candidate for the control of these phytopathogens.” It is important to analyze that, in order for a microbial isolation to be considered as an agent for the control of a phytopathogen in the field, it must meet at least the following requirements: a) It must be safe for humans and other animals, b) It must be able to product it at a large scale in low-cost culture media, c) It must be formulated in such a way that it is easily used and stored by farmers. An isolate with an extraordinary ability for biological control is of little use if it has a pathogenic potential for humans, or its production cannot be scaled-up in an inexpensive way, or it does not have a sufficiently broad shelf-life (i.e. two years). Additionally, it must be able to convince farmers in terms of its cost-benefits in comparison with conventional agrochemicals.
In relation to the statement claiming that “… it would represent an agroecological alternative for the control of “WW” in the region of “FF,” since it is a native strain that may have greater possibilities of adaptability and success, in comparison with the currently available commercial strains,” it is necessary to mention that, in addition to the technical-biological requirements, one of the greatest bottlenecks in the commercialization of a BCA is the high cost of the registration process before the relevant agricultural authorities, and the health authorities (such as COFEPRIS), in each country in which the product is intended for legal sale. This registration process includes the verification by third parties of the innocuousness of the product and its effectiveness against a phytopathogen in a particular crop. The latter is, in itself, a problem from a commercial point of view, since biological effectiveness tests must be carried out for each phytopathogen-crop pair to become correspondingly registered. The commercial success of biological products available in the market is largely based on its broad antagonist spectrum. There is no commercial product that can survive in the market having only one registration for a single pathogen/agricultural crop and/or for a particular agricultural zone, as the majority of the scientific literature suggests. The costs for registration are one of the most relevant factors in the placement of this type of products in the market.
The basic phytopathology work, including the knowledge of the complex interactions of an BCA with biotic and/or abiotic factors of the agroecosystem (as pointed out by Córdova-Albores et al., 2021) is crucial for the development of new biological control agents. However, if it is expected to benefit farmers in the management of diseases, it is essential to think and act in a multidisciplinary manner. I consider that the article by Köhl et al. (2011) should be mandatory reading for any phytopathologist, microbiologist or biotechnologist who wishes their work to become an effective reality for farmers. Likewise, I would recommend that phytopathologists read biotechnology papers, biotechnologists read phytopathology papers, and that both read about technological innovation. If we want our investigations to have a true social impact, we must not only strive for excellence in our specialized field, but also engage with researchers from other disciplines, who speak other languages and help us see beyond the relatively limited monodisciplinary horizon.
We are more used to the fact that innovations (i.e., discoveries introduced in the market, which is the only way to fulfill their social function of generating wealth) come from abroad. Most of the inputs purchased by Mexican farmers are produced using technology developed outside of Mexico’s borders. In the field of biological control of phytopathogens, this is also the case, with only a few exceptions (Galindo et al., 2013). Worldwide, biological control agents have been estimated to constitute only about 5% of the value of the crop protection industry market (this includes insect control, mainly using B. thuringensis toxins) (Lahlali et al, 2022). However, due to regulatory pressure and the consumer preference for safer products, the biological control market (particularly for the control of phytopathogens, which is the least developed), is expected to grow significantly. Therefore, in Mexico, we have an extraordinary opportunity, as we have the main ingredient, which is human talent. However, without a multidisciplinary perspective, this talent will hardly ensure that science and technology in this field will reach consumers. Thus, we must continue having excellence in the research in phytopathology and biotechnology, though in different ways and with significant social commitment. One of these ways is scientific entrepreneurship. If there are no companies interested in our developments, then let’s create such companies. The story of a Mexican case has been published in the literature (Galindo et al., 2013), describing how an investigation that began with the isolation of microorganisms antagonistic to Colletotrichum gloeosporioides ended in the launching of a commercial product now registered to control six diseases caused by fungi in approximately 25 crops.
In countries that have achieved spectacular economic growth in recent decades, such as South Korea and Israel, entrepreneurship is one of the most successful forms of technology transfer. Of course, scientific entrepreneurship is not for all researchers, although for recent Ph.D. graduates it can be a real career alternative, given the limited amount of highly qualified jobs currently available. However, for those who decide to take this path, I assure you it will not be easy, but definitely will be very rewarding. To be able to witness that a technological development which began in our laboratories is solving specific problems to the farmers is, with no doubt, one of the greatest professional rewards that one can have as a researcher.