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Use of nanotechnology in post-harvest decontamination of fruits and flowers, focusing on citrus canker and gray mold control


Brazilian agriculture was responsible for moving 243 billion reais in 2021, even in the midst of the health crisis from which we are still recovering, it was the sector that remained warm the most. In addition to the expressive numbers generated with the sales of commodities (products of monocultures and agricultural inputs), it is also one of the main responsible for offering numerous direct and indirect jobs. The target markets of this proposal are citrus and Brazilian ornamental flowers, with a focus mainly on citrus canker and gray mold, diseases of significant economic importance. The idea of working in this segment arose in the midst of a similar project (PIPE Phase 1 - process 2019/16412-2) in which nanoparticles capable of increasing the shelf life of 'Tahiti' acid limes were developed. During the development of phase 1, we explored both sectors, aiming to create a line of complementary products, with the purpose of reducing the microbial load found in the post-harvest. With this, new nanoformulations were developed and evaluated in the control of citrus canker and gray mold. Preliminary results for both diseases showed great potential for nanoformulations to inhibit the growth of the citrus canker bacteria in citrus and the gray mold fungus in cut roses. Given the above, the objective of this proposal is the validation of nanoformulations with a broad spectrum of action against the bacterium Xanthomonas citri subsp. citri (Xac), which causes citrus canker and also the fungus Botrytis cinerea, which causes gray mold. The methodologies used for the tests will be: the use of in natura fruits contaminated with Xac immersed or sprinkled with solutions containing different concentrations of the nanoformulations that obtained better results in a previous stage (in vitro assays), evaluation of the fungicidal and fungistatic activity of the nanoformulations against phytopathogens commonly found in citrus post-harvest, evaluation of in vitro antifungal activity against the fungus B. cinerea (preliminary results performed directly on the flowers). In the case of formulations that will be in contact with workers almost daily and that will be discarded as effluents, cytotoxicity and toxicity studies are necessary. Then, cytotoxicity assays will be carried out in MRC-5 cells, toxicity in lettuce seeds (L. sativa) according to the guidelines of the regulatory agency MAPA, toxicity in microcrustaceans (Daphnia simplex), according to ABNT NBR 12.713/201614 and guidelines 202 of OECD15, tests to verify the efficiency of nanoformulations in the laboratory, training for the correct use of the NPsmart prototype, user evaluation table and verification of the absence of microorganisms on the surface of the tested fruits (processors). As a result, it is expected to obtain nanostructured, stable formulations with low toxicity, broad spectrum of antimicrobial action, effective and low cost. This proposal was validated through more than 300 interviews with different actors in the Brazilian agricultural sector and, based on the problems reported, a business model was created with a view to developing a product that solves the main "pains" of citrus and flower growers. In addition, this proposal has already been validated in in vitro tests (Xac) in partner laboratories and tests on cut roses, within the Cooperflora experimental park. (AU)

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