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Certificatorio with mineral in tomato cherry, Solanum lycopersicum L., with interest for human nutrition

Periodic Reporting for period 1 - BIOTOMATO (Certificatorio with mineral in tomato cherry, Solanum lycopersicum L., with interest for human nutrition)

Reporting period: 2017-09-01 to 2018-08-31

Vegetables are of great importance due to their richness in bioactive compounds such as minerals, vitamins, antioxidants and so forth. Mineral nutrition is an essential factor for the proper development of the human body, as much for adults as for children. It has been estimated, that the human body needs twenty-two essentials minerals, some in high and others in lower amounts. Taking into account that vegetables are the primary font of minerals in the human diet, is it beneficial, or perhaps even necessary, that we provide consumers with vegetable products with optimised mineral levels. A complex issue in modern agriculture is to produce vegetables that can guarantee the amount of minerals necessary for excellent maintenance of human health. It is in this context that biofortification has been recognised as a potential strategy to increase the mineral contents in the edible parts of crops. Broadly speaking, when referred to as an “agronomic” approach, biofortification is optimisation of mineral fertiliser applications used on plants. The objective of the Horizon 2020 research project BIOTOMATO, is to biofortify cherry tomatoes with essential minerals for human nutrition, without genetic modification. Our objective has been that mineral biofortification reaches 15% of the mineral Recommended Daily Allowance in 100 grams of cherry tomatoes. Such levels grant authorisation by European Union legislation and by the European Food Safety Authority (EFSA), for labelling the cherry tomatoes as a source of a specific mineral. The final results of the research may offer an excellent opportunity to bring an innovative food to market, and guarantee a healthier product to European consumers that respects of the environment and biodiversity.
The first set of analyses investigated the impact of a series of foliar spray applications every fifteen days using different mineral concentrations. The minerals tested were Selenium , Iron , Zinc and Manganese. The Selenium was a chemical reagent, while the other minerals were a commercial fertiliser. Before applying the foliar treatments, we marked the branches with open flowers, and we halted the experiment when we observed ripe tomatoes on the marked branches. Following this, the ripe tomatoes were harvested and dried in a hooven at 70 ˚C and pulverised. Finally, the tomato powders were analysed with an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), and the mineral contents were compared to 100 grams (g) of fresh tomatoes. During the treatments, a visual analysis was performed to detect any signs of toxicity in the tomato plant leaves due to the mineral applications. Some evidence of mineral content increase in the tomato fruits were found in Zinc and Manganese. Despite the positive results, the targeted mineral levels of 15% in relation to the Recommended Daily Allowance was still far, especially for Zinc, while in Manganese our results inspired greater optimism that we might reach our objectives. Disappointingly, no substantial evidence was found in plants treated with Selenium and Iron.

The most striking result to emerge from this first set of data is that we were able to biofortify the cherry tomatoes with Zinc and Manganese. However, the quantity of minerals accumulated in tomato fruits was lower than the 15% of the Recommended Daily Allowance. Despite this limitation, our findings suggested that it’s possible to test a higher concentration of minerals, due to the absence of toxic sings observed in treated tomato plants. The experiment was then repeated with a less time-consuming approach, to have an agile protocol for subsequent tests. In particular, only one foliar application was performed, and the tomatoes were harvested six days after the foliar application. On average, we found a significant correlation between treated and untreated plants for Selenium, Zinc and Manganese. Interestingly, we reached the highest accumulation in Selenium and Manganese, that we had obtained so far, despite still being quite far from the 15% of the Recommended Daily Allowance, especially for Selenium .

Finally, considering the positive result obtained in the previous experiment, we decided to continue in one foliar application with Selenium, but with higher concentrations. Also, before applying the foliar treatments, we marked the branches with open flowers, and we harvested when was observed ripe tomatoes on the marked branches.Strong evidence of toxic sings was found with all the Zinc concentrations tested and with Manganese, excepted the lowest concentration of Manganese tested. On another hand, no sign of toxicity was found with all the concentration tested of Selenium. Interestingly, high mineral accumulation in fruits was found with Selenium and Manganese. Despite the toxicity induced in plants by the treatment with Zinc, the analysis was performed in any case, showed significant accumulation in fruits The most striking results to emerge from this data is that in Manganese we reached almost 30% of the Daily Recommended Allowance for Manganese and as far as we know, no other authors or inventors have found a biofortification protocol in Tomato, with such high accumulation level of this mineral.
Our findings would seem to suggest that it is possible to biofortify cherry tomatoes with Selenium, Zinc and Manganese with one foliar application. As far as we know, no other authors have found an agronomic biofortification protocol with Zinc and Manganese, in cherry tomatoes. The impact of our work lies in a potential benefit for public health, with Selenium, Zinc and Manganese biofortification of tomatoes. Although the performance was not optimal, we nevertheless believe that ensuring the right amount of minerals in vegetables, might avoid mineral malnutrition. It has been suggested that mineral malnutrition or “hidden-hunger” is widely considered to be a vital factor in maintaining individual well-being, and in influencing social welfare and economic productivity. Mineral malnutrition does not only refer to developing countries but also in industrialised ones. For example, the UK has recorded significant Zinc deficiency in young men and women, and Selenium deficiency has been an important issue in Scandinavian countries. Although its deficiency is rare, in our view also Manganese biofortification may be relevant. As mentioned by different scientific studies, inadequate Manganese dietary intake has been correlated with the reduced bone formation and skeletal defects, lowered fertility and altered carbohydrate metabolism. Furthermore, we believe that biofortification with Selenium, Zinc and Manganese might increase the post-harvest of cherry tomatoes, and potentially make possible new opportunities for research and collaborations.
In conclusion, we have outlined a biofortification protocol for Selenium, Zinc and Manganese, without genetic engineering. The mineral accumulations in fruits does not reach the 15% of Daily Recommended Allowance guidelines, but might guarantee good mineral apports anyway. Also, with only one foliar application, it would appear that the cherry tomatoes benefited from extended post-harvest.