Coline PONS (ID4FEED and University Avignon thesis student): « Better know secondary metabolism pathways »
Coline PONS is a student from the QualiSud* Joint Research Unit at University Avignon (France).
In April 2019, she was hired as a doctoral student by ID4FEED to work on the following thesis topic: «UV radiation effects on carotenoids and capsaicinoids concentrations of two chili genotypes”. Coline explains us the three objectives of her research work which will last three years to better understand metabolic pathways involved in secondary metabolism.
“In animal nutrition, antibiotics are widely used to improve the “technical-economic performance” of animals, which causes pathogenic microorganisms resistance problems. Some molecules are particularly interesting to support animal performance and welfare such as capsaicinoids, which have been shown to act directly on the reactions of the oxido-inflammatory cycle of animals, and carotenoids, which are known as powerful antioxidants. These two types of molecules exist in different amounts in some Capsicum genus plants species, in other words chili. The Scoville scale, which indicate the chili pungency is correlated to the fruit capsaicinoid content. Sweet chili pepper have a value between 0 and 1 000 Scoville units meanwhile hot chili peppers reach 2 500 to more than 1 000 000 units (Barbero et al., 2016). It is important to choose a high capsaicinoids level variety before elicitation.
Several biotic or abiotic factors (physical or chemical), such as temperature, lack of water or nutrition conditions, are likely to influence the secondary metabolism of plants such as capsaicinoids and carotenoids concentrations of peppers. Among the physical factors, UV radiation is currently highly studied because when it is perceived by plants, it can stimulate signaling and metabolic pathways involved in secondary metabolism.
During my thesis, the effects of some specific UV radiation (applied before or after harvest) on the synthesis and accumulation of carotenoids and capsaicinoids of two chili genotypes will be studied.
The first objective of the work is to identify the most effective treatment modalities (or combinations of treatments) to increase the interest molecules concentrations of two chili genotypes, a hot chili pepper and a sweet one. Dose and power tests will be performed on fruit in the field or greenhouse on whole plants during the summer season and during storage.
The second objective is to use a metabolomic approach (UPLC-MS) to characterize and quantify in details the effect of the specific UV applications.
The third objective is to use this data to improve our understanding of the perception, signaling and regulation pathways involved in the effects of UV on the biosynthetic pathways of capsaicinoids and carotenoids in chili peppers. The practical applications of this knowledge is to improve ID4FEED ability to maximize concentrations of these molecules through reliable procedures.
At this stage, combinations of treatments have been performed and the results are being analyzed”.
*QualiSud is specialized in the field of food processing. Its activities range from the post-harvest development process of food to appraisal of sensory quality in the mouth, to its nutritional quality, its health benefit, its harmlessness and its technological properties.
Barbero, G. F., Liazid, A., Azaroual, L., Palma, M., & Barroso, C. G. (2016). Capsaicinoid contents in peppers and pepper-related spicy foods. International journal of food properties, 19(3), 485-493.