Putativas inter-relações entre a síntese de carotenóides, ácido abscísico, flavonoides e ácido L-ascórbico durante a maturação de morangos (Fragaria x ananassa cv. San Andreas)

Abstract

The strawberry, Fragaria x ananassa Duch., is widely consumed due to its attractive sensory characteristics such as flavor, aroma and appearance. In addition to being an important crop, strawberry is a research model for non-climacteric fruits, due to its size and rapid cultivation. Several studies have reported the role of Abscisic Acid (ABA), a phytohormone originating from the degradation of photosynthetic carotenoids, in the induction of anthocyanins in non-climacteric fruits. However, the interrelationships between ABA, carotenoids and compounds of specialized metabolism, such as phenylpropanoids and L-ascorbic acid (AsA) have not yet been elucidated, and little is known about the temporal dynamics of accumulation of specialized compounds in this fruit. In the present work, the objective was to put the hypothesis to the test that for the ripening process of the fruits to occur, there is initially an increase in the synthesis of carotenoids, followed by the bioconversion into ABA, culminating in the induction of the ripening process of strawberry fruits. Therefore, the experimental design was designed to cover the largest number of development stages, totaling 9 stages of the San Andreas cultivar. To test the hypothesis, two dimensions of analysis were designed, one biochemical through UFLC-MS/MS (high performance liquid chromatography coupled to a tandem mass spectrometer) and another genomic through RT-qPCR (polymerase chain reaction real-time quantitative). Despite this, only some of the biochemical analyzes planned were performed, namely: total soluble solids; ABA content, ABA-glycosylated, phaseic acid, dehydrophaseic acid; L-ascorbic acid content; phenylpropanoids; anthocyanins. These results were compiled in an article, whose theme was the relationship between ABA and AsA and phenylpropanoids, offering new perspectives on the regulation of ABA. In this study, it was observed that the total soluble solids content decreased in the initial stages and increased in the growth stages and decreased again during ripening. In addition, with ripening, an increase in the content of ABA, AsA and pelargonidins was observed. The cyanidin content increased in the initial stages and then reduced, showing a negative correlation with the ABA content. PCA (principal component analysis) and PLS (partial least squares regression) allowed us to define distinct groups of samples according to their biochemical profile and to verify that the compounds that most contributed to this distinction were AsA, catechin and pelargonidin 3 glycoside. However, due to setbacks, the main thrust of the hypothesis cannot be questioned, and the relationship of carotenoids and ABA still remains inconclusive. Questions about the xanthophyll cycle still remain, which seems relevant to understand the regulation of ABA, the availability of AsA and their respective accumulation in the fruits. Thus, it is expected that this study can contribute to new scientific and technological studies that will come about plant cells and the process of ripening in fruits.