Transcriptional Regulation of Ascorbic Acid During Fruit Ripening in Pepper (Capsicum annuum) Varieties with Low and High Antioxidants Content

Abstract

Research on plant antioxidants, such as ascorbic acid (AsA) and polyphenols, is of increasing interest in plant science because of the health benefits and preventive role in chronic diseases of these natural compounds. Pepper (Capiscum annuum L.) is a major dietary source of antioxidants, especially AsA. Although considerable advance has been made, our understanding of AsA biosynthesis and its regulation in higher plants is not yet exhaustive. For instance, while it is accepted that AsA content in cells is regulated at different levels (e.g., transcriptional and post-transcriptional), their relative prominence is not fully understood. In this work, we identified and studied two pepper varieties with low and high levels of AsA to shed light on the transcriptional mechanisms that can account for the observed phenotypes. We quantified AsA and polyphenols in leaves and during fruit maturation, and concurrently, we analyzed the transcription of 14 genes involved in AsA biosynthesis, degradation, and recycling. The differential transcriptional analysis indicated that the higher expression of genes involved in AsA accumulation is a likely explanation for the observed differences in fruits. This was also supported by the identification of gene-metabolite relations, which deserve further investigation. Our results provide new insights into AsA differential accumulation in pepper varieties and highlight the phenotypic diversity in local germplasm, a knowledge that may ultimately contribute to the increased level of health-related phytochemicals.

Influence of Fruit Ripening on the Total and Individual Capsaicinoids and Capsiate Content in Naga Jolokia Peppers (Capsicum chinense Jacq.)

“…For several decades, the association between nutrition and health has been gaining popularity, and therefore, increased importance has been given to diets based on antioxidant-rich vegetables and fruits [1]. Pepper (Capsicum spp.)…”

The Use of Antioxidants in the Treatment of Migraine

“…Apart from supplementation, dietary sources of natural antioxidants particularly include products of plant origin, vegetables, fruits, flowers of edible plants, and plant-derived spices [45,46]. The most common plant antioxidants are carotenoids (xantophylls and carotenes), polyphenols (phenolic acid, anthocyanins, lignans, flavonoids, and phenolic acid), and vitamins C and E [47][48][49].…”

Accumulation of Ascorbic Acid in Tomato Cell Culture: Influence of the Genotype, Source Explant and Time of In Vitro Cultivation

“…The ascorbic acid content was estimated on fruit pericarp and after 15, 30, 45 and 60 days of in vitro culture from ten randomly chosen calli for each experimental thesis. Samples were taken during the first hours of the light period, weighted, frozen in liquid nitrogen and stored at −80 • C. Ascorbic acid was extracted as reported by [23] and it was measured as previously described [13,37]. AsA quantities were determined by subtracting the reduced AsA (rAsA) from the total Asa (tAsA).…”

“…Frozen tissues (approximately 100 mg) were homogenized with a TissueLyser (Qiagen, Milan, Italy) according to the manufacturer's instructions. Total RNA was isolated and quantified as described [13]. First strand cDNA was synthesized using 1 µg of total RNA using the RevertAid First Strand cDNA Synthesis Kit (ThermoFisher Italia, Milan, Italy) according to the manufacturer's guidelines.…”

“…A known source of trait variation within a plant species is represented by genetic factors [12]. In various trees and horticultural species, varieties differ in the amount of ascorbic acid in edible organs [13][14][15]. Moreover, a range of endogenous and external factors, including phenological, physiological and environmental cues, can have a significant effect on the accumulation of AsA in the different plant tissues [12].…”