Morphological and Biochemical Variation in Carrot Genetic Resources Grown under Open Field Conditions: The Selection of Functional Genotypes for a Breeding Program

Abstract

Carrot (Daucus carota), one of the most economically important root vegetables, shows a wide range of morphological and biochemical diversity. However, there is a lack of simultaneous systematic study regarding the biochemical composition and morphological characteristics in carrot genetic resources, which is crucial for crop improvement. For this reason, the morphological characteristics, carotenoids, and free sugar content of 180 carrot genetic resources grown in open field conditions from March to June 2020 were accessed to select the lines for a potential breeding program. Altogether, 15 qualitative and 4 quantitative agronomical characteristics were evaluated and grouped into four categories based on root color (orange, yellow, white, and purple). Three carotenoids (lutein, α-carotene, and β-carotene) and three free sugars (fructose, glucose, and sucrose) were also analyzed. The results revealed wide genetic variation in both qualitative and quantitative traits. Most of the genetic resources were orange (n = 142), followed by white (n = 16), yellow (n = 14), and purple (n = 8). Carotenoid profile and content were highly dependent on root color and showed wide genetic variability, while sugar content and profile were independent of the root color. Alpha- and β- carotene were the major carotenoids in orange carrots representing 43.3 and 41.0% of total carotenoids. In contrast, lutein was most dominant in other colored carrots (79.7–98.6% of total carotenoids). In most of the genetic resources, sucrose was the most dominant free sugar, followed by glucose and fructose. The results of this study showed that some genetic resources elevated carotenoid and sugar content. The morphological and biochemical diversity observed in this study might be useful for improving the agronomic traits and biochemical content of carrot lines for breeding programs.

Influence of Root Color and Tissue on Phytochemical Contents and Antioxidant Activities in Carrot Genotypes

“…Three carotenoids (α-carotene, β-carotene, and lutein) were analyzed using highperformance liquid chromatography (HPLC) according to Bhandari et al [7]. Briefly, 0.2 g of carrot powder was extracted in 5.0 mL of chloroform: MeOH (1:1, v/v), diluted with methanol (100%), filtered, and injected into an HPLC system (Agilent Technologies, Santa Clara, CA, USA) equipped with a diode array detector (DAD) set at 470 nm.…”

“…Three major free sugars, namely, glucose, fructose, and sucrose, were analyzed based on the method described by Bhandari et al [7]. Carrot powder (0.2 g) was extracted in distilled water (5.0 mL) at 80 • C for 20 min, cooled immediately, centrifuged, filtered, and injected into an HPLC system equipped with a refractive index (RI) detector.…”

“…The health benefits of carrots are mainly attributed to the presence of a wide range of bioactive compounds, including carotenoids, phenolics, flavonoids, vitamins, anthocyanins, minerals, and fatty acids [2][3][4][5]. Carotenoids are one of the most important phytochemicals in carrots, with αand β-carotene being the most abundant, accounting for 80-90% of the total carotenoid content in most carrot genotypes [6], although their composition is highly dependent on root color and genotype [7,8]. In general, orange carrots have high levels of αand β-carotene, whereas purple carrots have high anthocyanin and polyphenol content [7,8].…”

“…Carotenoids are one of the most important phytochemicals in carrots, with αand β-carotene being the most abundant, accounting for 80-90% of the total carotenoid content in most carrot genotypes [6], although their composition is highly dependent on root color and genotype [7,8]. In general, orange carrots have high levels of αand β-carotene, whereas purple carrots have high anthocyanin and polyphenol content [7,8]. Carotenoids protect DNA and proteins and reduce the risk of non-alcoholic fatty liver disease (NAFLD), heart diseases, and lipid oxidation, prevent cancer, and maintain normal vision [6,[9][10][11][12][13][14][15].…”

“…The functional quality and composition of bioactive compounds in carrots are significantly influenced by genetic and environmental factors (developmental stage, climatic conditions, growing seasons, agricultural practices, and postharvest storage conditions) and root color [2,5,7,8,24,[26][27][28][29], altering the accumulation of bioactive compounds and their health potential [5,7,8]. The composition of bioactive compounds and their availability in carrot roots may be altered in carrot tissues, as the outer tissue (epidermis and pericarp) and inner tissue (xylem and pith) have different functions in the translocation of compounds.…”