Morpho-phytochemical screening and biological assessments of aerial parts of Iranian populations of wild carrot (Daucus carota L. subsp. carota)

Abstract

This study investigated the morphological and phytochemical characteristics of 118 genotypes of Daucus carota L. subsp. carota, collected from natural habitats in five populations across West Azerbaijan. The main objectives were to evaluate the variability among these populations and to explore their correlations with the local climatic conditions. The ultimate goal was to identify potential candidates for domestication and contribute to pre-breeding programs. Our findings revealed notable differences in plant height (PH), which ranged from 71.96 cm to 96.08 cm, with the tallest samples originating from the Gharib Hassan population (DCP5). The number of nodes on the main branch (NNMMB) was highest in DCP3 and DCP5, with mean values of 6.44 and 6.13, respectively. Essential oil (EO) content varied among the populations, from 0.88 to 1.37 (% V/W), peaking in DCP3. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses detected 23 chemical compounds, accounting for 88.49% to 95.5% of the essential oils. The primary compounds included oxygenated sesquiterpenes (47.84% to 76.26%) and hydrocarbon monoterpenes (2.33% to 37.37%). Carotol was the dominant compound in all populations, particularly high in DCP4 (74.03%) and DCP5 (73.61%). Based on essential oil composition, populations were classified into distinct chemotypes: DCP1 as chemotype I (carotol-bornyl acetate), DCP3 as chemotype II (carotol-α-pinene), and DCP2, DCP4, and DCP5 as chemotype III (carotol content of 64.03% to 74.03%). Correlation analysis revealed a significant negative relationship between carotol and several compounds, including daucene (-0.83), β-pinene (-0.65). Among the aerial parts, DCP3 had the highest total phenolic content (54.81 mg GAE/g DW), while DCP2 and DCP3 exhibited high total flavonoid content in seeds (36.07 and 36.22 mg QE/g DW), respectively. Antibacterial activity tests showed that DCP3 and DCP5 had notable inhibitory effects against Escherichia coli and Staphylococcus aureus. Using circular cluster analysis, the genotypes were categorized into three main groups based on the assessed traits, revealing greater variability in phytochemical and morphological characteristics among different populations compared to variations within individuals.

Keywords: Antibacterial activity; Canonical correspondence analysis; Carotol, Heretical cluster analysis; DPPH%; Essential oil; Stepwise regression; Total flavonoid contents; Total phenolic contents.

Fig. 1

Detailed information about the study area including a and b) geographic maps c) Digital elevation model (DEM) d) slope, e) geological characteristics, and f) Exact locations of the five populations.

Fig. 2

Different organs from collected samples of D. carota.

Fig. 3

Two-ways clustering analysis with two distinct dendrograms rows × columns respectively including essential oil constituent’s × Daucus carota populations (DCPs).

Fig. 4

Simple correlation analysis of 23 phytochemicals in Daucus carota Populations (DCPs): Dark blue indicates strong positive correlation (range 0 to + 1) and dark red indicates strong negative correlation (range 0 to -1).

Fig. 5

Antibacterial effects of vegetative extracts from five wild carrot populations (DCPs) against two strains of E. coli and S. aureus: a) column chart b) Experimental photos: larger inhibition zones indicate a stronger effect of the samples.

Fig. 6

Combined graph of Mantel test and Pearson correlation heatmap. A combined graph presenting the results of the Mantel test and Pearson correlation heatmap was created to elucidate the relationships among phytochemical and morphological attributes. The Pearson correlation analysis illustrates the correlations among all evaluated traits, with blue indicating positive correlations and red indicating negative correlations. The number of asterisks (*) represents the degree of statistical significance for each correlation. Additionally, the Mantel test was employed to assess the relationship between phytochemical and morphological attributes and their effect on bacterial genera, as well as to explore the association of antioxidant activity with these traits. In this context, a larger Mantel’s r value and a smaller Mantel’s p-value signify a stronger interaction between the indicators.

Fig. 7

Canonical correspondence analysis (CCA) among the phytochemical, climatic and soil characterization, in the five studied Daucus carota populations (DCPs).

Fig. 8

Circular clustering of all combined attributes among 118 individuals of Daucus carota.