Watermelon (Citrullus lanatus) is a non-seasonal, economically important, cucurbit cultivated throughout the world, with Asia as a continent contributing the most. As part of the effort to diversify watermelon genetic resources in the already cultivated group, this study was devoted to providing baseline data on morphological quality traits and health-beneficial phytonutrients of watermelon germplasm collections, thereby promoting watermelon research and cultivation programs. To this end, we reported morphological traits, citrulline, and arginine levels of watermelon genetic resources obtained from the gene bank of Agrobiodiversity Center, Republic of Korea, and discussed the relationships between each. Diverse characteristics were observed among many of the traits, but most of the genetic resources (>90%) were either red or pink-fleshed. Korean originated fruits contained intermediate levels of soluble solid content (SSC) while the USA, Russian, Tajikistan, Turkmenistan, Taiwan, and Uruguay originated fruits had generally the highest levels of soluble solids. The citrulline and arginine contents determined using the High Performance Liquid Chromatography (HPLC) method ranged from 6.9 to 52.1 mg/g (average, 27.3 mg/g) and 1.8 to 21.3 mg/g (average, 9.8 mg/g), respectively. The citrulline content determined using the Citrulline Assay Kit ranged from 6.5 to 42.8 mg/g (average, 27.0 mg/g). Resources with high citrulline and arginine levels contained low SSC, whereas red- and pink-colored flesh samples had less citrulline compared to yellow and orange.

Glucosinolates (GSLs) are sulfur-containing secondary metabolites naturally occurring in Brassica species. The purpose of this study was to identify the GSLs, determine their content, and study their accumulation patterns within and between leaves of kimchi cabbage (Brassica rapa L.) cultivars. GSLs were analyzed using UPLC-MS/MS in negative electron-spray ionization (ESI⁻) and multiple reaction monitoring (MRM) mode. The total GSL content determined in this study ranged from 621.15 to 42434.21 μmolkg⁻¹ DW. Aliphatic GSLs predominated, representing from 4.44% to 96.20% of the total GSL content among the entire samples. Glucobrassicanapin (GBN) contributed the greatest proportion while other GSLs such as glucoerucin (ERU) and glucotropaeolin (TRO) were found in relatively low concentrations. Principal component analysis (PCA) yielded three principal components (PCs) with eigenvalues ≥ 1, altogether representing 74.83% of the total variation across the entire dataset. Three kimchi cabbage (S/No. 20, 4, and 2), one leaf mustard (S/No. 26), and one turnip (S/No. 8) genetic resources were well distinguished from other samples. The GSL content varied significantly among the different positions (outer, middle, and inner) of the leaves and sections (top, middle, bottom, green/red, and white) within the leaves. In most of the samples, higher GSL content was observed in the proximal half and white sections and the middle layers of the leaves. GSLs are regarded as allelochemicals; hence, the data related to the patterns of GSLs within the leaf and between leaves at a different position could be useful to understand the defense mechanism of Brassica plants. The observed variability could be useful for breeders to develop Brassica cultivars with high GSL content or specific profiles of GSLs.

In this study, 226 Capsicum chinense genetic resources were analyzed using high-performance liquid chromatography and a spectrophotometer to measure and compare their carotenoid content and American Spice Trade Association (ASTA) color values, respectively. The total carotenoid content and ASTA values of the 226 pepper genetic resources were found to be in the range of 7.04–2430.85 mg/100 g dry weight (DW) and 0–221.32, respectively. Capsanthin, capsorubin, lutein, zeaxanthin, antheraxanthin, violaxanthin, α-carotene, β-carotene, and β-cryptoxanthin were the individual carotenoids studied. The average content of each carotenoid (n = 226) in mg/100 g DW was as follows: capsanthin (325.77), antheraxanthin (136.34), capsorubin (82.36), β-carotene (59.11), violaxanthin (46.54), zeaxanthin (43.21), α-carotene (13.91), β-cryptoxanthin (9.67), and lutein (2.72). A strong positive correlation was observed between total carotenoid content and ASTA value (r = 0.965). Likewise, the individual carotenoid content and ASTA value revealed a strong correlation, such as antheraxanthin (r = 0.964), capsanthin (r = 0.946), and capsorubin (r = 0.858). Three genetic resources with a total carotenoid content above 2000 mg/100 g DW were obtained, such as IT261426 (2430.85 mg/100 g DW), IT183657 (2077.55 mg/100 g DW), and IT261213 (2062.54 mg/100 g DW). The findings of this study will assist in the selection of genetic resources with high carotenoid content and ASTA value that can be used to develop and breed new pepper varieties. Also, detailed results of ASTA value correlation with carotenoids in C. chinense genetic resources are provided.

Glucosinolates are sulfur-containing phytochemicals generally abundant in cruciferous vegetables such as pak choy. Glucosinolates participate in a range of biological activities essential for promoting a healthy human body. In this study, we aimed to elucidate glucosinolate variability present in pak choy germplasm that are under conservation at the Rural Development Administration Genebank, Jeonju, Republic of Korea. The Acquity Ultra-Performance Liquid Chromatography (UHPLC) analytical system was used in profiling the glucosinolate content in leaf samples of various accessions. We identified a total of 17 glucosinolates in the germplasm. Based on principal compoment analysis performed, three separate groups of the accessions were obtained. Group 1 contained the cultivar cheongsacholong which recorded high content of glucobrassicin (an indole), glucoerucin (aliphatic), gluconasturtiin (aromatic) and glucoberteroin (aliphatic). Group 2 consisted of six accessions, BRA77/72, Lu ling gaogengbai, 9041, Wuyueman, RP-75 and DH-10, predominatly high in aliphatic compounds including glucoiberin, glucocheirolin, and sinigrin. Group 3 comprised the majority of the accessions which were characterized by high content of glucoraphanin, epiprogoitrin, progoitrin, and glucotropaeolin. These results revealed the presence of variability among the pak choy germplasm based on their glucosinolate content, providing an excellent opprtunity for future breeding for improved glucosinolate content in the crop.

Intact glucosinolate (GSL) profile (five aliphatic; three aromatic, and one indolic glucosinolate) in the leaves of 50 germplasm collections and commercial cultivars of Brassica rapa , Brassica juncea , and Brassica oleracea collected from six different countries and grown under uniform cultural conditions were compared by UPLC-MS/MS. Total GSLs content ranged from 36.80 to 2383.12 μmol/kg DW. Aliphatic GSLs predominated among the entire samples representing from 23.0 to 98.9% of the total GSLs content, where gluconapin and glucobrassicanapin contributed the greatest proportion. Other GSLs such as, progoitrin (PRO), glucotropaeolin (TRO), and glucobarbarin (BAR) were found in relatively low concentrations. Principal Component Analysis (PCA) yielded three principal components with eigenvalue ≥ 1, representing 70.33% of the total variation across the entire data set. Accessions IT260822 & IT32750 , and commercial cultivar, “Hangamssam2”, were well distinguished from other samples in the PCA plot due to their significantly high amount of BAR, glucobrassicin (GBC), and glucoerucin (ERU), respectively. The inter- and intra-leaf variations of GSLs were examined in three kimichi cabbage varieties. The GSLs content varied significantly among leaves in different positions (outer, middle, and inner) and sections within the leaves (top, middle, bottom, green/red, and white). Higher GSL contents were observed in the proximal half & white section of the leaves and inner positions (younger leaves) in most of the samples. GBC, gluconasturtiin (NAS), and glucoberteroin (BER) should be studied profusely in Brassica plants as some of their degradation products of GBC and NAS are useful in cancer chemopreventive functions, whereas BER takes part in the process of suppressing aging of the skin. GSLs are regarded as allelochemicals; hence, the data related to the patterns of GSLs within the leaf and between leaves at different position could be useful to understand the defense mechanism of Brassica plants. The observed variability could be useful for breeders to develop Brassica crops with high GSL content or specific profiles of GSLs as required.

This study evaluated glucosinolate (GSL) composition and phenotypic traits in 72 radish (Raphanus sativus L. var. sativus) accessions, including 69 germplasm and 3 cultivars. Seven GSLs: glucoraphanin, glucoraphenin, glucoerucin, glucoraphasatin, glucobrassicin, glucobarbarin, and glucoberteroin were quantified using UPLC (mg/kg DW). Under the evaluated conditions, accession 10 (IT203308, Russia) showed high glucobarbarin (3976.9), while 38 (IT262009, Germany) and 39 (IT262067, North Korea) accumulated glucoraphasatin above 3500. Accession 40 (IT262091, North Korea) exhibited the highest glucoraphenin (612.9), and glucoerucin was enriched in 12 (IT204244, Israel), 19 (IT215036, Republic of Korea), and 35 (IT261962, Russia). Principal component analysis identified outliers: 10 (IT203308, Russia), 12 (IT204244, Israel), 19 (IT215036, Republic of Korea), 35 (IT261962, Russia), 38 (IT262009, Germany), 40 (IT262091, North Korea), 34 (IT261948, Kyrgyzstan), and 59 (IT306725, Malaysia), separated from central accessions. Multivariate analyses indicated that GSL accumulation and phenotypic variation were not consistently associated. These findings identify high-GSL and PCA-defined outlier accessions as potential donor resources for the breeding of radish with improved glucosinolate-related nutritional quality, while demonstrating that glucosinolate profiles cannot be reliably predicted from external phenotypes.