Watermelon is the most significant, natural plant source of L-citrulline, a non-proteinaceous amino acid that benefits cardiovascular health and increases vasodilation in many tissues of the body. Watermelon is a member of the Cucurbitaceae, which includes squash, melon, pumpkin, and cucumber. It is possible that other cucurbits could be good sources of citrulline or of arginine, its direct precursor. Twenty-one cultigens were evaluated in triplicate at two locations in North Carolina to estimate citrulline and arginine amounts and variation due to cultigen, replication, and environment. Cultigens containing the highest amount of citrulline (based on LS means) in g/kg fresh weight were ’Crimson Sweet’ watermelon (2.85), ’Dixielee’ watermelon (2.43), casaba-type melon (0.86), mouse melon (0.64), and horned melon rind (0.45). Additionally, mouse melon, horned melon, and bitter gourd (arils) may be interesting sources of arginine-family amino acids, perhaps because of their large seed and aril content relative to mesocarp.

Tomato steroidal glycoalkaloids (tSGAs) are a class of cholesterol-derived metabolites uniquely produced by the tomato clade. These compounds provide protection against biotic stress due to their fungicidal and insecticidal properties. Although commonly reported as being anti-nutritional, both in vitro as well as pre-clinical animal studies have indicated that some tSGAs may have a beneficial impact on human health. However, the paucity of quantitative extraction and analysis methods presents a major obstacle for determining the biological and nutritional functions of tSGAs. To address this problem, we developed and validated the first comprehensive extraction and ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) quantification method for tSGAs. Our extraction method allows for up to 16 samples to be extracted simultaneously in 20 min with 93.0 ± 6.8 and 100.8 ± 13.1% recovery rates for tomatidine and alpha-tomatine, respectively. Our UHPLC-MS/MS method was able to chromatographically separate analytes derived from 18 tSGA peaks representing 9 different tSGA masses, as well as two internal standards, in 13 min. Tomato steroidal glycoalkaloids that did not have available standards were annotated using high resolution mass spectrometry as well as product ion scans that provided fragmentation data. Lastly, we utilized our method to survey a variety of commonly consumed tomato-based products. Total tSGA concentrations ranged from 0.2 to 3.4 mg/serving and represent some of the first reported tSGA concentrations in tomatobased products. Our validation studies indicate that our method is sensitive, robust, and able to be used for a variety of applications where concentrations of biologically relevant tSGAs need to be quantified.

19Tomato steroidal glycoalkaloids (tSGAs) are a class of cholesterol-derived metabolites uniquely 20 produced by the tomato clade. These compounds provide protection against biotic stress due to 21 their fungicidal and insecticidal properties. Although commonly reported as being anti-nutritional, 22 both in vitro as well as pre-clinical animal studies have indicated that some tSGAs may have a 23 beneficial impact on human health. However, the paucity of quantitative extraction and analysis 24 methods presents a major obstacle for determining the biological and nutritional functions of 25 tSGAs. To address this problem, we developed and validated the first comprehensive extraction 26 and UHPLC-MS/MS quantification method for tSGAs. Our extraction method allows for up to 16 27 samples to be extracted simultaneously in 20 minutes with 93.0 ± 6.8% and 100.8 ± 13.1% 28 recovery rates for tomatidine and alpha-tomatine, respectively. Our ultra-high-performance liquid 29 chromatography tandem mass spectrometry (UHPLC-MS/MS) method was able to 30 chromatographically separate analytes derived from 16 tSGAs representing 9 different tSGA 31 masses, as well as two internal standards, in 13 minutes. Tomato steroidal glycoalkaloids that did 32 not have available standards were annotated using high resolution mass spectrometry as well as 33 product ion scans that provided fragmentation data. Lastly, we utilized our method to survey a 34 variety of commonly consumed tomato-based products. Total tSGA concentrations ranged from 35 0.7 to 3.4 mg/serving and represent some of the first reported tSGA concentrations in tomato-36 based products. Our validation studies indicate that our method is sensitive, robust, and able to be 37 used for a variety of applications where concentrations of biologically relevant tSGAs need to be 38 quantified. 39 40 Introduction 41Solanaceous plants produce a spectrum of cholesterol derived compounds called steroidal 42 glycoalkaloids. While each solanaceous clade produces its own unique assortment of steroidal 43 glycoalkaloids, these metabolites share commonality in their role as phytoanticipins and anti-44 herbivory agents (Etalo et al., 2015; Fontaine et al., 1948; Irving et al., 1945; Ökmen et al., 2013). 45Tomato (Solanum lycopersicum and close relatives) is no exception, and over 100 tomato steroidal 46 glycoalkaloids (tSGAs, Fig. 1) have been suggested (Iijima et al., 2013(Iijima et al., , 2008. Although these 47 compounds are typically reported as anti-nutritional (Ballester et al., 2016; Cárdenas et al., 2016 Cárdenas et al., , 48 2015 Itkin et al., 2013), other studies suggest a health-promoting role. In fact, emerging evidence 49 suggests that some tSGAs may play a role in positive health outcomes associated with tomato 50 consumption (Cayen, 1971; Choi et al., 2012; Cooperstone et al., 2017; Lee et al., 2004). While 51 these compounds continue to be evaluated both in planta and in vivo, there is a lack of quantitative 52 and validated methods to extract and measure tSGAs from tomato...

Watermelon fruit [Citrullus lanatus (Thumb) Matsum & Nakai] is a natural source of phytonutrients, including lycopene, citrulline, and arginine. Two segregating, highly outcrossed North Carolina watermelon populations, NC High Yield (NCHYW) and NC Small Fruit (NCSFW), were evaluated for these traits and for indicators of ripeness (pH and soluble solids content). Parents tested in 2015 (N SF = 300, N HY = 300) were sampled for the above and offspring were tested in 2016 if the sampled fruit of the parents were of qualifying ripeness [soluble solids concentration (SSC) ‡8, pH 5.5-6.5], resulting in 251 families (N SF = 72, N HY = 175). Narrow-sense heritability was estimated in each of the populations using the methods of 1) parent-offspring regression and 2) variance of half-sibling family means. Heritability for citrulline in NCHYW was moderate in both parent-offspring and half-sibling estimations (38% and 43%), as was arginine (40% and 44%) and lycopene (46% and 47%, respectively). Estimates for these traits in NCSFW were considerably different, with parent-offspring and half-sibling estimations for citrulline (65% and 22%), arginine (9% and 20%), and lycopene (44% and 68%). In NCHYW, moderate phenotypic correlations were found between SSC and citrulline (0.40), arginine (0.40), their combination (0.45), and lycopene (0.30) all of which were significant, except lycopene. Lycopene was significantly and weakly correlated to citrulline (0.22), but was not correlated to arginine (0.06). Similar correlations were found in NCSFW; SSC was significantly correlated to citrulline (0.24), arginine (0.18), and their combination (0.23), whereas lycopene was slightly correlated to citrulline (0.15) and not significantly correlated to arginine. Based on these heritabilities and phenotypic correlations, tandem selection for high lycopene and citrulline content may be accomplished efficiently using progeny rows with minimal replication using the NCSFW population, whereas replication with multiple years, rows, and locations may be necessary for creating stable lines using the NCHYW population.