Leaf Metabolites Research Articles

Untargeted metabolomics and comparative flavonoid analysis reveal the nutritional aspects of pak choi

Pak choi is a leafy vegetable with high economic value. Despite its importance, the information related to its metabolomics profile has still not been well-understood. This study aimed to determine the leaf metabolite composition of seven pak choi. In total, 513 metabolites belonging to 24 separate metabolite groups were detected. Pak choi leaves were rich in organic acids, amino acids, and flavonoids. There were ninety-two flavonoid compounds detected in pak choi leaves. Multivariate analysis revealed a distinct variation in the metabolite and flavonoid profile of green and purple leaved varieties. The flavonoid accumulation was comparatively greater in green leaved than purple leaf cultivar. This work provides novel insights into pak choi metabolomics profile, the flavonoids in particular, thus, to assess the nutritional value of this vegetable for humans.

Morphological and biochemical responses of tropical seagrasses (Family: Hydrocharitaceae) under colonization of the macroalgae Ulva reticulata Forsskål.

BackgroundCoastal land development has deteriorated the habitat and water quality for seagrass growth and causes the proliferation of opportunist macroalgae that can potentially affect them physically and biochemically. The present study investigates the morphological and biochemical responses of seagrass from the Hydrocharitaceae family under the macroalgal bloom of Ulva reticulata, induced by land reclamation activities for constructing artificial islands.MethodsFive seagrass species, Enhalus acoroides, Thalassia hemprichii, Halophila ovalis, Halophila major, and Halophila spinulosa were collected at an Ulva reticulata-colonized site (MA) shoal and a non-Ulva reticulata-colonized site (MC) shoal at Sungai Pulai estuary, Johor, Malaysia. Morphometry of shoots comprising leaf length (LL), leaf width (LW), leaf sheath length (LSL), leaflet length (LTL), leaflet width (LTW), petiole length (PL), space between intra-marginal veins (IV) of leaf, cross vein angle (CVA) of leaf, number of the cross vein (NOC), number of the leaf (NOL) and number of the leaflet (NOLT) were measured on fresh seagrass specimens. Moreover, in-situ water quality and water nutrient content were also recorded. Seagrass extracts in methanol were assessed for total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid radical cation scavenging activity (ABTS), and ferric reducing antioxidant power (FRAP).ResultsSeagrasses in the U. reticulata-colonized site (MA) had significantly higher (t-test, p < 0.05) leaf dimensions compared to those at the non-U. reticulata colonized site (MC). Simple broad-leaved seagrass of H. major and H. ovalis were highly sensitive to the colonization of U. reticulata, which resulted in higher morphometric variation (t-test, p < 0.05) including LL, PL, LW, and IV. Concerning the biochemical properties, all the seagrasses at MA recorded significantly higher (t-test, p < 0.05) TPC, TFC, and ABTS and lower DPPH and FRAP activities compared to those at MC. Hydrocharitaceae seagrass experience positive changes in leaf morphology features and metabolite contents when shaded by U. reticulata. Researching the synergistic effect of anthropogenic nutrient loads on the interaction between seagrasses and macroalgae can provide valuable information to decrease the negative effect of macroalgae blooms on seagrasses in the tropical meadow.

Investigation of Possible Changes Induced by RNA Silencing in Some Leaf Metabolites of Transgenic Sugar Beet Events

Sugar beetis vulnerable to rhizomania as the most destructive viral disease. Two selected events of transgenic sugar beet carrying cassettes inducing RNA silencing mechanism, 219-T3:S3-13.2 (S3) and 6018-T3:S6-44 (S6), were shown to inhibit propagation of Beet Necrotic Yellow Vein Virus, the causative agent. As a method for signifying the substantial equivalence, we analyzed the levels of some metabolites through LC-MS in order to demonstrate possible unintended changes in the leaves of the transgenic events. There was no significant difference in the concentrations of examined key metabolites but cis-aconitate and fructose-1,6-bisphosphatase which were decreased in S3. Also, ATP was reduced in both genetically modified sugar beets. Among free amino acids, only glycine level in S6 was increased compared to the wild plant, while the production levels of 5 and 12 ones were increased in S3 compared to S6 event and the wild type plants, respectively.

Silencing of δ‐aminolevulinic acid dehydratase via virus induced gene silencing promotes callose deposition in plant phloem

ABSTRACT The δ-aminolevulinic acid dehydratase (ALAD) enzyme is an intermediate in the biosynthetic pathway of tetrapyrroles. It combines two δ‐aminolevulinic acid (δ‐ALA) molecules to form the pyrrole, porphobilinogen, an important precursor for plant pigments involved in photosynthesis, respiration, light-sensing, and nutrient uptake. Our recent efforts showed that, in citrus, silencing of ALAD gene via Citrus tristeza virus-induced gene silencing, caused yellow spots and necrosis in leaves and in developing new shoots. Silencing of ALAD gene reduced leaf pigments and altered leaf metabolites. Moreover, total phenolic content, H2O2, and reactive oxygen species (ROS) increased, indicating that silencing of ALAD induced severe stress. Herein, we hypothesized that conditions including lower sucrose, elevated ROS, alteration of microRNA involved in RNAi regulatory protein Argonaute 1 (AGO1) and ROS lead to higher deposition of callose in phloem tissues. Using aniline blue staining and gene expression analysis of callose synthases, we showed significant deposition of callose in ALAD-silenced citrus.

Effects of chiral herbicide dichlorprop on Arabidopsis thaliana metabolic profile and its implications for microbial communities in the phyllosphere

Dichlorprop (2-(2,4-dichlorophenoxy) propionic acid, DCPP), a commonly used herbicide for weed control, can be residually detected in soil. It is still unclear whether chiral DCPP exerts an enantioselective adverse effect on plant metabolism and the microbial community of the phyllosphere. In this study, we selected Arabidopsis thaliana as a model plant to explore the effects of R- and S-DCPP enantiomers on plant physiological activities, metabolism, and associated changes in the phyllosphere microbial community. Results indicated that the fresh weight of plants decreased by 37.6% after R-DCPP treatment, whereas it increased by 7.6% after S-DCPP treatment. The R-DCPP enantiomer also caused stronger disturbance to leaf morphology, mesophyll cell structure, and leaf metabolites compared with S-DCPP. GC-MS analysis of DCPP-treated Arabidopsis leaves pointed out a differential profile mostly in carbohydrates, organic acids, and fatty acids, between S-DCPP and R-DCPP treatments. The diversity of phyllospheric microorganisms decreased and the stability of microbial community in the phyllosphere increased after R-DCPP treatment, whereas the opposite result was detected after S-DCPP exposure. The correlation analysis revealed that chiral herbicides may affect microbial communities in the phyllosphere by influencing leaf metabolism, while sugars and terpenoids were considered the main factors in reshaping the microbial community structure in the phyllosphere. Our study provides a new perspective for evaluating the effect of residual DCPP enantiomers on plant physiology and corresponding phyllosphere microorganism changes via the regulation of leaf metabolism, and clarifies the ecological risk of DCPP enantiomer application in agriculture.

Leveraging a graft collection to develop metabolome-based trait prediction for the selection of tomato rootstocks with enhanced salt tolerance.

Grafting has been demonstrated to significantly enhance the salt tolerance of crops. However, breeding efforts to develop enhanced graft combinations are hindered by knowledge-gaps as to how rootstocks mediate scion-response to salt stress. We grafted the scion of cultivated M82 onto rootstocks of 254 tomato accessions and explored the morphological and metabolic responses of grafts under saline conditions (EC = 20 dS m−1) as compared to self-grafted M82 (SG-M82). Correlation analysis and Least Absolute Shrinkage and Selection Operator were performed to address the association between morphological diversification and metabolic perturbation. We demonstrate that grafting the same variety onto different rootstocks resulted in scion phenotypic heterogeneity and emphasized the productivity efficiency of M82 irrespective of the rootstock. Spectrophotometric analysis to test lipid oxidation showed largest variability of malondialdehyde (MDA) equivalents across the population, while the least responsive trait was the ratio of fruit fresh weight to total fresh weight (FFW/TFW). Generally, grafts showed greater values for the traits measured than SG-M82, except for branch number and wild race-originated rootstocks; the latter were associated with smaller scion growth parameters. Highly responsive and correlated metabolites were identified across the graft collection including malate, citrate, and aspartate, and their variance was partly related to rootstock origin. A group of six metabolites that consistently characterized exceptional graft response was observed, consisting of sorbose, galactose, sucrose, fructose, myo-inositol, and proline. The correlation analysis and predictive modelling, integrating phenotype- and leaf metabolite data, suggest a potential predictive relation between a set of leaf metabolites and yield-related traits.

The Impact of Diaphorina citri-Vectored 'Candidatus Liberibacter asiaticus' on Citrus Metabolism.

'Candidatus Liberibacter asiaticus' is associated with the devastating citrus disease Huanglongbing (HLB). It is transmitted by grafting infected material to healthy plants and by the feeding of the Asian citrus psyllid (Diaphorina citri). Previously, we demonstrated that a metabolomics approach using proton-nuclear magnetic resonance spectroscopy discriminates healthy from diseased plants via grafting. This work assessed the capability of this technology in discriminating healthy and diseased plants when the bacterium is vectored by psyllids. One-year-old greenhouse-grown 'Lisbon' lemon trees were exposed to either carrier psyllids (exposed, n = 10), or psyllids that were free of 'Candidatus Liberibacter asiaticus' (control, n = 6). Leaf metabolites were tracked for 1 year and disease diagnosis was made using quantitative PCR. Overall, 31 water-soluble metabolites were quantified in leaves, including four sugars and 12 amino acids. Analysis via nonmetric multidimensional scaling and principal component analysis revealed significant differences between the leaf metabolome of control versus infected trees beginning at 8 weeks postexposure, including alterations in glucose and quinic acid concentrations. These findings provide a longitudinal overview of the metabolic effects of HLB during the early phases of disease, and confirm previous experimental work demonstrating that infection elicits changes in the leaf metabolome that enables discrimination between healthy and infected plants. Here we demonstrate that the mode of inoculation (i.e., graft versus psyllid) results in a similar pathology.

Cervical anticancer activities of Annona squamosa Linn. leaf isolate.

Background and Aim:Cancer is one of the leading causes of death, the need for new anticancer herbal drugs is becoming more urgent considering the side effects of synthetic drugs. This study aimed to determine the anticancer activity of isolates derived from the methanol extract of Annona squamosa Linn. leaves and to identify the compounds that have an active effect against HeLa cells.Materials and Methods:The leaf metabolites of A. squamosa L. were extracted using methanol at room temperature (28°C) and were partitioned into n-hexane, chloroform, and n-butanol. The toxicity test of these extracts was conducted using a brine shrimp lethality assay. Furthermore, the most toxic extracts were separated and purified using silica gel column chromatography to yield four isolate fractions: FA, FB, FC, and FD. The most toxic isolates were tested for anticancer against HeLa cells, and their compounds were identified using liquid chromatography-mass spectrometry.Results:The results showed that the most toxic isolate with an LC50 value of 100.00 ppm had a potency similar to that of an anticancer agent with an IC50 value of 70.9021 ppm. Furthermore, the five compounds identified in this isolate include (6S, 7aR)-6-hydroxy-4,4,7a-trimethyl-6,7-dihydro-5H-1-benzofuran-2-one or loliolide, cocamidopropyl betaine, N-[3-(dimethylamino)propyl]dodecanamide or lauramidopropyl dimethylamine, linolenic acid, and 1-dodecyl-2-azepanone or laurocapram.Conclusion:It can be concluded that the leaf isolates of A. squamosa Linn. had shown anticancer activities against cervical cancer.

Generous Hosts: 'Candidatus Liberibacter asiaticus' Growth in Madagascar Periwinkle (Catharanthus roseus) Highlights Its Nutritional Needs.

'Candidatus Liberibacter asiaticus', the putative causal agent of citrus greening, is not available in pure culture yet. In addition to trees of citrus and citrus relatives, 'Ca. L. asiaticus' can grow in Madagascar periwinkle (Catharanthus roseus). Using gas chromatography-mass spectrometry, we compared the phloem sap composition in sweet orange 'Valencia' (Citrus sinensis) and periwinkle plants after the infection with 'Ca. L. asiaticus'. Interestingly, in contrast to our previous studies of total leaf metabolites, we found that, compared with uninfected phloem sap, the organic acids implicated in the tricarboxylic acid cycle (TCA) cycle including citrate, isocitrate, succinate, fumarate, and malate were reduced significantly in the infected phloem saps of both species. As a result of the reduction of organic acids content, the pH of infected phloem saps was increased. We hypothesize that the bacterial growth induces the mitochondrial TCA cycle in parenchyma cells to produce more of these compounds to be used as a bacterial carbon source. Once these compounds reach a low level in the phloem sap, the bacterium may send a signal, yet to be identified, to initiate a feedback loop to further induce the TCA cycle. Phloem blockage might be another reason behind the reduced translocation of TCA cycle intermediates within the phloem. The net result, localized availability of organic acids, likely benefits bacterial growth and may explain the unequal distribution of 'Ca. L. asiaticus' within infected trees. These findings may help in designing media for the pure culturing of 'Ca. L. asiaticus'.

Metabolome Profiling of Heat Priming Effects, Senescence, and Acclimation of Bread Wheat Induced by High Temperatures at Different Growth Stages.

Our previous study described stage-specific responses of ‘Norin 61’ bread wheat to high temperatures from seedling to tillering (GS1), tillering to flowering (GS2), flowering to full maturity stage (GS3), and seedling to full maturity stage (GS1–3). The grain development phase lengthened in GS1 plants; source tissue decreased in GS2 plants; rapid senescence occurred in GS3 plants; all these effects occurred in GS1–3 plants. The present study quantified 69 flag leaf metabolites during early grain development to reveal the effects of stage-specific high-temperature stress and identify markers that predict grain weight. Heat stresses during GS2 and GS3 showed the largest shifts in metabolite contents compared with the control, followed by GS1–3 and GS1. The GS3 plants accumulated nucleosides related to the nucleotide salvage pathway, beta-alanine, and serotonin. Accumulation of these compounds in GS1 plants was significantly lower than in the control, suggesting that the reduction related to the high-temperature priming effect observed in the phenotype (i.e., inhibition of senescence). The GS2 plants accumulated a large quantity of free amino acids, indicating residual effects of the previous high-temperature treatment and recovery from stress. However, levels in GS1–3 plants tended to be close to those in the control, indicating an acclimation response. Beta-alanine, serotonin, tryptophan, proline, and putrescine are potential molecular markers that predict grain weight due to their correlation with agronomic traits.

Effects of temperatures on growth, physiological, and antioxidant characteristics in Houttuynia cordata

Houttuynia cordata Thunb. (HC) is a traditional medicinal plant with a variety of pharmaceutical activities. The objective of this study was to investigate the growth, photosynthetic parameters, and antioxidant properties of HC plants in response to various temperatures. Pots of HC plants were maintained in day/night temperatures of 15/10 °C, 20/15 °C, 25/20 °C (control), 30/25 °C, and 35/30 °C for two months in each of five growth chambers having a 13.5 h photoperiod at 396, 432, 474, 449, and 619 µmol·m-2·s-1 radiation, respectively. Eight plants for each temperature were randomly placed in a growth chamber. HC plants survived at 30/25 °C and 35/30 °C treatments and had significantly higher plant heights, leaf numbers, and soil-plant analysis development (SPAD) and normalized difference vegetation index (NDVI) values compared to other treatments. However, long-term 35/30 °C treatment caused reductions in leaf length and width, significantly decreasing shoot and leaf fresh weight (FW) and dry weight (DW) compared to 30/25 °C treatment and controls. These results indicate that HC leaf development was affected during the 35/30 °C treatment, and that both SPAD and NDVI can help in advancing our understanding of the photosynthesis process in HC. Moreover, all plants subjected to 15/10 °C suffered more severely in all traits and parameters than other treatments. Therefore, HC plants tended to be heat-tolerant and exhibited adaptive morphologic plasticity to 30/25 °C conditions. Positive and significant correlations were observed among temperatures and total phenolics (TP), total flavonoids (TF), chlorogenic acid (CGA), and hyperoside (HO) content, and all bioactive contents increased as temperature increased, except that both CGA and HO content were remarkably decreased after 30/25 °C treatment. Thus, 30/25 °C treatment would be more beneficial for high marketability resulting from increased leaf number, DW, and all secondary metabolites compared to other treatments, and for use as a health food and for medicinal purposes. In addition, leaf growth, physiological parameters, and secondary metabolite accumulations in HC plants can be optimized for commercial production via temperature control technologies. This approach may also be applicable to leafy vegetables to produce stable industrial supplies having high leaf yields and metabolite content.

Cultural Extension of Ginkgo biloba L. in Slovakia

Ginkgo biloba L. is the oldest species of tree on our planet. It is a dioecious species characterized by exceptional resistance to climate change and natural influences, which predetermines it as a suitable species for urban planting. Not to be overlooked is the ginkgo benefit in terms of the medical effects of leaf metabolites. Due to its aesthetic value ginkgo is becoming popular in family gardens. The aim of our research was the evidence and description of ginkgo trees in Slovakia. The study presents the completion of data on the cultural distribution of this tree. We confirmed the occurrence on more than one hundred localities (103 localities). Some previously registered localities (18) were not found, or trees were felled for various reasons (5). We evaluated the basic dendrometric and growth parameters of the oldest ginkgo trees (aged 242 – 111 years), found in 35 localities of Slovakia. The presented research results bring several new information concerning the tree gender determination, tree habitus, phenological rhythm of development and others. Morphologically interesting solitary trees, including trees with shoots known as lignotubers or “basal chichi” (locality Hajná Nová Ves), or the occurrence of fruits on the leaves, referred to as cv. Ohatsuki (Lučenec) are described and documented by photos.

Metabolic responses to drought stress and rehydration in leaves and roots of three Citrus scion/rootstock combinations

Drought is one of the most destructive environmental challenges for agriculture, and citrus trees are cultivated in semiarid areas. The current study used physiological and untarget mass spectrometry analysis to assess the differential response to drought and rehydration in leaves and roots of three scion/rootstock combinations in which the same scion Valencia Orange was grafted onto three different rootstocks, namely, ‘Rangpur Lime’, ‘Sunki Maravilha’ and ‘Sunki Tropical’, known to have a different response to drought. The main question to be answer was whether the soil disease tolerant ‘Sunki Tropical’ could be used as alternative to the drought tolerant/disease susceptible rootstock ‘Rangpur lime’ to cultivate citrus in semiarid areas. Thirty-seven metabolites in leaves and forty-six in roots, mainly amino acids, as well as a few carbohydrates and organic acids were found differentially expressed after drought and/or rehydration in the three combinations. Overall, the results demonstrated that the three scion/rootstock combinations responded differently at metabolite levels to water changes. The few leaf metabolites found in the scion grafted on ‘Rangpur Lime’ and ‘Sunki Maravilha’ support the respective drought avoidance and tolerance strategy, already observed in those rootstocks.‘Rangur Lime’ and ‘Sunki Tropical’ shared at roots levels several common drought response mechanisms. Moreover, the high number of differential metabolites triggered in the scion by 'Sunki Tropical' seems to be useful for overcoming the drought effects without depleting the fruit quality. From our data, we argue that ‘Sunki Tropical’ is a drought tolerant genotypes that could be used as alternative to ‘Ranpur Lime’ to sustain citrus production in semiarid areas.

Assessing Drought and Heat Stress-Induced Changes in the Cotton Leaf Metabolome and Their Relationship With Hyperspectral Reflectance.

The study of phenotypes that reveal mechanisms of adaptation to drought and heat stress is crucial for the development of climate resilient crops in the face of climate uncertainty. The leaf metabolome effectively summarizes stress-driven perturbations of the plant physiological status and represents an intermediate phenotype that bridges the plant genome and phenome. The objective of this study was to analyze the effect of water deficit and heat stress on the leaf metabolome of 22 genetically diverse accessions of upland cotton grown in the Arizona low desert over two consecutive years. Results revealed that membrane lipid remodeling was the main leaf mechanism of adaptation to drought. The magnitude of metabolic adaptations to drought, which had an impact on fiber traits, was found to be quantitatively and qualitatively associated with different stress severity levels during the two years of the field trial. Leaf-level hyperspectral reflectance data were also used to predict the leaf metabolite profiles of the cotton accessions. Multivariate statistical models using hyperspectral data accurately estimated (R2 > 0.7 in ∼34% of the metabolites) and predicted (Q2 > 0.5 in 15–25% of the metabolites) many leaf metabolites. Predicted values of metabolites could efficiently discriminate stressed and non-stressed samples and reveal which regions of the reflectance spectrum were the most informative for predictions. Combined together, these findings suggest that hyperspectral sensors can be used for the rapid, non-destructive estimation of leaf metabolites, which can summarize the plant physiological status.

Evaluation of Metabolomic Profile and Growth of Moringa oleifera L. Cultivated with Vermicompost under Different Soil Types

Moringa oleifera is a highly versatile plant with potential use in the agro-food and biochemical industry. The goals of this study were to evaluate the effect of chemical fertilization and vermicompost on plant growth, and to analyze the metabolomic profile of M. oleifera crops cultivated over agricultural and native soils. The extracts were obtained from 90-day-old leaves via extraction with a hydroalcoholic mixture. Multivariate data analyses, such as principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA), were used to differentiate the distribution of leaf metabolites according to the soils or types of fertilizers used for the cultivation of Moringa oleifera. The results indicated that there was no significant effect on parameters such as plant height, root length and dry weight of leaves (p &lt; 0.05). UPLC-ESI-MS/MS analysis of leaf extracts revealed a wide range of flavonoids, alkaloids and organic acids. The results of PCA and PLS-DA confirmed that the type of fertilizer had an effect on the metabolomic profile of M. oleifera leaves. The application of vermicompost induced changes in the metabolomic profile, but not in the morphometric variables of Moringa oleifera. These results are important for metabolite production via organic cultures and over different soil types in the industrialization of Moringa.

Effects of polyester microfibers (PMFs) and cadmium on lettuce (Lactuca sativa) and the rhizospheric microbial communities: A study involving physio-biochemical properties and metabolomic profiles

Microfibers (MFs) and cadmium (Cd) are widely distributed in soil ecosystems, posing a potential threat to soil biota. To explore potential risks of single MFs and in combination with Cd (co-PMFs/Cd) to soil environment, we systematically investigated the effects of PMFs and co-PMFs/Cd treatments on physio-biochemical performance and metabolomic profile of lettuce (Lactuca sativa), as well as the rhizospheric bacterial communities. Our results showed that both PMFs and co-PMFs/Cd treatments adversely disturbed the plant shoot length, photosynthetic, and chlorophyll content. Co-PMFs/Cd specifically increased the activities of antioxidant enzymes. The metabolites in lettuce leaf were significantly altered by PMFs and co-PMFs/Cd treatments. A significant reduction in the relative abundance of amino acids sugar and sugar alcohols indicated the altered nitrogen and carbohydrates related metabolic pathways. Additionally, PMFs and co-PMFs/Cd treatments altered the structure of rhizospheric bacterial communities and caused significant changes in some key beneficial/functional bacteria involved in the C, and N cycles. The present study provides a novel insight into the potential effects of PMFs on plant and rhizosphere bacterial communities and highlights that PMFs can threaten the terrestrial ecosystem and should be further explored in future research.

Metabolite Profiling of Dioscorea (Yam) Leaves to Identify Bioactive Compounds Reveals Their Potential as Renewable Resources.

Yams (Dioscorea spp.) are cultivated and consumed as edible tubers, while their leaves are discarded as waste or burned with negative environmental impact. Herein, the metabolites of two yam species (Danma, DAN; Dunggeunma, DUN), harvested in June, July, and August, were profiled using GC-TOF-MS and UHPLC-LTQ-Orbitrap-MS/MS and the antioxidant activity of the extracts was evaluated to stimulate the utilization of yam leaves as a by-product. We observed that the relative levels of amino acids, organic acids, sugars, and saponins decreased linearly with prolonged harvest time, while fatty acid, phenanthrene, and flavonoid levels gradually increased. Furthermore, the leaf extracts obtained in August exhibited the highest antioxidant activity. To determine the antioxidant-contributing metabolites, OPLS-DA was performed for the leaf metabolites of DAN and DUN leaves harvested in August. Hydroxytyrosol-glucoside, apigenin-rhamnoside, and rutin were more abundant in DUN, while luteolin, phenanthrene derivatives, epicatechin, and kaempferide were relatively higher in DAN and their respective metabolites were positively correlated with the antioxidant activity. Moreover, secondary metabolites were more abundant in the leaves than in the roots, and consequently, the antioxidant activity of the former was also higher. Overall, the potential value of yam leaves as a renewable source of bioactive compounds is proposed.

Leaf density and chemical composition explain variation in leaf mass area with spectral composition among 11 widespread forbs in a common garden.

Leaf mass per area (LMA) is a key leaf functional trait correlated with plant strategies dictating morphology, physiology, and biochemistry. Although sunlight is generally accepted as a dominant factor driving LMA, the contribution of each spectral region of sunlight in shaping LMA is poorly understood. In the present study, we grew 11 widespread forb species in a common garden and dissected the traits underpinning differences in LMA, such as its morphological components (leaf density [LD] and leaf thickness [LT]), macroelement, and metabolite composition under five spectral-attenuation treatments: (1) transmitting c. 95% of the whole solar spectrum (> 280 nm), (2) attenuating ultraviolet-B radiation (UV-B), (3) attenuating both UV-A and UV-B radiation, (4) attenuating UV radiation and blue light, (5) attenuating UV radiation, blue, and green light. We found that LMA, LD, and chemical traits varied significantly across species depending on spectral treatments. LMA was significantly increased by UV-B radiation and green light, while LD was increased by UV-A but decreased by blue light. LMA positively correlated with LD across treatments but was only weakly related to LT, suggesting that LD was a better determinate of LMA for this specific treatment. Regarding leaf elemental and metabolite composition, carbon, nitrogen, and total phenolics were all positively correlated with LMA, whereas lignin, non-structural carbohydrates, and soluble sugars had negative relationships with LMA. These trends imply a tradeoff between biomass allocation to structural and metabolically functional components. In conclusion, sunlight can spectrally drive LMA mainly through modifying functional and structural support.

Variations in the leaf metabolite profile between hydroponic and field grown Moringa oleifera Lam. genotypes

Medicinal and herbal plants are increasingly cultivated on commercial scale all around the world, to satisfy the large demand for natural remedies associated with plant bioactive compounds. Moringa oleifera Lam. is one of these attractive plant species, being cultivated across the world, with most of the production in Africa and Asia. However, it is increasingly reported that the composition and concentration of bioactive compounds in medicinal plants, are largely influenced by factors such as the growing environment, harvesting time, and climatic factors among others. The aim of this study was therefore to determine the differences in the leaf metabolite profile between hydroponic and field grown M. oleifera plants due to cultivation system, harvesting time and genotypes. 1H NMR was used for data acquisition, and MestReNova software was used for the pre-processing of the spectral data. Multivariate data analysis by means of PCA and OPLS-DA was conducted, followed by targeted metabolite analyses. The results show variations in the leaf metabolite profile as influenced by cultivation systems, harvesting time and genotypes. In both PKM-1 and Malawi hybrid genotypes, the concentration level of chlorogenic acid, ferulic acid, vanillic acid, and wogonin compounds were higher in the hydroponic leaf material, whereas the concentration level of esculetin, niazirin and GABA were slightly higher in the field harvested leaf materials. With regards to harvesting time effect, the concentration level of all seven targeted compounds were higher in February (summer) harvest as compared to May (autumn) harvest. Among the genotypes, PKM-1 showed to have higher concentration of certain targeted compounds as compared to Malawi hybrid, but on the other hand certain compounds from the Malawi hybrid showed also higher concentrations. These results provide insight on the possible alternative production system that can be adopted to optimise and improve accumulation of bioactive compounds in M. oleifera leaf materials.

The Effects of Different Rates of Chicken Manure and Harvest Intervals on the Bioactive Compounds of Bitter Leaf (Vernonia amygdalina Del.)

Bitter leaf (Vernonia amygdalina Del.) is a valuable functional vegetable and traditional medicinal plant in many tropical countries including Indonesia. Bitter leaf is commonly used to remedy hypertension and diabetes among Indonesian people. The leaf extract comprises bioactive compounds such as sesquiterpene lactones, steroid glycosides, and flavonoids. Despite its growing market demand, there is insufficient data on agronomic practice in order to obtain optimum yield with high bioactive compounds. The experimental design used was a randomized complete block design with two factors namely chicken manure rates (0, 2.5, 5, and 7.5 kg per plant) and harvest intervals (2 and 3 months). There was a significant difference in fresh and dry weights of leaves, chlorophyll a and b, carotenoids, nitrogen concentration, anthocyanins, and flavonoids among different manure treatment. The highest concentration and production of bioactive compounds on the bitter leaf was found on the highest treatment of 7.5 kg chicken manure per plant. The harvest interval of three months significantly increased fresh and dry weights of leaves, concentration of anthocyanins, phosphorus, and potassium, uptake of phosphorus and potassium, and production of anthocyanins and flavonoids. Cultivation using chicken manure with frequent period of pruning can enhance the production of biomass as well as secondary metabolites in bitter leaf.