Short-term water stress responses of grafted pepper plants are associated with changes in the hormonal balance

Phytohormones play an important role in regulating the plant behavior to drought. In previous studies, NIBER® pepper rootstock showed tolerance to drought in terms of production and fruit quality compared to ungrafted plants. In this study, our hypothesis was that short-term exposure to water stress in young, grafted pepper plants would shed light on tolerance to drought in terms of modulation of the hormonal balance. To validate this hypothesis, fresh weight, water use efficiency (WUE) and the main hormone classes were analyzed in self-grafted pepper plants (variety onto variety, V/V) and variety grafted onto NIBER® (V/N) at 4, 24, and 48h after severe water stress was induced by PEG addition. After 48h, WUE in V/N was higher than in V/V, due to major stomata closure to maintain water retention in the leaves. This can be explained by the higher abscisic acid (ABA) levels observed in the leaves of V/N plants. Despite the interaction between ABA and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), in relation to stomata closure is controversial, we observed an important increase of ACC at the end of the experiment in V/N plants coinciding with an important rise of the WUE and ABA. The maximum concentration of jasmonic acid and salicylic acid after 48h was found in the leaves of V/N, associated with their role in abiotic stress signaling and tolerance. Respect to auxins and cytokinins, the highest concentrations were linked to water stress and NIBER®, but this effect did not occur for gibberellins. These results show that hormone balance was affected by water stress and rootstock genotype, where NIBER® rootstock displayed a better ability to overcome short-term water stress

Impact of overexpression of 9-cis-epoxycarotenoid dioxygenase on growth and gene expression under salinity stress

To better understand abscisic acid (ABA)’s role in the salinity response of tomato (Solanum lycopersicum L.), two independent transgenic lines, sp5 and sp12, constitutively overexpressing the LeNCED1 gene (encoding 9-cis-epoxycarotenoid dioxygenase, a key enzyme in ABA biosynthesis) and the wild type (WT) cv. Ailsa Craig, were cultivated hydroponically with or without the addition of 100 mM NaCl. Independent of salinity, LeNCED1 overexpression (OE) increased ABA concentration in leaves and xylem sap, and salinity interacted with the LeNCED1 transgene to enhance ABA accumulation in xylem sap and roots. Under control conditions, LeNCED1 OE limited root and shoot biomass accumulation, which was correlated with decreased leaf gas exchange. In salinized plants, LeNCED1 OE reduced the percentage loss in shoot and root biomass accumulation, leading to a greater total root length than WT. Root qPCR analysis of the sp12 line under control conditions revealed upregulated genes related to ABA, jasmonic acid and ethylene synthesis and signalling, gibberellin and auxin homeostasis and osmoregulation processes. Under salinity, LeNCED1 OE prevented the induction of genes involved in ABA metabolism and GA and auxin deactivation that occurred in WT, but the induction of ABA signalling and stress-adaptive genes was maintained. Thus, complex changes in phytohormone and stress-related gene expression are associated with constitutive upregulation of a single ABA biosynthesis gene, alleviating salinity-dependent growth limitation

Overproduction of ABA in rootstocks alleviates salinity stress in tomato shoots

To determine whether root-supplied ABA alleviates saline stress, tomato (Solanum lycopersicum L. cv. Sugar Drop) was grafted onto two independent lines (NCED OE) overexpressing the SlNCED1 gene (9-cis-epoxycarotenoid dioxygenase) and wild type rootstocks. After 200 days of saline irrigation (EC = 3.5 dS m−1), plants with NCED OE rootstocks had 30% higher fruit yield, but decreased root biomass and lateral root development. Although NCED OE rootstocks upregulated ABA-signalling (AREB, ATHB12), ethylene-related (ACCs, ERFs), aquaporin (PIPs) and stress-related (TAS14, KIN, LEA) genes, downregulation of PYL ABA receptors and signalling components (WRKYs), ethylene synthesis (ACOs) and auxin-responsive factors occurred. Elevated SlNCED1 expression enhanced ABA levels in reproductive tissue while ABA catabolites accumulated in leaf and xylem sap suggesting homeostatic mechanisms. NCED OE also reduced xylem cytokinin transport to the shoot and stimulated foliar 2-isopentenyl adenine (iP) accumulation and phloem transport. Moreover, increased xylem GA3 levels in growing fruit trusses were associated with enhanced reproductive growth. Improved photosynthesis without changes in stomatal conductance was consistent with reduced stress sensitivity and hormone-mediated alteration of leaf growth and mesophyll structure. Combined with increases in leaf nutrients and flavonoids, systemic changes in hormone balance could explain enhanced vigour, reproductive growth and yield under saline stress

Comparative Analysis of Hot and Cold Brews from Single-Estate Teas (<i>Camellia sinensis</i>) Grown across Europe: An Emerging Specialty Product

Tea is grown around the world under extremely diverse geographic and climatic conditions, namely, in China, India, the Far East and Africa. However, recently, growing tea also appears to be feasible in many regions of Europe, from where high-quality, chemical-free, organic, single-estate teas have been obtained. Hence, the aim of this study was to characterize the health-promoting properties in terms of the antioxidant capacity of traditional hot brews as well as cold brews of black, green and white teas produced across the European territory using a panel of antioxidant assays. Total polyphenol/flavonoid contents and metal chelating activity were also determined. For differentiating the characteristics of the different tea brews, ultraviolet-visible (UV-Vis) spectroscopy and ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry were employed. Overall, our findings demonstrate for the first time that teas grown in Europe are good quality teas that are endowed with levels of health-promoting polyphenols and flavonoids and that have an antioxidant capacity similar to those grown in other parts of the world. This research is a vital contribution to the characterization of European teas, providing essential and important information for both European tea growers and consumers, and could be of guidance and support for the selection of teas grown in the old continent, along with having the best brewing conditions for maximizing the health benefits of tea

Environmental and Experimental Botany

To investigate whether shoot-to-root communication modulates physiological (leaf water relations and growth), phytohormonal and transcriptomic responses to phosphorus (P) deprivation, soybean (Glycine max L. Merr.) plants received a factorial combination of low P conditions and girdling. Stem phloem tissue was surgically excised from the first internode between the cotyledonary and the first unifoliate leaf, immediately before imposing different P treatments (250 and 5 μM P in hydroponics). Root and leaf expression of genes involved in P homeostasis, sucrose metabolism and transporters, starch metabolism, hormone homeostasis and ABA signalling were analysed, to determine their regulation and relationships to tissue P / ABA concentrations. P deprivation mainly upregulated root and leaf P homeostasis gene expression only in intact plants, acting to maintain foliar P homeostasis. Although girdling suppressed root expression of these genes, it increased root P concentrations and decreased leaf P concentrations. Initially, P deprivation decreased stomatal conductance before leaf water status decreased, irrespective of girdling. Later, stomatal closure of girdled P-deprived plants was greater than intact P-deprived plants at the same, lower leaf water status, coincident with enhanced foliar ABA accumulation and expression of ABA biosynthesis genes. In contrast, P deprivation decreased foliar concentrations of the antitranspirant jasmonic acid and increased root and leaf SA concentrations at the end of the experiment. P deprivation also decreased foliar cytokinin and gibberellin concentrations before leaf growth was inhibited and leaf water status declined, suggesting non-hydraulic growth regulation. Girdling and P deprivation increased foliar sucrose and hexoses, corresponding to increased sucrose invertase and transporter gene expression in the leaves, while decreasing root sucrose and hexoses concentrations and downregulating sucrose metabolism but increasing transporter gene expression. Girdling perturbs multiple root and shoot phytohormonal responses that modulate physiological adaptation to P deprivationPCV, PMM and ICD thank the SEW-REAP Project (EuropeAid ECRIP ICI+/2014/348-010) for supporting this work, while PCV was part-supported by a Lancaster University Faculty PhD studentship. FPA thanks the Spanish MINECO-FEDER (project PID2021-128979OB-I00) for supporting hormonal research under nutrient stress in his labPeer reviewe

Protective Effect (Safener) of Melatonin on Vigna Radiata L. Seedlings in the Presence of the Fungicide Copper Oxychloride

Melatonin (N-acetyl-5-methoxytriptamine) is a novel plant regulatory molecule currently under study. Its role as a biostimulator and protector against abiotic and biotic stressors, through the regulation of the redox network and change in the expression of many elements of primary and secondary metabolism, is of great interest. The possible protective effect of melatonin in mungbean seedlings, previously primed seed treated with the fungicide copper oxychloride, was studied. The effect of melatonin and fungicide in growth of seedlings and photosynthetic pigments, leakage membranes, lipid peroxidation, antioxidant activity, and phytomelatonin content was studied. Also, the effect of exogenous melatonin on endogenous plant hormones indoleacetic acid, gibberellins, cytokinins, abscisic acid, salicylic acid, and jasmonic acid levels, in the absence and presence of fungicide, was analyzed. Melatonin improved growth of roots and aerial parts in the presence of fungicide; chlorophyll and carotenoid contents were protected by melatonin in the presence of melatonin and in melatonin-fungicide co-treatments. Membrane damage due to fungicide was lessened by melatonin. The hormonal profile (auxin, gibberellins, cytokinins, abscisic acid, ethylene precursor, salicylic acid, and jasmonic acid) in roots and leaves was greatly affected by copper fungicide and melatonin treatments. In general, an increasing in plant tolerance response has been detected, proposing melatonin as a natural safener molecule of plants in the presence of copper fungicideOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work has been funded through the project of the Ministry of Science and Innovation "R + D + I Projects," State Program for the Generation of Knowledge and Scientific and Technological Strengthening of the R + D + I System and R + D + I Oriented to the Challenges of Society of the State Plan for Scientific and Technical Research and Innovation 2017–2020, Grant PID2020-113029RB-I00 funded by MCIN/AEI/1013039/501100011033. More information in: https://www.um.es/en/web/phytohormones/, accessed on september 24, 2022 (Phytohormones & Plant Development Lab)Peer reviewe

Stem girdling enhances ABA-induced stomatal closure of phosphorus-deprived soybean plants

To investigate whether shoot-to-root communication modulates physiological (leaf water relations and growth), phytohormonal and transcriptomic responses to phosphorus (P) deprivation, soybean (Glycine max L. Merr.) plants received a factorial combination of low P conditions and girdling. Stem phloem tissue was surgically excised from the first internode between the cotyledonary and the first unifoliate leaf, immediately before imposing different P treatments (250 and 5 μM P in hydroponics). Root and leaf expression of genes involved in P homeostasis, sucrose metabolism and transporters, starch metabolism, hormone homeostasis and ABA signalling were analysed, to determine their regulation and relationships to tissue P / ABA concentrations. P deprivation mainly upregulated root and leaf P homeostasis gene expression only in intact plants, acting to maintain foliar P homeostasis. Although girdling suppressed root expression of these genes, it increased root P concentrations and decreased leaf P concentrations. Initially, P deprivation decreased stomatal conductance before leaf water status decreased, irrespective of girdling. Later, stomatal closure of girdled P-deprived plants was greater than intact Pdeprived plants at the same, lower leaf water status, coincident with enhanced foliar ABA accumulation and expression of ABA biosynthesis genes. In contrast, P deprivation decreased foliar concentrations of the antitranspirant jasmonic acid and increased root and leaf SA concentrations at the end of the experiment. P deprivation also decreased foliar cytokinin and gibberellin concentrations before leaf growth was inhibited and leaf water status declined, suggesting non-hydraulic growth regulation. Girdling and P deprivation increased foliar sucrose and hexoses, corresponding to increased sucrose invertase and transporter gene expression in the leaves, while decreasing root sucrose and hexoses concentrations and downregulating sucrose metabolism but increasing transporter gene expression. Girdling perturbs multiple root and shoot phytohormonal responses that modulate physiological adaptation to P deprivation.Premio Anual Publicación Científica Destacada de la US. Escuela Técnica Superior de Ingeniería Agronómic

Bumblebees sense rootstock-mediated nutrition and fertilization regime in tomato

Since producing more with less is required for increasing agricultural sustainability and reducing its environmental impact, breeding varieties with increased yield stability under reduced fertilizer application is an important goal, particularly in high valued horticultural crops such as tomato (Solanum lycopersicum L.). However, because of the difficulties to conciliate yield and fertilizer use efficiency through breeding, the graft-compatible genetic biodiversity existing in horticultural species offers the possibility to directly approach this objective in high-yielding elite varieties through improving nutrient capture and promoting ecosystem services such as insect pollination. We hypothesized that rootstocks affect pollinator foraging decisions through the nutritional status that impacts yieldThe authors are very grateful to the Spanish MICINN-FEDER (projects RTI2018-099113-B-I00, PDC2022-133986-I00) and to the Fundación Séneca de la Región de Murcia (project 20907/PI/18; postdoc-training grants of the Plan de Empleo Juvenil-FEDER and Saavedra Fajardo Program to ASP and JAM, respectively), for supporting research on vegetable grafting and pollinators in our lab. The authors are also very grateful to Dr. Monica Borghi (University of Utah) for the assessment of the manuscript and her valuable comments and Dr. José Alberto Egea (CEBAS-CSIC) for his assistance with statistical analysis. This research has been partially funded by the European Union´s HORIZON-EIC-PATHFINDEROPEN programme under grant agreement No. 101098680Peer reviewe

Insights on the Hypoglycemic Potential of Crocus sativus Tepal Polyphenols: An In Vitro and In Silico Study

Post-prandial hyperglycemia typical of diabetes mellitus could be alleviated using plant-derived compounds such as polyphenols, which could influence the activities of enzymes involved in carbohydrate digestion and of intestinal glucose transporters. Here, we report on the potential anti-hyperglycemic effect of Crocus sativus tepals compared to stigmas, within the framework of valorizing these by-products of the saffron industry, since the anti-diabetic properties of saffron are well-known, but not those of its tepals. In vitro assays showed that tepal extracts (TE) had a greater inhibitory action than stigma extracts (SE) on α-amylase activity (IC50: TE = 0.60 ± 0.09 mg/mL; SE = 1.10 ± 0.08 mg/mL; acarbose = 0.051 ± 0.07) and on glucose absorption in Caco-2 differentiated cells (TE = 1.20 ± 0.02 mg/mL; SE = 2.30 ± 0.02 mg/mL; phlorizin = 0.23 ± 0.01). Virtual screening performed with principal compounds from stigma and tepals of C. sativus and human pancreatic α-amylase, glucose transporter 2 (GLUT2) and sodium glucose co-transporter-1 (SGLT1) were validated via molecular docking, e.g., for human pancreatic α-amylase, epicatechin 3-o-gallate and catechin-3-o-gallate were the best scored ligands from tepals (−9.5 kcal/mol and −9.4 kcal/mol, respectively), while sesamin and episesamin were the best scored ones from stigmas (−10.1 kcal/mol). Overall, the results point to the potential of C. sativus tepal extracts in the prevention/management of diabetes, likely due to the rich pool of phytocompounds characterized using high-resolution mass spectrometry, some of which are capable of binding and interacting with proteins involved in starch digestion and intestinal glucose transport

The Interaction between Hydromulching and Arbuscular Mycorrhiza Improves Escarole Growth and Productivity by Regulating Nutrient Uptake and Hormonal Balance

To improve water and nutrient use efficiencies some strategies have been proposed, such as the use of mulching techniques or arbuscular mycorrhizal fungi (AMF) inoculation. To gain insights into the interaction between the use of hydromulch and AMF inoculation on plant growth and productivity, escarole plants (Cichorium endivia, L.) were inoculated with the AMF Rhizophagus irregularis and grown with non-inoculated plants under different soil cover treatments: ecological hydromulching based on the substrate of mushroom cultivation (MS), low-density black polyethylene (PE), and non-covered soil (BS). AMF inoculation or the use of mulching alone, but especially their interaction, increased the plant growth. The growth improvement observed in AMF-inoculated escarole plants grown under hydromulching conditions was mainly associated with the upgrading of nitrogen and phosphorous use efficiency through the regulation of the hormonal balance. Both hydromulching and AMF inoculation were found to increase the active gibberellins (GAs) and cytokinins (CKs), resulting in a positive correlation between these hormones and the growth-related parameters. In contrast, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and abscisic acid (ABA) decreased in AMF-inoculated plants and especially in those grown with the MS treatment. This study demonstrates that there exists a positive interaction between AMF and hydromulching which enhances the growth of escarole plants by improving nutrient use efficiency and hormonal balance