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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 À1 ), 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 GA 3 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.

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.

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 fungicide.

Teak (Tectona grandis) is one of the most important wood sources, and it is cultivated in tropical regions with a significant market around the world. Abiotic stresses are an increasingly common and worrying environmental phenomenon because it causes production losses in both agriculture and forestry. Plants adapt to these stress conditions by activation or repression of specific genes, and they synthesize numerous stress proteins to maintain their cellular function. For example, APETALA2/ethylene response factor (AP2/ERF) was found to be involved in stress signal transduction. A search in the teak transcriptome database identified an AP2/ERF gene named TgERF1 with a key AP2/ERF domain. We then verified that the TgERF1 expression is rapidly induced by Polyethylene Glycol (PEG), NaCl, and exogenous phytohormone treatments, suggesting a potential role in drought and salt stress tolerance in teak. The full-length coding sequence of TgERF1 gene was isolated from teak young stems, characterized, cloned, and constitutively overexpressed in tobacco plants. In transgenic tobacco plants, the overexpressed TgERF1 protein was localized exclusively in the cell nucleus, as expected for a transcription factor. Furthermore, functional characterization of TgERF1 provided evidence that TgERF1 is a promising candidate gene to be used as selective marker on plant breeding intending to improve plant stress tolerance.

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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.

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.