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Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) is a nutritional crop, which has high rutin, and is good for health. Until now, plant genetic engineering is insufficient for Tartary buckwheat. Abscisic acid (ABA), as one of phytohormones, is involved in the regulation of plant growth and development, and responses to diverse environmental challenges. Although ABA receptors have been well characterized in Arabidopsis , it is little understood in Tartary buckwheat. In this study, we identified 12 ABA receptors, designated as FtRCAR1 through FtRCAR12 in Tartary buckwheat. FtRCARs are divided into three subfamily. Based on the similarity, we could predict that FtRCARs comprise of the monomeric (FtRCAR1, 3, 4, 5, 9, 10, 11 and 12) and the dimeric (FtRCAR2, 7 and 8) state in solution. The analysis of the transcript pattern indicated that most of FtRCARs were significantly variable among the root, stem, leaf, flower and seed, while FtRCAR4 transcript was undetectable under in all tissues. The transcript levels of FtRCARs under ABA treatment indicated that most FtRCARs transcripts were depressed, indicating a possible feedback regulation of ABA signaling. The analysis of rutin biosynthesis related-genes indicated that ABA up-graduated CHS , CHI , F3 ′ H , F3H and FLS transcript levels, while transcripts of 4CL and PAL were down-regulated. In addition, the transcription factors that mediated the rutin biosynthesis related-genes were also regulated by exogenous ABA. Thus, the identification and the characterization of FtRCARs would enable us to further understand the role of ABA signal in Tartary buckwheat. • The identification of abscisic acid receptors (FtRCARs) in Tartary Buckwheat. • The characteristics of FtRCARs are shown in the paper. • The genes in rutin biosynthesis signaling pathway were predicted to be mediated by exogenous ABA. • The transcription factors that regulate the rutin biosynthesis in Tartary Buckwheat could also be regulated by ABA. [ABSTRACT FROM AUTHOR]

The abscission zone (AZ) is a specialized tissue that usually develops at the base of an organ and is highly sensitive to phytohormones, e.g., abscisic acid (ABA), ethylene (ET), and gibberellins (GAs). A current model of organ abscission assumes that the formation of an auxin gradient around the AZ area determines the time of shedding; however, that thesis is supported by studies that are primarily concerned with auxin transporters. To better understand the events underlying the progression of abscission, we focused for the first time on indole-3-acetic acid (IAA) distribution following AZ activation. We performed a series of immunolocalization studies in proximal and distal regions of floral AZ cells in yellow lupine, which is an agriculturally important legume. The examined phytohormone was abundant in natural active AZ cells, as well as above and below parts of this structure. A similar gradient of IAA was observed during the early steps of abscission, which was induced artificially by flower removal. Surprisingly, IAA was not detected in inactive AZ cells. This paper is also a consequence of our comprehensive studies concerning the phytohormonal regulation of flower abscission in yellow lupine. We present new data on interactions between IAA and ET, previously pointed out as a strong modulator of flower separation. The detailed analysis shows that disruption of the natural auxin gradient around the AZ area through the application of synthetic IAA had a positive effect on ET biosynthesis genes. We proved that these changes are accompanied by an accumulation of the ET precursor. On the other hand, exposure to ET significantly affected IAA localization in the whole AZ area in a time-dependent manner. Our results provide insight into the existence of a spatio-temporal sequential pattern of the IAA gradient related to the abscission process; this pattern is maintained by interactions with ET. We present new valuable evidence for the existence of conservative mechanisms that regulate generative organ separation and can help to improve the yield of agronomically significant species in the future. [ABSTRACT FROM AUTHOR]

Abstract Besides their protective role, polyamines also serve as signalling molecules. However, further studies are needed to elucidate the polyamine signalling pathways, especially to identify polyamine-regulated mechanisms and their connections with other regulatory molecules. Reduced height (Rht) genes in wheat are often used in breeding programs to increase harvest index. Some of these genes are encoding DELLA proteins playing role in gibberellic acid signalling. The aim of the present paper was to reveal how the mutations in Rht gene modify the polyamine-regulated processes in wheat. Wild type and two Rht mutant genotypes (Rht 1: semi-dwarf; Rht 3: dwarf mutants) were treated with polyamines. Polyamine treatments differently influenced the polyamine metabolism, the plant growth parameters and certain hormone levels (salicylic acid and abscisic acid) in these genotypes. The observed distinct metabolism of Rht 3 may more likely reflect more intensive polyamine exodus from putrescine to spermidine and spermine, and the catabolism of the higher polyamines. The lower root to shoot translocation of putrescine can contribute to the regulation of polyamine pool, which in turn may be responsible for the observed lack of growth inhibition in Rht 3 after spermidine and spermine treatments. Lower accumulation of salicylic acid and abscisic acid, plant hormones usually linked with growth inhibition, in leaves may also be responsible for the diminished negative effect of higher polyamines on the shoot growth parameters observed in Rht 3. These results provide an insight into the role of polyamines in plant growth regulation based on the investigation of gibberellin-insensitive Rht mutants. Highlights • Polyamine treatments differently influenced the polyamine metabolism in Rht lines. • More intensive polyamine exodus observed in dwarf mutant. • Lower salicylic acid and abscisic acid levels in the leaves of spermine-treated dwarf mutant. • The above mentioned are responsible for the lack of growth inhibition in dwarf mutant. [ABSTRACT FROM AUTHOR]

Little is known about systemic plant responses to abiotic stress. Two recent papers now shed light on the identification of long-distance signals in response to drought or light stress. The new data suggest that leaf transpiration via abscisic acid (ABA) is controlled by remote signals from roots and leaves for efficient use of water. [ABSTRACT FROM AUTHOR]

The aims of this paper are to develop our understanding of the ways by which soil water deficits influence early wheat root growth responses, particularly how seminal roots respond to soil drying and the extent to which information on differences in soil water content are conveyed to the shoot and their impact on shoot behaviour. To achieve this, wheat seedlings have been grown, individually for around 25 days after germination in segmented soil columns within vertical plastic compartments. Roots were exposed to different soil volumetric moisture contents (SVMC) within the two compartments. Experiments where the soil in the lower compartment was allowed to dry to different extents, while the upper was maintained close to field capacity, showed that wheat seedlings allocated proportionally more root dry matter to the lower drier soil compartment. The total production of root, irrespective of the upper or lower SVMC, was similar and there were no detected effects on leaf growth rate or gas exchange. The response of seminal roots to proportionally increase their allocation of dry matter, to the drier soil was unexpected with such plasticity of roots system development traditionally linked to heterogeneous nutrient distribution than accessing soil water. In experiments where the upper soil compartment was allowed to dry, root growth slowed and leaf growth and gas exchange declined. Subsequent experiments used root growth rates to determine when seminal root tips first came into contact with drying soil, with the intentions of determining how the observed root growth rates were maintained as an explanation for the observed changes in root allocation. Measurements of seminal root ABA and ethylene from roots within the drying soil are interpreted with respect to what is known about the physiological control of root growth in drying soil. [ABSTRACT FROM AUTHOR]

• This is the first study to report anatomy and endogenous hormonal profiles in the early seedling stage of kohlrabi. • The de novo formation of supplementary vascular bundles and phloem ring are the key features of kohlrabi stem. • IAA, IAAsp, GA and tZ profiles were significantly varied in the stems while the ABA profile was different in the leaves. • The stunted stem and vascular activity of cambium are positively correlated with endogenous GA and cytokinin in kohlrabi stem. To unveil the mechanism of tuberous stem formation at early growth stages in kohlrabi, the comparative stem morphology, anatomy, and endogenous plant hormone profiles were studied at different days after germination (10 to 30 DAG). Stem anatomy revealed that the notable feature of the kohlrabi stem during the transition from primary to secondary growth was the formation of vascular bundle circles, with many phloems formed separately and arranged in a circular pattern along with the cambium layer, resulting in an expanded ring of primary and secondary phloem. In addition, medullary supplemental vascular bundles were differentiated in the central region of pith and successively supplied small-sized meristematic parenchymatous cells which contribute to the tuber initiation in kohlrabi. Six phytohormones were quantified in the stems and leaves of both genotypes. The absence of Gibberellin A4 (GA4) in kohlrabi stem might be the cause of the stunted stem of kohlrabi. The total endogenous cytokinin in stem of kohlrabi was more than twice of that of broccoli, where trans-zeatin was the most abundant bioactive form. This can be explained by the meristematic nature of the cambium of kohlrabi stem. Profiles for Indole-3-acetic acid, Indole-3-acetylaspartic acid, and Abscisic acid of the stems and leaves of kohlrabi and broccoli were significantly different at several time points tested. Thus, the key features of kohlrabi during the initiation of tuberous stem were the formation of the phloem ring along with the cambium and the supplemental vascular bundles. This is the first paper showing the hormonal profile in the early seedling stage of kohlrabi. These findings provide useful information to elucidate the mechanism of tuberous stem formation of kohlrabi and other tuber crops. [ABSTRACT FROM AUTHOR]

The ABA responsive protein (ABR) is an important transcription factor in plants, which plays a unique role in the regulation of plant growth and stress response. Previously, ZjABR1/ERF10 was screened by our work from transcriptome database of Zoysia japonica under salt stress, but the detailed regulatory mechanism of this gene involved in is not well elucidated. In this paper, the ZjABR1 was isolated from Zoysia japonica and its function was identified in Oryza sativa. Analysis of gene expression showed that ZjABR1 might play a regulatory role in Abscisic Acid (ABA), ethylene and salt stress response. Compared with wild-type plants, ZjABR1 overexpression transgenic Oryza sativa showed lower seed setting rate, dwarfing and salt resistance. Furthermore, protein interaction experiments indicated that ZjABR1 interacted with a protein functioned in the regulation of GA signaling pathway, which is ZjCIGR1. Therefore, these results establish that ZjABR1 can be a potential multifunctional genetic gene in the cell signal transduction regulation of GA-ABA cross-talking, which affects the development and stress resistance of plants. • Compared with wild-type plants, exogenous ABA, ethylene and salt stress can significantly affect the expression of ZjABR1. • ZjABR1 transgenic Oryza sativa showed seed setting rate decreased, sprouting earlier and dwarfing. • ZjABR1 transgenic plants showed enhanced tolerances to salt stress. • ZjABR1 interacting with ZjCIGR1 may be involved in the cell signal transduction regulation of GA-ABA cross-talking. [ABSTRACT FROM AUTHOR]

• Anthocyanin synthesis determines fruits color, which is an important commodity trait. • Applying plant growth regulators is an efficient means to enhance anthocyanin content. • Different plant growth regulators have different effects on anthocyanin accumulation. • Choosing appropriate plant growth regulators and scientifically applying them are crucial to improve fruits quality. Fruit color is an important indicator of fruit quality, which is mainly determined by anthocyanin accumulation. Therefore, increasing anthocyanin content is an important way to improve the nutritional and commodity value of fruits. Anthocyanin synthesis is not only regulated by internal genetic factors but also affected by external factors such as light, temperature and nutritional levels, etc. In addition, plant growth regulators also play an important role in the regulation of anthocyanin synthesis. They mainly affect anthocyanin synthesis by affecting physiological and biochemical metabolism, the expression of structural genes and the activity of MBW complex. In the production of fruit, the application of plant growth regulators is an important means of promoting coloration. But there are still many problems during application, such as incorrect application time, inappropriate application concentration and so on. This paper reviews the physiological and molecular mechanism of anthocyanin synthesis regulated by plant growth regulators. It concludes that exogenous application of abscisic acid, jasmonate and brassinosteroid can promote the accumulation of anthocyanin. By contrast, ethylene, auxin, cytokinin and gibberellin have dual effects on anthocyanin synthesis. This review provides a theoretical basis for further study on the molecular mechanism of plant growth regulators regulating anthocyanin accumulation and theoretical guidance for scientific and efficient application of plant growth regulators in fruit production. [ABSTRACT FROM AUTHOR]

Flower abscission is a highly regulated developmental process activated in response to exogenous (e.g. changing environmental conditions) and endogenous stimuli (e.g. phytohormones). Ethylene (ET) and abscisic acid (ABA) are very effective stimulators of flower abortion in Lupinus luteus , which is a widely cultivated species in Poland, Australia and Mediterranean countries. In this paper, we show that artificial activation of abscission by flower removal caused an accumulation of ABA in the abscission zone (AZ). Moreover, the blocking of that phytohormone’s biosynthesis by NDGA (nordihydroguaiaretic acid) decreased the number of abscised flowers. However, the application of NBD – an inhibitor of ET action – reversed the stimulatory effect of ABA on flower abscission, indicating that ABA itself is not sufficient to turn on the organ separation. Our analysis revealed that exogenous ABA significantly accelerated the transcriptional activity of the ET biosynthesis genes ACC synthase ( LlACS ) and oxidase ( LlACO ), and moreover, strongly increased the level of 1-aminocyclopropane-1-carboxylic acid (ACC) – ET precursor, which was specifically localized within AZ cells. We cannot exclude the possibility that ABA mediates flower abscission processes by enhancing the ET biosynthesis rate. The findings of our study will contribute to the overall basic knowledge on the phytohormone-regulated generative organs abscission in L. luteus . [ABSTRACT FROM AUTHOR]

• Wax was easily removed from scales by a brief rinse with chloroform but the underlying tissue was severely damaged. • The damage by chloroform was strongly reduced by a preparatory ABA treatment of the scales to close the stomata. • The elimination of wax from scale explants pre-treated with ABA increased the growth of regenerating bulblets by 50 %. • The ABA pre-treatment reduced growth and increased contamination significantly. The aerial parts of plants are covered by the cuticle, a skin containing among others waxes. The cuticle inhibits the outflow of compounds, in particular water, from the plant to the environment, and without a cuticle, plants dehydrate rapidly. In the cuticle, waxes are the chief actors in the blocking. In tissue culture, the humidity in the headspace is very high (close to 100 %) so evaporation is limited and the cuticle is less needed. The cuticle also inhibits the entry of compounds from the environment into plants. In tissue culture, the inflow of medium components occurs predominantly via wounds, primarily those made when explants are cut. The removal of the barrier is expected to enhance the uptake of medium components. This paper addresses the question as to whether the removal of the epidermal inflow barrier enhances growth in tissue culture of lily. Waxes were removed from scale explants by a short rinse (5 s) with chloroform. During this rinse, the stomata had to be closed since otherwise the tissue was severely damaged by the inflow of chloroform into the cavities below the stomata. The closure was achieved by an abscisic acid (ABA) pre-treatment. Removal of wax resulted in increased growth (50 %) relative to nonchloroform-treated explants. This procedure is, however, not suitable for practical application because the benefit was undone by an inhibitory effect of the ABA pre-treatment. The ABA pre-treatment also increased the percentage of contaminated cultures, probably because during surface-sterilization the disinfectant did not reach the contaminants inhabiting the cavities below the stomata when the stomata had been closed. [ABSTRACT FROM AUTHOR]

Quantification of endogenous hormones in plants is essential to understand their growth, development and response to biotic and abiotic stresses. However, it is challenging to develop high-throughput sample treatments from complex plant tissues containing low amounts of structurally unrelated and labile phytohormones while delivering clean and analyte-enriched extracts. In this paper we propose the use of supramolecular solvents (SUPRASs) made up or inverted hexagonal nanostructures of alkanols to address this challenge. The strategy was applied, as a proof of concept, to the quantification of stress-related phytohormones belonging to different categories (abscisic acid, salicylic acid, jasmonic acid, methyl jasmonate and 3-indoleacetic acid) in melon and pepper leaves. Sample treatment consisted in a single extraction-cleanup step involving the use of a low volume of SUPRAS (244 μL), the stirring (5 min) and centrifugation (15 min) of the sample at room temperature, and the direct analysis of the extract by liquid chromatography tandem mass spectrometry (LC-MS/MS). This high-throughput sample treatment method delivered excellent results for the target phytohormones regarding absolute recoveries (80–92%), method quantification limits (0.05–2 ng g−1), reproducibility (1–7%) and matrix effects (+13 to −31%), in both melon and pepper leaves, compared to reported methods based on repetitive solvent extraction, purification and solvent evaporation steps. The method was successfully applied to determine target hormones in melon and pepper plants for the evaluation of the effect of thermal stress. It was found that their concentration increased in the ranges 1.2–1.9 and 1.3–3.8 times in melon and pepper leaves, respectively, compared with control samples. Image 1 • A high-throughput sample treatment was proposed for multiclass phytohormones. • It is based on a single-step extraction-purification with supramolecular solvents. • High extraction efficiencies and low matrix effects were obtained in a fast way. • It was applied to thermally stressed and standard melon and pepper leaves. • The developed method is valuable for understanding plant growth and responses. [ABSTRACT FROM AUTHOR]

• Trichoderma are soil-borne fungi that produce signaling molecules for other organisms. • Some fungal strains are agents for the biocontrol of plant pathogens. • Trichoderma can promote plant growth and induce defense responses. • These fungi establish multitrophic interactions with arthropods and plants. Trichoderma spp. are universal saprotrophic fungi in terrestrial ecosystems, and as rhizosphere inhabitants, they mediate interactions with other soil microorganisms, plants, and arthropods at multiple trophic levels. In the rhizosphere, Trichoderma can reduce the abundance of phytopathogenic microorganisms, which involves the action of potent inhibitory molecules, such as gliovirin and siderophores, whereas endophytic associations between Trichoderma and the seeds and roots of host plants can result in enhanced plant growth and crop productivity, as well as the alleviation of abiotic stress. Such beneficial effects are mediated via the activation of endogenous mechanisms controlled by phytohormones such as auxins and abscisic acid, as well as by alterations in host plant metabolism. During either root colonization or in the absence of physical contact, Trichoderma can trigger early defense responses mediated by Ca2+ and reactive oxygen species, and subsequently stimulate plant immunity by enhancing resistance mechanisms regulated by the phytohormones salicylic acid, jasmonic acid, and ethylene. In addition, Trichoderma release volatile organic compounds and nitrogen or oxygen heterocyclic compounds that serve as signaling molecules, which have effects on plant growth, phytopathogen levels, herbivorous insects, and at the third trophic level, play roles in attracting the natural enemies (predators and parasitoids) of herbivores. In this paper, we review some of the most recent advances in our understanding of the environmental influences of Trichoderma spp., with particular emphasis on their multiple interactions at different trophic levels. [ABSTRACT FROM AUTHOR]

• Drought stress decreased water content directly in nodules and caused degradation of symbiosome. • Hormonal changes evoked by water deficit are reflected by the affection of ET and ABA biosynthesis pathway. • The stress factor negatively regulated the expression of LlBOP and LlLbl genes responsible for the proper functioning of the nodules. • We provide several potential molecular and hormonal markers related to the response on soil drought. The ability of symbiosis with Rhizobium bacteria is an extremely important trait of Lupinus luteus L. Its cultivation increases soil fertility and reduces the necessity of using chemical fertilizers, thus makes lupine an excellent proecological and agronomical species. Nevertheless, nodule functioning associated with nitrogen fixation can be strongly affected by soil drought. On the face of changing climatic conditions, the emphasis should be given to get the knowledge concerning the phytohormonal and molecular markers of early response on water deficit in soil. In this paper, we have shown that soil drought stress, by causing water loss in nodules and affecting their structure, evokes degradation of symbiosome and leads to hormonal and molecular changes. The stress factor modulated abscisic acid (ABA) and ethylene (ET) biosynthesis pathways. It was reflected by increased expression of LlZEP (ZEAXANTHIN EPOXIDASE) involved in ABA biosynthesis and strong accumulation of this phytohormone. At the same time, the mRNA of synthase (LlACS) and oxidase (LlACO) of 1-aminocyclopropane-1-carboxylic acid (ACC) were elevated, while ACC accumulated significantly. Moreover, drought stress negatively influenced the expression of LlBOP (BLADE-ON-PETIOLE) and LlLbI (LEGHEMOGLOBIN), previously pointed out as regulators of nodule functioning. Simultaneously the iron and nitrogen content drastically decreased in the stressed nodules. Presented novel information describing phytohormonal changes during drought stress directly in the nodules can help to elucidate the hormonal and molecular mechanisms that control plant response to water loss. [ABSTRACT FROM AUTHOR]