Gibberellin-like Activity Research Articles

Design, Synthesis and Gibberellin-Like Activity of Novel 1-Substituted 3-[3-(Trifluoromethyl)phenyl]thiourea Derivatives

Design, Synthesis and Gibberellin-Like Activity of Novel 1-Substituted 3-[3-(Trifluoromethyl)phenyl]thiourea Derivatives

Natural biostimulants as upscale substitutes to synthetic hormones for boosting tomato yield and fruits quality

Natural biostimulants are one of the most promising and eco-sustainable technologies, which can improve the qualitative and productive attributes of horticultural crops. The positive effects of their application derive from their “signaling role” as elicitors of auxin- and gibberellin-like activity, thus constituting a valid alternative to synthetic hormones. Our research aimed to assess the efficacy of a plant extract (Heptamin®) and a bacterial culture filtrate (Capxium®), both rich in natural auxins, and of a synthetic auxin (Auxyger® LG) on the quantitative and qualitative performance, as well as on the economic returns of greenhouse table tomato (Solanum lycopersicum L. cv. Pitagora). The application of plant extract increased the marketable yield (+25.8%), firmness (+25.7%), and fruit lycopene content (+42.5%) compared to the untreated control. In particular, natural biostimulants outperformed synthetic auxin by inducing higher fruit weight (13.1%) and marketable yield (16.2%). On the other hand, no significant differences were recorded as a result of the treatments regarding total soluble solids, pH, and titratable acidity of the fruit juice. Our results suggest that plant biostimulants with auxin-like activity are an excellent tool for boosting tomato production and fruit quality in an eco-sustainable approach. Finally, economic analysis revealed that the application of natural biostimulants resulted in overall higher profitability

The Technique of Water Extract Preparation from Goat Willow Leaves with Allowance for Circadian Rhythm of Their Biological Activity to Stimulate Scots Pine Seed Germination

The preparative technique for water extraction of goat willow (Salix caprea L.) growing leaves was elaborated in order to stimulate Scots pine (Pinus sylvestris L.) seed germination by the extracts (patent no. 2662999). It was shown that the effects of the extract were accounted for by its biological activity, which considerably varied depending on the time of day for extract sampling. The maximal increase in gibberellin-like activity (equivalent to 3.4–3.6 µM GA3) and marked decrease in ABA-like activity (equivalent to 0.15‒0.30 µM ABA) were recorded in the willow leaf extracts harvested in the morning (8:00 a.m.) or evening (8:00 p.m.) in South Karelia (60° N) in mid-May. Application of the extracts to pine seeds afforded the maximal effects on their germination. Thus, the second-class seeds displayed qualitative characteristics of the first-class seeds (germination exceeding 80%) after the treatment. It is concluded that the introduction of the method into practice will allow utilization of the accessible, widespread plant raw material for production of the effective natural preparation, which is capable of improving sowing qualities of Scots pine seeds.

Morphological and Physiological Responses Induced by Protein Hydrolysate-Based Biostimulant and Nitrogen Rates in Greenhouse Spinach

Plant-derived protein hydrolysates (PHs) are gaining prominence as biostimulants due to their potential to improve yield and nutritional quality even under suboptimal nutrient regimens. In this study, we investigated the effects of foliar application of a legume-derived PH (0 or 4 mL L−1) on greenhouse baby spinach (Spinacia oleracea L.) under four nitrogen (N) fertilization levels (0, 15, 30, or 45 kg ha−1) by evaluating morphological and colorimetric parameters, mineral composition, carbohydrates, proteins, and amino acids. The fresh yield in untreated and biostimulant-treated spinach plants increased in response to an increase in N fertilization from 1 up to 30 kg ha−1, reaching a plateau thereafter indicating the luxury consumption of N at 45 kg ha−1. Increasing N fertilization rate, independently of PH, lead to a significant increase of all amino acids with the exception of alanine, GABA, leucine, lysine, methionine, and ornithine but decreased the polyphenols content. Interestingly, the fresh yield at 0 and 15 kg ha−1 was clearly greater in PH-treated plants compared to untreated plants by 33.3% and 24.9%, respectively. This was associated with the presence in of amino acids and small peptides PH ‘Trainer®’, which act as signaling molecules eliciting auxin- and/or gibberellin-like activities on both leaves and roots and thus inducing a “nutrient acquisition response” that enhances nutrients acquisition and assimilation (high P, Ca, and Mg accumulation) as well as an increase in the photochemical efficiency and activity of photosystem II (higher SPAD index). Foliar applications of the commercial PH decreased the polyphenols content, but on the other hand strongly increased total amino acid content (+45%, +82%, and +59% at 0, 15, and 30 kg ha−1, respectively) but not at a 45-kg ha−1-rate. Overall, the use of PH could represent a sustainable tool for boosting yield and nitrogen use efficiency and coping with soil fertility problems under low input regimens.

Gibberellin-like activity of fungi associated with vermicast in corn and rice

Gibberellin-like activity of fungi associated with vermicast in corn and rice

Helminthosporic acid functions as an agonist for gibberellin receptor.

Helminthosporol was isolated from a fungus, Helminthosporium sativum, as a natural plant growth regulator in 1963. It showed gibberellin-like bioactivity that stimulated the growth of the second leaf sheath of rice. After studying the structure-activity relationship between the compound and some synthesized analogs, it was found that helminthosporic acid (H-acid) has higher gibberellin-like activity and chemical stability than helminthosporol. In this study, we showed that (1) H-acid displays gibberellin-like activities not only in rice but also in Arabidopsis, (2) it regulates the expression of gibberellin-related genes, (3) it induces DELLA degradation through binding with a gibberellin receptor (GID1), and (4) it forms the GID1-(H-acid)-DELLA complex to transduce the gibberellin signal in the same manner as gibberellin. This work shows that the H-acid mode of action acts as an agonist for gibberellin receptor.

Biostimulant activity of humic substances extracted from leonardites

Biostimulants are natural compounds that enhance plant growth and plant nutrient use efficiency. In this study, biostimulant effects of humic substances (HS) extracted from leonardites were analysed on the metabolism of maize plants grown in hydroponic conditions. HS extracted from four leonardites were tested for their auxin-like and gibberellin-like activities. Then, 11 day old maize seedlings were treated for 48 h with five concentrations (0, 0.1, 0.5, 1, and 10 mg C L−1) of HS. After sampling, root growth and morphology, glutamine synthetase (GS) activity, glutamate synthase (GOGAT) activity, total protein content, soluble sugars content, phenylalanine ammonia-lyase (PAL) activity, soluble phenols, and free phenolic acids were analysed. HS from leonardites had similar spectroscopic pattern, with small differences. The HS from the South Dakota lignite (HS_USA) had more carboxylic groups, whereas the three from Turkish mines had more aromatic and aliphatic structures. HS_USA best enhanced total root growth, root surface area, and proliferation of secondary roots. Plant nutrient use efficiency was enhanced by HS_4, HS_USA and HS_B, with increment of GS and GOGAT enzymes activity and total protein production. HS stimulated also PAL enzyme activity, followed by a higher production of total soluble phenols, p-hydroxybenzoic acid, p-coumarilic acid, and chlorogenic acid. This study found that, although the activity of the HS depended on the origin of the leonardite, these compounds can be attributed to the biostimulant products, eliciting plant growth, nitrogen metabolism, and accumulation of phenolic substances.

Biological Activity of Vegetal Extracts Containing Phenols on Plant Metabolism.

The influence of vegetal extracts derived from red grape, blueberry fruits and hawthorn leaves on Zea mays L. plant growth and the activity of phenylalanine ammonia-lyase (PAL), a key enzyme of the phenylpropanoid pathway, was investigated in laboratory experiments. The extracts were characterized using FT-IR and Raman spectroscopies in order to obtain a pattern of the main functional groups. In addition, phenols content was determined by HPLC, whereas the content of indoleacetic acid and isopentenyladenosine hormones was determined by ELISA test and the auxin and gibberellin-like activities by plant-bioassays. The treated maize revealed increased root and leaf biomass, chlorophyll and sugars content with respect to untreated plants. Hawthorn, red grape skin and blueberry at 1.0 mL/L induced high p-coumaric content values, whilst hawthorn also showed high amounts of gallic and p-hydroxybenzoic acids. PAL activity induced by hawthorn at 1.0 mL/L had the highest values (11.1-fold UNT) and was strongly and linearly related with the sum of leaf phenols. Our results suggest that these vegetal extracts contain more than one group of plant-promoting substances.

Snow vole (Chionomys nivalis Martins) affects the redistribution of soil organic matter and hormone-like activity in the alpine ecosystem: ecological implications.

In alpine environments, colonies of snow vole (Chionomys nivalis Martins) cause strong pedoturbation, which may affect humification process and soil organic matter (SOM) cycling, with repercussions on the hormone-like activity of organics. We investigated the effect of snow vole pedoturbation on the chemical and spectroscopic features of soil organic fractions, and the potential hormone-like activity of humic and fulvic acids (HA, FA). The study site was located on the high-mountain environment of the Majella massif (central Italy). Pedoturbated and regular soils were morphologically described and characterized for pH and content of total organic carbon, total extractable carbon, HA, and FA. Both HA and FA were extracted and investigated using attenuated total reflectance/Fourier transform infrared (ATR/FTIR), nuclear magnetic resonance with high-resolution magic angle spinning (HRMAS-NMR), and (1)H-(13)C heteronuclear single quantum coherence (HSQC). HA and FA were also tested for their auxin-like and gibberellin-like activities. Results provide evidences that bioturbated and regular soils contain a poorly decomposed SOM, but HA and FA with a well-defined molecular structure. The HA and FA from both bioturbated and regular soils show a hormone-like activity with a different allocation along the soil profile. In the regular soil, the highest auxin-like activity was shown by HA and FA from Oe1 horizon, while gibberellin-like activity was expressed by FA from Oe2 horizon. Burrowing activity determines a redistribution of organics throughout the profile with a relatively high auxin-like activity in the FA from straw tunnel wall (STW) and gibberellin-like activity in the HA from vole feces (VF). The relative high presence of carboxylic acids, amides, proteins, and amino acids in the FA from STW and the aromatic moieties in the HA from VF put evidences for their different behavior. The fact that snow vole activity has modified the chemical and biological properties of SOM in these soils otherwise considered governed only by low temperature has important ecological implications such as the preservation of soil fertility and vegetal biodiversity.

Computational insight into the structure-activity relationship of novel N-substituted phthalimides with gibberellin-like activity.

N-substituted phthalimides (NSPs) that show multiple gibberellin (GA)-like effects on the growth and development of higher plants have been reported. These NSPs may represent a potential alternative to commercial GAs. Therefore, in this work, molecular docking and molecular dynamics simulations were used to explore the mode of interaction between some NSPs and the GA receptor GID1A in order to clarify the relationship between structure and GA-like activity in the NSPs. The results obtained demonstrate that both a multiple-hydrogen-bond network and a "hat-shaped" hydrophobic interaction play important roles in the binding of the NSPs to GID1A. The carbonyl group of a phthalimide fragment in the NSPs acted in a similar manner to the pharmacophore group 6-COOH in GAs, forming multiple-hydrogen-bond interactions with residues Ser191 and Tyr322 in the binding domain of GID1A. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were used to further study the 3D quantitative structure-activity relationship (3D-QSAR) of the NSPs. It was confirmed that the GA-like activity of these NSPs is strongly linked to a few H-bond donor and acceptor field contributions of the NSPs to the H-bond interactions with GID1A. Five new NSP molecules D1-D5 were designed using the binding domain of GID1A and then docked into the receptor. D1 and D4 were shown to have good docking scores due to enhanced hydrophobic contact. We hope that these results will provide useful guidance in the rational design of new NSPs.

Evaluation of hormone-like activity of the dissolved organic matter fraction (DOM) of compost and digestate

Biomasses are usually applied to soil for their agronomic properties (fertilization and amendment properties). Biomass can also have bio-stimulating effects on plants because of the presence of hormones and hormone-like molecules. Although compost has been the subject for studies of this aspect, no data have yet been reported on the extraction of this kind of molecule from digestate biomass. The aim of this work is to study the auxin- and gibberellin-like activity of pig slurry digestate in comparison with those of pruning and garden wastes compost's dissolved organic fraction (DOM). DOM (i.e., fraction<0.45μm) is the most reactive among the organic matter fractions readily available to microbial and plant metabolism. No gibberellin-like activities were found for either compost or digestate, whereas digestate showed auxin-like properties which were found to be located in its neutral hydrophobic (NHo) DOM fractions. Hormone activity was due principally to the presence of auxin coming from the anaerobic digestion of aromatic amino acids.

Production of an enzymatic protein hydrolyzate from defatted sunflower seed meal for potential application as a plant biostimulant

An extensive protein hydrolyzate was produced starting from sunflower defatted seed meal, an abundant by-product of biodiesel chain oil extraction. Two-step enzymatic hydrolysis was carried out using sequentially Alcalase-Flavourzyme enzymes and a high quality hydrolyzate was produced with an interesting composition in terms of nutrient, amino acid, and peptide content for application in conventional and organic agriculture. The biostimulant properties of the hydrolyzate were investigated by carrying out auxin and gibberellin-like activity assays in Petri dishes on garden cress (Lepidium sativum L.) and lettuce (Lactuca sativa L.) seedlings and by conducting experiments in pot on maize plants. The sunflower hydrolyzate showed auxin-like, but no gibberellin-like activity and interesting effects on plant root elongation suggesting a potential use of the product as an effective biostimulant in the agricultural field.

Involvement of phytohormones in the development of interaction between wheat seedlings and endophytic Bacillus subtilis strain 11BM

Wheat (Triticum aestivum L., cv. Kazakhstanskaya 10) seedling growth activation by the endophytic 11BM strain of the bacterium Bacillus subtilis Cohn and the involvement of phytohormones in this process were studied. At the concentration used, bacteria enhanced wheat root and shoot growth as compared to control. Biotests demonstrated auxin-, cytokinin-, and gibberellin-like activities of the endophyte, but the result depended on the way of experiment performing. When wheat seeds were treated with the spores of B. subtilis 11BM strain, the concentrations of IAA and ABA increased transiently in the roots and shoots of the seedlings. The involvement of IAA oxidase in the plant response to inoculation with bacteria was shown; it was accompanied by a decrease in enzyme activity, which occurred later than auxin accumulation. It was concluded that observed changes in the hormonal status of wheat plants under the influence of the endophytic bacterial strain may be one of the mechanisms for seedling growth stimulation.

Effects of a Municipal Sewage Sludge Amendment on Triasulfuron Soil Sorption and Wheat Growth

The influence of municipal sewage sludge (SL) as a soil amendment on the sorption and activity of the herbicide triasulfuron (TRS, [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide]) was studied. Weed control was checked in a greenhouse on a wheat (Triticum turgidum L. subsp. durum) crop. At the highest SL amount allowed by Italian regulation, TRS sorption onto soil increased by 7 times and weed control was unaffected. A vegetative bloom and an early heading phase were noted. To compare inorganic fertilization (N, P, and K) and SL amendment, a greenhouse fertilization experiment was carried out. The SL-amended crop developed larger leaf surfaces, higher biomass, and a forward heading compared to that fertilized with N, P, and K. The SL hormone-like activity was evaluated by measuring auxin- and gibberellin-like activity of sewage sludge.

Genomic insights in moss gibberellin biosynthesis

Gibberellins are phytohormones that are essential for proper growth and development of flowering plants. In bryophytes, however, the presence of gibberellins has not been firmly established, because previous reports of gibberellin-like activities were not accompanied by definitive chemical identification. By comparison, the other classical phytohormones auxin, cytokinin, abscisic acid and ethylene have been unambiguously detected in both mosses and liverworts, and their functions have been demonstrated to be very similar to those in flowering plants. The study of gibberellins in bryophytes lagged behind those of other phytohormones presumably because of the bewildering complexity and diversity in their chemical structures. In addition, working with bryophytes becomes even more challenging given their small size and the lack of obvious developmental mutants in the gibberellin signaling pathway. On the other hand, the recent sequencing of the Physcomitrella patens genome provides exciting opportunities to tackle this problem. Genes that may be involved in gibberellin biosynthesis have now been identified, paving the way for molecular genetic experiments that could reveal the role of gibberellins in bryophyte development. As bryophytes represent the earliest diverging lineages of land plants, such studies can also provide insights into how the gibberellin pathway may have evolved in the course of land plant evolution.

The production of gibberellin-like substances by Colletotrichum gloeosporioides associated with lupin anthracnose

The most characteristic symptoms of lupin ( Lupinus spp.) anthracnose caused by the fungus Colletotrichum gloeosporioides, are twisting and bending of stems and petioles. These might be related to the production of gibberellin-like activity by the pathogen. The barley aleurone bioassay was used to determine whether two isolates of C. gloeosporioides could produce gibberellin-like substances. Ethyl acetate extracts from isolates SHK 2148 and SHK 1033, grown in liquid minimal medium, had gibberellin-like activities of 0.21 μg GA 3 equivalents and > 0.26μg GA 3 equivalents per g dry mass of mycelium, respectively. Provided that the strong association between gibberellins and this specific pathogen/host interaction can be established, this knowledge may be helpful in screening lupin cultivars for anthracnose resistance.

Soil organic matter properties after 40 years of different use of organic and mineral fertilisers

Organic inputs can help maintain soil fertility by improving chemical and biological soil properties. The effects of 40 years of organic, mineral and mixed fertilisations on soil organic properties were evaluated in a continuous maize system. The following properties were analysed: total organic carbon (TOC), humic carbon (HC) and its molecular weight distribution, HC/TOC and the hormone—(auxin and gibberellin-like) activities of the humic substances and their effects on two key enzymes (nitrate reductase (NR) and glutamine synthetase (GS)) involved in nitrate assimilation in maize seedlings. Farmyard manure fertilisation sustained TOC in the top layers while mineral treatments alone or mixed with organic exhibited a minor influence on the organic matter evolution: over 40 years the average TOC depletion was 23% with liquid manure and mixed fertilisations, 43% with mineral fertilisers alone and 51% in the control. The different treatments also influenced the HC molecular complexity. Farmyard fertilisations improved the production of humus with a high degree of policondensation, a fraction usually linked to soil fertility; the absence of organic fertiliser inputs determined the opposite, with a higher percentage of non-complex and light-weight humus. The hormone-like and biochemical activities of humus substances were evident with the organic and mixed fertilisations. The humus extracted by the soil treated with farmyard manure exhibited the best gibberellin-like activity and the highest increases of NR (+42%) and GS (+49%) activities with respect to the control. The other treatments showed intermediate stimulations as in the case of mixed fertilisations (NR + 22% and GS + 24%), or no activities as in the case of mineral inputs.

Hormone-like activities of humic substances in different forest ecosystems.

• In order to understand the phytohormone-like activity of humic substances (HS) with respect to vegetation, different forest ecosystems were considered. For this study, 32 soil horizons from a large area of northern Italy typical for silver fir ( Abies alba ) were evaluated. • The development of organic and humic matter in the five silver fir forest types was assessed by quantifying chemical and biochemical parameters. Phytohormone-like activity of HS was evaluated by measuring auxin-like (indoleacetic acid (IAA)-like) and gibberellin-like (GA-like) activities as well as invertase and peroxidase activities. • Differences between ecosystems were obtained by comparing the five silver fir types with previous work in beech forests, which investigated three large groups: thermophilous, mesophilous and acidophilous. In these eight forests it was reconfirmed that acid conditions were essential for the release of the IAA-like activity, whereas neutral conditions promoted GA-like activity. • Humic substances are of ecological importance because their phytohormone-like activity stands out not only within the five silver fir forest types, but also between the silver fir and beech types. Our results demonstrated a different collocation of the hormone-like activity along the profile in accordance with the different growth conditions, seed germination and the first stage of seedling growth. Humic substances evoke the greatest response on seed germination and on the first stage of seedling growth, particularly in stressed environmental conditions.

Hormone-like activity of humic substances in Fagus sylvaticae forests.

• Soil A horizons from a large area typical for beech (Fagus sylvatica) in northern Italy were investigated to understand the phyto-hormone-like activity of humic substances (HS) with respect to the vegetation. These soils had developed under thermophilous (Cephalonthero-Fagion with Carici albae-Fagetum), mesophilous (Fagion sylvaticae with Dentario pentaphylli-Fagetum and Galio-odourati-Fagetum) or acidophilous (Luzulo-Fagion with Luzulo niveae-Fagetum) beech forests. • The development of organic and humic matter in the three forest types was assessed by quantifying chemical parameters. Phyto-hormone-like activity of HS was evaluated by measuring auxin-like (IAAlike ) and gibberellin-like (GAlike ) activity as well as IAA concentration, invertase and peroxidase activities. • Soil pH differed between the forest types. Soil C: N distinguished the thermophilous and the mesophilous from the acidophilous types but did not distinguish thermophilous from the mesophilous types. Phyto-hormone-like activity of HS varied significantly across the beech forests. Acid conditions were essential for the release of IAAlike activity whereas neutral conditions promoted GAlike activity. Plant isoenzymatic polymorphism confirmed the different auxin activities of HS. • The phyto-hormone-like activity of HS is highly suitable, and better than soil chemical parameters, for differentiating between these ecosystems.

Soil organic matter mobilization by root exudates of three maize hybrids

In order to study the macromolecular behaviour of humic substances, we treated humic material (from the Ah horizon of an Eutric Cambisol) either with exudates from 10 day-old seedlings obtained in axenic conditions from three maize cultivars (Zea mays L.; cv. Paolo, cv. Polaris and cv. Sandek) or with the organic acids (succinic and fumaric) present in the exudates and followed the change in molecular size distribution. Succinic acid, Polaris and Sandek exudates shifted the humic absorbance from high to low molecular weight in size exclusion chromatograms, while Paolo exudates were not able to produce the same shift and gave an absorbance profile like that of humic substance alone. Our results are evidence of the micellar behaviour of humic substances in solution and of the importance of hydrophobic bonds in holding humic molecular together. Exudates were also used to separate soil organic fractions from the same soil. Soil organic extracts were characterized by low pressure gel permeation chromatography, hormone-like activities, and 1H-NMR. The data, compared with water extract and KOH extract, indicate that maize exudates, fumaric and succinic acids mobilize soil organic fractions in small quantities, but these extracts are endowed with auxin- and/or gibberellin-like activity. Water extract and maize exudates exhibit no hormone-like activity, while KOH extract shows a negligible one. Moreover, only Polaris and Sandek exudates and succinic acid are able to disaggregate an organic fraction with low apparent molecular size (<13KDs) from the bulk of the soil. The 1H-NMR data indicate that water and succinic extracts are largely composed of carbohydrate and aliphatic constituents. Sandek exudate and fumaric acid can liberate aromatic components, Polaris exudate releases carbohydrates from soil, while Paolo slightly influences the aliphatic constituents. The role of organic acids released by maize seedlings in mobilising soil organic fractions is presented.