Role Of Plant Hormones Research Articles

Transcriptomic analysis of Chinese yam (Dioscorea polystachya Turcz.) variants indicates brassinosteroid involvement in tuber development.

Dioscorea is an important but underutilized genus of flowering plants that grows predominantly in tropical and subtropical regions. Several species, known as yam, develop large underground tubers and aerial bulbils that are used as food. The Chinese yam (D. polystachya Turcz.) is one of the few Dioscorea species that grows well in temperate regions and has been proposed as a climate-resilient crop to enhance food security in Europe. However, the fragile, club-like tubers are unsuitable for mechanical harvesting, which is facilitated by shorter and thicker storage organs. Brassinosteroids (BRs) play a key role in plant cell division, cell elongation and proliferation, as well as in the gravitropic response. We collected RNA-Seq data from the head, middle and tip of two tuber shape variants: F60 (long, thin) and F2000 (short, thick). Comparative transcriptome analysis of F60 vs. F2000 revealed 30,229 differentially expressed genes (DEGs), 1,393 of which were differentially expressed in the growing tip. Several DEGs are involved in steroid/BR biosynthesis or signaling, or may be regulated by BRs. The quantification of endogenous BRs revealed higher levels of castasterone (CS), 28-norCS, 28-homoCS and brassinolide in F2000 compared to F60 tubers. The highest BR levels were detected in the growing tip, and CS was the most abundant (439.6 ± 196.41 pmol/g in F2000 and 365.6 ± 112.78 pmol/g in F60). Exogenous 24-epi-brassinolide (epi-BL) treatment (20 nM) in an aeroponic system significantly increased the width-to-length ratio (0.045 ± 0.002) compared to the mock-treated plants (0.03 ± 0.002) after 7 weeks, indicating that exogenous epi-BL produces shorter and thicker tubers. In this study we demonstrate the role of BRs in D. polystachya tuber shape, providing insight into the role of plant hormones in yam storage organ development. We found that BRs can influence tuber shape in Chinese yam by regulating the expression of genes involved cell expansion. Our data can help to improve the efficiency of Chinese yam cultivation, which could provide an alternative food source and thus contribute to future food security in Europe.

Distribution of Plant Hormones and Their Precursors in Cambial Region Tissues of Quercus myrsinifolia and Castanopsis cuspidata var.sieboldii after Bending Stems or Applying Ethylene precursor

The role of plant hormones in tension wood (TW) formation has been studied but is still unclear. IAA, ABA, ACC, tZ, tZR, iP, and iPR in cambial region tissues were identified and quantified by liquid chromatography/mass spectrometry (LC/MS). We examined the distribution of plant hormones and their precursors in the stems of Quercus myrsinifolia Blume and Castanopsis cuspidata var.sieboldii Nakai after bending the stems or applying an ethylene precursor (ACC). After 3 weeks of bending, though not after 1 week of bending, the auxin (IAA) and abscisic acid (ABA) amounts were larger on the TW side than on the opposite wood (OW) side and in upright trees. After 2 weeks of bending, the peak concentrations of IAA in cambium on the TW side were obviously higher than those on the OW side. After 1 week of bending, the ACC amounts on both sides were larger than in upright trees, but after 3 weeks of bending, they were smaller than in upright trees. Applied ACC did not enhance TW formation but induced axical parenchyma and phloem formation in C. cuspidata var.sieboldii. These results indicated that the distribution patterns of IAA and ABA might have important roles in TW formation in these two species. The role of ACC might be limited in the early stages of TW formation.

The Role of Plant Hormone on Root Development

Plant hormones, commonly referred to as phytohormones, are distinct chemical substances that are created by plants and are essential in controlling numerous aspects of plant growth and development. These hormones are created in particular sections of the plant, like the shoot apex or the root meristem, and are then transferred to other parts of the plant where they have their effects in tiny, concentrated amounts. The influence of a particular hormone can vary depending on the target tissue it acts upon, and the interplay between different hormones is crucial for proper plant development. Auxin, abscisic acid, ethylene, gibberellins, cytokinins, salicylic acid, strigolactones, brassinosteroids, and nitrous oxide are the most common plant hormones. Each hormone has specific roles and functions in plant physiology. For example, auxin is involved in controlling cell elongation, tropisms, and root initiation, while abscisic acid regulates seed dormancy and stomatal closure in response to water stress. Ethylene influences fruit ripening and senescence, and gibberellins promote stem elongation and seed germination. Cytokinins regulate cell division and shoot formation, while salicylic acid is involved in plant defense mechanisms against pathogens. Strigolactones are important for root development and symbiotic interactions, and brassinosteroids play a role in various growth processes. Nitrous oxide, although primarily known for its role in atmospheric chemistry, has been shown to have effects on plant growth as well. Under stressful conditions, such as drought, high salinity, or extreme temperatures, these hormones play a crucial role in enabling plants to tolerate and adapt to their surroundings

The role of plant hormones on the reproductive success of red and brown algae.

Seaweeds or macroalgae are important primary producers that serve as a habitat for functioning ecosystems. A sustainable production of macroalgae has been maintained by a diverse range of life cycles. Reproduction is the most dynamic change to occur during its life cycle, and it is a key developmental event to ensure the species' survival. There is gradually accumulating evidence that plant hormones, such as abscisic acid and auxin, have a role on the sporogenesis of brown alga (Saccharina japonica). Recent studies reported that 1-aminocylopropane-1-carboxylic acid, an ethylene precursor, regulates sexual reproduction in red alga (Neopyropia yezoensis) independently from ethylene. In addition, these macroalgae have an enhanced tolerance against abiotic and biotic stresses during reproduction to protect their gametes and spores. Herein, we reviewed the current understanding on the regulatory mechanisms of red and brown algae on their transition from vegetative to reproductive phase.

Physiological and transcriptome analyses reveal the response of Ammopiptanthus mongolicus to extreme seasonal temperatures in a cold plateau desert ecosystem

Ammopiptanthus mongolicus is the only evergreen broad-leaved shrub present in arid areas of Northwest China and plays an important role in maintaining the stability of the local desert ecosystem. It can survive under extreme temperatures (e.g., extreme low temperature: − 24.8 °C and extreme high temperature: 37.7 °C). To understand the gene expression-physiological regulation network of A. mongolicus in extreme temperature environments, we monitored the changes in gene expression and photosynthetic traits of the leaves. The results showed that at low temperatures, the net photosynthetic rates (A), Fv'/Fm' and electron transport rate (ETR) decreased, the Fv/Fm ratio was only 0.32, and the proportion of nonregulatory heat dissipation Y(NO) increased. Based on a KEGG analysis of the differentially expressed genes, 15 significantly enriched KEGG pathways were identified, which were mainly related to circadian rhythm, photosynthesis, lipid metabolism, carbohydrate metabolism, plant hormones and other life activities. At high temperatures, the A value increased, and the proportion of regulatory energy dissipation Y(NPQ) increased. The KEGG analysis identified 24 significantly enriched KEGG pathways, which are mainly related to circadian rhythm, carbon sequestration of photosynthesis, carotenoid biosynthesis, secondary metabolites, cofactors and vitamin metabolism. In general, at the expense of photosynthesis, A. mongolicus can ensure the survival of leaves by increasing Y(NO) levels, regulating the circadian rhythm, increasing the synthesis of unsaturated fatty acids and changing the role of plant hormones. Under high-temperature stress, a high photosynthetic capacity was maintained by adjusting the stomatal conductance (gsw), increasing Y(NPQ), consuming excess light energy, continuously assembling and maintaining PSII, and changing the production of antioxidants.

Role Of Plant Hormones Under Abiotic Stress Conditions

Role Of Plant Hormones Under Abiotic Stress Conditions

Contents and compositions of amino acids in rice grains and their regulation: a review

<p id="C2">Amino acids in cereal grains are important nutrients for both human and animals. Increasing the content of amino acids in the rice grain, especially lysine and other essential amino acids, plays a very important role in improving the nutritional standard of people in the countries with rice as staple food. This paper reviewed some research progresses in the contents and compositions of amino acids in the mature grain of rice and their distribution in the different parts of a grain, the synthesis and metabolism of amino acids in the grain, the role of plant hormones in regulating the synthesis and metabolism of on amino acids, and the effects of environmental factors and cultivation practices on the contents and compositions of amino acids in the grain, and discussed the existing problems and key points for future research. It merits further investigating the temporal (at different filling stages) and spatial (at different parts of a grain) distribution characteristics of the contents and compositions of amino acids in a grain during the filling, their physiological and biochemical mechanism, and cultivation regulation and its principle. Such a study is expected to gain new insight into the mechanism in the formation and distributions of amino acids in a rice grain, and explore a new way to increase the contents of amino acids, especially essential amino acids such as lysine, in milled rice.

The Impact of Dormancy Breakers on Hormone Profiles, Fruit Growth and Quality in Sweet Cherry

Chemical dormancy breakers are often used to manipulate floral bud break in sweet cherry production, and their use is increasing due to unpredictable climate effects. The role of plant hormones in regulating the critical transition of floral buds from dormant to opening in deciduous trees is now emerging. By monitoring changes in endogenous hormone levels within floral buds that are undergoing the transition from dormant to the growing state in response to various cues (environmental and/or chemical inducers), we can begin to distinguish the plant hormones that are the drivers of this process. This study sought to identify key hormonal regulators of floral bud break using sweet cherry as a model and modifying timing of bud break through the application of two chemical dormancy breakers, hydrogen cyanamide (HC, Dormex®) and emulsified vegetable oil compound (EVOC, Waiken®), and to determine the effect of these chemicals on fruit growth and quality. Treatments were applied at label rates 35–40 days before estimated bud break. We found that HC-treated tree buds broke earlier, and this was associated with a significant early elevation of the cytokinins dihydrozeatin and dihydrozeatin riboside compared to the control and EVOC-treated tree buds. In contrast, changes in auxin and abscisic acid content did not appear to explain the hastened bud burst induced by hydrogen cyanamide. While HC-treated trees resulted in larger fruit, there was a higher incidence of cracked fruit and the pack-out of A-grade fruit was reduced. The increase in fruit size was attributed to the earlier flowering and hence longer growing period. Harvest assessment of fruit quality showed no treatment effect on most quality parameters, including fruit dry matter content, total soluble solids or malic acid content, but a reduction in fruit compression firmness and stem pull force in EVOC-treated trees was observed. However, all fruit still met the Australian industry fruit quality export market standards. This study offers important insights into bud hormonal activities underpinning the action of these chemical regulators; understanding bud responses is critically important to ensuring consistent and sustainable fruit tree production systems into the future. It also demonstrates that the dormancy-breaking agents HC and EVOC have no detrimental impact on fruit quality at harvest or following storage, however growers need to be aware of the potential for increased fruit cracking when earlier bud break results in a longer growing season which has the potential to increase fruit size. Further studies are required to determine the role of gibberellin in hastening bud break by dormancy breakers.

The Role of Plant Hormones in the Interaction of Colletotrichum Species with Their Host Plants.

Colletotrichum is a plant pathogenic fungus which is able to infect virtually every economically important plant species. Up to now no common infection mechanism has been identified comparing different plant and Colletotrichum species. Plant hormones play a crucial role in plant-pathogen interactions regardless whether they are symbiotic or pathogenic. In this review we analyze the role of ethylene, abscisic acid, jasmonic acid, auxin and salicylic acid during Colletotrichum infections. Different Colletotrichum strains are capable of auxin production and this might contribute to virulence. In this review the role of different plant hormones in plant—Colletotrichum interactions will be discussed and thereby auxin biosynthetic pathways in Colletotrichum spp. will be proposed.

Different regulatory mechanisms of plant hormones in the ripening of climacteric and non-climacteric fruits: a review.

This review contains the regulatory mechanisms of plant hormones in the ripening process of climacteric and non-climacteric fruits, interactions between plant hormones and future research directions. The fruit ripening process involves physiological and biochemical changes such as pigment accumulation, softening, aroma and flavor formation. There is a great difference in the ripening process between climacteric fruits and non-climacteric fruits. The ripening of these two types of fruits is affected by endogenous signals and exogenous environments. Endogenous signaling plant hormones play an important regulatory role in fruit ripening. This paper systematically reviews recent progress in the regulation of plant hormones in fruit ripening, including ethylene, abscisic acid, auxin, jasmonic acid (JA), gibberellin, brassinosteroid (BR), salicylic acid (SA) and melatonin. The role of plant hormones in both climacteric and non-climacteric fruits is discussed, with emphasis on the interaction between ethylene and other adjustment factors. Specifically, the research progress and future research directions of JA, SA and BR in fruit ripening are discussed, and the regulatory network between JA and other signaling molecules remains to be further revealed. This study is meant to expand the understanding of the importance of plant hormones, clarify the hormonal regulation network and provide a basis for targeted manipulation of fruit ripening.

Understanding the Role of Gibberellic Acid and Paclobutrazol in Terminal Heat Stress Tolerance in Wheat.

Understanding the physiological mechanism of tolerance under stress conditions is an imperative aspect of the crop improvement programme. The role of plant hormones is well-established in abiotic stress tolerance. However, the information on the role of gibberellic acid (GA) in abiotic stress tolerance in late sown wheat is still not thoroughly explored. Thus, we aimed to investigate the role of endogenous GA3 level in stress tolerance in contrasting wheat cultivars, viz., temperature-tolerant (HD 2643 and DBW 14) and susceptible (HD 2189 and HD 2833) cultivars under timely and late sown conditions. We created the variation in endogenous GA3 level by exogenous spray of GA3 and its biosynthesis inhibitor paclobutrazol (PBZ). Tolerant genotypes had higher antioxidant enzyme activity, membrane stability, and photosynthesis rate, lower lipid peroxidase activity, and better growth and yield traits under late sown conditions attributed to H2O2 content. Application of PBZ escalated antioxidant enzymes activity and photosynthesis rate, and reduced the lipid peroxidation and ion leakage in stress, leading to improved thermotolerance. GA3 had a non-significant effect on antioxidant enzyme activity, lipid peroxidation, and membrane stability. However, GA3 application increased the test weight in HD 2643 and HD 2833 under timely and late sown conditions. GA3 upregulated GA biosynthesis and degradation pathway genes, and PBZ downregulated kaurene oxidase and GA2ox gene expression. GA3 also upregulated the expression of the cell expansins gene under both timely and late sown conditions. Exogenous GA3 did not increase thermotolerance but positively affected test weight and cell expansins gene expression. No direct relationship existed between endogenous GA3 content and stress tolerance traits, indicating that PBZ could have conferred thermotolerance through an alternative mechanism instead of inhibiting GA3biosynthesis.

Analysis of Phytohormone Signal Transduction in Sophora alopecuroides under Salt Stress.

Salt stress seriously restricts crop yield and quality, leading to an urgent need to understand its effects on plants and the mechanism of plant responses. Although phytohormones are crucial for plant responses to salt stress, the role of phytohormone signal transduction in the salt stress responses of stress-resistant species such as Sophora alopecuroides has not been reported. Herein, we combined transcriptome and metabolome analyses to evaluate expression changes of key genes and metabolites associated with plant hormone signal transduction in S. alopecuroides roots under salt stress for 0 h to 72 h. Auxin, cytokinin, brassinosteroid, and gibberellin signals were predominantly involved in regulating S. alopecuroides growth and recovery under salt stress. Ethylene and jasmonic acid signals may negatively regulate the response of S. alopecuroides to salt stress. Abscisic acid and salicylic acid are significantly upregulated under salt stress, and their signals may positively regulate the plant response to salt stress. Additionally, salicylic acid (SA) might regulate the balance between plant growth and resistance by preventing reduction in growth-promoting hormones and maintaining high levels of abscisic acid (ABA). This study provides insight into the mechanism of salt stress response in S. alopecuroides and the corresponding role of plant hormones, which is beneficial for crop resistance breeding.

Role of plant hormones in flowering and exogenous hormone application in fruit/nut trees: a review of pecans

Pecan is the only native north American tree nut. The USA produces approximately 80% of the world’s pecans. Pecan trees have an extended juvenility, 10 years to the first nut crop. With mature bearing they begin alternate bearing; alternating large and small crops. Theoretically, a heavy crop inhibits flower induction in current year resulting in a low crop the following year. The flowering of perennial trees involves a complex interplay of multiple hormones. The possible molecular mechanisms regulating tree flowering can be revealed by endogenous plant hormone quantification, exogenous hormone application and RNA-sequencing. In this review, we synthesize the investigations of transcriptomic analysis and exogenous hormone treatments on bud break and flowering in fruit/nut trees with a focus on pecan. Knowledge of how hormones regulate flowering suggest they are a potential tool for improving return bloom and mitigating alternate bearing.

The role of light in regulating seed dormancy and germination

Seed dormancy is an adaptive trait in plants. Breaking seed dormancy determines the timing of germination and is, thereby essential for ensuring plant survival and agricultural production. Seed dormancy and the subsequent germination are controlled by both internal cues (mainly hormones) and environmental signals. In the past few years, the roles of plant hormones in regulating seed dormancy and germination have been uncovered. However, we are only beginning to understand how light signaling pathways modulate seed dormancy and interaction with endogenous hormones. In this review, we summarize current views of the molecular mechanisms by which light controls the induction, maintenance and release of seed dormancy, as well as seed germination, by regulating hormone metabolism and signaling pathways.

Machine Learning Technology Reveals the Concealed Interactions of Phytohormones on Medicinal Plant In Vitro Organogenesis.

Organogenesis constitutes the biological feature driving plant in vitro regeneration, in which the role of plant hormones is crucial. The use of machine learning (ML) technology stands out as a novel approach to characterize the combined role of two phytohormones, the auxin indoleacetic acid (IAA) and the cytokinin 6-benzylaminopurine (BAP), on the in vitro organogenesis of unexploited medicinal plants from the Bryophyllum subgenus. The predictive model generated by neurofuzzy logic, a combination of artificial neural networks (ANNs) and fuzzy logic algorithms, was able to reveal the critical factors affecting such multifactorial process over the experimental dataset collected. The rules obtained along with the model allowed to decipher that BAP had a pleiotropic effect on the Bryophyllum spp., as it caused different organogenetic responses depending on its concentration and the genotype, including direct and indirect shoot organogenesis and callus formation. On the contrary, IAA showed an inhibiting role, restricted to indirect shoot regeneration. In this work, neurofuzzy logic emerged as a cutting-edge method to characterize the mechanism of action of two phytohormones, leading to the optimization of plant tissue culture protocols with high large-scale biotechnological applicability.

Regulation of Shoot Apical Meristem and Axillary Meristem Development in Plants

Plants retain the ability to produce new organs throughout their life cycles. Continuous aboveground organogenesis is achieved by meristems, which are mainly organized, established, and maintained in the shoot apex and leaf axils. This paper will focus on reviewing the recent progress in understanding the regulation of shoot apical meristem and axillary meristem development. We discuss the genetics of plant meristems, the role of plant hormones and environmental factors in meristem development, and the impact of epigenetic factors on meristem organization and function.

The role of plant hormones in tree-ring formation

The spatial and temporal distributions of plant hormones during tree-ring formation are beginning to be elucidated. Plant hormones play specific roles in tree-ring formation depending on the developmental zone in which they operate. Tree rings are the result of the seasonal activity of the vascular cambium, the secondary meristem of woody angiosperms and gymnosperms. During tree-ring formation, a combination of endogenous and environmental factors affects cambial division, cell differentiation and maturation; this, in turn, affects wood quantity and quality. Among the endogenous factors affecting tree-ring formation, plant hormones are recognized as determinant players in regulating many aspects of the features and fate of each xylem cell. Most of our knowledge regarding the roles of plant hormones on tree-ring formation comes from herbaceous plants, although an increasing interest involves the analysis of the hormonal patterns in tree-species. This paper reviews the state of knowledge of the role of plant hormones during tree-ring formation by focusing on experiments performed on woody species. An overview of the main plant hormones and their main activities during radial tree growth will be followed by discussion of their role in each tree-ring developmental stage and in the overall tree-ring seasonal pattern.

The Roles of Plant Hormones and Their Interactions with Regulatory Genes in Determining Meristem Activity.

Plants, unlike animals, have developed a unique system in which they continue to form organs throughout their entire life cycle, even after embryonic development. This is possible because plants possess a small group of pluripotent stem cells in their meristems. The shoot apical meristem (SAM) plays a key role in forming all of the aerial structures of plants, including floral meristems (FMs). The FMs subsequently give rise to the floral organs containing reproductive structures. Studies in the past few decades have revealed the importance of transcription factors and secreted peptides in meristem activity using the model plant Arabidopsis thaliana. Recent advances in genomic, transcriptomic, imaging, and modeling technologies have allowed us to explore the interplay between transcription factors, secreted peptides, and plant hormones. Two different classes of plant hormones, cytokinins and auxins, and their interaction are particularly important for controlling SAM and FM development. This review focuses on the current issues surrounding the crosstalk between the hormonal and genetic regulatory network during meristem self-renewal and organogenesis.

The growth impairment of salinized fenugreek (Trigonella foenum-graecum L.) plants is associated to changes in the hormonal balance

Fenugreek is a legume cultivated for its medicinal value, especially in arid and semi-arid regions, where soil salinity is an increasing problem. In fact, salinity is one of the major environmental factors limiting plant growth and productivity. Plant hormones are known to play vital roles in the ability of the plants to acclimatize to varying environments by mediating growth, development, and nutrient allocation. Thus, to gain insights about the role of plant hormones in the growth responses of salinized fenugreek plants (Trigonella foenum-graecum L.), a medium-term experiment was conducted under moderate (100 mM NaCl) and high (200 mM NaCl) salinity levels. Results showed that moderate, but especially high salinity stress, impaired shoot growth, total leaf area and leaf number. Salinity also provoked a reduction in relative water content, stomatal conductance and photosynthesis-related pigments, but, surprisingly, photosynthetic rate increased in the leaves of fenugreek plants. Na accumulated in the leaves, particularly at high salinity levels, while most mineral nutrients decreased. Furthermore, important changes in the main hormone classes were observed, associated to growth reduction under salinity. The active cytokinin form, trans-zeatin, and active cytokinin and gibberellin concentrations decreased with salinity in the leaves of fenugreek plants, whereas the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, accumulated in the roots of fenugreek plants, especially at high salinity levels. Importantly, leaf abscisic acid concentrations increased under salinity, which could limit leaf transpiration to adapt growth to the stressful conditions. Therefore, plant hormones seem to play a critical role in the growth responses of fenugreek plants under salinity stress and they could have potential interest in salt tolerance programmes for this species.

Integrated transcriptome and hormone profiling highlight the role of multiple phytohormone pathways in wheat resistance against fusarium head blight.

Fusarium head blight (FHB or scab) caused by Fusarium spp. is a destructive disease of wheat. Since the most effective sources of FHB resistance are typically associated with unfavorable agronomic traits, breeding commercial cultivars that combine desired agronomic traits and a high level of FHB resistance remains a considerable challenge. A better understanding of the molecular mechanisms governing FHB resistance will help to design more efficient and precise breeding strategies. Here, multiple molecular tools and assays were deployed to compare the resistant variety Sumai3 with three regionally adapted Canadian cultivars. Macroscopic and microscopic disease evaluation established the relative level of Type II FHB resistance of the four varieties and revealed that the F. graminearum infection process displayed substantial temporal differences among organs. The rachis was found to play a critical role in preventing F. graminearum spread within spikes. Large-scale, organ-specific RNA-seq at different times after F. graminearum infection demonstrated that diverse defense mechanisms were expressed faster and more intensely in the spikelet of resistant varieties. The roles of plant hormones during the interaction of wheat with F. graminearum was inferred based on the transcriptomic data obtained and the quantification of the major plant hormones. Salicylic acid and jasmonic acid were found to play predominantly positive roles in FHB resistance, whereas auxin and ABA were associated with susceptibility, and ethylene appeared to play a dual role during the interaction with F graminearum.