Application Of Phytohormones Research Articles

Effect of phytohormone and seed density toward growth, disease and bulb yield of True Shallot Seeds

Shallot can be propagated generatively in the form True Seed of Shallot (TSS). The research purpose was to study phytohormone and sown seed density's effect on growth, disease, and bulbs yield. The research was conducted at Indonesian Vegetables Research Institute (1,250 m asl), Lembang-West Java, from August 2017 until April 2018. The research used a factorial randomized completely block design with two factors repeated three times. The first factor was kind of phytohormone (A1 = BAP, A2 = NAA, A3 = GA3, A4 = control) and the second factor was the sown seed density (B1 = 5 g/m2, B2 = 7 g/m2, B3 = 9 g/m2). The result showed that: Phytohormone application did not affect germination and growth of TSS, living plant number, and bulb yield. The best-sown seed density to plant growth was 7 g seeds/m2. Elisa’s test result did not detect the viruses as seed-borne diseases such as SYSV, OYDV, or LYSV. The intensity of disease symptoms Alternaria porri (11%), Stemphylium vesicatorium, Colletotrichum gleosporiodes, and Peronospora destructor each (12%). In general, the most bulb yield was informed single cloves.

Effect of inoculation of Bacillus strains on flowering of carnation (Dianthus caryophyllus)

The carnation flower (Dianthus caryophyllus) is one of the most accepted and distributed worldwide, for its production, fertilization and the application of phytohormones have been optmized, thereby seeking to improve flower quality. However, little has been tested on the effect of the application of plant growth promoting bacteria. In the present work, carnation plants cv. Lilliput, were inoculated with 5X107 cells of Bacillus megaterium M6 and Bacillus subtilis P12, both individually and in interaction (M6 x P12), registering agronomic parameters related to flowering. The results showed that none of the inoculations had an effect on the percentage of flowering plants, neither on the height nor the diameter of the flower, only P12 increased flower number per plant by 38 %, compared to the control without inoculation. Being the period between 96 and 127 days after transplantation (dat), where tha highest number of total flowers was recorded (70) with respect to the other treatments (M6:36, M6 x P12: 24 and control: 32). In conclusion, Bacillus subtilis P12 has a promoter activity to improve the flowering of carnation plants.

Application of Exogenous Phytohormones at Silking Stage Improve Grain Quality under Post-Silking Drought Stress in Waxy Maize.

The application of exogenous plant growth regulator can improve plant resistance to drought stress. The effects of application of exogenous cytokinin (CTK), brassinolide (BR), or gibberellic acid (GA) at the silking time on the grain quality of two waxy maize hybrids under drought stress at grain formation stage were studied. Grain weight of both hybrids was unaffected by exogenous phytohormones under control conditions but increased under drought conditions with the application of BR. The grain starch content in response to drought varied with hybrid and phytohormone. Starch granule size and protein content in grains were increased by drought under all conditions, but various phytohormones exerted different forms of influence. The starch λmax in Yunuo7 was unaffected by single or interaction of phytohormones and water deficit, λmax in Jingkenuo2000 with BR was unaffected but with CTK or GA increased by drought. Relative crystallinity was reduced by drought without the application of phytohormone, but with phytohormones in response to drought it was different. Flour peak viscosity was reduced by drought. The value was increased with BR spraying under control and drought conditions. Retrogradation percentage under drought conditions was unaffected by exogenous phytohormones in Jingkenuo2000. In Yunuo7, retrogradation percentage was unaffected by BR but reduced by CTK and GA. In conclusion, spraying phytohormones at the silking stage can affect grain weight and starch quality, grains with a sticky taste can be improved by applying BR, and grains with low retrograde tendency can be produced by applying CTK.

Application of methyl jasmonate and salicylic acid lead to contrasting effects on the plant’s metabolome and herbivory

Phytohormone applications are used to mimic herbivory and can induce plant defences. This study investigated (i) metabolomic changes in leaf tissues of Jacobaea vulgaris and J. aquatica after methyl jasmonate (MeJA) and salicylic acid (SA) applications and (ii) the effects on a leaf-chewing, a leaf-mining and a piercing-sucking herbivore. MeJA treated leaves showed clearly different metabolomic profiles than control leaves, while the differences in metabolomic profiles between SA treated leaves and control leaves were less clear. More NMR peaks increased than decreased after MeJA treatment while this pattern was reversed after SA treatment. The leaf-chewing (Mamestra brassicae) and the leaf-mining herbivores (Liriomyza trifolii) fed less on MeJA-treated leaves compared to control and SA-treated leaves while they fed equally on the latter two. In J. aquatica but not in J. vulgaris, SA treatment reduced feeding damage by the piercing-sucking herbivore (Frankliniella occidentalis). Based on the herbivory and metabolomic data after phytohormone application, we made speculations as follows: For all three herbivore species, plants with high levels of threonine and citric acid showed less herbivory while plants with high levels of glucose showed more herbivory. Herbivory by thrips was lower on plants with high levels of alanine while it was higher on plants with high levels of 3,5-dicaffeoylquinic acid. The plant compounds that related to feeding of piercing-sucking herbivore were further verified with previous independent experiments.

An overview of recent advancement in phytohormones-mediated stress management and drought tolerance in crop plants

Plants face a continuous threat of abiotic stresses under the changing environment. Because of climate change, water scarcity has been shown to be a significant environmental constraint on plant productivity. Droughts in particular have been shown to affect plant growth and development, lead to alteration in quality and quantity of crop production, and result in global food insecurity. Phytohormones are known to play critical roles in regulating diverse processes of plant adaption to a drought environment. They regulate cellular functions at molecular levels via various cell signaling. Among various phytohormones, abscisic acid (ABA) is known for its role in drought-stress tolerance in plants. Other phytohormones such as auxins, brassinosteroids (BRs), cytokinins (CK), ethylene (ET), gibberellins (GA), jasmonic acid (JA), and salicylic acid (SA) are also crucial in plant drought tolerance. Several plant growth-promoting microbes have been reported to enhance the phytohormone levels in plants to mitigate the negative effect of drought. However, the transgenic approach appears to be a boon to engineering the genes responsible for regulating phytohormones to develop a drought-tolerant trait. Expression analyses have revealed that genes encoding transcription factors such as bZIP11, DREB2, MYB14, MYB48, WRKY2, WRKY56, WRKY108715, and RD22 play a very crucial role in phytohormone mediated drought response. Furthermore, exogenous applications of phytohormones are shown to enhance endogenous phytohormones. This review highlights the most recent advancements in phytohormone-mediated drought tolerance in major crop plants.

Salicylic Acid Modulates Antioxidant System, Defense Metabolites, and Expression of Salt Transporter Genes in Pisum sativum Under Salinity Stress

At present plants continuously exposed to salinity stress due to the challenging environment that has reduced the crop growth and productivity worldwide. Application of phytohormones by using seed priming method emerges as one of the most reliable and cost effective to alleviate the toxic effect of salinity stress. In this study, we evaluate the effect of seed-primed salicylic acid (SA) to reduce the adverse effect of different salt concentrations (0, 100, 200, and 300 mM NaCl) in pea (Pisum sativum L.) seedlings. After seedling emergence, percent seed germination was calculated; however, after 60 days; plants were sampled for studying the growth and photosynthetic traits, lipid peroxidation level, antioxidant activities, ions accumulation, and its sequestration. The results depicted that salinity treatments hampered overall growth performance and induced oxidative stress in a dose-dependent manner. Salinity also has negatively influence on ion accumulation as Na+ ion increased while K+ ion decreased. On the other hand, seed priming with SA significantly reduced the salinity-induced effects on the overall performance of plants, including growth and photosynthetic attributes. SA alleviated the adverse effect of salinity even at higher salinity level by inducing enzymatic and non-enzymatic antioxidant systems, soluble sugars, and proline accumulation, and regulating ion homeostasis along with up-regulation of Na+/H+ antiporters (SOS1 and NHX1). Thus, seed priming with SA shows a comprehensive role in mitigation of salinity stress and can be used as a model for promising salinity tolerant cultivation.

A Review on Practical Application and Potentials of Phytohormone-Producing Plant Growth-Promoting Rhizobacteria for Inducing Heavy Metal Tolerance in Crops

Water scarcity and high input costs have compelled farmers to use untreated wastewater and industrial effluents to increase profitability of their farms. Normally, these effluents improve crop productivity by serving as carbon source for microbes, providing nutrients to plants and microbes, and improving soil physicochemical and biological properties. They, however, may also contain significant concentrations of potential heavy metals, the main inorganic pollutants affecting plant systems, in addition to soil deterioration. The continuous use of untreated industrial wastes and agrochemicals may lead to accumulation of phytotoxic concentration of heavy metals in soils. Phytotoxic concentration of heavy metals in soils has been reported in Pakistan along the road sides and around metropolitan areas, which may cause its higher accumulation in edible plant parts. A number of bacterial that can induce heavy metal tolerance in plants due to their ability to produce phytohormones strains have been reported. Inoculation of crop plants with these microbes can help to improve their growth and productivity under normal, as well as stressed, conditions. This review reports the recent developments in heavy metal pollution as one of the major inorganic sources, the response of plants to these contaminants, and heavy metal stress mitigation strategies. We have also summarized the exogenous application of phytohormones and, more importantly, the use of phytohormone-producing, heavy metal-tolerant rhizobacteria as one of the recent tools to deal with heavy metal contamination and improvement in productivity of agricultural systems.

Regulatory effect of gibberellic acid (GA3) on the biomass productivity and some metabolites of a marine microalga, Isochrysis galbana

The application of phytohormones is an effective and economical way to accelerate biomass growth and the synthesis of valuable metabolites in the microalgae industry. In this study different levels of gibberellic acid (GA3), including 0 (control), 1, 2, 4, and 6 mg L−1, were added to the growth medium of Isochrysis galbana to evaluate the growth performance, metabolites (i.e., chlorophyll a, protein, lipid, carbohydrate, and ash), and fatty acids profile, compared with the control group (0 mg L−1 GA3) during a 14-day experiment. The highest cell number (14.2 × 106 cells mL−1) and the lowest doubling time (4.31 day) were obtained in 4 mg L−1 GA3 (P < 0.05) and the highest specific growth rate was recorded in the treatments with GA3 at 2 and 4 mg L−1. The production of chlorophyll a was elevated by increasing GA3 concentration up to 4 mg L−1, while the lowest value was recorded in 6 mg L−1 GA3 (P < 0.05). The highest level of protein was measured in 1, 2, and 4 mg L−1 GA3, while the lowest value was obtained in the control group (P < 0.05). In addition, the lipid content of the microalgae treated with different GA3 concentrations was significantly increased compared with the control group. The highest polyunsaturated fatty acid (PUFA) content was achieved using GA3 at 6 mg L−1, while the highest saturated and monounsaturated fatty acids were determined in 2 mg L−1 GA3. The findings showed that GA3 at 4 mg L−1 could effectively improve the growth and biosynthesis of most metabolites in I. galbana.

Global Trends in Phytohormone Research: Google Trends Analysis Revealed African Countries Have Higher Demand for Phytohormone Information

The lines of research conducted within a country often reflect its focus on current and future economic needs. Analyzing “search” trends on the internet can provide important insight into predicting the direction of a country in regards to agriculture, health, economy, and other areas. ‘Google Trends’ collects data on search terms from different countries, and this information can be used to better understand sentiments in different countries and regions. Agricultural output is responsible for feeding the world and there is a continuous quest to find ways to make agriculture more productive, safe, and reliable. The application of phytohormones has been used in agriculture world-wide for many years to improve crop production and continues to be an active area of research for the application in plants. Therefore, in the current study, we searched ‘Google Trends’ using the phytohormone search terms, abscisic acid, auxins, brassinosteroids, cytokinin, ethylene, gibberellins, jasmonic acid, salicylic acid, and strigolactones. The results indicated that the African country Zambia had the greatest number of queries on auxin research, and Kenya had the most queries in cytokinin and gibberellin research world-wide. For other phytohormones, India had the greatest number of queries for abscisic acid and South Korea had the greatest number of ethylene and jasmonic acid search world-wide. Queries on salicylic acid have been continuously increasing while the least number of queries were related to strigolactones. Only India and United States of America had significant numbers of queries on all nine phytohormones while queries on one or more phytohormones were absent in other countries. India is one of the top five crop-producing countries in the world for apples, millet, orange, potato, pulses, rice, sugarcane, tea, and wheat. Similarly, the United States of America is one of the top five crop-producing countries of the world for apples, grapes, maze, orange, potato, sorghum, sugarcane, and wheat. These might be the most possible factors for the search queries found for all the nine phytohormones in India and the United States of America.

Exogenous application of plant hormones in the field alters aboveground plant\u2013insect responses and belowground nutrient availability, but does not lead to differences in plant\u2013soil feedbacks

Plant–soil feedbacks of plants that are exposed to herbivory have been shown to differ from those of plants that are not exposed to herbivores. Likely, this process is mediated by jasmonic acid (JA) and salicylic acid (SA) defense pathways, which are induced by aboveground herbivory. Furthermore, exogenous application of these phytohormones to plants alters belowground communities, but whether this changes plant–soil feedbacks in natural systems is unknown. We applied exogenous sprays of JA and SA individually and in combination to field plots in a restored grassland. Control plots were sprayed with demineralized water. After three repeated application rounds, we transplanted seedlings of the plant–soil feedback model plant Jacobaea vulgaris as phytometer plants to test the effects of potential phytohormone-mediated changes in the soil, on plant performance during the response phase. We further measured how exogenous application of phytohormones altered plant-related ecosystem characteristics (plot-level); soil chemistry, plot productivity, insect communities and predation. Biomass of the phytometer plants only co-varied with plot productivity, but was not influenced by phytohormone applications. However, we did observe compound-specific effects of SA application on insect communities, most notably on parasitoid attraction, and of JA application on soil nitrogen levels. Although we did not find effects on plant–soil feedbacks, the effects of exogenous application of phytohormones did alter other ecosystem-level processes related to soil nutrient cycling, which may lead to legacy effects in the longer term. Furthermore, exogenous application of phytohormones led to altered attraction of specific insect groups.

Human, Animal and Plant Health Benefits of Glucosinolates and Strategies for Enhanced Bioactivity: A Systematic Review.

Glucosinolates (GSs) are common anionic plant secondary metabolites in the order Brassicales. Together with glucosinolate hydrolysis products (GSHPs), they have recently gained much attention due to their biological activities and mechanisms of action. We review herein the health benefits of GSs/GSHPs, approaches to improve the plant contents, their bioavailability and bioactivity. In this review, only literature published between 2010 and March 2020 was retrieved from various scientific databases. Findings indicate that these compounds (natural, pure, synthetic, and derivatives) play an important role in human/animal health (disease therapy and prevention), plant health (defense chemicals, biofumigants/biocides), and food industries (preservatives). Overall, much interest is focused on in vitro studies as anti-cancer and antimicrobial agents. GS/GSHP levels improvement in plants utilizes mostly biotic/abiotic stresses and short periods of phytohormone application. Their availability and bioactivity are directly proportional to their contents at the source, which is affected by methods of food preparation, processing, and extraction. This review concludes that, to a greater extent, there is a need to explore and improve GS-rich sources, which should be emphasized to obtain natural bioactive compounds/active ingredients that can be included among synthetic and commercial products for use in maintaining and promoting health. Furthermore, the development of advanced research on compounds pharmacokinetics, their molecular mode of action, genetics based on biosynthesis, their uses in promoting the health of living organisms is highlighted.

Improving the Red Color and Fruit Quality of ‘Kent’ Mango Fruit by Pruning and Preharvest Spraying of Prohydrojasmon or Abscisic Acid

Pre-harvest application of prohydrojasmon (PDJ) or abscisic acid (ABA) induces the red color in fruits that were exposed to sunlight at the orchard. In this large-scale work, we evaluated the effect of two different pruning techniques of ‘Kent’ mango orchards, one leading to opening the orchard canopy to expose as much fruit as possible to sunlight, while the second pruning leads to square-shaped trees and subsequently reduces the amount of sunlight reaching the fruit. These two pruning methods were combined with preharvest spraying with prohydrojasmon (PDJ) or abscisic acid (ABA) using two different types of sprayers, i.e., regular and air-jet sprayer. Pruning the canopy of the orchards to open and closed trees exposed 80% or 30% of fruits to sunlight, respectively. Both of the application with air-jet and regular sprayers effectively covered the fruit without causing fruit detachment and damage to yield. Both the phytohormones (PDJ and ABA) application treatments induced red blush skin, red intensity, anthocyanin, and flavonoids, particularly in fruit grown outside the tree canopy in both open and closed trees. PDJ and ABA treatments exhibited marginally reduced acidity than the untreated control, while the brix was not affected much by any of the treatments. Besides these, exposure to sunlight and PDJ treatment also reduced postharvest decay and increased chlorophyll degradation and yellowing in comparison to the controls. This study promoted applicative evidence about the positive effects of exposure to sunlight, prohydrojasmon (PDJ), and abscisic acid (ABA) on red color development without compromising the mango fruit’s quality.

Characterization of the wheat cultivars against Tilletia controversa K\xfchn, causal agent of wheat dwarf bunt

Wheat is one of the most important staple crops. Tilletia controversa Kühn is the causal agent of wheat dwarf bunt. In this study, a resistant wheat cultivar displayed significantly higher expression of pathogenesis-related genes than a susceptible cultivar at 7 days post inoculation (DPI) with T. controversa. Similarly, the expression was high in the resistant cultivar after exogenous application of phytohormones, including salicylic acid. The expression of pathogenesis-related genes, especially chitinase 4, was high in the resistant cultivar, while LPT-1 was down regulated after T. controversa infection. Callose deposition was greater in the resistant cultivar than in the susceptible cultivar at 10 DPI. Confocal microscopy was used to track the fungal hyphae in both cultivars in anther and ovary cells. The anthers and ovaries of the susceptible cultivar were infected by T. controversa at 7 and 15 DPI. There were no fungal hyphae in anther and ovary cells in the resistant cultivar until 10 and 23 DPI, respectively. Moreover, anther length and width were negatively influenced by T. controversa at 16 DPI. The plant height was also affected by fungal infection. Ultimately, resistance to T. controversa was achieved in cultivars via the regulation of the expression of defense-related and pathogenesis-related genes.

Microclimate changes, photomorphogenesis and water consumption of Moringa oleifera cuttings under different light spectrums and exogenous phytohormone concentrations

Moringa oleifera is one of the most important plants in the world due to its multiple uses as well tolerance to abiotic stress. However, it may presents low quality seedlings in protected environment under thermal and luminous stresses. The current study aimed to evaluate environmental microclimate changes; photomorphogenesis and water use of M. oleifera cuttings under light spectral and phytohormones variations, as well as to identify the most important variables to explain those effects. A completely randomized experimental design was used in a 4 x 4 factorial design with four replications. Four luminosity conditions, white (a transparent plastic layer), blue (two layers of blue cellophane paper), red (two layers of red cellophane paper), and extreme red lights (one layer of red cellophane and one of alternating blue cellophane) and four phytohormones concentrations (0, 25, 50, and 100%) were applied. M. oleifera semi-woody cuttings were collected from 7 am to 9 am from the M. oleifera mother plants, grown on a rural property located in the city of Lagoa Seca, Paraíba, Brazil, with the following characteristics: 15 cm in length, 4 to 5 mm in diameter, and 2 or 3 buds. Throughout the experimental period, environments were monitored to determine illuminance, average air temperature, relative humidity, soil average temperature, and evapotranspirated water consumption by cuttings. The numbers of shoots were recorded weekly. The number of surviving roots and shoots were measured 60 days after M. oleifera cuttings planting. Illuminance was reduced in environments under blue, red, and extreme red lights, respectively. The air temperature was reduced under blue light, while red and extreme red lights induced the increase on air temperature and relative humidity, soil temperature, and therefore, water consumption of cuttings. Protected environments when irradiated with blue light and application of phytohormones at concentrations of 25 and 50% enabled the shootings and survival of cuttings, although no root formation was observed after 60 days from planting. All variables were considered important to explain the effects.

Different Classes of Phytohormones Act Synergistically to Enhance the Growth, Lipid and DHA Biosynthetic Capacity of Aurantiochytrium sp. SW1.

In the present study, the impact of eight phytohormones from six different classes on the growth, lipid and docosahexaenoic acid (DHA) biosynthetic capacity of Aurantiochytrium sp. SW1 (SW1) was evaluated. Kinetin (KIN), jasmonic acid (JA) and gibberellic acid (GA) significantly enhanced the growth and DHA production of SW1 by 16%–28% and 66%–84% in comparison to the control, respectively. The synergistic effect of these three phytohormones, evaluated by the response surface methodology (RSM), showed that a combination of 3.6 mg/L GA, 2.0 mg/L KIN and 20.0 mg/L JA further increased the growth and DHA production of SW1 by 16% to 28% and 22% to 36%, respectively, in comparison to the individual supplementation. The synergistic effect of these phytohormones was also shown to be time-dependent, where feeding at 24 h of cultivation led to 15%, 26% and 35% further increments in the biomass, lipid and DHA production in comparison to that of 0 h, respectively. The determination of stress markers, antioxidant enzymes and key enzymes involved in fatty acid biosynthesis aided to elucidate the potential mechanism underlying the improvement of growth and DHA production by SW1 at various times of feeding. Supplementation with the phytohormones at 24 h exhibited the maximum impact on reducing the level of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as augmented the antioxidants (superoxide dismutase and catalase) and key metabolic enzymes involved in lipogenesis (malic, glucose-6-phosphate dehydrogenase and ATP-citrate lyase) in comparison to the control and other time points. This study signifies the potential application of phytohormones for improving the growth, lipid and DHA production in Aurantiochytrium spp.

Exogenous application of phytohormones mitigates the effect of salt stress on Carica papaya plants

ABSTRACT The salinity has complex effects on the physiological, nutritional and hormonal interactions of plants. This study aimed to evaluate the mitigating action of exogenous application of different types and concentrations of phytohormones on Carica papaya under salt stress. The experiment was conducted in greenhouse, using a randomized block design with treatments formed from a 2 x 3 x 5 factorial scheme, relative to two concentrations of salts in the irrigation water (0.6 and 2.4 dS m-1), three types of phytohormones [Auxin = indole-3-acetic acid; Cytokinin = CPPU (N-(2-chloro-pyridyl)-N-phenylurea) and Gibberellin = gibberellic acid(AG3)], and five concentrations of the phytohormone (0, 12.5, 25.0, 37.5 and 50.0 µM L-1), with three repetitions, totaling 90 plots, and the experimental unit consisted of six plants. C. papaya cv. ‘Sunrise Solo’ was grown on polyethylene trays of 162 cells, with capacity for 50 mL. The plants were evaluated for survival percentage and phytomass accumulation until 25 days after sowing. Increase in irrigation water salinity has deleterious effects on C. papaya plants regardless of the application of phytohormones. Exogenous application of gibberellin has a positive effect in mitigating salt stress on C. papaya plants, greater than the effects of auxins and cytokinins. Exogenous application of gibberellin and auxin at concentration of 37.5 µM L-1 mitigates the effects of salinity on C. papaya plants. Exogenous application of cytokinin at concentrations of 12.5 to 50.0 µM L-1 is not viable for C. papaya plants.

EFFECT OF PLANT HORMONES ON THE PRODUCTION OF BIOMASS AND LIPID EXTRACTION FOR BIODIESEL PRODUCTION FROM MICROALGAE Chlorella Sp.

The economic globalization and rapid energy depletion require alternative forms of energy which is more reliable, sustainable and renewable without causing adverse effects to the life forms. Microalgae are currently considered to be one of the most promising alternative sources for biodiesel and the application of phytohormones has also been considered a promising way to increase the production of lipid from microalgae recently. The present study is aimed to cultivate the algal species, Chlorella as a feedstock and the effect of various concentrations of phytohormones such as 6-Benzylaminopurine (BAP), Gamborg’s b-5 vitamins, Indole-3-butyric acid (IBA), 2, 4-Dichlorophenoxyacetic acid (2,4-D) was used for the production of lipid. The extracted lipid oils were then converted into methyl ester via the transesterification process. Indole-3-butyric acid (IBA) relatively supported the maximum growth of 7.185 g/ ml and the lipid yield was 3.5g/ml. The GC-MS characterization showed many peaks corresponding to the fatty acid methyl esters. Among those Ethylbenzene, o-Xylene, Benzene,1,2,4-trimethyl and Decane peaks of hydrocarbons were found important in the biofuel production. The current study demonstrates that the phytohormone IBA accelerate the microalgae growth and also induce the production of lipid oils for biodiesel production.

Different effects of phytohormones on Fusarium head blight and Fusarium root rot resistance in Brachypodium distachyon

ABSTRACT Fusarium graminearum is a devastating pathogen of small grain cereals causing both Fusarium head blight (FHB) and Fusarium root rot (FRR). Exogenous application of phytohormones has been shown to affect FHB resistance. In contrast to FHB, FRR remains poorly characterised and it is unknown whether phytohormones play similar roles in FHB and FRR. In this present study, B. distachyon floral tissues at mid-anthesis and root tissues from seedlings were exogenously treated with several phytohormones before inoculation with F. graminearum. The canonical defence-associated phytohormones had differing effects on FHB and FRR. Salicylic acid (SA) significantly increased susceptibility to FRR but not to FHB while jasmonic acid (JA) and ethylene increased resistance to FRR but increased susceptibility to FHB. Additionally, the growth-associated phytohormones auxin and cytokinin significantly increased resistance and susceptibility, respectively, to both diseases. This study is the first to compare phytohormone effects between FHB and FRR in the same host. Highlight The tissue-dependent effects of defence phytohormones and tissue-independent effects of development phytohormones on F. graminearum-induced Fusarium head blight and Fusarium root rot diseases in the model cereal Brachypodium distachyon. Abbreviations: ACC, 1-aminocyclopropane-1-carboxylic acid; BABA, 3-aminobutanoic acid; dpi, days post inoculation; FHB, Fusarium head blight; FRR, Fusarium root rot; IAA indole-3-acetic acid; JA, jasmonic acid; NAA, 1-naphthaleneacetic acid; PDA, potato dextrose agar; RNL, root necrosis length; SA, salicylic acid

Genome-wide characterization of NtHD-ZIP IV: different roles in abiotic stress response and glandular Trichome induction

BackgroundThe plant-specific homeodomain-leucine zipper class IV (HD-ZIP IV) gene family has been involved in the regulation of epidermal development.ResultsFifteen genes coding for HD-ZIP IV proteins were identified (NtHD-ZIP-IV-1 to NtHD-ZIP-IV-15) based on the genome of N. tabacum. Four major domains (HD, ZIP, SAD and START) were present in these proteins. Tissue expression pattern analysis indicated that NtHD-ZIP-IV-1, − 2, − 3, − 10, and − 12 may be associated with trichome development; NtHD-ZIP-IV-8 was expressed only in cotyledons; NtHD-ZIP-IV-9 only in the leaf and stem epidermis; NtHD-ZIP-IV-11 only in leaves; and NtHD-ZIP-IV-15 only in the root and stem epidermis. We found that jasmonates may induce the generation of glandular trichomes, and that NtHD-ZIP-IV-1, − 2, − 5, and − 7 were response to MeJA treatment. Dynamic expression under abiotic stress and after application of phytohormones indicated that most NtHD-ZIP IV genes were induced by heat, cold, salt and drought. Furthermore, most of these genes were induced by gibberellic acid, 6-benzylaminopurine, and salicylic acid, but were inhibited by abscisic acid. NtHD-ZIP IV genes were sensitive to heat, but insensitive to osmotic stress.ConclusionNtHD-ZIP IV genes are implicated in a complex regulatory gene network controlling epidermal development and abiotic stress responses. The present study provides evidence to elucidate the gene functions of NtHD-ZIP IVs during epidermal development and stress response.

Embryogenesis efficiency and genetic stability of Dianthus caryophyllus embryos in response to different light spectra and plant growth regulators

Carnation is an important cut flower with industrial and medicinal applications. To establish an efficient protocol without somaclonal variation for micropropagation of Dianthus caryophyllus, direct and indirect somatic embryogenesis (DSE and ISE) were investigated under six different light spectra (white, red, green, blue, red + blue and far red + red) and four combinations of different plant growth regulators (PGRs) never tested so far for carnation. The best results were achieved with 2,4-dichlorophenoxyacetic acid (2,4-D) + N-(2-chloro-4-pyridyl)-N′-phenylurea (4-CPPU) for ISE and picloram + 4-CPPU or naphthoxyacetic acid (NOA) + 6-benzylaminopurine (BAP) for DSE. The DSE method was faster (3 weeks compared to 8 weeks) and easier (no subculturing compared to two rounds of subculture with ISE methods) but the percentage of somatic embryos in the ISE method was higher compared to the DSE method. Our results showed that the highest DSE, formation of embryogenic callus, embryo maturation (generation of globular, heart and torpedo shapes) and ISE rate was observed in carnation explants exposed to blue light (450–495 nm). In contrast, green (495–570 nm), red (610–700) and far red (710–730 nm) lights caused negative effects on embryogenesis compared to white light controls (380–750 nm). For the first time, genetic stability of regenerated carnation plants was estimated using inter-simple sequence repeat (ISSR) markers. The amplified products showed 75 distinct and scorable bands, and regenerants [plants obtained by primary (PSE) and secondary SE (SSE)] were completely identical to the mother plant. Similarly, flow cytometric analysis confirmed that somatic embryo-derived plants had on average 1.53 pg nuclear DNA (2C), and all plants maintained their ploidy. In conclusion, obtained embryos under blue light were big in size and torpedo-shaped and their germination was highest compared to other light spectra. Moreover, blue light was effective for direct and indirect somatic embryogenesis in carnation without induction of somaclonal variation. An effective protocol through application of phytohormones is introduced. Blue light can be used to improve in vitro propagation of carnation by somatic embryogenesis. Genetic stability of regenerated carnation plants was confirmed using inter-simple sequence repeat (ISSR) markers.