Gibberellin Inhibitor Research Articles

Gibberellin Inhibitors Molecules as a Safeguard against Secondary Growth in Garlic Plants

Secondary growth in garlic depreciates its visual aspect and thereby renders the crop unviable for trade. Therefore, farmers commonly reduce fertilization and impose drought and oxidative stress caused by high-dose pesticides to reduce secondary growth in garlic plants. However, these procedures can be considered adverse, unhealthy, and environmentally inappropriate. To remedy this scenario, we investigated whether spraying growth inhibitors would prevent secondary growth in garlic plants. First, we evaluated the effects of abscisic acid, trinexapac-ethyl, chlormequat chloride, and paclobutrazol treatments on garlic plants grown in polyethylene tanks (250 m3). We then analyzed the effects of deficit irrigation combined with the application of trinexapac-ethyl (sprayed two or three times) and the application of trinexapac-ethyl, chlormequat chloride, or paclobutrazol alone (each sprayed two or three times) on garlic plants grown in the field, comparing them with the effects of deficit irrigation (control treatment) alone. The in-field experiment was replicated with the following treatments: control (deficit irrigation) and trinexapac-ethyl (sprayed two or three times) treatments. We analyzed the physiological, biometric, and production parameters affecting secondary growth in garlic plants. We observed that trinexapac-ethyl could efficiently regulate secondary growth without causing physiological disturbances in garlic plants. Our results provide valuable information that will contribute to the development of a sustainable technique to replace the current practices used by farmers to prevent secondary growth in garlic plants.

Tratamento foliar com metil jasmonato na restrição do crescimento e na anatomia de foliar de Begônia ‘Dragon Wing’

Abstract The application of plant growth regulators, primarily gibberellin inhibitors, is the main approach used for controlling the growth of ornamental plants. However, there is a growing interest in alternative products due to the risk of environmental toxicity associated with traditional methods. Methyl jasmonate (MeJa) is a natural substance found in plants and is considered to have low toxicity when used appropriately. Its use as a growth regulator has shown promise for controlling plant growth, but its effects have not been extensively explored in ornamental growth restriction. This study investigated the effects of foliar application of different concentrations of MeJa (0, 50, 100, and 150 µM) on the growth and leaf anatomy of Begonia ‘Dragon Wing’ Pink and Red. Plant growth parameters were evaluated, and qualitative-quantitative histological analyses of Begonia leaves were conducted. MeJa was efficient in compacting the plants, reducing height in 17.57% and diameter in 8.98% without compromising biomass, root growth, and flowering aspects. The average concentration studied also caused changes in leaf anatomy, increasing the thickness of the abaxial epidermis, reducing mesophyll thickness, the number of calcium oxalate crystals, and the size and number of stomata. The results demonstrated the promising effect of MeJa on controlling the growth of potted ornamental plants.

Effect of Photoperiod and Gibberellin on the Bolting and Flowering of Non-Heading Chinese Cabbage

Non-heading Chinese cabbage (cabbage) is an essential green leafy vegetable, and bolting and flowering are necessary for reproduction. However, further research is needed to study the effect of photoperiod on the bolting and flowering of cabbage, particularly on the development of the stem. In this study, we performed phenotypic analysis and measured endogenous gibberellin levels in the cabbage. We carried out these experiments under four different photoperiodic treatments, 12 h (light)/12 h (dark), 14 h (light)/10 h (dark), 16 h (light)/8 h (dark), and 18 h (light)/6 h (dark). The results showed that the time of bolting and flowering gradually decreased with increasing light duration. The development of stems was optimal under the 16 h (light)/8 h (dark) photoperiod treatment, and the same result was obtained via cytological observation. In addition, the changes in the endogenous gibberellin3 (GA3) content under different photoperiodic treatments were consistent with the development of stems and peaked at 16 h (light)/8 h (dark). At the same time, qRT-PCR analysis showed that the relative expression of the key gibberellin synthase genes, BcGA3ox2 and BcGA20ox2, exhibited upregulation. When treated with exogenous GA3 and its synthesis inhibitor, paclobutrazol (PAC), exogenous gibberellins significantly promoted bolting; conversely, gibberellin inhibitors suppressed the bolting, flowering, and stem elongation of cabbage. Therefore, the photoperiod may regulate cabbage bolting by regulating endogenous GA3.

Synthetic seeds for in vitro preservation of Asparagus officinalis L.

BackgroundAsparagus (Asparagus officinalis) is a perennial vegetable of economic importance for its high nutritional and medicinal value. Male plants are more desirable because of their higher spear yield. Therefore, the aim of this study was to evaluate the efficiency of the gibberellin inhibitors; paclobutrazol (PBZ) and cycocel (CCC) for in vitro preservation by encapsulation of in vitro-derived shoot tips of the superior germplasm of the first generation of asparagus male hybrid; cultivar Mary Washington 500W. MethodsAn efficient technique for synthetic seeds production was achieved, consisting of 3% (w/v) Na-alginate dissolved in water, Murashige and Skoog (MS) medium, MS medium with the growth inhibitors; PBZ and CCC at different concentrations, and 0.1 M calcium chloride (CaCl2.2H2O). Synthetic seeds were stored at 4 ℃ and then cultured after different storage durations (0, 2, 4, 8, 12, 16, 20 and 24 weeks) on MS medium supplemented with 1 mg l−1 kinetin, 0.2 mg l−1 naphthalene acetic acid and 0.5 mg l−1 gibberellic acid for shoot tip multiplication; then, recovered shoots were transferred to MS medium supplemented with 1 mg l−1 indole butyric acid and 0.5 mg l−1 PBZ for rooting.ResultsThe beads containing 1 mg l−1 PBZ considered the optimum for producing complete well-developed plantlets of Asparagus officinalis from recovered shoot tips after 24 weeks of storage that successfully acclimatized in the greenhouse.ConclusionsThis protocol is efficient for in vitro preservation by encapsulation of shoot tips and regeneration of Asparagus officinalis F1 male hybrid (Mary Washington 500w), using anti-gibberellin plant growth regulators within the beads to prolong the duration of storage and provide a continuous supply of the plant.

Plant growth regulation and the rebound effect when prohexadione calcium is applied to fairway‐height annual bluegrass and creeping bentgrass swards

AbstractPlant growth regulators (PGRs) are commonly used to manage turfgrass growth on golf courses. Growing degree day (GDD) models predict the need for reapplication of PGRs, such as trinexapac‐ethyl (TE) resulting in a potential loss of regulation. Optimal GDD models for application of prohexadione calcium (PC), a late‐stage gibberellin inhibitor, on fairway‐height turfgrasses are currently unknown. The effect of PC and TE on plant growth and stand health were evaluated in two separate seasons on mixed stands of creeping bentgrass (Agrostis stolonifera L.) and annual bluegrass (Poa annua L.) maintained at 9‐mm height at the Guelph Turfgrass Institute. Five treatments (control, PC 2.8 g 100 m−2 [0.09 oz 1000 ft−2], PC 5.6 g 100 m−2 [0.18 oz 1000 ft−2], PC 8.4 g 100 m−2 [0.27 oz 1000 ft−2], and TE 8.0 mL 100 m−2 [0.26 fl oz 1000 ft−2]) were applied based on a label rate GDD schedule. Plant clipping dry weight (DW), visual color ratings and normalized difference vegetative index (NDVI) were assessed. Most PC and TE treatments effectively reduced DW and had a positive effect on visual color and NDVI. A relationship was observed between PC application rates, suggesting that higher application rates allow for greater regulation of plant growth. Rebound effects or periods of excess growth, occurred when reapplication intervals exceeded 350 GDD and had an average of thermal time greater than 21.0 GDD over a 10‐day period. Using optimal GDD models for PC will assist in the effective regulation of turfgrass growth and improved stand health.

Effect of antigibberellins on morphogenesis, photosynthetic apparatus, productivity and their residual content in tomato fruits

The application of growth and development regulators on crops in order to optimize their production process is one of the leading tasks of modern plant physiology. Retardants – gibberellin inhibitors are widely used for this purpose. We investigated the effect of foliar treatment with EW-250, ССС-750 and 2-СEPA on morphogenesis, leaf apparatus, content of photosynthetic pigments, indices of chlorophyll fluorescence induction, CO2 gas exchange, and residual amounts of drugs in the fruits of tomato (Lycopersicon esculentum Mill.) Bobcat hybrid. The field experiment was laid on plots with an area of 33 m2. The treatment of the plants was carried out at the budding stage. Morphometric indices were determined at the stages of flowering and fruit formation. The chlorophylls content was determined in the raw material by the spectrophotometric method. Indices of photosystem II (PSII) photochemical activity were determined according to the parameters of chlorophyll fluorescence induction after a half-hour exposure of plants in the dark using a portable single-beam fluorimeter "Floratest". The determination of the residual content of retardants in the fruits was carried out on a Shimadzu GC gas chromatograph with a mass spectrometric detector – GCMS- QP2020 EI. All gibberellin inhibitors reduced linear plant size. The number of leaves on the plants decreased under 2-CEPA treatment, and increased after the application of EW-250. Treatment with 2-CEPA decreased, EW-250 significantly increased, and CCC-750 practically did not change the leaves’ fresh and dry weight. Leaf area and leaf index decreased under 2-CEPA treatment, but practically did not change when EW-250 and ССС-750 were applied. All antigibberellin drugs increased the leaf specific leaf weight and thickened the leaf lamina due to the growth of chlorenchyma cells. At the same time, growth inhibitors increased the volume of columnar parenchyma cells and practically did not change the size of spongy parenchyma cells. Retardants increased the chlorophylls content in leaves, while the ethylene producer 2-CEPA did not change this index. The plants’ chlorophyll index after treatment with drugs increased significantly. The whole plant dry weight increased under EW-250 treatment, decreased after 2-CEPA application, and did not change under CCC-750. It was established that the photosynthetic rate increased under the EW-250 treatment, both in the flowering stage and in the stage of fruit formation, while when using 2-CEPA and CCC-750, it occurred only at the stage of fruit formation. The most significant positive changes of PSII photochemical activity indices were observed under the use of EW-250. Under the action of the drug, the maximum and actual quantum efficiency of PSII increased, the linear electron transport accelerated, and the fraction of reaction centers that did not transfer electrons from the primary acceptor QA to QB decreased, at the same time the chlorophyll fluorescence decay coefficient significantly increased, which indicates an increase in the CO2 assimilation intensity. Retardants increased the proportion of the fruit in the whole plant dry weight. All growth regulators increased net photosynthetic efficiency. A significant increase in fruit yield occurred under EW-250 treatment. When using CCC-750, the index tended to increase, while under the influence of 2-CEPA the yield decreased. The residual amounts of EW-250 and CCC-750 in the fruits did not exceed the maximum permissible concentrations.

Morphological and metabolic differences between turfgrass and row‐crop biotypes of goosegrass (Eleusine indica)

AbstractThe research was conducted to evaluate Eleusine indica (L.) Gaertn. (goosegrass) phenotypic diversity in biotypes collected from managed turfgrass, noncrop, and row crop environments. A common‐garden experiment was conducted to quantify morphological characteristics. Biotypes were primarily distinguished along a single principal component that separated taller growing crop types with lower tiller numbers, larger leaves, and more spikelets per seedhead, contrasted with managed turfgrass and noncrop types with shorter height, greater tillering, fewer spikelets per seedhead but more total seedheads. A dwarf phenotype of E. indica (Texas‐GCPG) collected from a golf course putting green having shorter internodes, shorter leaves, and fewer spikelets per seedhead was distinct phenotypically compared with all other biotypes. Plant growth regulators were tested on biotypes collected from a cropping environment (PBU‐crop) and managed turfgrass (RB‐GC and Texas‐GCPG). Gibberellin inhibitors (paclobutrazol, flurprimidol, and trinexapac‐ethyl) had a negative impact on the growth of all three biotypes. Furthermore, the application of GA3 (gibberellin A3) increased Texas‐GCPG height compared with nontreated plants, suggesting it is a GA‐sensitive mutant. Molecular and biochemical research on such biotypes could shed light on pathways and mutations in any causal gene/s that prohibit or reduce active gibberellic acid production.

The effects of growth regulators on the photosynthetic apparatus of the sweet pepper (Capsicum annuum L.) in relation to the productivity

The effects of growth stimulants 6-benzylaminopurine (6-BAP), gibberellic acid (GA3) and 1-naphthaleneacetic acid (1-NAA) as well as gibberellin inhibitors tebuconazole (EW-250), ethephon (2-chloroethylphosphonic acid, 2-CEPA) and chloromequate chloride (ССС-750), which differ in their action mechanism, on growth, development, leaf apparatus formation, CO2 and H2O gas exchange, photochemical activity of Photosystem II (PSII) and productivity traits of sweet pepper plants were studied. It was shown that treatment with growth stimulants increased, and gibberellin inhibitors decreased the linear sizes of sweet pepper plants of the Antei variety. It was established that all growth regulators, except for 2-CEPA, increased the number and the mass of leaves on the plant. Under the action of all preparations, except for 2-CEPA, the area of the leaves increased. Gibberellin inhibitors and 6-BAP significantly increased the amount of chlorophyll in pepper leaves. However, it decreased under the action of GA3 and did not practically change in treatment with 1-NAA. All growth substances, except GA3, increased the total chlorophyll content in the plant. The impact of growth regulators on the activity of photosynthetic processes was more pronounced at the stage of fruit formation than at the flowering stage. The CO2 assimilation rate at the flowering stage increased under the treatment of 1-NAA, 6-BAP, 2-CEPA and EW-250, but decreased under the action of GA3 and CCC-750. At the same time, all studied growth regulators increased the CO2 assimilation rate at the stage of fruit formation. Changes in the CO2 assimilation rate were closely correlated with changes in stomatal conductance (r = 0.79—0.85). Growth regulators increased transpiration in the light at fruit formation stage while the transpiration in the dark was reduced at the flowering stage. Growth regulators increased the operating quantum efficiency of PSII in the light, photochemical quenching of chlorophyll fluorescence, and intensity of linear electron transport in chloroplasts, and reduced non-photochemical quenching (NPQ) fluorescence. The specified morphological, physiological and biochemical changes in plants of sweet pepper of the Antei variety contributed to improvement of crop productivity traits. The use of growth stimulants 6-BAP and GA3, and retardants EW-250 and ССС-750 was most effective.

Widely targeted metabolite profiling of mango stem apex during floral induction by compond of mepiquat chloride, prohexadione-calcium and uniconazole.

Insufficient low temperatures in winter and soil residues caused by paclobutrazol (PBZ) application pose a considerable challenge for mango floral induction (FI). Gibberellin inhibitors SPD (compound of mepiquat chloride, prohexadione-calcium and uniconazole) had a significant influence on enhancing the flowering rate and yield of mango for two consecutive years (2020-2021). Researchers have indicated that FI is regulated at the metabolic level; however, little is known about the metabolic changes during FI in response to SPD treatment. Here, ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS)-based widely targeted metabolomic analysis was carried out to assess the metabolic differences in the mango stem apex during different stage of mango FI (30, 80, 100 days after SPD/water treatment). A total of 582 compounds were annotated and 372 metabolites showed two-fold differences in abundance (variable importance in projection, VIP ≥ 1 and fold change, FC≥ 2 or≤ 0.5) between buds at 30, 80, 100 days after SPD/water treatment or between buds under different treatment. Lipids, phenolic acids, amino acids, carbohydrates, and vitamins were among metabolites showing significant differences over time after SPD treatment. Here, 18 out of 20 lipids, including the lysophosphatidylethanolamine (12, LPE), lysophosphatidylcholine (7, LPC), and free fatty acids (1, FA), were significantly upregulated from 80 to 100 days after SPD treatment comared to water treatment. Meanwhile, the dormancy release of mango buds from 80 to 100 days after SPD treatment was accompanied by the accumulation of proline, ascorbic acid, carbohydrates, and tannins. In addition, metabolites, such as L-homocysteine, L-histidine, and L-homomethionine, showed more than a ten-fold difference in relative abundance from 30 to 100 days after SPD treatment, however, there were no significant changes after water treatment. The present study reveals novel metabolites involved in mango FI in response to SPD, which would provide a theoretical basis for utilizing SPD to induce mango flowering.

PECULIARITIES OF THE MESOSTRUCTURAL ORGANIZATION OF THE LEAF AND ANATOMICAL STRUCTURE OF THE TOBACCO STEM UNDER THE ACTION OF GROWTH INHIBITORS

Tobacco plants of Ternopil 14 variety were treated with gibberellin inhibitors 2-CEPA, EW-250 and CCC-750. Under the influence of antigibberellins, the leaf blades of tobacco thickened due to the growth of chlorenchyma. The greatest increase in leaf thickness was found after the use of 2-CEPA and EW-25. These same drugs increased the volume of the cells of the columnar parenchyma. The size of the cells of the spongy parenchyma under the action of gibberellin inhibitors was reduced significantly.CCC-750 was found to increase the number of epidermal cells per unit abaxial leaf surface, while 2-CEPA and EW-250 decreased. All growth inhibitors reduced the number of stomata and increased the area of the stomata. All drugs thickened the layer of the primary periderm, and retardants thickened the layer of the collenchyma. EW-250 increased the size of sclerenchymal fiber cells, while other drugs reduced them. All antigibberellins thickened the membranes of sclerenchyma cells. Ethylene producer increased the thickness of the layer of the secondary periderm, and other drugs reduced this figure. EW-250 increased, 2-CEPA decreased, and CCC-750 did not change the thickness of the xylem layer. The diameter of the largest vessels decreased with 2-CEPA and CCC-750 and did not change after treatment with EW-250.

An alternative method for medium-term in vitro conservation of different plant species through gibberellin inhibitors

An alternative method for medium-term in vitro conservation of different plant species through gibberellin inhibitors

The SNF5-type protein BUSHY regulates seed germination via the gibberellin pathway and is dependent on HUB1 in Arabidopsis.

The SNF5-type protein BUSHY plays a role in the regulation of seed germination via the gibberellin pathway dependent on HUB1 in Arabidopsis thaliana. SWITCH/SUCROSE NONFERMENTING (SWI/SNF) complexes play diverse roles in plant development. Some components have roles in embryo development and seed maturation, however, whether the SNF5-type protein BUSHY (BSH), one of the components, plays a role in Arabidopsis seed related traits is presently unclear. In our study, we show that a loss-of-function mutation in BSH causes increased seed germination in Arabidopsis. BSH transcription was induced by the gibberellin (GA) inhibitor paclobutrazol (PAC) in the seed, and BSH regulates the expression of GA pathway genes, such as Gibberellin 3-Oxidase 1 (GA3OX1), Gibberellic Acid-Stimulated Arabidopsis 4 (GASA4), and GASA6 during seed germination. A genetic analysis showed that seed germination was distinctly improved in the bshga3ox1ga3ox2 triple mutant, indicating that BSH acts partially downstream of GA3OX1 and GA3OX2. Moreover, the regulation of seed germination by BSH in response to PAC is dependent on HUB1. These results provide new insights and clues to understand the mechanisms of phytohormones in the regulation of seed germination.

Gibberellin Inhibitor Treatments Before Planting Control Plant Height of Narcissus tazetta by Affecting Growth Parameters

The effects of flurprimidol and paclobutrazol, treatments as preplant bulb soaks on plant height, growth parameters and other properties of Narcissus tazetta L. grown in pots were investigated. Bulbs were soaked in flurprimidol at 0, 10, 20 mg L-1 or paclobutrazol at 0, 100, 200 mg L-1 before planting. The effects of gibberellin inhibitors on the flower number, flowering time, flower life, plant height, leaf length and quantitative measurements (specific leaf area, leaf area ratio, leaf thickness, leaf weight ratio and stem weight ratio) were determined. When narcissus reached to the sale stage, plants were taken to the laboratory where the temperature stable at 20°C to evaluate the postproduction quality. The shortest plant height (6.25 cm, 63% shorter than control) was obtained from the 20 mg L-1 flurprimidol application. Plants applied with 200 mg L-1 paclobutrazol were 59% shorter than control with 7.00 cm plant height. Gibberellin inhibitors also shortened the leaf length and increased the leaf thickness, whereas decreased leaf area ratio and specific leaf area by shortening the plant height. The effects of gibberellin inhibitors on plant height continued after harvest (production) in marketing and consumer (laboratory) conditions. The plant heights of treated plants were 10.87 (20 mg L-1 flurpirmidol) and 10.37 (200 mg L-1 paclobutrazol) cm, while with the control plants were 26.75 cm in with laboratory conditions.

PLANT HEIGHT CONTROL OF HYACINTHUS ORIENTALIS BY GIBBERELLIN INHIBITORS

In this study, effect of gibberellin inhibtors as preplant bulb soaks on plant height of Hyacinthus orientalis cv. ‘Jan Bos’ grown in pots were investigated. Bulbs of hyacints were soaked in flurprimidol at 0, 10, 20 ppm and paclobutrazol at 0, 100, 200 ppm before planting. Effect of gibberellin inhibitors on the flowering time, flower diameter and length, leaf length, plant height, flower life, chlorophyll content of leaves were determined. In addition, after hyacints grown in pots in the greenhouse arrived at the sales stage to determine the changes that occur in the plant height, plants were taken to the laboratory where temperature was held constant at 20 °C. The shortest plant height was obtained from the 200 ppm paclobutrazol and 20 ppm flurprimidol treatment as given bulb soaks. In this treatments, plant heihgt was 7.33 and 8.61 cm and were 49% , 41% shorter than untreated control. The lower dose of 10 ppm flurprimidol and 100 ppm paclobutrazol were also effective on height control with 9.11 and 9.71 cm plant height, respectively. Gibberellin inhibitors also shortened leaf lenght. Flurprimidol and paclobutrazol treatments resulted in higher chlorophyll content per unit area in the leaves than untreated controls. The highest chlorophyll contetnt was obtained from the plants treated 200 ppm paclobutrazol with 83.36 CCI (Chlorophyll content index), while the control was 50.56 CCI. The effects of treatments on plant height were maintained in lab conditions (home-office). The shortest plant height was obtained from 200 paclobutrazol treatment with 9.75 cm, while the control was 21.5 cm during post production period.

Effects of a Gibberellin Inhibitor on Flowering, Vegetative Propagation, and Production of Rapid Generation Cycling Gladiolus for Potted Plant Production

Gladiolus (Gladiolus ×hybridus) is an asexually propagated, herbaceous perennial and an economically important cut flower crop. In commercial production, gladioli have tall flower stalks, which limit their use to cut flowers and annual garden plants. The gladiolus breeding program at the University of Minnesota has bred and selected rapid generation cycling (RGC) cycle 1 gladiolus, which can flower in <1 year from seed instead of the norm of 3 to 5 years (which are vegetatively propagated as corms). Gibberellin inhibitors, such as ancymidol, are used as plant growth retardants to control height in potted plants. Higher concentrations can inhibit flowering along with other negative side effects. The aim of this study was to investigate the growth, flowering, and corm/cormel production response of cycle 1 gladiolus to the gibberellin inhibitor, ancymidol (0, 100, and 400 mg·L−1 soak) in comparison with noncycle 1 genotypes and commercial cultivars for potted gladiolus production. Cycle 1 genotypes flowered with all ancymidol concentrations while noncycle 1 genotypes had significantly fewer flowers or were completely nonflowering under higher concentrations. All tested genotypes had increased leaf width as ancymidol concentration increased. Conversely, flower stalk heights were shorter as the ancymidol concentration increased while the number of stalks was nonsignificant. Corms, cormel number, and fresh weights decreased in all genotypes except for one cycle 1 genotype, which had an increase in both corm number and fresh weight when treated with 100 mg·L−1 ancymidol. Cycle 1 gladiolus are more resilient to this gibberellin inhibitor even at high concentrations and can potentially be used for gladiolus potted plant production.

MiR169 and PmRGL2 synergistically regulate the NF-Y complex to activate dormancy release in Japanese apricot (Prunus mume Sieb. et Zucc.).

This study is the first to demonstrate that GA4-induced dormancy release is associated with the NF-Y complex, which interacts with gibberellin inhibitor RGL2 in Japanese apricot. Seasonal dormancy is not only vital for the survival in cold winter but also affects flowering of temperate fruit trees and the dormancy release depends on the accumulation of the cold temperatures (Chilling requirement-CR). To understand the mechanism of dormancy release in deciduous fruit crops, we compared miRNA sequencing data during the transition stage from paradormancy to dormancy release in the Japanese apricot and found that the miR169 family showed significant differentially up-regulated expression during dormancy induction and was down-regulated during the dormancy release periods. The 5' RACE assay and RT-qPCR validated its target gene NUCLEAR FACTOR-Y subunit A (NF-YA), which exhibited the opposite expression pattern. Further study showed that exogenous GA4 could inhibit the expression of the gibberellic acid (GA) signal transduction suppressor PmRGL2 (RGA-LIKE 2) and promote the expression of NF-Y. Moreover, the interaction between the NF-Y family and GA inhibitor PmRGL2 was verified by the yeast-two-hybrid (Y2H) system and a bimolecular fluorescence complementarity (BiFC) experiment. These results suggest that synergistic regulation of the NF-Y and PmRGL2 complex leads to the activation of dormancy release induced by GA4. These findings will help to elucidate the functional and regulatory roles of miR169 and NF-Y complex in seasonal bud dormancy induced by GA in Japanese apricot and provide new insights for the discovery of dormancy release mechanisms in woody plants.

Genetic variation of seedling traits responded to brassinosteroid and gibberellin inhibitors in maize (Zea mays) doubled haploid lines

AbstractThe purpose of this study was to examine the genotypic variation in maize doubled haploid (DH) lines response to brassinosteroid and gibberellin inhibitors. Plant responses to hormone inhibitors were determined in growth chamber experiments using germination paper for three different seedling treatments: application of propiconazole (Pcz), uniconazole (Ucz) or water (control). Mesocotyl length (ML) was more sensitive to hormone inhibitors, especially to the Ucz treatment, than other seedling traits. ML was significantly correlated with other traits in the Ucz treatment. All the seedling traits showed moderate‐to‐high broad sense heritability values, ranging from 0.39 to 0.82. The Euclidian genetic distances of inbred line pairs ranged from 1.27 to 19.94, indicating there was a high level of variability across the maize DH lines used in this study. DH lines with extreme MLs were identified, which can provide valuable breeding resources for improving abiotic stress tolerance, and for further genetic studies.

Influence of gibberellin inhibitors on the accumulation and redistribution of various forms of carbohydrates and nitrogen-containing compounds in plants of Solanum melongena L.

The 0.025% tebuconazole (EW-250), 0.25% chlormequat chloride (CCC-750), and 0.15% ethephon (2-CEPA) influences growth processes, the leaf apparatus, chlorophyll concentration and various carbohydrates forms, and total nitrogen content in Solanum melongena L. The decrease in the linear dimensions of the aubergine was established for all preparations. The most significant decrease in height was observed after the application of 2-HEPCs. The retardants increased the number of leaves, the dry matter mass of leaves, the leaf area, chlorophyll content, and the surface density of the leaf. EW-250 and ССС-750 retardants strengthened carbohydrate accumulation in aubergine fruits, mainly due to reducing forms. During the growing season, the total and protein nitrogen content decreased in roots and stems both in control and in experiment variants. EW-250 and CCC-750 accelerated total and protein nitrogen outflow from roots and stems and increased its content in leaves. Increasing the carbohydrates content in fruits the retardants simultaneously reduced the content of various nitrogen forms. Such changes in the dynamics of total nitrogen under the influence of tebuconazole led to enhanced fruit formation on each plant. Thus, retardants EW-250 and ССС-750 changed the nature of the donor-acceptor relations in them by increasing the outflow of plastic substances from vegetative organs to fruits and increasing the culture productivity.

Increased endogenous gibberellin level inhibits root growth of Pinus massoniana Lamb. plantlets during long-term subculture

In this study, we investigated the roles of the plant hormones indole-3-acetic acid (IAA) and gibberellin (GA) in regulating Pinus massoniana Lamb. plantlet regeneration during long-term in vitro subculture. Six generations (1st, 5th, 10th, 20th, 30th and 40th with 40 days for each transfer cycle) of subcultured shoots derived from mature and juvenile explants were characterised for their different rooting capacities. In the present experiment, shoots were subcultured on rooting medium containing indole-3-acetic acid (IAA), naphthaleneacetic acid (NAA) or gibberellin (GA) inhibitor (paclobutrazol, PBZ). In addition, high-performance liquid chromatography (HPLC) was used to analyse endogenous hormone levels in shoots developed on medium with low concentrations of NAA. The concentration of endogenous IAA was highest in the 20th generation shoots, which also exhibited the strongest rooting ability. However, the highest GA concentration was observed in the 40th generation shoots, which exhibited a poor rooting capacity. For shoots subcultured for 40 generations, incubation on rooting medium containing IAA caused an enhanced root number, shoot length and survival rate. This suggested that the effects of IAA on shoot and root formation were positive. PBZ promoted plantlet regeneration from in vitro cultures but impaired shoot elongation at high levels. Furthermore, PBZ improved performance of in vitro cultures after long-term (3 to 4 y) subculture. These results suggest the inhibitory role of a high endogenous GA level in plant regeneration and the use of appropriate levels of PBZ for plant regeneration of P. massoniana.

A STUDY ON PLANT HEIGHT CONTROL OF IRIS FLOWERS

We investigated the effect of paclobutrazol as preplant bulb soaks on plant heightof Iris x hollandica cv. ‘Frans Hals’ and ‘Blue Magic’cultivars which were grownin pots. Bulbs of iris were soaked into gibberellin inhibitor paclobutrazol solutionat 0, 15, 30 ppm before planting. Effect of paclobutrazol on the flowering time,flower diameter and length, leaf length, plant height, flower life, and chlorophyllcontent of leaves were determined. The shortest plant height was obtained from the‘Blue Magic’ cultivar treated with 30 ppm paclobutrazol which gave plants with11.3 cm, 68% shorter than untreated control. ‘Frans Hals’ cultivar treated with 30ppm paclobutrazol was 20.9 cm and 50% shorter than control. In ‘Blue Magic’ and‘Frans Hals’cultivars the lower dose of 15 ppm paclobutrazol were also effectiveon height control with 11.8 and 21.5 cm plant height, respectively. This gibberellininhibitor also shortened the leaf length of iris cultivars. Paclobutrazol treatmentsresulted in higher chlorophyll content per unit area in the leaves. The highestchlorophyll content (57.00 CCI) was obtained from the ‘Blue Magic’ iris treatedwith 30 ppm paclobutrazol, while the control plants had 32.70 CCI chlorophyll intheir leaves. Chlorophyll content of ‘Frans Hals’ treated with 30 ppm paclobutrazolwere 52.87 CCI, while control plants of this cultivar were 28.80 CCI. Plantsapplied with paclobutrazol resulted with smaller flower diameter compared to thecontrol plants of both cultivars. The smallest flower diameter was obtained from 30ppm paclobutrazol treatment with 38.83 mm in ‘Blue Magic’ iris while the controlof this cultivar was 99.63 mm. The flower diameter of ‘Frans Hals’ cultivar treatedwith 30 ppm paclobutrazol was 109.1 mm, while the control one was 112 mm.