Showing papers on "Gibberellic acid published in 2022"

Hormonal interactions underlying parthenocarpic fruit formation in horticultural crops

Abstract: Abstract In some horticultural crops, such as Cucurbitaceae, Solanaceae, and Rosaceae species, fruit set and development can occur without the fertilization of ovules, a process known as parthenocarpy. Parthenocarpy is an important agricultural trait that can not only mitigate fruit yield losses caused by environmental stresses but can also induce the development of seedless fruit, which is a desirable trait for consumers. In the present review, the induction of parthenocarpic fruit by the application of hormones such as auxins (2,4 dichlorophenoxyacetic acid; naphthaleneacetic acid), cytokinins (forchlorfenuron; 6-benzylaminopurine), gibberellic acids, and brassinosteroids is first presented. Then, the molecular mechanisms of parthenocarpic fruit formation, mainly related to plant hormones, are presented. Auxins, gibberellic acids, and cytokinins are categorized as primary players in initiating fruit set. Other hormones, such as ethylene, brassinosteroids, and melatonin, also participate in parthenocarpic fruit formation. Additionally, synergistic and antagonistic crosstalk between these hormones is crucial for deciding the fate of fruit set. Finally, we highlight knowledge gaps and suggest future directions of research on parthenocarpic fruit formation in horticultural crops.

Interplays between auxin and GA signaling coordinate early fruit development

Abstract: Abstract Phytohormones and their interactions are critical for fruit development and are key topics in horticulture research. Auxin, together with gibberellic acid (GA), promotes cell division and expansion, thereby regulating fruit development and enlargement after fertilization. Auxin- and GA-related mutants show parthenocarpy (fruit formation without fertilization of the ovule) in many plant species, indicating that these hormones and possibly their interactions play a key role in the regulation of fruit initiation and development. Recent studies have shown clear molecular and genetic evidence that ARF/IAA and DELLA proteins interact with one another and regulate both auxin and GA signaling pathways in response to auxin and GA during fruit growth in horticultural plants such as tomato (the most studied fleshy fruit) and strawberry (the model for Rosaceae). These recent findings provide new insights into the mechanisms by which the plant hormones auxin and GA regulate fruit development.

The miR166 mediated regulatory module controls plant height by regulating gibberellic acid biosynthesis and catabolism in soybean.

Abstract: MicroRNAs (miRNAs) are endogenous small non-coding RNAs that play critical roles in regulating plant growth and development. Here, we used Short Tandem Target Mimic (STTM) technology to generate soybean (Glycine max L. Merr.) miRNA knockdown lines and identify miRNAs that regulate plant height, a key agronomic trait that affects yield. STTM166 successfully silenced miR166 in soybean and upregulated the expression of miR166 target genes, such as ATHB14-LIKE. The miR166 knockdown lines (GmSTTM166) displayed a reduced plant height phenotype. Moreover, GmSTTM166 plants contained lower levels of bioactive gibberellic acid (GA3) than wild-type plants, and application of exogenous GA partially rescued the dwarf phenotype of GmSTTM166. Knockdown of miR166 altered the expression of genes involved in GA biosynthesis and catabolism. Further analysis revealed that ATHB14-LIKE directly represses transcription of the GA biosynthesis genes GmGA1 and GmGA2, while activating transcription of the GA catabolic gene GIBBERLLIN 2 OXIDASE 2 (GmGA2ox2). Collectively, these results reveal a pivotal role for miR166 in the genetic control of plant height in soybean, thereby providing invaluable insights for molecular breeding to improve soybean yield. This article is protected by copyright. All rights reserved.

Heat stress mitigation in tomato (Solanum lycopersicum L.) through foliar application of gibberellic acid

Abstract: Abstract Phytohormones mediate physiological, morphological, and enzymatic responses and are important regulators of plant growth and development at different stages. Even though temperature is one of the most important abiotic stressors for plant development and production, a spike in the temperature may have disastrous repercussions for crop performance. Physiology and growth of two tomato genotypes ('Ahmar' and 'Roma') were studied in two growth chambers (25 and 45 °C) when gibberellic acid (GA 3 ) was applied exogenously. After the 45 days of planting, tomato plants were sprayed with GA 3 at concentrations of 25, 50, 75, and 100 mg L −1 , whereas untreated plants were kept as control. Under both temperature conditions, shoot and root biomass was greatest in 'Roma' plants receiving 75 mg L −1 GA 3 , followed by 50 mg L −1 GA 3 . Maximum CO 2 index, photosynthetic rate, transpiration rate, and greenness index were recorded in 'Roma' plants cultivated at 25 °C, demonstrating good effects of GA 3 on tomato physiology. Likewise, GA 3 enhanced the proline, nitrogen, phosphorus, and potassium levels in the leaves of both genotypes at both temperatures. Foliar-sprayed GA 3 up to 100 mg L −1 alleviated the oxidative stress, as inferred from the lower concentrations of MDA and H 2 O 2, and boosted the activities of superoxide dismutase, peroxidase, catalase. The difference between control and GA 3 -treated heat-stressed plants suggests that GA 3 may have a function in mitigating heat stress. Overall, our findings indicate that 75 mg L −1 of GA 3 is the optimal dosage to reduce heat stress in tomatoes and improve their morphological, physiological, and biochemical characteristics.

Postharvest dormancy-related changes of endogenous hormones in relation to different dormancy-breaking methods of potato (Solanum tuberosum L.) tubers

Abstract: Development of an efficient and eco-friendly technique to break tuber dormancy in potato (Solanum tuberosum L.) is highly demanded due to the production of two or more crops annually. Several physiological and hormonal changes have been found to be related to the breaking of tuber dormancy; however, their consistency with genotypes and different protocols have not been well clarified. This study aims to evaluate the effectiveness of four dormancy-breaking methods, that is, plant growth regulator (PGR) dipping in 30, 60, or 90 mgL−1 benzyl amino purine (BAP) and 10, 20, or 30 mgL−1 gibberellic acids (GA3) alone and in the combination of optimized concentrations; electric current application at 20, 40, 60, or 80 Vs; cold pre-treatment at 2, 4, or 6 °C; irradiation at 1, 1.5, 2, 2.5, 3, or 3.5 kGy. In addition, changes in endogenous levels of abscisic acid (ABA), zeatin (ZT), and gibberellin A1 (GA1) in six potato genotypes after subjecting to these methods were investigated. Overall, the highest effective method for dormancy duration was the PGR application which shortened the duration by 18 days, followed by electric current (13 days), cold pre-treatment (9 days), and then irradiation (7 days). The solution of 60 mgL−1 BAP significantly reduced the dormancy duration in all genotypes but did not have a significant effect on the sprout length. While 20 mgL−1 GA3 produced maximum sprout length with a non-significant effect on dormancy duration. The genotype × PGR interaction for dormancy duration was more pronounced in short- and medium-term dormancy genotypes than in long-term dormancy genotypes. The genotypes displayed a significant positive correlation between dormancy duration and ABA levels but exhibited a negative correlation between dormancy duration and ZT as well as GA1 levels. From the first to the third week of storage, ABA was decreased in tubers while, however, ZT and GA1 were increased. The obtained results could be useful for the postharvest storage of potato tuber and the related field of physiological investigation in future.

Cytokinin and gibberellic acid-mediated waterlogging tolerance of mungbean (Vigna radiata L. Wilczek)

Abstract: Background Mungbean (Vigna radiata L. Wilczek) is one of the most important pulse crops, well-known for its protein-rich seeds. Growth and productivity are severely undermined by waterlogging. Methods In this study, we aim to evaluate how two promising phytohormones, namely cytokinin (CK) and gibberellic acid (GA3), can improve waterlogging tolerance in mungbean by investigating key morphological, physiological, biochemical, and yield-related attributes. Results Our results showed that foliar application of CK and GA3 under 5-day of waterlogged conditions improved mungbean growth and biomass, which was associated with increased levels of photosynthetic rate and pigments. Waterlogged-induced accumulation of reactive oxygen species and the consequently elevated levels of malondialdehyde were considerably reduced by CK and GA3 treatments. Mungbean plants sprayed with either CK or GA3 suffered less oxidative stress due to the enhancement of total phenolics and flavonoids levels. Improvement in the contents of proline and total soluble sugars indicated a better osmotic adjustment following CK and GA3 treatments in waterlogged‐exposed plants. Most fundamentally, CK or GA3-sprayed waterlogged-stressed mungbean plants demonstrated better performance in the aforementioned parameters after the 15-day recovery period as compared to water-sprayed waterlogged-exposed plants. Our results also revealed that CK and GA3 treatments increased yield-associated features in the waterlogged-stressed plant. Here, both phytohormones are efficient in improving mungbean resistance to waterlogging. However, CK was found to be more effective. Overall, our findings suggested that CK or GA3 could be used for managing waterlogging-induced damage to mungbean and perhaps in other cash crops.

Foliar Application of GA3 Stimulates Seed Production in Cauliflower

Abstract: This study aimed to evaluate the influence of gibberellic acid on both concentration and time of application on the seed production ability of BU cauliflower-1. The experiment was conducted to determine seed production ability at five concentrations of GA3: G0 = Control, G1 = 100 ppm, G2 = 200 ppm, G3 = 300 ppm, G4 = 400 ppm, along with four application times at different growth stages including T1 = Foliar application at 3 weeks after planting, T2 = Foliar application at 4 weeks after planting, T3 = Foliar application at 5 weeks after planting and T4 = Foliar application at 6 weeks after planting. Results revealed that 200 ppm GA3 gave the highest plant height (44.05 cm), the number of primary (10.88) and secondary flowering branches (31.33), stalk length (79.53 cm), seeded pods per plant (465), pod length (4.975 cm), seeds per pod (10.87), seed yield per plant (16.16 g), seed yield (0.24 ton/ha), and weight of thousand seeds (4.826 g) with the earliest curd (51.02 days) and flower initiation (84.17 days). It also gave the highest net return (Tk. 4.7 lakh/ha) and benefit-cost ratio (4.34). GA3 application at 3 weeks after transplanting had the highest numbers of primary and secondary flowering branches, pods, seeded pods, and seed yield per plant. The treatment combination of G2T1 gave the earliest curd initiation (49.60 days), the highest number of secondary flowering branches (34.87), seed yield per plant (22.75 g), and seed yield (0.27 ton/h). In contrast, the G2T2 treatment resulted in the earliest flower initiation (81.77 days) with the highest pod length (5.20 cm), the number of pods per plant (707), and seeded pods per plant (507), and seeds per pod (11.30). Hence, 200 ppm GA3 applied three weeks after transplanting could be used as the best combination for cauliflower seed production with the highest net return and benefit-cost ratio. Enhancing seed yield is our ultimate goal; hence, we suggest 200 ppm GA3 three weeks after transplanting for increased cauliflower seed production with the highest return and benefit-cost ratio in the study area. As we performed the study in a particular location, we recommend multilocation trials in different agro-ecological regions to study the genotype–environment interaction for final confirmation of the results.

2-Hydroxymelatonin Promotes Seed Germination by Increasing Reactive Oxygen Species Production and Gibberellin Synthesis in Arabidopsis thaliana

Abstract: It was recently reported that 2-hydroxymelatonin (2-OHM) is responsible for inducing reactive oxygen species (ROS) in plants. ROS are crucial molecules that promote germination through interaction with hormones such as gibberellic acid (GA). In this study, to confirm the pro-oxidant role of 2-OHM, we investigated its effect on seed germination in Arabidopsis thaliana (L.) Heynh. Columbia-0. We found that 2-OHM treatment stimulated seed germination by 90% and 330% in non-dormant and dormant seeds, respectively, whereas melatonin marginally increased germination (~13%) in both seed types compared to untreated control seeds. The germination promotion effects of exogenous 2-OHM treatment were due to increased ROS production followed by the induction of GA synthesis and expression of responsive genes. Accordingly, melatonin 2-hydroxylase (M2H), the gene responsible for 2-OHM synthesis, was strictly expressed only during the germination process. Further molecular genetic analyses using m2h knockout mutant and M2H overexpression clearly supported an increase in ROS triggered by 2-OHM, followed by increased expression of GA-related genes, which shortened the time to germination. Notably, 2-OHM application to m2h knockout mutant seeds fully recovered germination to levels comparable to that of the wild type, whereas melatonin treatment failed to increase germination. Together, these results indicate that 2-OHM is a pivotal molecule that triggers increased ROS production during seed germination, thereby enhancing germination via the GA pathway in Arabidopsis thaliana.

Growth Regulators Improve Outcrossing Rate of Diverse Rice Cytoplasmic Male Sterile Lines through Affecting Floral Traits

Abstract: Cytoplasmic male sterility (CMS) provides an irreplaceable strategy for commercial exploitation of heterosis and producing high-yielding hybrid rice. The exogenous application of plant growth regulators could improve outcrossing rates of the CMS lines by affecting floral traits and accordingly increase hybrid rice seed production. The present study aimed at exploring the impact of growth regulators such as gibberellic acid (GA3), indole-3-acetic acid (IAA), and naphthalene acetic acid (NAA) on promoting floral traits and outcrossing rates in diverse rice CMS lines and improving hybrid rice seed production. The impact of foliar applications of growth regulators comprising GA3 at 300 g/ha or GA3 at 150 g/ha + IAA at 50 g/ha + NAA at 200 g/ha versus untreated control was investigated on floral, growth, and yield traits of five diverse CMS lines. The exogenously sprayed growth regulators, in particular, the combination of GA3, IAA, and NAA (T3) boosted all studied floral, growth, and yield traits in all tested CMS lines. Moreover, the evaluated CMS lines exhibited significant differences in all measured floral traits. L2, L3, and L1 displayed the uppermost spikelet opening angle, duration of spikelet opening, total stigma length, style length, stigma brush, and stigma width. In addition, these CMS lines exhibited the highest plant growth and yield traits, particularly under T3. Consequently, exogenous application of GA3, IAA, and NAA could be exploited to improve the floral, growth, and yield traits of promising CMS lines such as L2, L3, and L1, hence increasing outcrossing rates and hybrid rice seed production.

Intracellular reactive oxygen species trafficking participates in seed dormancy alleviation in Arabidopsis seeds.

Abstract: Reactive Oxygen Species (ROS) release seed dormancy through an unknown mechanism. We used different seed dormancy breaking treatments to decipher the dynamics and localization of ROS production during seed germination. We studied the involvement of ROS in the breaking of Arabidopsis seed dormancy by cold stratification, gibberellic acid (GA3) and light. We characterized the effects of these treatments on abscisic acid and gibberellins biosynthesis and signaling pathways. ROS, mitochondrial redox status and peroxisomes were visualized or/and quantified during seed imbibition. At last we performed a cytogenetic characterization of the nuclei from the embryonic axes during seed germination. We show that mitochondria participate in the early ROS production during seed imbibition and that a possible involvement of peroxisomes in later stages should still be analysed. At the time of radicle protrusion, ROS accumulated within the nucleus which correlated with nuclear expansion and chromatin decompaction. Taken together our results evidence the role of ROS trafficking between organelles and of the nuclear redox status in the regulation of seed germination by dormancy.

Seed Priming Enhances Seed Germination and Morphological Traits of Lactuca sativa L. under Salt Stress

Abstract: Seed germination is the stage in which plants are most sensitive to abiotic stress, including salt stress (SS). SS affects plant growth and performance through ion toxicity, decreasing seed germination percentage and increasing the germination time. Several priming treatments were used to enhance germination under SS. The objectives of this study were (1) to identify priming treatments to shorten the emergence period, (2) to evaluate priming treatments against the SS, and (3) to induce synchronized seed germination. Salt-sensitive ‘Burpee Bibb’ lettuce seeds were treated with 0.05% potassium nitrate, 3 mM gibberellic acid, and distilled water. All the primed and non-primed seeds were subjected to 100 mM sodium chloride (NaCl) or 0 mM NaCl (control). The seven-day experiment, arranged in a complete randomized block design with four replications, was conducted in a growth chamber maintained with 16/8 h photoperiod (light/dark), 60% relative humidity, and a day/night temperature of 22/18 °C. The result indicated that hydro-primed (HP) seeds were better synchronized under SS. Similarly, fresh mass (FM) and dry mass (DM) of cotyledon, hypocotyl, and radicle were the highest in HP lettuce regardless of SS. Electrolyte leakage was the lowest in the HP lettuce, while other priming methods under SS increased membrane permeability, leading to osmotic stress and tissue damage. Overall, hydro-priming can be a good priming method for synchronizing germination and increasing FM and DM by creating the least osmotic stress and ion toxicity in lettuce under SS.

Plant Development of Early-Maturing Spring Wheat (Triticum aestivum L.) under Inoculation with Bacillus sp. V2026

Abstract: The effect of a plant growth-promoting bacterium (PGPB) Bacillus sp. V2026, a producer of indolyl-3-acetic acid (IAA) and gibberellic acid (GA), on the ontogenesis and productivity of four genotypes of early-maturing spring wheat was studied under controlled conditions. The inoculation of wheat plants with Bacillus sp. V2026 increased the levels of endogenous IAA and GA in wheat of all genotypes and the level of trans-Zeatin in Sonora 64 and Leningradskaya rannyaya cvs but decreased it in AFI177 and AFI91 ultra-early lines. Interactions between the factors “genotype” and “inoculation” were significant for IAA, GA, and trans-Zeatin concentrations in wheat shoots and roots. The inoculation increased the levels of chlorophylls and carotenoids and reduced lipid peroxidation in leaves of all genotypes. The inoculation resulted in a significant increase in grain yield (by 33–62%), a reduction in the time for passing the stages of ontogenesis (by 2–3 days), and an increase in the content of macro- and microelements and protein in the grain. Early-maturing wheat genotypes showed a different response to inoculation with the bacterium Bacillus sp. V2026. Cv. Leningradskaya rannyaya was most responsive to inoculation with Bacillus sp. V2026.

A simple, rapid, and quantifiable system for studying adventitious root formation in grapevine

Abstract: Woody cutting is customarily utilized as a material in research on grape adventitious root formation (ARF). However, phenotypic heterogeneity caused by the complex background influenced its use for molecular mechanism research of ARF of grape. The present study tested various types of explants from grape tissue culture plantlets and found that the whole leaf: blade with the petiole (LP) was the simplest unit that can easily form adventitious roots (ARs). LP explants which can be easily obtained, directly generate ARs via de novo organogenesis from the base of the petiole. Plantlet age, node position, blade size, the health condition of leaves, and light intensity have been demonstrated to affect the homogeneity of the ARF phenotype in LP. By controlling these parameters, selected LPs cultured on a medium with 6 g·L-1 agar and 10 g·L-1 sucrose under dark conditions started rooting at 6–7 days after culture (DAC) and reached 100% rooting rate within 13–14 DAC. Using this system, the core role of auxin on ARF was verified by exogenous application of indole butyric acid (IBA) and N-1-naphthylphthalamic acid (NPA). Strikingly, we found that light promoted ARF in the absence of sucrose, but inhibited ARF in the presence of sucrose (10 g·L-1), while a low concentration of 0.34 µM NPA partially relieved the inhibition. Finally, this study confirmed that exogenous plant growth regulators (PGRs), including 6-benzyl aminopurine (6-BA), gibberellic acid 3 (GA3), and 2,4-epibrassinolide (EBR), significantly inhibited ARF. This simple, rapid, quantifiable ARF research system provides a new approach to studying the factors influencing the formation and development of grape adventitious roots and establishes a framework for investigating the mechanism of grape adventitious root induction and initiation.

Osmoprotection in Salvia hispanica L. seeds under water stress attenuators.

Abstract: Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

Grafting enhances drought tolerance by regulating stress-responsive gene expression and antioxidant enzyme activities in cucumbers

Abstract: Water scarcity is a major limiting factor for crop yield production in arid and water-stressed areas worldwide. Cucumber plants have a high transpiration ratio and are vulnerable to drought. Grafting commercial genotypes onto selected strong rootstocks has been useful in mitigating the effects of drought. Therefore, this study aimed to evaluate the possibility of using a novel rootstock plant's tolerance to water-deficit stress in inducing drought tolerance in cucumbers by activating the stress-response gene expression and the antioxidant system, which improved the cucumber quality and yield under water-deficit conditions. This field experiment was conducted for > 2 years, 2020 and 2021, with five drought stress tolerant genotypes (i.e., rootstock) and drought-sensitive genotype Luerans (i.e., a scion). They were subjected to various deficit irrigation levels for 12 days, and their agro-physiological and molecular responses to water-deficit stress were assessed. The results of the study showed that the agronomical parameters, including the leaf area (LA), leaf water content (LWC), number of leaves, plant height, root dry matter shoot dry matter, rates of leaf appearance and stem elongation, and total yield significantly increased with grafted cucumber plants than with non-grafted cucumber plants (control) under normal and stressful conditions.Similar results were observed in the physiological measurements in terms of antioxidant enzymes, abscisic acid levels, gibberellic acid content, and lower lipid peroxidation (malondialdehyde, MDA). Grafting of Luerans (section) on five rootstocks significantly raised the activity of antioxidant enzymes (catalase and peroxidase), improved the gibberellic acid and proline accumulation, and reduced the content of lipid peroxidation and abscisic acid. Furthermore, the real-time polymerase chain reaction expression results revealed that transcript levels of the stress-response genes CsAGO1 and CsDCLs increased rapidly and continuously in five rootstock grafting. Concurrently, these findings suggest that grafting with local varieties of novel drought-tolerant rootstock genotypes could improve drought tolerance in drought-sensitive cucumber genotypes.

Grafting enhances drought tolerance by regulating stress-responsive gene expression and antioxidant enzyme activities in cucumbers

Abstract: Water scarcity is a major limiting factor for crop yield production in arid and water-stressed areas worldwide. Cucumber plants have a high transpiration ratio and are vulnerable to drought. Grafting commercial genotypes onto selected strong rootstocks has been useful in mitigating the effects of drought. Therefore, this study aimed to evaluate the possibility of using a novel rootstock plant's tolerance to water-deficit stress in inducing drought tolerance in cucumbers by activating the stress-response gene expression and the antioxidant system, which improved the cucumber quality and yield under water-deficit conditions. This field experiment was conducted for > 2 years, 2020 and 2021, with five drought stress tolerant genotypes (i.e., rootstock) and drought-sensitive genotype Luerans (i.e., a scion). They were subjected to various deficit irrigation levels for 12 days, and their agro-physiological and molecular responses to water-deficit stress were assessed. The results of the study showed that the agronomical parameters, including the leaf area (LA), leaf water content (LWC), number of leaves, plant height, root dry matter shoot dry matter, rates of leaf appearance and stem elongation, and total yield significantly increased with grafted cucumber plants than with non-grafted cucumber plants (control) under normal and stressful conditions.Similar results were observed in the physiological measurements in terms of antioxidant enzymes, abscisic acid levels, gibberellic acid content, and lower lipid peroxidation (malondialdehyde, MDA). Grafting of Luerans (section) on five rootstocks significantly raised the activity of antioxidant enzymes (catalase and peroxidase), improved the gibberellic acid and proline accumulation, and reduced the content of lipid peroxidation and abscisic acid. Furthermore, the real-time polymerase chain reaction expression results revealed that transcript levels of the stress-response genes CsAGO1 and CsDCLs increased rapidly and continuously in five rootstock grafting. Concurrently, these findings suggest that grafting with local varieties of novel drought-tolerant rootstock genotypes could improve drought tolerance in drought-sensitive cucumber genotypes.

Artificial Neural Networks Elucidated the Essential Role of Mineral Nutrients versus Vitamins and Plant Growth Regulators in Achieving Healthy Micropropagated Plants

Abstract: The design of an adequate culture medium is an essential step in the micropropagation process of plant species. Adjustment and balance of medium components involve the interaction of several factors, such as mineral nutrients, vitamins, and plant growth regulators (PGRs). This work aimed to shed light on the role of these three components on the plant growth and quality of micropropagated woody plants, using Actinidia arguta as a plant model. Two experiments using a five-dimensional experimental design space were defined using the Design of Experiments (DoE) method, to study the effect of five mineral factors (NH4NO3, KNO3, Mesos, Micros, and Iron) and five vitamins (Myo-inositol, thiamine, nicotinic acid, pyridoxine, and vitamin E). A third experiment, using 20 combinations of two PGRs: BAP (6-benzylaminopurine) and GA3 (gibberellic acid) was performed. Artificial Neural Networks (ANNs) algorithms were used to build models with the whole database to determine the effect of those components on several growth and quality parameters. Neurofuzzy logic allowed us to decipher and generate new knowledge on the hierarchy of some minerals as essential components of the culture media over vitamins and PRGs, suggesting rules about how MS basal media formulation could be modified to assess the quality of micropropagated woody plants.

Effect of plant growth regulators on potato tuber yield and quality

Abstract: The aim of the study conducted in 2019–2021 was to determine the effect of biostimulants and growth regulators on the yield size and structure, as well as the chemical composition of edible potato tubers. The cultivar evaluated was Vineta. Asahi SL, Kelpak SL, Aminoplant, Tytanit, gibberellic acid (GA3) and Moddus 250 EC were applied in potato cultivation. The application of biostimulants Asahi SL and Tytanit increased the total and marketable tuber yield, as well as the average tuber weight. Aminoplant had a beneficial effect only on the marketable yield, while Moddus 250 EC decreased tuber yield and mean tuber weight, especially under conditions of high rainfall. Biostimulant Asahi SL caused a decrease in the number of tubers formed, while gibberellic acid stimulated tuberisation. Both preparations increased the share of deformed tubers in the total yield. The effect of biostimulants and growth regulators on the formation of the chemical composition of potato tubers was multidirectional. Tytanit increased protein content in tubers, while the remaining preparations, with the exception of the growth regulator Moddus 250 EC, decreased the amount of this component. GA3 and Moddus 250 EC decreased the content of crude fibre and, in the case of Moddus 250 EC, also the content of mineral components. The highest concentration of nitrates (V) was characteristic for potato tubers treated with Asahi SL and the lowest for those treated with Moddus 250 EC.

Origin, evolution, and molecular function of DELLA proteins in plants

Abstract: Gibberellic acid (GA), a ubiquitous phytohormone, has various effects on regulators of plant growth and development. GAs promote growth by overcoming growth restraint mediated by DELLA proteins (DELLAs). DELLAs, in the GRAS family of plant-specific nuclear proteins, are nuclear transcriptional regulators harboring a unique N-terminal GA perception region for binding the GA receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1) and a C-terminal GRAS domain necessary for GA repression activity via interaction with multiple regulatory proteins. The N-terminal conserved region of DELLAs evolved to form a mode of GID1/DELLA-mediated GA signaling originating in bryophytes and ferns. Binding of GA to GID1 increases the affinity between DELLAs and a SCF E3 ubiquitin–ligase complex, thus promoting the eventual destruction of DELLAs by the 26S proteasome. DELLAs negatively regulate GA response by releasing transcription factors to directly activate downstream genes and indirectly regulate GA biosynthesis genes increasing GA responsiveness and feedback control by promoting GID1 transcription. GA communicates extensively with other plant hormones and uses crosstalk to regulate plant growth and development. In this review, we summarize current understanding of evolutionary DELLA-mediated gibberellin signaling and functional diversification of DELLA, focusing primarily on interactions of DELLAs with diverse phytohormones.

Improvement of In Vitro Seed Germination and Micropropagation of Amomum tsao-ko (Zingiberaceae Lindl.)

Abstract: Black cardamom (Amomum tsao-ko Crevost & Lemarié) is a spice plant of great commercial value in Vietnam, but with limited propagation ability. Its seeds are characterized by a thick and hard seed coat, a small endosperm, and a small embryo, which are the causes of the physical dormancy of the seeds and low germination. Attempts in this study to improve the germination rate and achieve uniform germination included mechanical scarification, immersion in hot or cold water, acid scarification, and the application of plant growth regulators. Although immersion of seeds in cold water and application of plant growth regulators (PGRs) (gibberellic acid (GA3) and 1-naphtaleneacetic acid (NAA)) showed positive effects on seed germination and subsequent seedling growth, mechanical scarification provided the highest germination rate of black cardamom seeds (68.0%) and significantly shortened germination time (53.7 days) compared to control (16.0% and 74.7 days). On the other hand, an efficient micropropagation protocol has been established using shoot tip explants derived from in-vitro-grown seedlings. Murashige and Skoog (MS) medium supplemented with 4.0 mg/L 6-benzylaminopurine (BAP) + 0.5 mg/L NAA proved to be most suitable for rapid multiplication and rooting, providing a mean of 5.4 shoots per explant, 6.8 cm shoot length, and 16.2 roots per explant after 7 weeks of culture. Well-rooted black cardamom plantlets have been successfully adapted to ex vitro conditions. “Fasco” bio-soil was more suitable for acclimatization, with a 48.9% survival rate, 23.3 cm plant length, and 5.7 leaves per plant after 3 months of planting. Improved germination and multiplication protocols can be used to improve propagation performances and to develop elite of black cardamom planting material.

The L-Type Lectin-like Receptor Kinase Gene TaLecRK-IV.1 Regulates the Plant Height in Wheat

Abstract: Dwarfing is important for the production of wheat (Triticumaestivum L.). In model plants, receptor-like kinases have been implicated in signal transduction, immunity, and development. However, functional roles of lectin receptor-like kinases in wheat are poorly understood. In this study, we identified an L-type lectin receptor-like kinase gene in wheat, designated as TaLecRK-IV.1, and revealed its role in plant height. Real time quantitative PCR analyses indicated that TaLecRK-IV.1 transcript level was lower in a dwarf wheat line harboring the Rht-D1b gene compared to its transcript level detected in a taller wheat line CI12633. Importantly, the virus-induced gene silencing results showed that silencing of TaLecRK-IV.1 in the wheat line CI12633 led to dwarf plants. The results of the disease resistance test performed after the gene silencing experiment suggest no significant role of TaLecRK-IV.1 in the resistance reaction of wheat line CI12633 to sharp eyespot. Gene expression analysis revealed that the transcript abundance of TaLecRK-IV.1 was more up-regulated after the exogenous application of gibberellic acid and auxin, two development-related phytohormones, compared to the gene transcript levels detected in the control plants (mock treatment). These findings support the potential implication of TaLecRK-IV.1 in the pathway controlling plant height rather than the disease resistance role, and suggest that TaLecRK-IV.1 may be a positive regulator of plant height through the gibberellic acid and auxin-signaling pathways.

The growth of summer savory (Satureja hortensis) affected by fertilization and plant growth regulators in temperature stress

Abstract: Satureja hortensis L. (summer savory) is among the most important medicinal plants, grown in different parts of the world including Iran. The objective was to enhance the morphological properties of different genotypes of summer savory in temperature (warm, mild and cold) stress by fertilization and plant growth regulators (PGRs), as it has not been previously investigated, to our knowledge. The effects of fertilization (F1) (MI, 2 g L−1), and PGRs (sprayed four times during the season) including amino acid (F2) (A, 2 g L−1), gibberellic acid (F3) (GA, 2 mM), and control (F4) (using water) were examined on plant growth. The summer savory genotypes (Khuzestani, Mutika and Bakhtiari) were planted on the 8th of April (13.0 °C), May (20.8 °C), and June (26.0 °C), and a wide range of plant growth parameters were determined. Genotype Mutika was the most responsive one with significantly higher growth under all temperature conditions. Even under the cold stress Mutika root fresh weight was significantly higher than that of the other genotypes. However, fertilization and PGRs significantly increased the fresh weight of aerial part in all genotypes. All treatments significantly increased the flower number in cold stress. MI, compared with the PGRs, significantly increased side stem height, in different temperatures. The highest effects of treatments were observed on root volume, aerial part and total fresh weights, stem height and flower number. It is possible to plant and improve S. hortenesis morphological properties in different climatic conditions using the tested treatments and the appropriate genotype affecting plant physiological metabolisms.