Gibberellic Acid Levels Research Articles

The impact of varying levels of Gibberellic Acid (GA3) on plant growth, flowering, flower quality, seed yield, and quality of Petunia(Petunia × hybrida Vilm.)

Petunia, a popular ornamental plant, is known for its vivid flowers and wide color range. Petunia has long been valued for its aesthetic appeal, but recent research has begun to shed light on its possible medicinal properties. Petunia × hybrida is widely recognized for its medicinal characteristics, phytochemical content, and potential health benefits. A research study was undertaken between the years 2021 and 2022. The field experiment was laid out in a randomized complete block design (RCBD), with 11 treatments replicated three times. The treatments included 10 GA3 concentrations from 25 to 250 ppm applied 45 days post-transplantation, along with control—Petunia cv. 'White' seedlings were transplanted in main plots with 30 × 30 cm spacing. Based on the results, it was noted that foliar feeding the leaves with 200 ppm GA3 produced notable outcomes in various characteristics. This treatment recorded a higher plant height (53.45 cm), spread (50.32 cm), and branches per plant (26.77 cm). It also minimized time to first flowering (78.81 days), 50 % flowering (96.67 days), and peak flowering (107.33 days). Furthermore, 200 ppm GA3 optimized flowering duration (123.47 days), flower diameter (6.76 cm), flowers per plant (405.60), seeded capsules per plant (367.13), and seeds per capsule (535.67). Seed yield was maximized at all levels: per plant (12.51 g), per plot (54.33 g), and per hectare (380.33 kg). Seed quality parameters also peaked, including 1000-seed weight (93.65 mg), germination (93.75 %), germination speed (10.59), seedling length (3.63 cm), and dry weight (0.331 mg). Vigor indices I (340.54) and II (30.99) were significantly higher, while seed electrical conductivity was significantly low (77.13 μSm-1) with this treatment.

Metabolomic and Physiological Analyses Reveal the Effects of Different Storage Conditions on Sinojackia xylocarpa Hu Seeds.

Sinojackia xylocarpa Hu is a deciduous tree in the Styracaceae family, and it is classified as a Class II endangered plant in China. Seed storage technology is an effective means of conserving germplasm resources, but the effects of different storage conditions on the quality and associated metabolism of S. xylocarpa seeds remain unclear. This study analyzed the physiological and metabolic characteristics of S. xylocarpa seeds under four storage conditions. Our findings demonstrate that reducing seed moisture content and storage temperature effectively prolongs storage life. Seeds stored under that condition exhibited higher internal nutrient levels, lower endogenous abscisic acid (ABA) hormone levels, and elevated gibberellic acid (GA3) levels. Additionally, 335 metabolites were identified under four different storage conditions. The analysis indicates that S. xylocarpa seeds extend seed longevity and maintain cellular structural stability mainly by regulating the changes in metabolites related to lipid, amino acid, carbohydrate, and carotenoid metabolic pathways under the storage conditions of a low temperature and low seed moisture. These findings provide new insights at the physiological and metabolic levels into how these storage conditions extend seed longevity while also offering effective storage strategies for preserving the germplasm resources of S. xylocarpa.

Endogenous phytohormone analysis during sequential stages of somatic embryogenesis in Musa AAA cv. Grand Naine (subgroup Cavendish)

Abstract This is the first initiative study to provide quantified levels of four endogenous phytohormones during the induction, regeneration, maturation and germination stages of somatic embryogenesis (SE) in banana, using immature male bud explants, in the popular commercial triploid cultivar Grand Naine (AAA). Phytohormones are known to play a major role in the regulation of SE and most protocols have been developed for various cultivars of banana following empirical approaches. Although, several reports are available with regard to the impact of growth regulators exogenously supplemented to the media, the vital role of endogenous growth hormones in various developmental stages of SE remain unclear in banana. Reverse Phase High Performance Liquid Chromatography (RP-HPLC) was used to analyze endogenous status of indole acetic acid (IAA), zeatin, gibberellic acid (GA) and abscisic acid (ABA). Results from this study revealed that endogenous IAA and GA along with exogenous auxin play a major role in the induction of embryogenic competence of male bud explants. The levels of endogenous IAA and zeatin were found to be higher in embryogenic calli than non-embryogenic calli, although three different types of exogenous auxins were supplemented in callogenesis medium, but not cytokinin. Higher level of ABA and GA was observed in early and late developmental stages of somatic embryo, respectively. GA also played a predominant role in germination of somatic embryos. These findings will be applied for improvement of SE protocol in recalcitrant banana cultivars by suitably altering or supplementing exogenous growth hormones.

Enhancing Soybean Growth with Phytohormone-enriched PGPR Bioinoculants and Biofertilizers in Plant Stress Physiology

Background: The present investigation aimed to evaluate the effects of plant growth-promoting rhizobacteria (PGPR) bioinoculants and their carrier-based biofertilizers on the physiology of soybean. Methods: Seeds of two soybean varieties (cv. NARC-1 and cv. William-82) were either soaked in broth cultures of two PGPR strains, Planomicrobium chinense (MF616408) and Pseudomonas putida (KX574857), containing 106 cells/mL, or coated with biofertilizers. Three biofertilizers, namely biostimulant, biozote and biofert, were used. Result: Significant increases in root and shoot weight were observed with both liquid bioinoculants and carrier-based biofertilizers compared to the control. The consortium of P. chinense and P. putida resulted in the highest proline content and superoxide dismutase (SOD) activity. Biostimulant-treated plants exhibited higher catalase (CAT) activity and phenolics content. Indole-3-acetic acid (IAA) and gibberellic acid (GA) levels were enhanced in plants treated with PGPR and biofertilizers. Specifically, P. chinense and the biostimulant significantly promoted IAA content in cv. William-82, while biozote and P. chinense treatments increased GA content in both varieties. The consortium of P. chinense and P. putida showed the lowest ABA levels. The highest IAA/ABA and GA/ABA ratios were observed in plants treated with P. chinense. Liquid bioinoculants had a more pronounced effect on plant growth than carrier-based biofertilizers, though biofertilizers had stronger residual effects on rhizosphere soil organic matter. The combined effects of phytohormones, sugar, protein and proline production and antioxidant enzyme activity influenced plant growth and development.

Characteristic of epicotyl dormancy and its hormonal regulation in Chinese cork oak (Quercus variabilis)

Emergence heterogeneity caused by epicotyl dormancy contributes to variations in seedling quality during large-scale breeding. However, the mechanism of epicotyl dormancy release remains obscure. We first categorized the emergence stages of Chinese cork oak (Quercus variabilis) using the BBCH-scale. Subsequently, we identified the key stage of the epicotyl dormancy process. Our findings indicated that cold stratification significantly released epicotyl dormancy by increasing the levels of gibberellic acid 3 (GA3) and GA4. Genes associated with GA biosynthesis and signaling also exhibited altered expression patterns. Inhibition of GA biosynthesis by paclobutrazol (PAC) treatment severely inhibited emergence, with no effect on seed germination. Different concentrations (50 μM, 100 μM, and 200 μM) of GA3 and GA4+7 treatments of germinated seeds demonstrated that both can promote the emergence, with GA4 exhibiting a more pronounced effect. In conclusion, this study provides valuable insights into the characterization of epicotyl dormancy in Chinese cork oak and highlights the critical role of GA biosynthesis in seedling emergence. These findings serve as a basis for further investigations on epicotyl dormancy and advancing large-scale breeding techniques.

Effect of Different Growing Media and Varying Levels of Gibberellic Acid on Seed Germination and Vigour of Acid Lime (citrus aurantifolia swingle.) cv.Kagzi Lime

Effect of Different Growing Media and Varying Levels of Gibberellic Acid on Seed Germination and Vigour of Acid Lime (citrus aurantifolia swingle.) cv.Kagzi Lime

TaTPS11 enhances wheat cold resistance by regulating source-sink factor

The presence of sugar in plant tissue can lead to an increase in the osmotic pressure within cells, a decrease in the freezing point of plants, and protection against ice crystal damage to the tissue. Trehalose is closely related to sucrose, which comprises the largest proportion of sugar and has become a hot topic of research in recent years. Our previous studies have confirmed that a key trehalose synthesis gene, TaTPS11, from the cold-resistant winter wheat DM1, could enhance the cold resistance of plants by increasing sugar content. However, the underlying mechanism behind this phenomenon remains unclear. In this study, we cloned TaTPS11-6D, edited TaTPS11-6D using CRISPR/Cas9 technology and transformed ‘Fielder’ to obtain T2 generation plants. We screened out OE3-3 and OE8-7 lines with significantly higher cold resistance than that of ‘Fielder’ and Cri 4–3 edited lines with significantly lower cold resistance than that of ‘Fielder’. Low temperature storage limiting factors were measured for OE3-3, OE8-7 and Cri 4–3 treated at different temperatures.The results showed that TaTPS11-6D significantly increased the content of sugar in plants and the transfer of sugar from source to storage organs under cold conditions. The TaTPS11-6D significantly increased the levels of salicylic, jasmonic, and abscisic acids while also significantly decreasing the level of gibberellic acid. Our research improves the model of low temperature storage capacity limiting factor.

The apple MdGA2ox7 modulates the balance between growth and stress tolerance in an anthocyanin-dependent manner

Apple (Malus domestica Borkh.) is a widely cultivated fruit crop worldwide but often suffers from abiotic stresses such as salt and cold. Gibberellic acid (GA) plays a pivotal in controlling plant development, environmental adaptability, and secondary metabolism. The GA2-oxidase (GA2ox) is responsible for the deactivation of bioactive GA. In this study, seventeen GA2-oxidase genes were identified in the apple genome, and these members could be clustered into four clades based on phylogenetic relationships and conserved domain structures. MdGA2ox7 exhibited robust expression across various tissues, responded to cold and salt treatments, and was triggered in apple fruit peels via light-induced anthocyanin accumulation. Subcellular localization prediction and experiments confirmed that MdGA2ox7 was located in the cytoplasm. Overexpression of MdGA2ox7 in Arabidopsis caused a lower level of active GA and led to GA-deficient phenotypes, such as dwarfism and delayed flowering. MdGA2ox7 alleviated cold and salt stress damage in both Arabidopsis and apple in concert with melatonin (MT). Additionally, MdGA2ox7 enhanced anthocyanin biosynthesis in apple calli and activated genes involved in anthocyanin synthesis. These findings provide new insights into the functions of apple GA2ox in regulating development, stress tolerance, and secondary metabolism.

Enhancing Post-Harvest Resilience: Investigating the Synergistic Effects of Essential Oil Combinations on Biochemical Profiles in Botrytis cinerea-Infected Apples

This study explored the impact of essential oil combinations on Botrytis cinerea-infected apples, focusing on how these treatments affect the levels of amino acids, anthocyanins, organic acids, phenolic compounds, and hormones. We discovered significant differences in amino acid concentrations, particularly asparagine, serine, histidine, glycine, and arginine, between control and fungus-treated apples. Preventive measures notably increased anthocyanins like delphinidin-3-glycoside and peonidin-3-glycoside, while combinations such as thymol + fungus balanced anthocyanin profiles effectively. Organic acid and phenolic compound analyses showed that curative strategies generally increased concentrations, with the thymol + cineole + fungus treatment being especially effective. Hormonal analysis highlighted the benefits of preventive measures in raising indole-3-acetic acid and gibberellic acid levels, whereas curative treatments increased abscisic acid and salicylic acid concentrations. The combination of cineole and thymol with fungicide emerged as a potent strategy for enhancing phenolic content. These findings underscore the potential of specific essential oil combinations in improving the biochemical composition of B. cinerea-infected apples, offering new avenues for enhancing fruit quality and sustainability in the agriculture sector.

Unveiling growth-promoting attributes of peanut root endophyte Micromonospora sp.

In this study, 20 endophytic actinobacteria were isolated from different parts of peanut plants growing in cropland with low and high salt in West Bengal, India. The endophytes underwent a rigorous morphological, biochemical, and genetic screening process to evaluate their effectiveness in enhancing plant growth. About 20% of these isolates were identified as potential plant growth-promoting endophytic actinobacteria, which showed high 16S rRNA gene sequence similarity (up to 99-100%) with different species of Micromonospora. Among these isolates, Micromonospora sp. ASENR15 produced the highest levels of indole acetic acid (IAA) and gibberellic acid (GA), while Micromonospora sp. ASENL2, Micromonospora sp. ANENR4, and Micromonospora sp. ASENR12 produced the highest level of siderophore. Among these leaf and root endophytic Micromonospora, strain ANENR4 was tested for its plant growth-promoting attributes. ANENR4 can be transmitted into the roots of a healthy peanut plant, enhances growth, and colonize the roots in abundance, suggesting the potential agricultural significance of the strain. Moreover, the study is the first report of endophytic Micromonospora in peanuts with PGP effects. The outcomes of this study open avenues for further research on harnessing the benefits of this endophytic Micromonospora for optimizing plant growth in agriculture.

Brassinosteroid decreases cadmium accumulation via regulating gibberellic acid accumulation and Cd fixation capacity of root cell wall in rice (Oryza sativa)

The precise mechanism behind the association between plants' reactions to cadmium (Cd) stress and brassinosteroid (BR) remains unclear. In the current investigation, Cd stress quickly increased the endogenous BR concentration in the rice roots. Exogenous BR also increased the hemicellulose level in the root cell wall, which in turn increased its capacity to bind Cd. Simultaneously, the transcription level of genes responsible for root Cd absorption was decreased, including Natural Resistance-Associated Macrophage Protein 1/5 (OsNRAMP1/5) and a major facilitator superfamily gene called OsCd1. Ultimately, the increased expression of Heavy Metal ATPase 3 (OsHMA3) and the decreased expression of OsHMA2, which was in charge of separating Cd into vacuoles and translocating Cd to the shoots, respectively, led to a decrease in the amount of Cd that accumulated in the rice shoots. In contrast, transgenic rice lines overexpressing OsGSK2 (a negative regulator in BR signaling) accumulated more Cd, while OsGSK2 RNA interference (RNAi) rice line accumulated less Cd. Furthermore, BR increased endogenous Gibberellic acid (GA) level, and applying GA could replicate its alleviative effect. Taken together, BR decreased Cd accumulation in rice by mediating the cell wall’s fixation capacity to Cd, which might relied on the buildup of the GA.

ELONGATED HYPOCOTYL 5a modulates FLOWERING LOCUS T2 and gibberellin levels to control dormancy and bud break in poplar.

Photoperiod is a crucial environmental cue for phenological responses, including growth cessation and winter dormancy in perennial woody plants. Two regulatory modules within the photoperiod pathway explain bud dormancy induction in poplar (Populus spp.): the circadian oscillator LATE ELONGATED HYPOCOTYL 2 (LHY2) and GIGANTEA-like genes (GIs) both regulate the key target for winter dormancy induction FLOWERING LOCUS T2 (FT2). However, modification of LHY2 and GIs cannot completely prevent growth cessation and bud set under short-day (SD) conditions, indicating that additional regulatory modules are likely involved. We identified PtoHY5a, an orthologs of the photomorphogenesis regulatory factor ELONGATED HYPOCOTYL 5 (HY5) in poplar (Populus tomentosa), that directly activates PtoFT2 expression and represses the circadian oscillation of LHY2, indirectly activating PtoFT2 expression. Thus, PtoHY5a suppresses SD-induced growth cessation and bud set. Accordingly, PtoHY5a knockout facilitates dormancy induction. PtoHY5a also inhibits bud-break in poplar by controlling gibberellic acid (GA) levels in apical buds. Additionally, PtoHY5a regulates the photoperiodic control of seasonal growth downstream of phytochrome PHYB2. Thus, PtoHY5a modulates seasonal growth in poplar by regulating the PtoPHYB2-PtoHY5a-PtoFT2 module to determine the onset of winter dormancy, and by fine-tuning GA levels to control bud-break.

Physiological Mechanisms Underlying Tassel Symptom Formation in Maize Infected with Sporisorium reilianum.

Head smut is a soil-borne fungal disease caused by Sporisorium reilianum that infects maize tassels and ears. This disease poses a tremendous threat to global maize production. A previous study found markedly different and stably heritable tassel symptoms in some maize inbred lines with Sipingtou blood after infection with S. reilianum. In the present study, 55 maize inbred lines with Sipingtou blood were inoculated with S. reilianum and classified into three tassel symptom types (A, B, and C). Three maize inbred lines representing these classes (Huangzao4, Jing7, and Chang7-2, respectively) were used as test materials to investigate the physiological mechanisms of tassel formation in infected plants. Changes in enzyme activity, hormone content, and protein expression were analyzed in all three lines after infection and in control plants. The activities of peroxidase (POD), superoxide dismutase (SOD), and phenylalanine-ammonia-lyase (PAL) were increased in the three typical inbred lines after inoculation. POD and SOD activities showed similar trends between lines, with the increase percentage peaking at the V12 stage (POD: 57.06%, 63.19%, and 70.28% increases in Huangzao4, Jing7, and Chang7-2, respectively; SOD: 27.01%, 29.62%, and 47.07% in Huangzao4, Jing7, and Chang7-2, respectively. These were all higher than in the disease-resistant inbred line Mo17 at the same growth stage); this stage was found to be key in tassel symptom formation. Levels of gibberellic acid (GA3), indole-3-acetic acid (IAA), and abscisic acid (ABA) were also altered in the three typical maize inbred lines after inoculation, with changes in GA3 and IAA contents tightly correlated with tassel symptoms after S. reilianum infection. The differentially expressed proteins A5H8G4, P09233, and Q8VXG7 were associated with changes in enzyme activity, whereas P49353, P13689, and P10979 were associated with changes in hormone contents. Fungal infection caused reactive oxygen species (ROS) and nitric oxide (NO) bursts in the three typical inbred lines. This ROS accumulation caused biofilm disruption and altered host signaling pathways, whereas NO signaling triggered strong secondary metabolic responses in the host and altered the activities of defense-related enzymes. These factors together resulted in the formation of varying tassel symptoms. Thus, interactions between S. reilianum and susceptible maize materials were influenced by a variety of signals, enzymes, hormones, and metabolic cycles, encompassing a very complex regulatory network. This study preliminarily identified the physiological mechanisms leading to differences in tassel symptoms, deepening our understanding of S. reilianum-maize interactions.

Effects of different levels of gibberellic acid and potassium nitrate solutions on the emergence and seedling vigor of amaranth and Cleome gynandra

AbstractThe effects of gibberellic acid and potassium nitrate on seed emergence and seedling growth of amaranth and Cleome gynandra were investigated in the greenhouse at Marondera University of Agricultural Sciences and Technology. The study was laid out in a factorial layout within a completely randomized design replicated three times. Potassium nitrate (dry seeds, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1%) and gibberellic acid (dry seeds, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 parts per million) were used, respectively. A total of 100 seeds of both crops were planted in each plastic pocket. Seed emergence percentage and vigor index of amaranth and C. gynandra were evaluated. The effects were more pronounced in seeds treated with gibberellic acid than in potassium nitrate. Seed emergence and vigor index of amaranth and C. gynandra seeds treated with gibberellic acid showed a significant difference at p < 0.01, while potassium nitrate showed no significant difference at p > 0.05. The maximum seed emergence percentage of amaranth and C. gynandra was 67.1% and 64.8%, which was obtained in 2022 and 2021, while the lowest was 35.5% and 37.5%, which was obtained in 2021. The highest vigor index I of amaranth and C. gynandrawas 590.3 and 586.2, which was observed in 2022 and 2021, while the lowest vigor index I was 45.2 and 170, which was obtained in 2021 and 2022. The results obtained indicated that the application of gibberellic acid on seeds of amaranth and C. gynandra can alleviate seed dormancy.

Response of Phosphorus, Sulphur and Foliar Spray of GA3 on Nutrient Content and Uptake of Soybean [Glycine max (L.) Merrill

Background: Soybean is an important oil seed crop grown in a varied range of climate and soils in India. Phosphorous and sulphur is an important macronutrient required for plants. Their deficiency in soil is a worldwide concern for production of oil seed crops. The gibberellic acid involved in plant growth and development. Therefore, investigation was carry out to study influenced of phosphorus, sulphur and gibberellic acid on nutrient content and uptake of soybean. Methods: An experiment conducted during kharif-2020 on soybean in sub-sub split plot design with three replications. The twenty four treatment combinations were comprised viz. four levels of phosphorus (Control, 20, 40 and 60 kg ha-1), three levels of sulphur (15, 30 and 45 kg ha-1) and two levels of gibberellic acid (Foliar spray of GA3 @ 75 ppm and no spray). Result: Results revealed that application of 40 kg phosphorus ha-1 and 30 kg sulphur ha-1 is optimum dose for obtaining higher available nitrogen, phosphorus, potassium and sulphur in the soil after crop harvest, nutrient content in seed and straw and uptake of soybean crop. The foliar spray of gibberellic acid @ 75 ppm is also beneficial for improving productivity and profitability of soybean crop.

Características do solo e morfofisiológicas de duas espécies de violeta (Viola sp.) influenciadas por ácido giberélico e nitrogênio

ABSTRACT Violet, with its pleasant scent and attractive flower color, is also important for its medicinal and edible uses, in addition to ornamental uses. Proper nutrition of the plant (violet) with essential nutrients and growth hormones improves the quantitative and qualitative characteristics and can increase the economic value and popularity of these flowers. In this regard, the current research aims to investigate the combined effect of nitrogen (N) and gibberellic acid (GA) on the morphophysiological traits of two native Iranian violet species (Viola tricolor and Viola odorata), as a factorial experiment with three factors including two species of violets, three levels of GA (0, 150 and 300 mg/L) and three levels of N (0, 100 and 200 mg/L) in a completely randomized design with 18 treatments, 3 replications and a total of 216 plants. Some characteristics of planting medium, morphophysiological traits and activity of antioxidant enzymes were evaluated. The results of ANOVA showed that the three-way effect of experimental treatments on all evaluated traits is significant. According to the results of comparing the averages the N application reduced the soil electrical conductivity (EC) versus its non-application in both violet species and at all GA levels. The highest soil N in both species was obtained from the application of 0 mg/L GA × 100 or 200 mg/L N. In two species of violets, the highest number of leaves, flowers, and stolons was obtained from the treatment of 300 mg/L GA × 200 mg/L N. The highest chlorophyll a and total chlorophyll among the treatments were related to V. odorata × 150 mg/L GA × 200 mg/L N. The application of GA and N in both species increased peroxidase activity versus the control. The highest level of this enzyme activity was related to 300 mg/L GA × 200 mg/L N. V. odorata had higher peroxidase activity than V. tricolor. The lowest and highest levels of catalase activity were recorded by control × V. tricolor (0.13 nM/g FW/min) and V. odorata × 300 mg/L GA × 200 mg/L N (0.676 nM/g FW/min), respectively. According to the results, with the application of 300 or 150 mg/L GA × 200 mg/L N, the ornamental and edible properties of these two types of violets are improved, and their economic value and marketability are increased, and there will be a change in the sales market of these flowers.

Melatonin enhances waterlogging tolerance of field-grown cotton through quiescence adaptation and compensatory growth strategies

ContextWaterlogging stress inhibits plant growth and development, resulting in significant yield losses. Melatonin, a naturally occurring molecule in plants, has attracted attention in recent years for its potential role in aiding plants in response to abiotic stresses. However, it remains unclear whether melatonin can enhance cotton’s tolerance to waterlogging stress. MethodsTo fill this gap, field-grown cotton plants at early flowering were subjected to a 10-day waterlogging stress and were foliar sprayed with melatonin during waterlogging. The effects of melatonin on the endogenous melatonin concentration, plant biomass, and related physiological and molecular events, as well as the seedcotton yield and yield components, were evaluated over two consecutive years. ResultsIn waterlogged cotton without melatonin treatment (W), melatonin concentration increased by 10.2%, but it increased by 26.9% with melatonin treatment (W+M), compared to the non-waterlogged cotton (NW). Under waterlogging without the application of melatonin, there was a reduction of 27.1% in biological yield and 46.6% in seedcotton yield. However, these reductions were reduced to 21.8% and 39.0%, respectively, following melatonin application. Quantitative real-time PCR analysis revealed that melatonin up-regulated the melatonin biosynthesis genes GhSNAT1 and GhCOMT, as well as the gibberellin biosynthetic gene GhGA20ox1 by 2.1, 3.6 and 1.8 times, respectively, compared to non-waterlogged cotton. However, melatonin down-regulated the ABA synthesis gene GhNCED2, the H2O2 generation related gene GhRBOHC, and the glycolysis and fermentation gene GhADH2 by 61.9%, 65.0% and 40.0%, respectively. Additionally, melatonin increased the leaf chlorophyll content, photosynthetic rate, levels of auxin (IAA) and gibberellic acid (GA), as well as the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Conversely, melatonin reduced contents of hydrogen peroxide (H2O2), malonaldehyde (MDA) and ABA, as well as the activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), compared to waterlogging without application of melatonin. ConclusionsThese findings demonstrate that foliar application of melatonin effectively improved the waterlogging tolerance of field-grown cotton, leading to a reduction in yield loss by 16.5% under waterlogged conditions. This outcome was achieved by a series of physiological, biological and molecular adjustments involved in quiescence adaption and compensatory growth strategies. Therefore, melatonin plays a crucial role in enhancing waterlogging tolerance and mitigating yield loss in waterlogged cotton through these strategies.

Effects of Elevated Temperature on Pisum sativum Nodule Development: II-Phytohormonal Responses.

High temperature is one of the most important factors limiting legume productivity. We have previously shown the induction of senescence in the apical part of nodules of the pea SGE line, formed by Rhizobium leguminosarum bv. viciae strain 3841, when they were exposed to elevated temperature (28 °C). In this study, we analyzed the potential involvement of abscisic acid (ABA), ethylene, and gibberellins in apical senescence in pea nodules under elevated temperature. Immunolocalization revealed an increase in ABA and 1-aminocyclopropane-1-carboxylic acid (ACC, the precursor of ethylene biosynthesis) levels in cells of the nitrogen fixation zone in heat-stressed nodules in 1 day of exposure compared to heat-unstressed nodules. Both ABA and ethylene appear to be involved in the earliest responses of nodules to heat stress. A decrease in the gibberellic acid (GA3) level in heat-stressed nodules was observed. Exogenous GA3 treatment induced a delay in the degradation of the nitrogen fixation zone in heat-stressed nodules. At the same time, a decrease in the expression level of many genes associated with nodule senescence, heat shock, and defense responses in pea nodules treated with GA3 at an elevated temperature was detected. Therefore, apical senescence in heat-stressed nodules is regulated by phytohormones in a manner similar to natural senescence. Gibberellins can be considered as negative regulators, while ABA and ethylene can be considered positive regulators.

Transcription Factor and Zeatin Co-Regulate Mixed Catkin Differentiation of Chinese Chestnut (Castanea mollissima)

Castanea mollissima is an important monoecious fruit crop with high economic and ecological value in China. However, its yield is restricted by an imbalanced ratio of male and female flowers for chestnut production. To address this issue, we examined the morphology of bisexual flower organs, measured the levels of endogenous hormones in the flowers, profiled gene expression related to plant hormone biosynthesis and signaling pathways and transcription factors, and investigated the effects of exogenous jasmonic acid (JA) and zeatin (ZT) hormone application on flower development in C. mollissima ‘Tanqiao’. Morphological studies indicated that the development of male and female flowers can be divided into nine and eight stages, respectively. Male flowers contained higher levels of gibberellic acid (GA3) and abscisic acid (ABA) than female flowers, whereas female flowers had higher levels of JA and ZT. The analysis of the Kyoto encyclopedia of genes and genomes (KEGG) pathways revealed that the major significant enrichment pathways of differentially expressed genes (DEGs) consisted of plant hormone signal transduction and zeatin biosynthesis. Through time-series analyses, we screened 3 genes related to jasmonic acid biosynthesis and signal transduction and 21 genes related to zeatin biosynthesis and transduction. Among these genes, only the gene family LOG, related to zeatin biosynthesis, was highly expressed in female flowers. This result indicated that LOG may be the core gene hormone family involved in regulating female flower development. However, a weighted gene co-expression network analysis (WGCNA) suggested that IDD7 was the core gene involved in regulating female flower development. The results of exogenous hormone application indicated that zeatin could greatly increase the quantity of fertile female flowers, but JA was not significant. These findings demonstrated that zeatin and transcription factors were crucial regulators in the formation of female flowers in C. mollissima.

The Natural Alternatives: The Impact of Plant Extracts on Snowbush (Breynia disticha Forst.) Cuttings’ Morpho-Physiological and Biochemical Characteristics

The utilization of cuttings remains a prevalent method for vegetative propagation in various plant species. Synthetic rooting hormones have conventionally been employed to enhance the rooting process; however, their high cost and potential environmental risks have necessitated the exploration of natural alternative compounds. In this study, the efficacy of natural plant extracts (pure honey, aloe extract, willow extract, moringa extract, and cinnamon powder) and synthetic auxin derivatives (indole-3-butyric acid and α-naphthaleneacetic acid) at a concentration of 2000 ppm was compared for their influence on rooting and vegetative growth of snowbush (Breynia disticha) cuttings, a significant ornamental and medicinal shrub. Results demonstrated that while the synthetic hormones produced the highest survival percentages and root number, the roots were consistently short, thick, friable, and largely void of secondary roots. Conversely, the alternative natural plant extracts, particularly aloe extract, exhibited promising outcomes, showcasing good rooting percentage and root number, significantly increased root length, and fresh and dry root weight. Furthermore, aloe extract demonstrated the potential to enhance shoot length and alter the chemical constituents of the cuttings. The highest values of total phenols and nitrogen percentage were recorded with cuttings treated with indole-3-butyric acid, followed by cuttings treated with aloe extract. While using aloe extract, we recorded the highest values of total carbohydrates, phosphorus, and potassium percentages. Notably, the highest endogenous levels of indole acetic acid and gibberellic acid, along with the lowest abscisic acid concentration in cutting tissues, were associated with the highest rooting percentage observed with indole-3-butyric acid, followed by the use of aloe extract. We hypothesized that natural plant extracts, specifically aloe extract, have potential as a viable alternative for synthetic auxins in promoting successful rooting and vegetative growth in snowbush cuttings. Further research is warranted to explore the underlying mechanisms and optimize the application of these natural compounds in vegetative propagation techniques.