Search Results (83)

Exogenous cytokinin supply is a crucial factor during the in vitro shoot multiplication of apples. Meta-topolin has been shown to cause improved multiplication rate, higher quality in vitro shoots with better rooting, and acclimatization ability than the widely used benzyl adenine. The effects of benzyl adenine and meta-topolin on mRNA transcription in in vitro shoots were analyzed by using mRNA-seq, bioinformatics analysis, GO annotation, and KEGG mapping. The present investigations revealed that there were about 6-fold more significantly up-, or down-regulated genes (DEGs) in shoots grown on the benzyl adenine-containing medium than in those grown on the meta-topolin-containing medium. DEG analyses showed that WRKYs, bHLH, and MYB were the most affected transcription factors after both cytokinin treatments, while the expression of MIKC-type MADS-box, ERF, and AP2 transcription factors changed only after benzyl adenine treatment. DEGs related to auxin transport and signaling, as well as auxin synthesis, were differently affected by the two cytokinins. The DEG encoding cytokinin hydroxylase-like protein and related to trans-zeatin biosynthesis was up-regulated only after benzyl adenine treatment. The DEG encoding gibberellin 20 oxidase 2-like was down-regulated after a benzyl adenine supply while it was up-regulated after a meta-topolin supply. Changes in the cytokinin–auxin balance and gibberellin biosynthesis in in vitro shoots may contribute to the morphological differences previously observed for the two cytokinins. Full article

Boron exerts regulatory control over various aspects of plant growth and morphogenesis, and the application of boron prior to anthesis has been recognized as a critical agronomic practice. However, the regulatory mechanisms by which boron influences fruit set and early ovary development in pear remain to be elucidated. In this study, boron application was used at three stages, including pre-flowering, full-flowering, and early fruiting in the ‘Kuerle Xiangli’ (Pyrus sinkiangensis Yu), with a focus on cell expansion and endogenous phytohormone. As a result, treatment with 0.3% boric acid significantly increased endogenous boron concentrations in both leaves and ovaries and enhanced ovary fresh weight as well as both longitudinal and transverse diameters. Histological analysis revealed pronounced cell expansion at 5, 10, and 15 days after pollination (DAP) following boron treatment. Furthermore, gibberellin and trans-zeatin concentrations at 5 and 10 DAP were significantly elevated, while the concentrations of abscisic acid and auxin were markedly reduced. Quantitative real-time PCR (qRT-PCR) analysis demonstrated that boron positively regulates the expression of auxin-related genes, like PbARFH, PbARFD and PbSAUR76-like. In the gibberellin signaling pathway, the expression PbGID1, PbGID1C-like and PbGID2 was activated to drive cell expansion with the boron application. In the abscisic acid signaling pathway, boron treatment induced downregulation of PbSRK2.4, PbABF2, and PbABF2-like in the ovary. Furthermore, boron treatment induced high expression of hormone signaling genes in cytokinin, brassinolide, jasmonic acid and salicylic acid signaling pathways. These findings provide insights into the mechanisms of cell expansion and hormonal changes by which boron modulates early ovary development, offering a basis for improving fruit quality through optimized boron application. Full article

Auxenochlorella pyrenoidosa, a promising edible bioresource, can be efficiently and safely cultivated using exogenous phytohormones to enhance its productivity. This study employed multi-omics analysis to systematically investigate the effects and mechanisms of exogenous trans-Zeatin (tZ) on the growth and metabolism of A. pyrenoidosa. Results demonstrated that 10 mg/L tZ significantly promoted algal growth, increasing biomass by 166 ± 3.35% at 72 hours (h), while concurrently elevating cellular soluble protein (SP), carbohydrate (CHO), and chlorophyll a (Chla) content. tZ also strengthened the antioxidant defense system, evidenced by reduced reactive oxygen species (ROS) levels, enhanced activities of antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)), upregulation of glutathione metabolism, and decreased lipid peroxidation product (malondialdehyde (MDA)). Furthermore, tZ activated key metabolic pathways, including nitrogen metabolism, photosynthetic carbon fixation, and porphyrin biosynthesis, leading to the accumulation of arginine and polyamines, etc. This study reveals that tZ promotes microalgal growth by coordinately regulating carbon–nitrogen metabolic networks and antioxidant systems, providing a theoretical foundation for phytohormone-augmented microalgae cultivation technologies. Full article

Arbuscular Mycorrhizal Fungi (AMF) can form symbiotic relationships with most plants. They can alleviate the toxic effects of heavy metals on plants. This study analyzed the effects of AMF (Diversispora versiformis, D.v.) on the physiological responses and root organic acid secretion of tomato (Solanum lycopersicum L.) under cadmium (Cd) stress, in order to elucidate how AMF enhance Cd tolerance. The results indicated that when the AMF inoculation rate of tomato seedlings ranged from 26.75% to 38.23%, the AMF treatment significantly promoted tomato growth. Cd significantly reduced the agronomic traits of tomato. However, AMF inoculation dramatically lowered the Cd level from 19.32 mg/kg to 11.54 mg/kg in tomato roots, and effectively reduced the negative effect of Cd toxicity on seedling growth. Cd stress also significantly reduced the chlorophyll fluorescence parameters, chlorophyll contents, and photosynthetic intensity parameters in seedling leaves, while the AMF treatment significantly increased these indicators. Under Cd stress, the AMF treatment significantly increased the activities of SOD, POD, and CAT, and reduced the levels of reactive oxygen species and the contents of osmotic regulatory substances in roots. Under Cd stress conditions, the AMF treatment also significantly increased the auxin level (57.24%) and reduced the abscisic acid level (18.19%), but had no significant effect on trans-zeatin riboside and gibberellin contents in roots. Cd stress markedly reduced the content of malic acid and succinic acid by 17.28% and 25.44%, respectively; however, after the AMF inoculation, these indicators only decreased by 2.47% and 2.63%, respectively. Under Cd stress, AMF could increase tomato roots’ antioxidant capacity to reduce ROS level, thereby alleviating the toxicity induced by ROS and maintaining reactive oxygen metabolism, enhancing the plant’s stress resistance. In summary, the AMF treatment enhances the osmotic regulation capacity and maintains the stability of cell membranes by reducing the levels of osmotic regulatory substances in roots. It also enhances the Cd tolerance of tomato plants by regulating the contents of root hormones and aerobic respiration metabolites, among other pathways. Therefore, inoculating plants with AMF is a prospective strategy for enhancing their adaptive capacity to Cd-polluted soils. Full article

Sedum alfredii is a cadmium (Cd) hyperaccumulator, but the regulatory mechanisms linking phytohormones and redox balance to Cd transporter expression remain unclear. In this study, we omitted external cadmium (Cd) stress to isolate and examine the interplay between phytohormone and reactive oxygen species (ROS) signaling. Exogenous treatments with abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA₃), trans-zeatin (t-Z), and H₂O₂ were combined with analyses of hormone levels, antioxidant enzyme activities, and transporter gene expression. Correlation and PLS-SEM analyses identified the CAT–H₂O₂ module as a key node: ABA and IAA enhanced CAT activity and alleviated ROS-mediated repression of transporters, while GA₃ and t-Z exerted opposite effects. Functional validation using an H₂O₂ scavenger revealed that the regulation of HMA3 and Nramp5 by ABA and t-Z is H₂O₂-dependent. In contrast, IAA modulates Nramp5 through a ROS-independent pathway, while the regulatory effects of GA₃ were negligible. Functional validation under Cd exposure suggests a model wherein HMA3 and Nramp5 act in a complementary manner to sequester and redistribute Cd in leaves, thereby supporting hyperaccumulation. These findings highlight hormone-specific ROS pathways as central to transporter regulation and provide mechanistic insights to improve phytoremediation efficiency. Full article

(1) Background: This study used the cold-tolerant cultivar “Daye No. 3” (DY) and the cold-sensitive cultivar “Longdong” (LD) as plant materials to study the metabolic changes in plant hormones in alfalfa (Medicago sativa L.) under cold stress. (2) Methods: The targeted quantitative detection of phytohormones in alfalfa was carried out by liquid chromatography–tandem mass spectrometry (LC-MS/MS) technology. Principal component analysis (PCA), orthogonal signal correction, and partial least squares discriminant analysis (OPLS-DA) were used to investigate sample classification and screen differential metabolites. (3) Results: The results showed that 17 differential metabolites were detected. Seven metabolites showed common changes in the two cultivars after low-temperature stress induction. The levels of tryptamine, N-jasmonoylisoleucine, trans-zeatin riboside, isopentenyladenine riboside, cis-zeatin riboside, and gibberellin A7 were decreased, while N6-isopentenyladenine levels increased. In addition, compared with the LD variety, DY had more metabolite changes in response to low-temperature stress. Abscisic acid and trans-zeatin were elevated, whereas IAA-alanine, dihydrozeatin riboside, and indole-3-carboxaldehyde showed reduced concentrations. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that differential plant hormones were more active in plant hormone signal transduction, zeatin biosynthesis, and tryptophan metabolism pathways. In addition, a total of 12 metabolites in these three pathways showed common changes under cold stress. (4) This study identified significant metabolomic differences between two alfalfa genotypes under stress. It highlighted key pathways and provided new insights into the metabolic changes of alfalfa under cold-stress conditions. Full article

Background/Objectives: Possessing red and white ecotypes, and utilized in traditional Guyanese medicine, Doliocarpus dentatus’ red ecotype is preferred locally for its purported superior therapeutic efficacy. Although therapeutic metabolites were detected in D. dentatus previously, phytohormones remain largely unexplored, until now. Cytokinins, phytohormones responsible for plant cell division, growth and differentiation, are gaining traction for their therapeutic potential in human health. This study screened and quantified endogenous cytokinins and correlated detected cytokinins with selected secondary metabolites. Methods: Liquid chromatography–mass spectrometry was used to acquire phytohormone and metabolite data. Bioinformatics tools were used to assess untargeted metabolomics datasets via statistical and pathway analyses, and chemical groupings of putative metabolites. Results: In total, 20 of the 35 phytohormones were detected and quantified in both ecotypes, with the red ecotype displaying higher free base and glucoside cytokinin concentrations and exhibited 6.2 times the total CK content when compared to the white ecotype. Pathway analysis revealed flavonoid and monoterpenoid biosynthesis in red and white ecotypes, respectively. Positive correlations between specific cytokinins and alkaloids, and between trans-Zeatin and isopentenyladenosine riboside with phenolic compounds were observed. Conclusions: These results suggest that the red ecotype’s elevated cytokinin levels coupled with flavonoid biosynthesis enrichment support its preference in Guyanese traditional medicine. Full article

Low phosphorus (P) stress impacts nitrogen (N) metabolism in soybeans. This study investigated the effects of exogenous cytokinin (Trans-Zeatin) on soybean N metabolism under low P stress by treating seeds with Trans-Zeatin and analyzing N accumulation, ¹⁵N abundance, nodule N fixation accumulation, nodule N fixation rate, nodule nitrogenase activity, soluble protein content, and free amino acid profiles. The results showed that exogenous cytokinin enhanced N accumulation in aboveground tissues, roots, and nodules, as well as nodule N fixation accumulation and fixation rate (from day 35 onward) under low P stress. Additionally, it promoted both acetylene reduction activity (ARA) and specific nitrogenase activity (SNA) in soybean nodules. By increasing the absorption of fertilizer-derived N, exogenous cytokinin alleviated the inhibitory effects of low P stress on the early growth and development of soybeans. Notably, under low P conditions, exogenous cytokinin significantly elevated the soluble protein content in nodules. However, the underlying mechanisms governing changes in free amino acid profiles require further investigation. This study provides a theoretical foundation for developing strategies to regulate soybean N metabolism under low P stress. Full article

Saccharina japonica (S. japonica) is a large-scale intertidal aquatic plant that exhibits characteristics such as rhizoid, holdfast, and blade differentiation. It demonstrates remarkable environmental adaptability. However, compared with higher plants, details about its phytohormone content, distribution, synthesis, and accumulation remain poorly understood. In this study, the phytohormone contents distribution and expression patterns of synthetic genes in different parts of S. japonica, including the rhizoid, petiole, basis, middle, and tip, were analyzed in detail by combining targeted metabolomics and transcriptomics analyses. A total of 20 phytohormones were detected in S. japonica, including auxin, abscisic acid (ABA), cytokinin (CTK), ethylene (ETH), gibberellin (GA), jasmonate acid (JA), and salicylic acid (SA), with significant site-differentiated accumulation. ABA and JA were significantly enriched in the tips (28.01 ng·g⁻¹ FW and 170.67 ng·g⁻¹ FW, respectively), whereas SA accumulated specifically only in the rhizoid. We also identified 12 phytohormones, such as gibberellin A1, methyl jasmonate, and trans-zeatin for the first time in S. japonica. Transcriptomic profiling revealed the tissue-specific expression of phytohormone biosynthesis genes, such as CYP735A (CTK synthesis), in the rhizoids and LOX/NCED (JA/ABA synthesis) in the tips. Key pathways, such as carotenoid biosynthesis and cysteine methionine metabolism, were found to be differentially enriched across tissues, aligning with hormone accumulation patterns. Additionally, an enrichment analysis of differentially expressed genes between various parts indicated that different parts of S. japonica performed distinct functions even though it does not have organ differentiation. This study is the first to uncover the distribution characteristics of phytohormones and their synthetic differences in different parts of S. japonica and elucidates how S. japonica achieves functional specialization through non-specific phytohormone regulation despite lacking organ differentiation, which provides an important theoretical basis for research on the developmental biology of macroalgae and their mechanisms of response to adversity. Full article

The plant hormones cytokinins are a class of heterogeneous active compounds that control multiple aspects of development and physiology. Among cytokinins, trans-zeatin (tZ), the most abundant cytokinin, has been extensively studied in relation to its effects on development, and it plays a key role in promoting cell differentiation. In analogy with tZ, here we demonstrate that dihydrozeatin (DHZ) controls (root) development by promoting cell differentiation. By means of pharmacological and genetic analysis, we demonstrate that DHZ is specifically and uniquely perceived by the histidine kinase (HK) receptor AHK3, and that this interaction is sufficient to promote cell differentiation in the root meristem via activation of the transcription factors ARABIDOPSIS RESPONSE REGULATOR 1, 12, and 11. We also show that DHZ and tZ activity might be conserved among plants. Our results support the idea that different types of cytokinins act via specific receptors to exert their roles and suggest new approaches to study their activity in differentiation. Full article

The enrichment of cadmium (Cd) is an important factor threatening crop growth and food safety. However, it is unclear whether exogenous selenium (Se) can simultaneously achieve Cd reduction and promote the growth of peppers. This study used Yuefeng 750 and Hongtianhu 101 as materials and investigated the interaction effects of different Se-Cd concentrations (Cd = 2 and 5 μM; Se = 0, 0.5, and 2 μM) on the uptake and transport of Cd and Se, resistance physiology, and growth and development of pepper seedlings in a hydroponic experiment. The organ Cd content was significantly increased in pepper seedlings, inhibiting their growth and aggravating their physiological stress under Cd application. However, the growth and photosynthetic capacity of peppers were promoted after Se application under Cd stress. The superoxide anion (O₂⁻), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and abscisic acid (ABA) contents and indole-3-acetic acid oxidase (IAAO) activity in the leaves showed a significantly progressive decline, while the proline (Pro), ascorbic acid (ASA), and trans zeatin riboside (ZR) contents showed a significant rising trend. Thus, the growth, development, and dry matter accumulation of peppers were enhanced by reducing Cd stress. Meanwhile, the application of exogenous Se significantly improved the accumulation of Se in seedlings. In addition, compared to Hongtianhu 101, the Yuefeng 750 cultivars had a greater Cd and Se enrichment capacity. The cultivation of Cd-excluding cultivars combined with exogenous Se addition can be used as a recommended solution to reduce Cd toxicity and achieve Cd reduction and Se enrichment in peppers under Cd pollution. Full article

The Panel on Climate Change has predicted an intensification of drought and heat waves. The aim of this study was to determine the physiological response of mandarin trees in a semi-arid area to the effects of a long period of irrigation with saline reclaimed water (RW) and freshwater (FW) in terms of leaf mineral constitution, free amino acids and phytohormone balance, and their influence on yield and fruit quality. Results showed that higher foliar levels of Cl⁻_, B, Li⁺, and Br⁻ were found in the RW treatment. In addition, fruit quality (juice content, soluble solid content, titratable acid, and maturity index) and yield (fruit weight and diameter) parameters and growth canopy were negatively affected by irrigation with RW. Regardless of the treatments, L-alanine (Ala) and proline were the most abundant amino acids, with Ala being described as a majority for the first time in the literature. Concretely, in FW, the total amino acid content was twice as high as the concentration in RW (51,359.46 and 23,833.31 ng g⁻¹, respectively). The most abundant hormones were 1-Aminocyclopropane-1-carboxylic acid and trans-zeatin in both treatments. The saline stress response would be reflected in the higher concentration of salicylic and abscisic acids in the leaves of RW trees. In view of the high correlations found in a simplified correlation matrix of (i) Ala with the canopy growth and (ii) the salicylic acid (SA) with most of the evaluated agrometabolic parameters, it can be concluded that the exogenous application of the Ala and SA would increase tree size and could mitigate the effects of salt stress, respectively. However, these treatments could be completed with the external application of ACC since this phytohormone presents the lowest parameter during treatment with RW. Full article

Propagation of hinoki cypress (Japanese cypress, Chamaecyparis obtusa, Cupressaceae) through adventitious bud multiplication was performed using leaf-segment explants from cutting plants of selected adult trees. Explants were successfully surface-sterilized (>90% asepsis) by agitating them in 2.5% (w/v available chlorine) sodium hypochlorite solution for 15 min and then rinsed with sterile distilled water. Explants approximately 2 cm long were cultured on plates containing medium supplemented with 6-benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid (2,4-D), 20 g/L sucrose, and 7 g/L agar. The cultures were kept at 25 ± 1 °C under a 16-h photoperiod with a photon flux density of approximately 65 µmol m⁻² s⁻¹. The optimal adventitious bud multiplication (31.5 buds per explant) was obtained on a medium supplemented with 10 µM BAP in combination with 1 µM 2,4-D. Proliferated adventitious buds were elongated better on medium supplemented with 1 µM trans-zeatin. The best rooting result (86%) was achieved on a rooting medium supplemented with 1 µM 3-indolebutyric acid in combination with 0.1 µM 1-naphthaleneacetic acid. However, rooting response varied according to genotypes. Clones related to the cultivar ‘Nangouhi’ (Na18, Na14 x Isa, Na14-14, Isa x Na14, and NaS) were easier to root than those derived from the cultivar ‘ShizuokaKenZairai’ (SKZ5 and SKZ8). Regenerated plantlets did not show morphological abnormalities and showed a high survival rate after acclimatization (>90%). Full article

Pinus yunnanensis Franch. is a common woodland species in the southwest of China. Its trunk frequently twists during growth, affecting timber quality. The explanation for the twisted-trunk formation is unknown. In this work, we examined the variety of endophytes and metabolites by comparing the straight and twisted trunk types of P. yunnanensis. The results showed that the twisted trunk had a distinct endosymbiont composition compared to the straight trunk. Pseudomonas and Craurococcus bacteria, as well as the fungus taxa Phaeosphaeria and Epichloë, spread significantly more in the twisted trunk compared to the straight trunk. However, there was less Dechloromonas in the twisted trunk. Metabolomic analysis revealed differences in metabolites in the straight and twisted trunks, which were associated with four metabolic pathways: beta-alanine metabolism, metabolism of Jasmonic acid and trans-Zeatin metabolism, linoleic acid metabolism, and pentose phosphate pathway. The compounds were linked to certain endophyte bacteria species. Our findings suggested that the twisted trunk was subjected to more stress than the straight trunk because of endosymbionts. Moreover, we speculated that hormone signal transduction and the absorption, transport, and utilization of phosphorus elements and their interaction with microorganisms may be closely connected to the formation of twists. This is the first study to characterize the microbiome and metabolome in the twisted trunks of P. yunnanensis, and the results enhance our understanding of the underlying causes of twisted-trunk formation in P. yunnanensis. Full article

The Mucuna macrocarpa Wall, a traditional Chinese medicinal plant, exhibits significant cultivation-dependent variations in the accumulation and yield of its medicinal components. Salicylic acid (SA) has demonstrated the potential to regulate plant growth, which can be strategically used to enhance medicinal yield, offering a promising approach for high-yield cultivation in medicinal plants. This study aimed to investigate the changes in the medicinal components of Mucuna macrocarpa seedlings (4 months old) at different concentrations of SA (0, 0.1, 0.5, 0.9, and 1.3 mM) in a pot experiment. The results indicate that SA significantly increased the basal diameter (BD) by 2.9% to 20.61% and the total biomass (TB) by 14.28% to 48.57%. Notably, SA treatments resulted in alterations in the endogenous hormone content, including indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellin A₃ (GA₃), and trans-zeatin-riboside (ZR), and the balance in leaves. SA regulated the content and balance of nitrogen (N), phosphorus (P), and potassium (K) in all organs, and K content and K: P in roots, stems, and leaves was significantly higher than that of the control under 0.9 mM SA treatment. Crucially, SA significantly enhanced the content of bioactive compounds. The total phenolic content (TPC) and total flavonoid content (TFC) in stems peaked at 0.9 mM (14.89 mg·g⁻¹ and 3.73 mg·g⁻¹, respectively), which were 11.87% and 11.68% higher than those in the control. Moreover, compared to the control, SA treatments increased total phenolic production by 20.00% to 61.45% and total flavonoid production by 3.89% to 90.56%. In addition, 0.9 mM SA was found to be more effective than other treatments for increasing total phenolic and d total flavonoid content. In summary, this study investigated the effect of SA as an eco-friendly elicitor to improve the total phenolic and total flavonoid production of Mucuna macrocarpa. Full article