Journal of Plant Growth Regulation最新文献

Licorice roots can release low-molecular-weight oxalic acid (OA). However, the allelopathic effects of OA on licorice are unknown. This study presents an investigation of the effects of exogenous OA treatment on licorice roots through transcriptomic and physiological analyses. Transcriptomic analysis demonstrated that following OA treatment, differentially expressed genes (DEGs) were primarily involved in the phenylpropanoid metabolism pathway. At 6 h, the expression levels of genes associated with this pathway, such as PAL, CHS, POD, cellulase, CPY, MYB, and bHLH, were upregulated. The metabolism of related metabolites, such as flavonoids and lignin, also increased. These findings suggest that the phenylpropanoid metabolism pathway may play a significant role in the response to OA treatment. In addition, the activities of GST, CAT, and POD markedly increased, whereas the content of H₂O₂ gradually decreased, indicating that OA can activate the antioxidant protective capabilities of licorice roots. These findings suggest that OA may enhance the antioxidant defense of licorice root, as well as the effectiveness of its flavonoid constituents (to a certain degree). Our findings provide valuable theoretical insight into the allelopathic effects of licorice roots.

Potassium sulfate (K₂SO₄) or 2,4-Epibrassinolide (EBL) mediated response to cadmium (Cd) stress in plants has been widely reported, but the joint effect both on plants in response to Cd stress remains obscure. Herein, our results showed the combined application of K₂SO₄ (10 mM) and EBL (0.2 μM) on tobacco plants under Cd stress (CdCl₂, 100 μM) relieved Cd toxicity by improving the activities of AOEs and reducing the contents of decreasing superoxide (H₂O₂ and O₂⁻) and cadmium ion. As a result, the synergetic application of K₂SO₄ and EBL protected the integrity of chloroplast, which ensured a normal process of photosynthesis without a significant decrease in photosynthetic pigment content. Additionally, the combined application of K₂SO₄ and EBL also inhibited the expression of the Cd transport-related gene NtNramp1 and enhanced the Cd efflux-related gene NtHMA2. Moreover, the combined treatment of EBL associated with K₂SO₄ also effectively reduced the Cd accumulation in tobacco leaves under Cd stress compared with the groups treated separately, which implied a potentially synergistic role of EBL and K₂SO₄ in alleviating Cd toxicity in tobacco plants. This study provides a theoretical reference for the further analysis of the molecular mechanism of K₂SO₄ and EBL in jointly mediating the response to heavy metals in plants.

Tulips are mainly asexually propagated by bulbs that are modified underground stems. Hormones, including auxin, play pivotal roles during plant development. In this study, we investigated the roles of the auxin receptor TRANSPORT INHIBITOR RESPONSE1 (TgTIR1) in tulip bulb growth. TgTIR1 promoter activity analysis showed that it is most abundant in fast growing tissues including hypocotyl, cotyledons, and lateral root in Arabidopsis. Expression of TgTIR1 in Arabidopsis activated lateral organ boundary domain (LBD) transcription factors to promote the outgrowth of axillary branches and lateral roots. TgTIR1 transgenic plants also exhibited increased primary root length, plant height and leaf width. Moreover, downregulation of endogenous TgTIR1 through virus-induced gene silencing (VIGS) inhibited the growth of tulip plants and daughter bulbs. Exogenous auxin promoted while the auxin transport inhibitor 1-N-naphthylphthalamic acid (NPA) repressed tulip daughter bulb growth. This study offered evidence that the auxin pathway was involved in lateral root initiation and tulip bulb growth.

The beneficial effects of endophytes on plant growth, development and yield are well known. Modulating plant growth-promoting substances and ameliorating biotic and abiotic stresses are some of the key mechanisms that are deployed by endophytes to facilitate host growth and defence. However, the understanding of the plant’s genome response to their presence is still limited. Therefore, this study provides an insight into the microbiome of B. juncea seeds as well as leaves, and its impact on plant growth and development. It also correlates their presence with the changes in plant. Removal of seed-borne culturable endophytes resulted in trade-off of accelerated growth with decreased biomass. 16S metagenomics revealed that bacterial endophyte diversity and density varied with stage of the plant. We found that 22 endophytic genera including Enterococcus, Halobacteroides, Planktothrix and Streptomyces were observed irrespective of Bavistin treatment and age of the plant. Removal of culturable endophytes also led to downregulation of crucial genes involved in growth, photosynthesis (Photosystem I assembly protein, Photosystem II reaction center protein and Rubisco), transport (nitrate transporter; NRT) and regulation of plant hormones (auxin homeostasis and signalling; CYP83A1) in B. juncea. To the best of our knowledge, this is the first report of the response of plant’ transcriptome to changes in endophyte composition indicating a strong possibility of host gene regulation by the endophytic partner. The exact mechanism of the same needs to be further explored.

Cold stress and fungal pathogens pose significant challenge to high-altitude agriculture, impeding plant growth and metabolism. Siderophore-producing plant growth-promoting (PGP) rhizobacteria offer a promising solution by enhancing iron uptake and engaging in pathogen biocontrol. The current research aims to investigate the potential of siderophore-producing psychrotrophic bacteria to manage fungal phytopathogens effectively for its possible application as a bio-inoculant. In our search for psychrotrophic PGP bacteria with biocontrol potential, we isolated 13 rhizobacterial morphotypes; among these, AMR01 showed excellent biofertilizer characteristics. Taxonomic analysis elucidated AMR01 as a potentially novel Pseudomonas species. At 10 °C, AMR01 produced 33.23% siderophore unit (PSU), increasing to 55.76 PSU through pH, NH₄NO₃, and iron concentration optimization. Furthermore, AMR01 exhibited other PGP attributes, including auxin and ammonia production (13.47 µg/ml and 25.08 mg/l), phosphate solubilization (295.1 µg/ml), nitrogen fixation, potassium solubilization, and hydrogen cyanide (HCN) production. Remarkably, AMR01 demonstrated biocontrol potential, inhibiting three phytopathogens. Seed bacterization with AMR01 enhanced the germination of fungus-infected seeds, as evidenced by increased root and shoot length, compared to uninoculated control, conferring protection against fungal infestation. Genome analysis identified genes involved in pyoverdine synthesis and PGP traits in AMR01. The biosynthetic gene cluster associated with siderophore, HCN, and NRPS further supported AMR01 as a potent biocontrol agent. This research underscores the capacity of a novel, Pseudomonas sp., to improve plant growth by aiding in nutrient uptake and protecting against phytopathogens. Physiological and genomic evidence supports the potential of AMR01 as a bio-inoculant for addressing fungal-induced diseases in crops grown in the Indian Himalayan region.

Hydroxyurea (HU) is a known suppressor of ribonucleotide reductase enzyme through enhanced hydrogen peroxide (H₂O₂) production, causing oxidative damage to DNA in plants. Kinetin (KI) has emerged as an important phytohormone in regulating development processes and antioxidant protection effects against environmental stresses. Therefore, this study aimed to investigate the potential and regulating mechanism of KI application on tolerance of Oryza sativa to HU-induced oxidative stress. Three-day-old rice seedlings were grown in 1/2 MS medium for seven days following different treatments: control, HU (1 mM), KI (40 nM), and HU + KI. The results showed that, compared to control, HU treatment significantly reduced the growth (e.g., dry weight and root length: 36% and 48%, respectively) and photosynthetic rate (e.g., Fv/Fm: 31%) and pigments (e.g., chlorophyll and carotenoid: 52% and 67%, respectively), by stimulating oxidative stress (e.g., H₂O₂) markers and malondialdehyde levels, causing DNA damage and G1/S (growth/synthesis) and G2/M (growth/mitotic) phase arrest on seven-day-old rice seedlings. Meanwhile, the follow-up treatment of KI to the HU stress plants enhanced the growth (14–31%) and photosynthetic (13–29%) parameters by regulating antioxidant enzyme (e.g., catalase, ascorbate peroxidase, peroxidase, and superoxide dismutase) activities as well as abscisic acid, salicylic acid, gibberellic acid, and indole-3-acetic acid hormone contents, coupled with a significant reduction in reactive oxygen species accumulation. Additionally, KI reduced the DNA damage in the plants exposed to HU stress by reducing the relative density of apurinic/apyrimidinic sites, as evidenced by both decrease and increase in transcriptional regulation of genes (e.g., ATM, ATR, PARP, RAD51A2, and RAD51C) involved in DNA damage response and cell cycle progression. Our findings indicate that exogenous application of KI to plants affected by oxidative stress improves the antioxidant defense system and phytohormone homeostasis as well as DNA damage response alleviating G1/S and G2/M arrest, contributing to enhancement of the rice seedling performance.

Humic substances (HS) have been defined as a potential plant biostimulant to improve crop yield in a sustainable and environmentally friendly way. Leonardite-suspension concentrate (SC) is a type of HS extracted from lignite that is currently employed to enhance various physiological aspects of plants. However, the different effects between both modes of SC application (root and foliar) are poorly understood, especially on photosynthesis performance. Therefore, this study aimed to investigate the influence of a leonardite-SC-based product (BLACKJAK®), on lettuce growth and photosynthesis efficiency, while comparing both methods of application. For this purpose, four root (R): R1 (0.20 mL/L), R2 (0.40 mL/L), R3 (0.60 mL/L), and R4 (0.80 mL/L), and four foliar: F1 (5.00 mL/L), F2 (7.50 mL/L), F3 (10.00 mL/L), and F4 (12.50 mL/L) BLACKJAK® doses were applied to lettuce plants. Related shoot and root growth parameters, photosynthetic efficiency, and sugar and starch content were assessed in lettuce plants. The results showed that BLACKJAK® improved shoot and root biomass, foliar area, and root length, especially at intermediate doses (R2, R3, F2, and F3), with R3 demonstrating the greatest growth increases. Similarly, the main photosynthetic parameters analyzed (net photosynthetic rate and Rubisco carboxylation efficiency), and the soluble sugars and starch content were improved by the same doses, with R3 showing the best photosynthetic performance. Hence, our study suggests that BLACKJAK® improves lettuce yield and photosynthetic efficiency, particularly with radicular application at R3.

Flowering time is critical for the regional adaptation, yield, and reproduction of crop plants. Tyrosine kinase-like (TKL) genes are protein kinases (PKs) that play important roles in various plant processes. However, the functions of only a few TKLs in controlling flowering time in plants have been characterized. As a genetic model system, Brachypodium distachyon has been widely used in the study of gramineous crop species. Here, we identified and characterized the function of the model plant Brachypodium (poaceae) tyrosine kinase-like kinase BdCTR1 in controlling flowering time. BdCTR1 mutation caused earlier flowering compared with wild-type (WT) plants. Transcriptomic analysis revealed 2261 differentially expressed genes (DEGs) related to the circadian rhythm, phytohormone signaling, and flavonoid biosynthesis pathways in Bdctr1 mutants compared with the wild type (WT). Quantitative reverse transcription–polymerase chain reaction (qRT–PCR) revealed that the expression levels of flowering-related genes, including FT, PPD1, CO, and FUL, and ET-related genes, including ETR, MKK, and ERF, were altered in Bdctr1 mutants compared with those in WT plants. Thus, our results show that BdCTR1 plays a role in controlling flowering time by regulating various signaling pathways and contribute to elucidating the molecular mechanisms of PKs in controlling plant flowering.

To adapt to a habitat, halophytes growing at the same saline–alkali levels develop their unique rhizosphere microbial communities, whereas same plant species growing at different saline–alkali levels have different rhizosphere microbial communities. Therefore, understanding the rhizosphere microbial community structure of halophytes in different saline–alkali soils can help explore the microbial diversity and functional potential of important soil microorganisms. In this study, rhizosphere soils of three typical halophytes, namely, Halocnemum strobilaceum, Phragmites communis, and Halostachys caspica, growing at severe, heavy, and moderate saline–alkali soils, respectively, were collected from southern Xinjiang. The community structure and physicochemical properties of fungal species in the total nine rhizosphere soils were investigated. Furthermore, the differences in the fungal community structure, diversity, and ecological functions were analyzed in terms of the extent of saline–alkali level and host plant specificity. Rhizosphere soils in the nine habitats had different physicochemical properties. In terms of host plant type, rhizosphere fungal species diversity and richness were the highest in P. communis, followed by H. caspica and H. strobilaceum. The fungal community diversity and richness followed the pattern of moderate > severe > heavy in different soil salinity and alkali types. Although the three host plants had similar rhizosphere fungal community structures under moderate and heavy saline–alkali conditions, these varied significantly under extremely severe saline–alkali conditions. In total, 315 species were identified across all samples, and they were affiliated with 12 phyla, 37 classes, 69 orders, 138 families, and 244 genera. The number of jointly owned ASVs was 189. In the nine habitats, Ascomycota and Basidiomycota were the dominant phyla, while Alternaria, Neocamarosporium, Filobasidium, and Acremonium were the common dominant genera. A prediction of fungal community functions revealed pathotroph-saprotroph-symbiotroph and saprotrophs to be dominant. At the same saline–alkali level, the functional clustering distance of fungal communities was closer. Factors such as soil organic matter (SOM), available nitrogen (AN), electronic conductivity (EC), and pH contributed to the distribution of microbial communities. This study revealed both similarities and distinctions in the composition of fungal communities within the rhizosphere soils of the three typical halophytes thriving in various saline–alkali habitats. At moderate and heavy saline–alkali levels, the fungal community structures were markedly influenced by the severity of salinity and alkalinity. In extremely severe saline–alkali soils, the host plant type significantly affected the fungal community structure. Ultimately, these findings lay a theoretical foundation for the improvement of soil a

As a perennial warm-season turfgrass species with great economic value, bermudagrass (Cynodon dactylon L.) simultaneously has three types of stems: shoot, stolon, and rhizome. However, molecular mechanisms underlying the specialization of the three types of stems remain poorly understood. In this study, the metabolome differences among the three types of stems were analyzed and compared through untargeted metabolomic profiling in combination with transcriptome-wide analyses of the genes participating in the metabolic pathways. A total of 949 metabolites were identified in the three stems, whereas 303, 473, and 330 metabolites were differentially accumulated between shoots and stolons, shoots and rhizomes, and stolons and rhizomes, respectively. Sugars and phenylpropanoids were two enriched categories of metabolites showing preferential accumulation in the three types of stems. Transcriptome and RT-qPCR analyses indicated that gene expression of key enzymes catalyzing the synthesis and transformation of sugars and phenylpropanoids, especially glucose-1-phosphate adenylyltransferase, starch synthase, and phenylalanine ammonia-lyase, were delicately regulated to maintain the sugar-starch and lignin-flavonoid homeostasis in the three stems. The results of this study not only expanded our understanding of metabolism regulation in bermudagrass, but also laid a foundation for molecular mechanism study of stem specialization in this glamorous plant species.