Journal of Plant Growth Regulation最新文献

An adequate provision of essential plant nutrients to cash crops such as potatoes not only ensures higher productivity and desired tuber quality but also promotes better development under unfavorable environments. The present trial was planned to investigate and understand the effects of various treatments of mineral fertilizers viz., nitrogen (N), phosphorus (P), and potassium (K) (NPK) in individual and combined forms on potato crops. Experimental treatments were comprised various combinations viz., control (no addition of any type of fertilizer); N = 150 kg ha⁻¹; P = 75 kg ha⁻¹; K = 225 kg ha⁻¹; NP = N + P; NK = N + K; PK = P + K; NPK = N + P + K in soil. The results indicated that different combinations of NPK fertilizer in individual and combined forms not only influence the growth attributes such as stem diameter (83.96%) and tuber yields (180.09%) but also enhance photosynthetic attributes by improving the total chlorophyll (135.63%), carotenoids contents (143.75%), and potato quality by increasing tuber starch contents (78.75%), plant sucrose contents (52.86%) and sucrose enzyme activity (69.68%). A linear decrease in the lipid per oxidation attributes was observed where a combined application of NPK was applied. It was obvious that all the yield and quality attributes were enhanced by the combined application of NPK fertilization and then decreased gradually with the individual application of NPK fertilization. In contrast, though, the P and K application in combined form showed inferior response as compared to NP and NK fertilization. A clear and significant change in potato plants was observed under the various types of treatments especially related to the content and uptake of NPK in plants. Moreover, a highly significant relationship was observed between the balanced combination of NPK fertilization with tuber quality. This study underscores the importance of balanced fertilization practices in bolstering growth, yield, tuber quality, and antioxidative defense mechanisms and mitigating oxidative damage in potato crops.

Drought stress is a major challenge for agriculture and horticulture, limiting crop growth and productivity. Melatonin, a naturally occurring hormone in plants, has been shown to have potential as a stress reliever and growth regulator. Nonetheless, limited research has perused the effect of melatonin on different morpho-physiological and biochemical parameters during prolonged drought stress and subsequent recovery in contrasting landraces. The study aimed to determine whether the exogenous application of melatonin to two contrasting landraces of fenugreek (Trigonella foenum-graecum L.) can improve drought adaptations through drought stress tolerance and/or drought recovery capability and to find the primary parameters associated with this likely improvement in superior treatments by examining photosynthetic pigment contents, chlorophyll fluorescence, gas exchange parameters, and plant growth and water relation indices. Our study revealed that the plants present different responses according to the intensity of drought stress (moderate and severe) and the time elapsed since re-watering (initial and full-recovery). Severe drought stress caused more damage to the drought-sensitive landrace (Shushtar), but at the same time, melatonin treatment was most effective in improving the performance of stressed plants in this landrace. Our findings further demonstrated that the melatonin function is landrace-specific. The drought tolerance response in sensitive landraces was associated with an increase in the chlorophyll content, improved chlorophyll fluorescence and carboxylation efficiency, and cellular membrane protection. This is the first study to report the advantage of melatonin in drought recovery capability, which was attained in tolerant landraces (Varamin) by a decrease in light reactions of photosynthesis and an improvement in dark reactions of photosynthesis and mitochondrial respiration.

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.