Journal of Plant Growth Regulation最新文献

In the past few decades, Cadmium-contaminated soil in agricultural fields has been a major global issue. The wide attention followed in agricultural production and the remediation of cadmium pollution in soil by cotton plants, due to the characteristics of wide planting area, the large biomass, strong capacity of cadmium accumulation, and non-edible properties of fiber. But the root secretion mechanism of cotton plants in response to cadmium threat is still unclear. In this study, four CdCl₂ concentrations (0, 150, 300,450 μmol/L) were applied to the soil at seedling stage, and physiological indicators of cotton seedling were detected and root exudates were collected after 10 days of cadmium exposure. The results showed that the cadmium tolerance of cotton seedlings was activated to the greatest extent under 300 μmol/L cadmium, and inhibited when the concentration reached 400 μmol/L. A total of 407 metabolites were detected based on UPLC-MS/MS. The composition and content of root exudates of cotton seedlings were significantly changed by cadmium stress, and there were 7 common differential accumulated metabolites, including isomaltulose, quinic acid, citric acid, γ-aminobutyric acid, isomaltulose, galactinol and gluconic acid. KEGG analysis showed that there were 7 metabolic pathways highly related to cadmium stress, including pyruvate metabolism, glyoxylate and dicarboxylate metabolism, citrate cycle, galactose metabolism, starch and sucrose metabolism, ABC transporters and carbon metabolism. These metabolic pathways were involved in osmoregulation, energy supply and resilience in plants. In addition, exogenous addition of citric acid can enhance the antioxidant capacity of cotton leaves, and promote the absorption and accumulation of cadmium in cotton. This study provides a theoretical basis for further research on elucidating the response mechanism of root exudates in cotton plants to cadmium stress and for utilizing root exudates such as citric acid to alleviate cadmium stress.

Sugarcane (Saccharum officinarum L.) is a heat-originated plant and it is valuable to investigate the adaptive mechanism of photosynthesis to low temperature. Here, we explored the photosynthetic properties at leaf and chloroplast level in Guitang 11 (GT11), Guitang 28 (GT28), Guitang 21 (GT21), and Xintaitang 22 (ROC22), which with different cold tolerance, and mesophyll (M), and bundle sheath (BS) chloroplasts of cold-sensitive variety ROC22 for metabolomics analysis at molecular level. The findings revealed that at leaf level, the net photosynthetic rate (P_n) was significantly reduced by low temperature, with the largest decrease in ROC22, and P_n was affected through a combination of stomatal and non-stomatal. The maximum photochemical efficiency of PSII (F_v/F_m) and PSI (P_m), and electron transfer rate (ETR) of sugarcane leaves were greatly decreased under chilling stress. At chloroplast level, the F_v/F_m of M and BS chloroplasts decreased significantly after low temperature. Metabolomics results showed that due to cold stress, there were 279 and 181 up-regulated and 314 and 252 down-regulated of differential metabolites of M and BS chloroplasts in ROC22, respectively. KEGG pathway analysis showed that biosynthesis of unsaturated fatty acids, purine, porphyrin and chlorophyll metabolism were enhanced in M and BS chloroplasts after low temperature. The xanthophyll cycle and ABC transporters were strengthened in M chloroplasts, while carotenoid biosynthesis was strengthened and ABC transporters was weakened in BS chloroplasts. These showed that M and BS chloroplasts respond structurally and functionally to chilling stress.

Abscisic acid (ABA) has been well known to strongly improve plant tolerance to heavy metals. However, the comprehensive mechanism of alleviating cadmium (Cd) stress in different plant organ was not been fully elucidated. In this study, foliar spray of 10 μM ABA significantly (p < 0.05) improved the plant height, root length, and the number of lateral roots, and reduced Cd accumulation and effectively restored the mineral contents caused by Cd induced change in leaves, stems, and roots of mung bean seedlings. Transcriptome analysis revealed that a total of 2241 differentially expressed genes (DEGs) (|fold-change|≥ 2.0 and FDR ≤ 0.05) were identified in the ABA + Cd-treated mung bean seedlings compared to the Cd-treated group, with 898, 908, and 859 DEGs identified in leaves, stems, and roots, respectively. Foliar application of ABA predominantly affected the KEGG pathways including phenylpropanoid biosynthesis, alpha-linolenic acid metabolism, starch and sucrose metabolism, and cyanoamino acid metabolism, and regulated the genes related to lipid metabolism, cell wall processes, secondary metabolism, defense and stress responses, hormone signal transduction, photosynthesis, and cell division to mitigate Cd toxicity of the mung bean seedlings. However, ABA exerted distinct effects on the gene profiles of leaves, stems, and roots under Cd stress. Interestingly, although exogenous ABA was applied to the leaves, the genes involved in hormone signaling were found to be regulated primarily in roots on the first day and subsequently in stems and leaves at later stages, indicating that exogenous ABA participates in mitigating Cd toxicity through signal transduction. Notably, significant upregulation of transporter-related genes was observed mainly in leaves and stems, including ABC transporters, NRT1/PTR FAMILY protein encoding genes, and WAT1-related protein encoding genes, which may contribute to the transportation of the ABA, Cd, and nutriments. Furthermore, the expression of genes encoding crucial photosynthetic proteins exhibited significant upregulation or downregulation upon exogenous ABA treatment, implying that exogenous ABA also ameliorated Cd stress by modulating leaf photosynthetic activity. This study may contribute to understanding the molecular mechanism of ABA-alleviated Cd stress in mung bean and identifying a number of highly regulated genes that could potentially be used to improve plant tolerance to heavy metals.

An efficient transformation and regeneration system is prerequisite for gene functional studies in rice, the staple food crop of the Asian subcontinent. Despite the availability of a large number of rice transformation protocols, it is hard to find a simple and minimum input based, but fail-safe protocol that ensures zero number of escapes (or the non-transformants). The fear of obtaining an unpredictable percentage of escapes at the end of rice tissue culture prompts carrying out multiple batches of transformation which not only consumes costly resources and time but also burdens one with screening of a large number of tissue culture derived plants. In the present study, we have described a simple but fail-safe rice transformation protocol for functional validation of the genes by overexpression and CRISPR-Cas9 mediated gene knockout systems. By taking the advantage of high transformability of japonica rice tissues, we have also revealed that the present rice transformation protocol can be effectively employed to visualize protein localization in various subcellular compartments of rice root and callus tissues, an alternative to conventional tobacco/onion peel infiltration or protoplast transformation which are either time consuming or tricky. Additionally, the paper also discusses the importance of Southern blotting in gene overexpression studies, utility of non-conventional antibiotic selection approaches and significance of sgRNA designing for gene knockout studies in rice. Various troubleshooting advice are also being presented. Overall, the present protocol might serve as an excellent guide for functional validation of several genes present in the rice genome waiting to be explored.

Foliar application effects of jasmonic acid (JA) and zinc oxide nanoparticles (ZnO NPs) was examined to mitigate water stress consequences on the Iranian monogerm sugar beet cultivar of “Shokofa,” the most popular cultivar in Iran. The experiment was designed using a split-plot layout based on a Randomized Complete Block Design (RCBD) with four replications over two growing seasons (2021–2023). The main plot consisted of three irrigation levels [50%, 75%, and 100% of irrigation water requirement (IWR)], while the sub-plot contained foliar application treatments (Control, JA, and ZnO NPs). Integrated Biomarker Response version 2 (IBRv2) was calculated twice for the sugar beet plants grown under 75% and 50% IWR and sprayed with distilled water (control), JA, and ZnO NPs, with the “100% IWR + Control” treatment serving as the reference site. Foliar application of ZnO NPs and JA under the 50% IWR caused increases in beta-glycine, sugar content, and the activities of antioxidant enzymes. The IBRv2 values for the first round were similar (18.245, 18.575, and 19.549), while for the second round, the lowest value (20.330) was obtained for the “50% IWR + JA” treatment, suggesting that JA may have a stronger moderating effect during severe drought stress conditions compared to the “50% IWR + ZnO NPs” and “50% IWR + Control” treatments. These findings demonstrated that foliar application of both stimulators could improve root yield, provoke the antioxidant enzymes’ activities, and growth promotion of sugar beet under water stress condition.

Bacopa monnieri (L.) Wettst. (BM) is popular for its medicinal properties which have been attributed to its rich collection of secondary metabolites. Its bioactive phytoconstituents have been used in therapeutic formulations for several human diseases. The use of traditional methods for increasing plant biomass and improving metabolite composition has gained substantial impetus in the past few years. Thus, the primary objective of the present study was to examine the effect of three different species of arbuscular mycorrhizal fungi (Glomus deserticola, G. mosseae, and G. intradices) and three different types of organic fertilizers (vermiculite, cocopeat, and perlite), both individually and in combination on morphological characteristics, physiological responses, metabolic regulation and bacoside-A production of BM. The findings demonstrated substantial improvement (P < 0.05) in various traits when treated with bio and organic fertilizers. Notably, as compared to the control, combination of three Glomus species and three organic fertilizers improved shoot length (1.2-folds; 2.0-folds), root length (3-folds; 2.6-folds), chlorophyll content (1.5-folds; 1.8-folds) and antioxidant activity (1.1-folds; 1.1-folds). Furthermore, use of mixtures of fertilizers led to an augmentation in the levels of both primary and secondary metabolites including lipids, alkanes, fatty acids, sugars, and terpenes. This application also enhanced the composition of bacosides A3, bacopaside II, bacopaside X, and bacopasaponin C and overall production of bacoside-A (1.2-folds). The findings obtained from the use of bio and organic fertilization techniques on the growth parameters and bacoside levels were analyzed and can be used as a potential alternative approach for mitigating the reliance on chemical fertilizers for improved growth of BM.

The aim of this study was to investigate adventitious root formation in cuttings obtained from physiologically different old stock material. The ornamental cherry Prunus subhirtella ´Autumnalis´ was used for the experiment. We examined three stock plants, namely a physiologically mature stock plant (about 60 years old) and physiologically juvenile plants (21 years old), which were previously propagated by cuttings, semi-mature stock material and in vitro juvenile stock material. We also investigated the role of phytohormones in the induction phase of adventitious root (AR) formation depending on the physiological age of the stock plant and the time after cutting. High performance liquid chromatography coupled with mass spectrometry (HPLC–MS/MS) was used to identify and quantify the phytohormones. The difference in rooting and quality of the developed AR is observed between semi-mature stock and mature stock material. Cuttings from semi-mature plants rooted in 95.00% of cases, while cuttings from mature stock plants only rooted in 68.33%. The high concentration of strigolactones and jasmonic acid (JA) immediately after severance had an inhibitory effect on the development of adventitious roots, especially in cuttings of mature origin. The development of AR is positively influenced by the increase in indole-3-acetic acid (IAA) 4 h after cutting from the stock plant. Our results show that the formation of adventitious root formation depends on the concentration and ratio between different phytohormones.

Salt stress is one of the major environmental factors that limits crop productivity. To mount an effective response to cope with salt stress, plants rely on the salt overly sensitive (SOS) pathway. The SOS1, SOS2 and SOS3 proteins are crucial for the maintenance of ion homeostasis and the sos1 mutant is hypersensitive to salt stress. Trichoderma harzianum, a beneficial fungus, increases the tolerance of plants to abiotic stresses. We examined the effect of the Trichoderma strain on the performance of the salt overly sensitive (sos1) mutant of Arabidopsis under salt stress. Compared to the isogenic glabra1 (gl1) control seedlings, the fresh weight, chlorophyll fluorescence, photosynthetic pigment content and transcript level of genes involved in ROS scavenging were increased in Trichoderma-inoculated sos1 plants under 150 mM salt stress. Trichoderma also enhanced the accumulation of the osmolytes proline, alanine, as well as the sucrose and glucose in the salt-stressed sos1, but not gl1 mutants, and the accumulation of Na⁺ was restricted in the sos1 mutant. The beneficial effects of T. harzianum could be attributed to higher colonization rates of the sos1 mutant compared to the gl1 controls. In conclusion, these findings underscore that the Trichoderma strain activates stronger salt protective responses in the salt-sensitive sos1 mutant than in control gl1 plants. Therefore, the Trichoderma strain is a valuable tool to investigate how a beneficial endophyte can stimulate salt tolerance responses in the host to promote its performance under stress.

Maize is a versatile cereal underpinning global food security and industrial applications. Salinity impedes plant growth and productivity of crops by disrupting the ionic and osmotic balance and hormonal regulation. The present study aimed to examine the potential of plant growth-promoting rhizobacteria strains PM34 (B. aryabhattai) in mitigating salinity stress in maize. The selected rhizobacterium exhibited notable tolerance to NaCl, thriving in concentrations ranging from 0.5 to 1.5 M in LB medium. The efficient B. aryabhattai PM34 strain demonstrated siderophore production capabilities (55.64–50.46%), phosphate solubilization (24.42–21.23 µg.mL⁻¹), secretion of indole-3-acetic acid (81.29–58.31 µM.mL⁻¹) and 1-aminocyclopropane-1-carboxylate deaminase (2.12–1.08 µM/mg protein/h) and exopolysaccharides production (680–810 µg.mL⁻¹) at concentrations from 0 to 750 mM salt stress. PM34 inoculation significantly enhanced maize growth, including improvements in shoot length (19.88–50%), root length (16.32–44.84%), fresh weight (23.53–37.93%), dry weight (10–25.71%) and leaf area (20.25–40.91%) at salinity stress 0 to 300 mM in PM34 inoculated plants as compared to non-inoculated plants. PM34 inoculated plants showed increase in chlorophyll a (2.72–32.88%), b (10.09–86.36%), total chlorophyll (9.87–47.98%), and carotenoids (26.39–66.13%) content as compared to non-inoculated plants. Moreover, improvement in the activities of antioxidant enzymes superoxide dismutase (35.03–55.14%), peroxidase (60.94–22.86%), catalase (20.31–30.24%), ascorbate peroxidase (9.03–15.34%) and the accumulation of osmotic regulators proline (11.47–16.21%) and glycine betaine (10.12–20.25%), when compared to non-inoculated controls under salt stress conditions. Furthermore, maize augmented with halotolerant bacteria displayed reduction in electrolyte leakage (14.81–28.65%), malondialdehyde (20.92–37%), and sodium uptake (9.43–36.98%) when subjected to salt stress. These results contribute to the theoretical foundation and can be concluded that the inoculation of this PGPR can alleviate the adverse effects of salinity stress on maize.

Plant pathogens pose a significant threat to agricultural production due to their ability to cause diseases with substantial economic and environmental consequences. Effective management of plant pathogens is crucial for ensuring global food security and sustainability in agriculture. Biocontrol agents (BCAs) offer eco-friendly alternatives to conventional pesticides, harnessing the beneficial effects of symbiotic relationships between plants and microbes. BCAs operate through two primary mechanisms: biofertilization, where microorganisms enhance mineral availability, or by outcompeting the pathogens. The manipulation of plant microbiomes presents a promising avenue for achieving sustainable agriculture by improving nutrient uptake and disease resistance. This review comprehensively evaluates various strategies BCAs employ for plant pathogen management. These strategies encompass competition for resources and the production of antimicrobial compounds that inhibit pathogen growth. Additionally, BCAs modulate plant hormone levels, enhancing plant defence against pathogens and inducing systemic resistance mechanisms, priming plants for future pathogen attacks. Emerging techniques, such as the utilization of viruses and RNA interference, are explored for their potential to enhance BCA efficacy within integrated pest management frameworks. By leveraging viral pathogens and RNA molecules, BCAs can precisely target specific pathogens, reducing collateral damage to beneficial organisms. Implementing BCA-based pest management strategies diminishes the reliance on synthetic insecticides, mitigating ecological repercussions associated with chemical use. Integrated pest management practices fostered by BCAs promote long-term agricultural resilience, ensuring the robustness and efficiency of farming yields while minimizing environmental degradation.