Journal of Plant Growth Regulation最新文献

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.

Kenaf (Hibiscus cannabinus L.) is an important fiber crop, which can be applied for the restoration of saline-alkali land. The objective of our study was to investigate the impacts of exogenous glutathione (GSH) on physiological and biochemical properties, ion balance, and DNA methylation of kenaf under salt stress. We used Hoagland nutrient solution containing 200 mM NaCl to simulate salt stress, and found the growth of kenaf seedlings was substantially hindered. 100 μM GSH pretreatment effectively increased the plant height, stem diameter, main root length, and fresh weight under salt stress, as well as reduced the uptake of Na⁺ and Cl⁻ and promoted the uptake of K⁺. Besides, exogenous GSH pretreatment protected kenaf plants from salt-induced adversities by reducing the ROS-induced oxidative damage, enhancing the contents of chlorophyll, proline, and soluble sugar. Salinity reduced the total DNA methylation level in kenaf genome, triggering higher mRNA expressions of HcGLP3, HcDOF1.4, HcULP3, HcVHA, HcPP2C39, and HcSRF6. However, GSH addition enhanced the total DNA methylation level. We further utilized virus-induced genes silencing technique to confirm that HcGLP3 played a positive role in the response of kenaf to salinity. Taken together, exogenous GSH could enhance salt tolerance in kenaf by mediating modulation of oxidative stress response and DNA methylation.

Graphical Abstract

Arbuscular Mycorrhizal (AM) fungi have substantial involvement in the existence of plants under heavy metal (HM)-stressed conditions. An overwhelming number of studies are there which advocate for the AM fungi as a future tool for remediation and revegetation of HM-polluted soils. One of the major complications associated with AM fungi facilitated phytoremediation is that the AM association is very much host as well as HM specific. Diverse strains of AM fungi behave differently with diverse hosts and HMs. AM fungi in association with host plants enhance the tolerance of HMs to the host. It enhances the absorption of nutrients in deficient soil, whereas it decreases the accumulation of HMs in polluted soils. AM fungi enhance the biomass production and, thus, dilute the HM concentration in plants. The association of AM fungi also protects the host roots from exposure of HMs by trapping them in the extracellular polymeric substances and the glomalin secreted by the AM fungal hyphae. The hyphal components also contain hydroxyl and carboxyl ligands that can bind the positively charged HMs and immobilize them outside the soil. In hyperaccumulator plants, AM fungi contribute differently as the transporters of HMs increase the uptake of HMs from the substrates. In this way, it enhances the accumulation of HMs beyond the permissible level. Inside the AM fungi as well as in the host cell, these HMs are either converted to the less toxic forms or conjugated with Metallothionein (MT), Glutathione (GSH), and Phytochelatin (PC) and safely stored in the vacuole. All these functions are specifically controlled by a number of transporters of HMs localized in the AM fungal hyphae, inside the AM fungi and inside the host cell. GintABC1 is one of the most studied transporters in AM fungi regulating the Zn. In this review, a deeper insight into the all-possible mechanisms of AM fungi facilitated HM stress alleviation in plants is summarized and discussed.

Microbial-mediated plant growth promotion is an eco-friendly and sustainable approach under unprecedented climatic conditions. Today, available beneficial microbes for plant growth promotion have some limitations such as required specific growth conditions, etc. However, a bacterium family Deinococci spp. identified has some extraordinary, radioresistance and desiccation tolerance capabilities, that can help it survive in extremely harsh conditions, irrespective of serious injury and unpredictable climatic conditions, making it special compared to other microbial bioagents. The present investigation demonstrated the plant growth-prompting potential of Deinoccci, in maize (Zea mays) and lentil (Lens culinaris) crops. The experiment was conducted both in in vitro (laboratory) and in vivo (glasshouse) conditions. The results indicate that different species of Deinococci exhibited varying responses in maize and lentil. For instance, the combined (seed bio-priming and soil pre-inoculation) application of D. radiodurans 38 in maize enhanced a significantly higher percentage of seed germination, maximum shoot (47.72 cm) and root (10.19 cm) length, fresh shoot (3.44 g) and root (0.39 g) weight, dry shoot (0.348 g) and root (0.095 g) weight, strong seedling vigor (5791.6) and R:S (0.214), while D. radiodurans R1 in lentil promote cent per cent seed germination, maximum shoot (24.3 cm) and root (7.94 cm) length, fresh shoot (0.40 g) and root (0.032 g) weight, dry shoot (0.085 g) and root (0.023 g) weight, strong seedling vigor (3028.6) and R:S (0.33) as compared to individual application. Overall, our findings suggested that the combined application of the Deinococci radiodurans 38 and R1 showed higher plant growth promotion in maize and lentil, respectively, as compared to other strains. This suggests that it could be potentially used as an efficient alternative to promote growth in maize and lentil crops for both seed germination and biomass development irrespective of unpredictable environmental conditions.

Although recent studies have reported stimulatory effect of trinexapac-ethyl (TE) on eucalyptus growth, there is no consensus regarding the best dose to promote this response. Since TE acts in the gibberellin (GA) biosynthesis pathway, the study of hormonal crosstalk between the leaves and the shoot apical bud (SAB) can provide important information for understanding the positive effect previously reported. We evaluate the TE dose–response curve for eucalyptus growth in different soil moisture conditions (well watered—WW and 40% of field capacity—40-FC) and its effects on plant physiology, as well as the hormonal crosstalk between the leaves and SAB. TE caused a 49% increase in WW eucalypt growth, but not to plants under 40-FC. Estimated dose for the greatest stimulatory effect on WW eucalypt plants is 202 g a.i. ha⁻¹. TE did not cause an increase in the plants' photosynthetic characteristics up to 15 days after application (DAA), suggesting a later increase in the eucalypt’s primary metabolism. Conversely to what have been reported for monocot crops, TE caused a fivefold increase in leaf GA₁ as a short-term effect (05 DAA), but significantly decreased SAB-GA₁ concentration. Leaf concentrations of indole-3-acetic acid, salicylic acid, abscisic acid and N⁶-isopentenyladenine also increased. TE caused changes in both 13-hydroxylated (GA₂₀, GA₁ and GA₈) and non-13-hydroxylated (GA₉, GA₄ and GA₃₄) GA metabolic pathways in an organ-specific manner. Our results provide information to support the use of this plant growth regulator in eucalyptus plantations, as well as insights into the hormonal crosstalk between leaves and SAB in response to TE.

Graphical Abstract

Zanthoxylum bungeanum (Zb), an economically important tree, is widely cultivated in China. However, its abundant and intricate thorns pose challenges in management and harvesting, thereby reducing its economic benefits. Although the origin and formation mechanism of stipule thorns in Zb remain unclear, it is hypothesized that thorn hardening may be associated with lignin synthesis and accumulation. In this study, we utilized histologic, transcriptomic, and metabolomic analysis methods with stipule thorns at five distinct developmental stages (25 days, 40 days, 55 days, 70 days, and 80 days after flowering) to investigate the mechanisms underlying lignin accumulation and synthesis. Our findings revealed that guaiacyl and syringyl lignin were present in the stipule thorns of Zb. Lignification occurs from the top to bottom and from the outside to inside. Through a weighted gene co-expression network analysis and construction of a gene regulation network, we identified 20 genes significantly involved in lignin synthesis and metabolism including 10 structural genes and 9 transcription factors such as MYB, bHLH, WRKY, and NAC. Notably, our target gene prediction results of hub genes indicated that four NAC genes play a critical role in lignin synthesis. Furthermore, we predicted a possible NAC-MYB model gene-regulatory network. This research provides novel insights into the synthesis of lignin in Zb, while offering a molecular foundation for breeding varieties of thornless or soft-thorned Zb.

Climate change poses a critical threat to global agriculture. Plant growth-promoting bacteria (PGPB) present a sustainable approach to increase climate resilience. The study focused on isolating and screening abiotic stress-resistant endophytic bacteria from the Arabian balsam tree (Commiphora gileadensis); these bacteria can lessen the phytotoxic impacts of heat, salinity, and drought stress. C. gileadensis is known for its resilience to diverse abiotic stresses and hosts a diverse array of PGPB. Isolated endophytic bacteria were evaluated for their growth-promoting activities, including phosphate and silicate solubilization and indole3-acetic acid production, and screened for tolerance to multiple abiotic stresses. Out of 20 distinct endophytic bacterial isolates exhibiting various plant growth-promoting (PGP) traits, the Staphylococcus epidermidis CK9 strain and the Bacillus australimaris CK11 strain demonstrated remarkable resilience to a range of abiotic stresses, including heat, salinity, and drought. Tomato inoculation with sole or a consortium of CK9 and CK11 under combined abiotic stresses led to significantly enhanced plant growth attributes and photosynthetic pigments (chlorophyll a, b and carotenoids), reduced Na⁺ uptake and maintained a high K⁺/Na⁺ ratio. Combined abiotic stress-induced oxidative stress (lipid peroxidation and superoxide anion) was significantly counteracted by the enhanced accumulation of antioxidant activities (catalase and peroxidase) and upregulated expression of Glutathione reductase and catalase (CAT) genes compared with noninoculated plants. Co-inoculation promoted phytohormones crosstalk by downregulating abscisic acid and jasmonic acid accumulation while stimulating salicylic acid accumulation under stress conditions. This hormonal crosstalk significantly induced abiotic stress-related heat shock protein (HSP) genes (HSP70 and HSP90) compared to noninoculated plants. This study provides valuable insights into the potential use of PGPB from C. gileadensis as a bioinoculant for enhancing tomato growth and yield under combined abiotic stress conditions. Future research will focus on the field assessment of this consortium in hot weather under saline- and drought-induced stresses to determine their effect on crop productivity.

This study aimed to investigate the impacts of the combined application of phosphorus (P) and zinc (Zn) on the root development and the rhizosphere soil environment of apple trees. A pot experiment was implemented with nine treatments, encompassing three P levels (0, 100, 200 mg kg⁻¹) and three Zn levels (0, 15, 30 mg kg⁻¹). The research focused on the effects of the combined application of P and Zn on root morphology, rhizosphere soil nutrients, soil enzyme activities, and the soil environment of M9-T337 apple rootstock seedlings. This was done to provide a scientific basis for the optimal application of P and Zn fertilizers in apple orchards. The results indicated that parameters such as the average root diameter, soil phosphatase activity, fractal dimension, total root length, total root volume, total root surface area, soil bacteria count, and catalase activity all increased first and then decreased as the zinc application rate increased. The highest values were observed in the P₂₀₀Zn₁₅ treatment. The number of root tips, total number of internal connections, root topological index, soil available Zn, available P, urease activity, actinomycetes count, fungi counts, and sucrase activity exhibited different trends with increasing Zn dosage, but the parameter values for each index were significantly higher than those of the control treatment. The synergistic application of P and Zn has notably influenced the root morphology and the rhizosphere soil environment of M9-T337 apple rootstock seedlings. The optimal effect was observed under the P₂₀₀Zn₁₅ treatment, demonstrating a synergistic interaction between P and Zn, thereby promoting root development and soil health. This improvement was manifested in the increased root diameter, enhanced soil phosphatase activity, expanded root length and volume, augmented root surface area, and heightened soil bacterial count and catalase activity. Moreover, the levels of available Zn, available P, and urease activity in the soil were elevated. Concurrently, the diversity of soil microbiota was also improved. These findings lay a solid foundation for maximizing the utility of P and Zn fertilizers in apple orchards, thus, aiding in the realization of sustainable agricultural practices and boosting apple production.

Sunflower (Helianthus annuus L.) capacity to synthesize and accumulate soluble carbohydrates that will ultimately contribute to grain filling, either via actual photosynthesis or previously stored reserves, has been largely neglected despite its relevance regarding crop yield. The present work is aimed at studying the effect of photoassimilate availability on the dynamics of production and distribution of soluble carbohydrates in the plant during vegetative and reproductive phases. Plant photoassimilate availability was modified from production crop level in two hybrids during two field experiments by shading or thinning plants, which resulted in a range of intercepted radiation between 20 and 300 MJ per plant and also by removal of the main sink, the capitulum. Plants under higher light availability developed larger leaves and accumulated much more biomass than shaded ones. In general, plant sugar storage increased up to flowering and was highest in the developing capitulum and upper stem internodes. Increasing light availability led to a strong growth promotion that was especially remarkable in the capitulum and stem upper internodes, which precluded an increase in sugar concentration in these parts. Capitulum removal led to sugar remobilization to the plant base, resulting in a strong growth promotion of roots, basal stem internodes, and even in leaves from the lower strata, showing an extremely high plasticity of all sunflower organs in response to photoassimilates. These results also suggest that sugars per se may drive plastic changes of organ size ultimately conditioning plant capacity to store sugars and crop yield.