Plant Growth Regulation最新文献

Phytohormones play crucial roles in fruit development and ripening. However, it is unclear the role of phytohormones in pear fruit quality, such as transverse and longitudinal diameters, fruit weight, soluble solid, titratable acid. In this study, four phytohormone treatments which included gibberellin (GA), Indole-3-acetic acid (IAA), abscisic acid (ABA), and ethylene (ETH) were performed to treat pear (Pyrus pyrifolia) fruit at different stages, including 30, 45, 60, 75 and 90 days after flower blooming (DAFB). As a result, exogenous GA treatment could promote fruit enlargement, reduce fruit firmness and inhibit the accumulation of titratable acid in ripening fruit (110DAFB). Both exogenous IAA and ABA treatments could also promote fruit enlargement. Moreover, both exogenous ABA and ETH treatment could promote the accumulation of soluble solids in 110DAFB, indicating the involvement of ABA and ETH in fruit ripening. Quantitative real-time PCR (qRT-PCR) analysis suggested that PbZEP1, PbNCED.B, PbSDR4 and PbAO3 are the crucial genes for ABA biosynthesis, PbACS1b and PbACO1 are crucial genes for ethylene biosynthesis in pear fruit. EMSA and Dual-luciferase assay suggested that PbABF.B and PbABF.C.2 directly bind to the promoter of PbACS1b, while PbABF.E.1 and PbABF.E.2 directly bind to the promoter of PbACO1 to enhance their activities. These results indicate that the four ABF proteins may be involved in ethylene biosynthesis during fruit ripening. Our study establishes the roles of GA, IAA, ABA and ethylene in pear fruit and finds the crosstalk between ABA and ETH during fruit ripening.

Main conclusion Freezing-tolerant Dendrobium catenatum cultivar responds to freezing stress by activating antioxidant enzyme systems and non-enzymatic systems including AsA and flavonoid biosynthetic pathways. Dendrobium catenatum (also named Dendrobium officinale) is a rare traditional Chinese medicinal plant, and has developed into 10 billion-grade industry by artificial breeding. Freezing stress is a devastating abiotic stress that hinders the growth and yield of D. catenatum. However, the cold response molecular mechanisms of D. catenatum are nearly unknown. Here, multi-omics including metabolomics, transcriptomics, and proteomics analyses were conducted under − 9 °C freezing stress using two varieties of D. catenatum, namely freezing-tolerant Jingpin Tianmushan (TMS) and freezing-sensitive Jingpin 6A2B (6A2B). TMS had significantly high levels of antioxidant enzymes including CAT, SOD, APX, and MDHAR, as well as high contents of the metabolites including quercetin, rutin, galacturonic acid, and ascorbic acid (AsA), compared to 6A2B. Rutin and AsA contents were positively related to the expression levels of the hub genes, including Dc4CL4/DcF3’H3 and DcGalUR1/DcGalUR2/DcGGP2/DcL-GalDH, which associate with freezing-responsive regulators comprising AP2/ERF, ARF, bHLH, bZIP, MYB, and ZF-HD members by co-expression network analysis. These results provide insights into the underlying freezing-tolerant molecular mechanism and promote freezing-resistant breeding of D. catenatum.

This opinion article offers a comprehensive analysis of recent developments in the exploration of endoplasmic reticulum (ER) stress signaling pathways and future opportunities for chemical mitigation strategies in plants. Encouraging results have been observed in the mitigation of ER stress in plants through the use of various chemical compounds commonly referred to as chemical chaperones; however, their mechanisms still require further exploration. The interconnectedness of stress responses is evident in the cross-talk between ER stress signaling and other stress signaling pathways. Additionally, the investigation of the role of ER stress signaling in plant defense and immunity has highlighted its significance in enhancing plant resistance. Looking ahead, future studies focusing on chemical mitigation of ER stress are positioned to provide valuable insights that can significantly expand our existing knowledge base. These advancements hold immense potential for enriching our understanding of ER stress signaling and facilitating the development of effective stress mitigation strategies in plants.

Currently, in agriculture, there is a tendency towards the partial replacement of chemical pesticides with microbiological plant protection products. In this work, we tested the ability of plant-growth promoting bacteria from the genus Azospirillum to reduce the negative effects of high concentrations of six different pesticides on wheat characteristics. Of the seven Azospirillum strains studied, five showed high resistance to at least one pesticide, and Niveispirillum irakense (formerly classified as Azospirillum until 2014) was one of the most resistant strains to all pesticides. In most cases, catalase activity increased in resistant strains in the presence of pesticides. Furthermore, we demonstrated that some of the most resistant Azospirillum strains (including N. irakense, A. brasilense, A. picis, A. thiophilum, and A. baldaniorum) can counteract pesticide-induced growth inhibition, suppress oxidative stress, as evidenced by a decrease in iron-induced chemiluminescence and the amount of oxidative damage to wheat seedling mtDNA in a pot experiment. However, the bacteria had no positive effect on the chlorophyll content of wheat seedlings. Azospirilla were found in the rhizosphere of wheat roots 3 months after a wheat planting in the field experiment. Pesticides led to a slight decrease in their quantity in the rhizosphere. Additionally, bacterial inoculation mitigated the pesticide-induced decrease in wheat biomass.

Chickpea (Cicer arietinum) establishes symbiotic relationships with several Mesorhizobium species and the three-way interaction between chickpea variety, Mesorhizobium strain, and environment, drives plant growth and nitrogen fixation. Here we quantified the phenotypic plasticity for shoot dry weight, nodule dry weight, nodules per plant, nodule colour, symbiotic effectiveness, and nitrogen cost in a factorial experiment combining five chickpea varieties, seven Mesorhizobium strains and three photothermal regimes. Plant growth and nitrogen fixation traits varied with variety, Mesorhizobium strain, photothermal environment and their interaction. Phenotypic plasticity was larger for nodules per plant (7.3-fold) than for shoot dry weight (2.7-fold), verifying a hierarchy of plasticities between these traits. Strain-driven plasticity of plant growth and nitrogen fixation traits was larger than variety-driven plasticity for our combination of varieties, strains, and photothermal environments, with strain-driven phenotypic plasticity being 2.7-fold vs 1.4-fold for shoot dry matter, 2.5-fold vs 1.7-fold for nodule dry weight, 7.3-fold vs 2.1-fold for nodules per plant, 3.7-fold vs 1.7-fold for nodule color, 2.9-fold vs 1.6-fold for symbiotic effectiveness, and 2.3-fold vs 1.6-fold for nitrogen cost. Our study provides insights on the phenotypic plasticity of the legume-rhizobia interaction by considering the plants as part of the rhizobia environment and vice-versa.

The loss of crop productivity due to soil salinity is an increasing threat to agriculture worldwide. Calcium (Ca²⁺) plays vital roles in salt-responsive signaling through the perception of various calcium-binding proteins, such as Ca²⁺-dependent lipid-binding proteins (CaLBs). Here, CaLBs from barley (Hordeum vulgare), a moderate salt-tolerant crop, and other green plants were selected for evolutionary and bioinformatics analysis. The emergence of the CaLB1 and C2 domains could be traced back to green algae, such as the chlorophyte alga Uronema belka (Uronemataceae). The physiological roles of HvCaLB1 in the salt-tolerant barley accession CM72 were investigated through gene silencing induced by barley stripe mosaic virus. Knockdown of HvCaLB1 significantly and differentially impaired the performance of plant growth, photosynthetic, and chlorophyll fluorescence parameters under the treatments of 200 and 400 mM NaCl. Moreover, the knockdown of HvCaLB1 disrupted the homeostasis of essential elements, particularly in the significant decrease of root potassium (K⁺) and Ca²⁺ contents in HvCaLB1 silencing plants compared to the control plants in response to salt stress. Significantly increased accumulation of reactive oxygen species (ROS), reduced cytosolic Ca²⁺ levels, as well as the decreased expression of HvHVP10 (Vacuolar H⁺-pyrophosphatase 10) and HvCaM1 (Calmodulin 1), were observed in the roots of the HvCaLB1-silencing plants subjected to 400 mM NaCl treatment compared to those of control plants. Taken together, CaLBs represent an ancient group of Ca²⁺-binding domain-containing proteins, and HvCaLB1 regulates NaCl-induced ion, ROS homeostasis, and gene expression in barley roots, demonstrating the potential application of CaLBs for crop improvement with increased tolerance to salt stress.

Nitrogen is a critical macro-nutrient for growth and development of soybeans (Glycine max L.). Improving nitrogen use efficiency and developing low nitrogen tolerance varieties are important approaches to mitigate excessive fertilization and maximize production benefits. Precise identification of low nitrogen tolerance germplasms serves as a crucial bridge for converting germplasm advantages into breeding advantages. In this study, we optimized a precise evaluation method for low-nitrogen tolerance in soybean seedlings based on Extreme Gradient Boosting (XGBoost) algorithm. Three hundred soybean germplasms were assessed for low-nitrogen tolerance under hydroponic conditions with normal (7.5 mM) and low (0.75 mM) nitrogen levels. Fourteen physiological traits related to low nitrogen tolerance, such as biomass, chlorophyll fluorescence, were measured. The XGBoost-based evaluation method was compared to a traditional fuzzy membership function comprehensive evaluation method for accuracy and applicability. Results showed that the XGBoost-based method ensured precision and reduced the number of determined physiological indicators compared to traditional methods. Furthermore, this approach reduces the number of traits required for precise identification, which reduces time and improves economic benefits. Consequently, the screening efficiency of soybean low nitrogen tolerance germplasms is improved, offering valuable insights for soybean breeding programs.

The model showcases the capability of phytoremediation to address environmental pollution by utilizing particular plant species to reduce harmful contaminants in soil, water, and air, promoting sustainable agriculture.

Base on atmosphere CO₂ concentration increases and Cd pollution stress, the response mechanism of rice to environmental change was studied. To explore the changes of endogenous hormones and organic acids in rice roots under high CO₂ and Cd stress, which provide the theoretical basis for future rice production under the double environmental impacts of atmospheric CO₂ changes and Cd stress. Rice seedlings (Oryza sativa L., “Beijing No. 2”) were treated from two-leaf stage, with two CO₂ concentrations (400 ± 20 μmol/mol and 800 ± 20 μmol/mol, controlled by an artificial climate chamber) and/or three CdCl₂ concentrations (0, 50, 150 μmol/L) for 7 days. The growth parameters of rice seedlings were measured. The root endogenous hormones and organic acids contents were determined by high-performance liquid chromatography (HPLC). Results:(1) Increased CO₂ concentration promoted the accumulation of aboveground dry weight by 45.6%. The IAA (Indole-3-acetic acid), GA₃ (Gibberellins A3) and ZT (Zeatin) contents increased by 15.7%, 1.6% and 26.7%. Citric and fumaric acid contents in roots increased11.7 and 19.8 fold, malic acid secreted from roots decreased by 23.4%. (2) The growth was inhibited under Cd stress alone, including the fresh weight and dry weight of the aboveground part decreased by 48.5% and 15.4%, respectively. The IAA, GA₃, ZT, ABA (Abscisic acid), SA (Salicylic acid) and JA (Jasmonic acid) contents increased in roots. The large accumulation of malic acid, lactic acid and citric acid under Cd stress. Tartaric acid content increased 87.5% in roots. (3) Compared with Cd stress, under high CO₂ and Cd stress, IAA, ZT and GA₃ contents and endogenous hormones ratios significantly increased, and root length and biomass of rice increased (29.9%, 34.1% under high CO₂ concentration and heavy Cd stress). The total organic acids secretions decreased. In conclusion, Cd stress inhibited the rice growth, the more produced (such as SA, JA and ABA) and the secreted (as Cd chelation agents) by roots were involved in the defense mechanisms and produced a detoxification mechanism; High CO₂ promoted the root growth and resistance to Cd stress by changing hormones and organic acids contents.

Cinnamomum burmannii, a medicinal plant with a history of traditional use in Chinese folk medicine, utilizes various plant parts, including bark, root bark, leaves, and stems, for therapeutic purposes. Recent investigations into the essential oil extracted from the twigs and leaves of C. burmannii have revealed a notable abundance of volatile monoterpenes, especially D-borneol, α-pinene, and camphene. In this study, an extensive chemical profiling on the essential oil of the roots, stems, and leaves of C. burmannii was conducted. The analysis results indicated that the root and leaf components exhibit the most diverse and the most abundant of volatile monoterpenes, respectively. To elucidate the biosynthesis of monoterpenes in C. burmannii, candidate genes with monoterpene synthase activities were identified through transcriptome sequencing. Subsequently, function characterization on three mono-terpene synthases (TPSs), designated as CbTPS1, CbTPS2, and CbTPS3, were conducted using phylogenetic analysis and heterogeneous expression in Escherichia coli. The primary enzymatic products were identified as 3-carene, α-phellandrene, and bornyl diphosphate (BPP), respectively. Additionally, a confocal laser microscopy assay suggested the chloroplast localization of these mono-TPSs through transient expression in tobacco. Further validation of their functionality was confirmed through eukaryotic expression in tobacco. In conclusion, this study has unveiled critical enzymes responsible for the biosynthesis of major monoterpenes in C. burmannii. These findings provide essential elements for future studies in synthetic biology, facilitating a deep understanding of the biosynthetic pathways and potential applications in medicinal plant engineering.