Plant Growth Regulation最新文献

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.

To explain changes in plant growth, root architecture, and endogenous hormones of different root-type alfalfa to phosphorus (P) stress (non-stressed control, 1.00 mmol·L⁻¹ KH₂PO₄, versus P stress treatment, 0.01 mmol·L⁻¹ KH₂PO₄). We used the sand culture of rhizomatous-rooted Medicago sativa ‘Qingshui’ (QS), tap-rooted M. sativa ‘Longdong’ (LD), and creeping-rooted M. varia ‘Gongnong No. 4’ (GN) to study the performance with contrasting degrees of P tolerance. After 34 days of P stress treatment, values for plant height, leaf area, specific root length, specific surface area, zeatin (ZT) level, and P content were decreased in response to stress treatment. In contrast, the contents of indole-3-acetic acid (IAA), abscisic acid (ABA), and gibberellin (GA₃), as well as the root/shoot ratio, total root length, taproot length, root angle, and the number of root tips and lateral roots, increased in the year and next year, respectively. The topological index and fractal dimension (FD) were small, while the fractal abundance (FA) and the average link length were large. The root branching patterns were dichotomous branching. The amplitude of this response of plant biomass, plant height, leaf length, leaf area, root/shoot ratio, total root length, number of root tips, root angle, specific surface area, and FD in GN of the year and next year was much smaller than those in LD and QS under low-P stress. From the point of view, GN was more tolerant than LD and QS under P condition.

The main objective of this study was to test how two chemically synthesized selenium (Se) and manganese (Mn) nanocomposites (NCs) based on the water-soluble polysaccharide arabinogalactan (AG) would separately and together affect the phytopathogenic bacterium Pectobacterium carotovorum and microbiome of soybean (Glycine max (L.) Merr.) seedlings, as well as their resistance to the infection caused by P. carotovorum. After nanopriming, seed germination, biometric traits (mass and length of the root and hypocotyl) and biochemical parameters (content of reactive oxygen species, activity of antioxidant enzymes, amount of lipid peroxidation products) of soybean seedlings were analyzed. It was shown that treatment with NCs increased germination rate of seeds infected by P. carotovorum by 50%. In addition, all biometric traits of these seedlings were improved compared to the control. A significant increase in diene conjugates (DC) was also noted in the hypocotyl tissues of their roots. The joint treatment by Mn/AG NC in combination with Se/AG NC (5.92% Se) also stimulated an increase in the length and mass of the roots in both uninfected seeds and infected seedlings, reduced the amount of reactive oxygen species (ROS) and peroxidase (POD) activity in the root tissues and DC in the hypocotyl tissues, and reduced the amount of pathogenic Bacillus spp. bacteria in the endomicrobiome of soybean seedlings. Thus, the Mn/AG and Se/AG NCs, separately or together, can be considered effective agents that have an antibacterial effect against phytopathogens and increase the resistance of soybeans to bacterial diseases caused by P. carotovorum.

Carnitine, a ubiquitous compound in living organisms, fulfills diverse roles in energy metabolism, stress resilience, and detoxification. Its antioxidant and osmolyte traits offer relief to stressed plants. Antagonizing abscisic acid (ABA), carnitine influences ABA-responsive genes. Our study, using Arabidopsis thaliana wild-type Ler. (Landsberg erecta) and ABA-insensitive abi2-1 mutants, explored carnitine’s impact on antioxidative responses and ABI2’s role in salt-induced carnitine metabolism. The application of 5 µM carnitine has alleviated the decrease in RWC, shoot weight, and rosette diameter WT plants caused by 80 mM salt stress for 4 days. Carnitine reduced cell membrane damage and salinity effects, evidenced by decreased lipid peroxidation and H₂O₂. In contrast, the impaired ABI2 of abi2-1, due to deficient phosphatase activity, further exacerbated the inhibitory effect of carnitine on the enzymes of the ascorbate-glutathione cycle, consequently reducing stress mitigation. While abi2-1 mutants exhibited unchanged superoxide dismutase (SOD) activity, they demonstrated increased catalase and peroxidase activity following carnitine treatment under salt stress compared to WT plants. Conversely, wild-type WT plants treated with carnitine exhibited elevated total glutathione content under salt stress, a response not observed in abi2-1 mutants under carnitine treatment. These results underscore the crucial role of ABI2-dependent ABA signaling in regulating plant carnitine metabolism.

Heat stress poses a serious threat to crop growth and development, yield, and quality. The function of heat shock factor A2 (HsfA2) to heat tolerance and its regulatory genes, heat shock proteins (Hsps), has been characterized in many plant species. However, the function of CsHsfA2 in heat tolerance of cucumber (Cucumis sativus L.) and its directly regulated genes is still unclear. In this study, CsHsfA2 was cloned from cucumber and its protein possessed typical characteristics of HsfA2 from other dicots. CsHsfA2 could be rapidly reduced by heat treatment within 30 min. The CsHsfA2 protein was localized in the nucleus and exhibited transcriptional activation activity. Furthermore, transient overexpression of CsHsfA2 in cucumber improved thermotolerance and stimulated the expression of CsHsp70-1. Virus induced gene silencing and ectopic expression in Arabidopsis confirmed the key role of CsHsfA2 in thermotolerance. Then, CsHsp70-1 was found to be the downstream gene directly activated by CsHsfA2. The function of CsHsp70-1 in thermotolerance was also confirmed through transient overexpression and virus induced gene silencing and ectopic expression in Arabidopsis. In addition, we discovered that CsHsfA2 can directly bind to its own promoter, which activates its own expression and establishes a positive autoregulation loop. Taken together, our study displayed the key roles of CsHsfA2 and CsHsp70-1, providing candidate genes for thermotolerance improvement of cucumber.

Thaumatin-like proteins (TLPs) are crucial for plant growth and development. However, the function of TLPs in pear pollen tube growth has not been fully elucidated. In this study, we characterized 40 PbrTLPs within the pear (Pyrus bretschneideri) genome and classified them into 10 groups according to their phylogenetic relationships, which exhibited significant similarities in gene structure and conserved motifs within each group. Microcollinearity analysis indicated that recent whole genome duplication (WGD) events significantly contributed to the expansion of the PbrTLP family, with purifying selection predominantly shaping the evolution of PbrTLPs. Transcriptomic data and qRT-PCR analysis revealed tissue-specific expression patterns of PbrTLP members. Notably, PbrTLP36 was identified as a strongly expressed gene in pollen tubes and confirmed to be a secreted protein. Functional assays in pollen tubes and tobacco cells suggested that knockdown the PbrTLP36 expression did not affect pollen tube growth, but the PbrTLP36 protein did confer antimicrobial activity. PbrTLP36 protein could effectively reduce the inhibitory effect of black spot fungi on pollen. The promoter cis-elements of PbrTLPs suggest potential responsiveness to a variety of abiotic and biotic stresses. Functional interaction network analysis suggested that several resistance genes acted synergistically with PbrTLP36. In conclusion, our study characterized the evolutionary pattern of the PbrTLP family and revealed the specific function of PbrTLP36, laying the groundwork for further functional investigations.

Drought is one of the abiotic stresses affecting agricultural production. WRKY transcription factors have important functions in response to drought. However, functions of only a few WRKY transcription factors are understood in soybean. Here, GmWRKY17 was cloned from soybean and shown to bind the W-box sequence. GmWRKY17 was tissue-specific and induced by drought. Overexpression of GmWRKY17 was found to decrease abscisic acid (ABA) sensitivity and increase drought tolerance in Arabidopsis thaliana. GmWRKY17 improved germination rate, leaf opening and greening, root length and chlorophyll content under osmotic stress and drought. GmWRKY17 reduced malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels under drought. GmWRKY17 promoted stomatal closure after treatment with 10% polyethylene glycol 6000 (PEG6000). Overexpression of GmWRKY17 increased superoxide dismutase (SOD) activity and catalase (CAT) activity, and GmWRKY17 promoted the expression of AtSOD1 and AtCAT1 under drought. Moreover, GmWRKY17 increased proline content and enhanced the expression of AtP5CS1, and GmWRKY17 up-regulated stress-related genes under drought stress. All results showed that overexpression of GmWRKY17 improved drought tolerance, and GmWRKY17 may regulate drought stress by enhancing antioxidant activity and upregulating stress-related genes in Arabidopsis thaliana.

The xanthophyll cycle plays a pivotal role in protecting plants and algae against photodamage. Although the resistance of the violaxanthin de-epoxidase enzyme (VDE) to high light stress in the xanthophyll cycle has been extensively studied, there is limited knowledge about VDE-related (VDR) proteins, which exhibit a close homologous relationship with VDEs. In this study, we preliminary investigated VDR protein, focusing on basic bioinformatics, spatiotemporal gene expression patterns, and high light stress treatment. VDR exhibited a significant homology with VDE, and the CsVDR protein was localized in the chloroplasts. CsVDR was expressed in all tissues of Arabidopsis and cucumber, with the highest expression level observed in mature leaves cultivated for 20 days in cucumber. Interestingly, both CsVDR and AtVDR were identified as high light response genes. Under high light stress, the non-photochemical quenching and Fv/Fm exhibited a decrease in both the Atvdr mutants and TRSV::CsVDR lines compared to the WT. Additionally, the de-epoxidation ratio (A + Z)/(A + Z + V) of the Atvdr mutants was significantly reduced. This suggested that the xanthophyll cycle in Atvdr mutants and TRSV::CsVDR lines were less effective and more susceptible to photoinhibition of PSII under high light stress. Our findings provide compelling evidence for the involvement of VDR proteins in regulating plant response to high light, thereby offering a theoretical basis for further investigation into plant photoprotective pathways.

Shoot shriveling severely threaten growth and development of deciduous trees in northern hemisphere, its essence is imbalance of water absorption and evaporation in the branches. In this study, the physiological characteristics of ‘Xiangling’ and ‘Liaohe (Liaoning No. 4)’ during the overwintering process were studied, and key overwintering periods were selected for transcriptome analysis. The results showed that plant hormone metabolism, wax metabolism and lignin metabolism were significantly enriched during the overwintering process. The expression of 4CL, a gene related to lignin metabolism, was significantly up-regulated. We used bioinformatics to analyze the 4CL family and study its expression under drought stress, and finally screened out a highly expressed gene (Jr4CL44) for subsequent functional verification. Overexpression of Jr4CL44 can effectively remove the reactive oxygen species produced by drought stress, increase lignin content and up-regulate the expression of related genes to improve the drought resistance of Arabidopsis thaliana. These results indicate that Jr4CL44 plays an important role in plant resistance to drought stress, which lays a foundation for further study on the functions in practice.

Drought is one of the important factors limiting crop growth. Plants can enhance resistance to various stressors by forming symbiotic relationships with arbuscular mycorrhizal fungi (AMF). However, the regulatory mechanism of AMF on the drought tolerance of kenaf remains unclear. Therefore, we studied the effects of inoculating Claroideoglomus etunicatum (C. etunicatum, Ce) on the growth, gaseous exchange, antioxidant enzymes activity, osmotic regulatory substances, endogenous hormones, elemental content, and drought resistance related gene expression in kenaf under different water conditions, as well as the changes in soil enzymes after inoculation with Claroideoglomus etunicatum (Ce). The results showed that the biomass of kenaf inoculated with AMF significantly increased under drought conditions; For the aboveground parts of kenaf, inoculation with AMF improved the gas exchange parameters, and synthesized more osmotic regulatory substances to resist drought stress. At the same time, AMF also enhanced the scavenging ability of reactive oxygen species and reducing the cell damage caused by ROS; For the root of kenaf, AMF promoted the root development, enhanced the ability of plant element and water absorption, and significantly increased the content of IAA and ABA in the roots of kenaf under drought stress, reaching 26.45% and 6.69%, respectively. The content of globulin-related soil proteins (GRSP) were increased after inoculation with AMF, and the soil enzymes activity was improved, making the soil easier to maintain water, for the growth of kenaf; Furthermore AMF regulate the expression of aquaporin related genes (HcPIP1;2, HcPIP2;7) and improved the tolerance of kenaf to drought. Our study is not limited to the direct effects of AMF on plants, but also indirectly affects plants by analyzing the effects of AMF on the physicochemical properties of soil in plant roots. These results indicate that AMF played an important role to promote the growth of kenaf under drought conditions.