Mechanisms Of Growth Promotion Research Articles

The Growth-Promoting and Colonization of the Pine Endophytic Pseudomonas abietaniphila for Pine Wilt Disease Control

In this study, we focused on evaluating the impact of Pseudomonas abietaniphila BHJ04 on the growth of Pinus massoniana seedlings and its biocontrol efficacy against pine wilt disease (PWD). Additionally, the colonization dynamics of P. abietaniphila BHJ04 on P. massoniana were examined. The growth promotion experiment showed that P. abietaniphila BHJ04 significantly promoted the growth of the branches and roots of P. massoniana. Pot control experiments indicated that strain BHJ04 significantly inhibited the spread of PWD. There were significant changes in the expression of several genes related to pine wood nematode defense in P. massoniana, including chitinase, nicotinamide synthetase, and triangular tetrapeptide-like superfamily protein isoform 9. Furthermore, our results revealed significant upregulation of genes associated with the water stress response (dehydration-responsive proteins), genetic material replication (DNA/RNA polymerase superfamily proteins), cell wall hydrolase, and detoxification (cytochrome P450 and cytochrome P450 monooxygenase superfamily genes) in the self-regulation of P. massoniana. Colonization experiments demonstrated that strain BHJ04 can colonize the roots, shoots, and leaves of P. massoniana, and the colonization amount on the leaves was the greatest, reaching 160,000 on the 15th day. However, colonization of the stems lasted longer, with the highest level of colonization observed after 45 d. This study provides a preliminary exploration of the growth-promoting and disease-preventing mechanisms of P. abietaniphila BHJ04 and its ability to colonize pines, thus providing a new biocontrol microbial resource for the biological control of plant diseases.

Exploring overlooked growth-promoting mechanisms by plant-associated bacteria

Abstract Agriculture-oriented microbiome studies try to develop microbiota beneficial to their plant hosts. This positive goal extends to the soil quality driving plant growth and disease resistance. In research aimed at identifying the causes of this beneficial action, a common interpretation is that microbes will synthesize metabolites useful to their hosts. This view assumes that important microbial metabolites are exported for use by their hosts. Yet, this seems unlikely for essential metabolites, without a counterpart imported from the plants, as the corresponding syntheses would often involve the consumption of resources without explicit benefit to the microbes. Illustrating this function with the example of Bacilli of the Subtilis clade, we emphasize here that the most direct access to the contents of microbial cells is through cell lysis, a phenomenon often linked to the process of sporulation. This process also releases macromolecules that are digested in the environment, releasing key metabolites such as queuine, an important base analog present in the anticodon of some transfer RNAs. This overlooked importance of cell lysis could also be a major cause of the ubiquitous presence of bacteriophages in microbiota.

Effects of Klebsiella michiganensis LDS17 on Codonopsis pilosula growth, rhizosphere soil enzyme activities, and microflora, and genome-wide analysis of plant growth-promoting genes.

We comprehensively evaluated the plant growth-promoting characteristics and heavy metal (HM) resistance ability of the LDS17 strain, as well as the effects of strain LDS17 inoculation on the Codonopsis pilosula seedling growth and the soil qualities in the Codonopsis pilosula rhizosphere. We conducted whole-genome analysis and identified lots of genes and gene clusters contributing to plant-beneficial functions and HM resistance, which is critical for further elucidating the plant growth-promoting mechanism of strain LDS17 and expanding its application in the development of plant growth-promoting agents used in the environment under HM stress.

Soil phosphorus transformation and plant uptake driven by phosphate-solubilizing microorganisms.

Phosphorus (P) is an important nutrient for plants, and a lack of available P greatly limits plant growth and development. Phosphate-solubilizing microorganisms (PSMs) significantly enhance the ability of plants to absorb and utilize P, which is important for improving plant nutrient turnover and yield. This article summarizes and analyzes how PSMs promote the absorption and utilization of P nutrients by plants from four perspectives: the types and functions of PSMs, phosphate-solubilizing mechanisms, main functional genes, and the impact of complex inoculation of PSMs on plant P acquisition. This article reviews the physiological and molecular mechanisms of phosphorus solubilization and growth promotion by PSMs, with a focus on analyzing the impact of PSMs on soil microbial communities and its interaction with root exudates. In order to better understand the ability of PSMs and their role in soil P transformation and to provide prospects for research on PSMs promoting plant P absorption. PSMs mainly activate insoluble P through the secretion of organic acids, phosphatase production, and mycorrhizal symbiosis, mycorrhizal symbiosis indirectly activates P via carbon exchange. PSMs can secrete organic acids and produce phosphatase, which plays a crucial role in soil P cycling, and related genes are involved in regulating the P-solubilization ability. This article reviews the mechanisms by which microorganisms promote plant uptake of soil P, which is of great significance for a deeper understanding of PSM-mediated soil P cycling, plant P uptake and utilization, and for improving the efficiency of P utilization in agriculture.

Multiple omics revealed the growth-promoting mechanism of Bacillus velezensis strains on ramie.

Beneficial bacteria that promote plant growth can shield plants from negative effects. Yet, the specific biological processes that drive the relationships between soil microbes and plant metabolism are still not fully understood. To investigate this further, we utilized a combination of microbiology and non-targeted metabolomics techniques to analyze the impact of plant growth-promoting bacteria on both the soil microbial communities and the metabolic functions within ramie (Boehmeria nivea) tissues. The findings indicated that the yield and traits of ramie plants are enhanced after treatment with Bacillus velezensis (B. velezensis). These B. velezensis strains exhibit a range of plant growth-promoting properties, including phosphate solubilization and ammonia production. Furthermore, strain YS1 also demonstrates characteristics of IAA production. The presence of B. velezensis resulted in a decrease in soil bacteria diversity, resulting in significant changes in the overall structure and composition of soil bacteria communities. Metabolomics showed that B. velezensis significantly altered the ramie metabolite spectrum, and the differential metabolites were notably enriched (P < 0.05) in five main metabolic pathways: lipid metabolism, nucleotide metabolism, amino acid metabolism, plant secondary metabolites biosynthesis, and plant hormones biosynthesis. Seven common differential metabolites were identified. Correlation analysis showed that the microorganisms were closely related to metabolite accumulation and yield index. In the B. velezensis YS1 and B. velezensis Y4-6-1 treatment groups, the relative abundances of BIrii41 and Bauldia were significantly positively correlated with sphingosine, 9,10,13-TriHOME, fresh weight, and root weight, indicating that these microorganisms regulate the formation of various metabolites, promoting the growth and development of ramie. Conclusively, B. velezensis (particularly YS1) played an important role in regulating soil microbial structure and promoting plant metabolism, growth, and development. The application of the four types of bacteria in promoting ramie growth provides a good basis for future application of biological fertilizers and bio-accelerators.

Multifarious plant growth-promoting traits of mangrove yeasts: growth enhancement in mangrove seedlings (Rhizophora mucronata) for conservation.

Plant Growth-Promoting Yeasts (PGPY) have garnered significant attention in recent years; however, research on PGPY from mangroves remains a largely unexplored frontier. This study, therefore, focused on exploring the multifaceted plant growth-promoting (PGP) capabilities of yeasts isolated from mangroves of Puthuvype and Kumbalam. The present work found that manglicolous yeasts exhibited diverse hydrolytic properties, with the predominance of lipolytic activity, in addition to other traits such as phosphate solubilization, and production of indole acetic acid, siderophore, ammonia, catalase, nitrate, and hydrogen cyanide. After screening for 15 PGP traits, three strains P 9, PV 23, and KV 35 were selected as the most potent ones. These strains also exhibited antagonistic activity against fungal phytopathogens and demonstrated resilience to abiotic stresses, making them not only promising biocontrol agents but also suited for field application. The potent strains P 9, PV 23, and KV 35 were molecularly identified as Candida tropicalis, Debaryomyces hansenii, and Aureobasidium melanogenum, respectively. The potential of these strains in enhancing the growth performance of mangrove seedlings of Rhizophora mucronata, was demonstrated using the pot-experiment. The results suggested that the consortium of three potent strains (P 9, PV 23, and KV 35) was more effective in increasing the number of shoot branches (89.2%), plant weight (87.5%), root length (83.3%), shoot height (57.9%) and total leaf area (35.1%) than the control seedlings. The findings of this study underscore the significant potential of manglicolous yeasts in contributing to mangrove conservation and restoration efforts, offering a comprehensive understanding of their diverse plant growth-promoting mechanisms and highlighting their valuable role in sustainable ecosystem management.

Speciation Features of Ferdinandcohnia quinoae sp. nov to Adapt to the Plant Host

The bacterial strain SECRCQ15T was isolated from seeds of Chenopodium quinoa in Spain. Phylogenetic, chemotaxonomic, and phenotypic analyses, as well as genome similarity indices, support the classification of the strain into a novel species of the genus Ferdinandcohnia, for which we propose the name Ferdinandcohnia quinoae sp. nov. To dig deep into the speciation features of the strain SECRCQ15T, we performed a comparative genomic analysis of the genome of this strain and those of the type strains of species from the genus Ferdinandcohnia. We found several genes related with plant growth-promoting mechanisms within the SECRCQ15T genome. We also found that singletons of F. quinoae SECRCQ15T are mainly related to the use of carbohydrates, which is a common trait of plant-associated bacteria. To further reveal speciation events in this strain, we revealed genes undergoing diversifying selection (e.g., genes encoding ribosomal proteins) and functions likely lost due to pseudogenization. Also, we found that this novel species contains 138 plant-associated gene-cluster functions that are unique within the genus Ferdinandcohnia. These features may explain both the ecological and taxonomical differentiation of this new taxon.

Peribacillus frigoritolerans T7-IITJ, a potential biofertilizer, induces plant growth-promoting genes of Arabidopsis thaliana.

This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient-poor rhizosphere soil of Thar desert plants and unravel their molecular mechanisms of plant growth promotion. Among our rhizobacterial isolates, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth (4-5-fold) in Arabidopsis thaliana under PEG-induced drought stress. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz., solubilization of phosphate (40-73µg/ml), iron (24±0.58mm halo on chrome azurol S media), and nitrate (1.58±0.01µg/ml nitrite), along with production of exopolysaccharides (125±20µg/ml) and auxin-like compounds (42.6±0.05µg/ml). Transcriptome analysis of A. thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of 445 plant genes (log2fold-change>1, FDR<0.05) for photosynthesis, auxin and jasmonate signalling, nutrient uptake, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of 503 genes (log2fold-change < -1) including many stress-responsive genes. T7-IITJ enhanced proline 2.5-fold, chlorophyll 2.5-2.8-fold, iron 2-fold, phosphate 1.6-fold, and nitrogen 4-fold, and reduced reactive oxygen species 2-4.7-fold in plant tissues under drought. T7-IITJ also improved the germination and seedling growth of Tephrosia purpurea, Triticum aestivum, and Setaria italica under drought and inhibited the growth of two plant pathogenic fungi, Fusarium oxysporum, and Rhizoctonia solani. P. frigoritolerans T7-IITJ is a potent biofertilizer that regulates plant genes to promote growth and drought tolerance.

Transcriptional alterations of peanut root during interaction with growth-promoting Tsukamurella tyrosinosolvens strain P9.

The plant growth-promoting rhizobacterium Tsukamurella tyrosinosolvens P9 can improve peanut growth. In this study, a co-culture system of strain P9 and peanut was established to analyze the transcriptome of peanut roots interacting with P9 for 24 and 72 h. During the early stage of co-culturing, genes related to mitogen-activated protein kinase (MAPK) and Ca2+ signal transduction, ethylene synthesis, and cell wall pectin degradation were induced, and the up-regulation of phenylpropanoid derivative, flavonoid, and isoflavone synthesis enhanced the defense response of peanut. The enhanced expression of genes associated with photosynthesis and carbon fixation, circadian rhythm regulation, indoleacetic acid (IAA) synthesis, and cytokinin decomposition promoted root growth and development. At the late stage of co-culturing, ethylene synthesis was reduced, whereas Ca2+ signal transduction, isoquinoline alkaloid synthesis, and ascorbate and aldarate metabolism were up-regulated, thereby maintaining root ROS homeostasis. Sugar decomposition and oxidative phosphorylation and nitrogen and fatty acid metabolism were induced, and peanut growth was significantly promoted. Finally, the gene expression of seedlings inoculated with strain P9 exhibited temporal differences. The results of our study, which explored transcriptional alterations of peanut root during interacting with P9, provide a basis for elucidating the growth-promoting mechanism of this bacterial strain in peanut.

The first released available genome of the common ice plant (Mesembryanthemum crystallinum L.) extended the research region on salt tolerance, C3-CAM photosynthetic conversion, and halophilism

Background The common ice plant (Mesembryanthemum crystallinum L.) is an annual herb belonging to the genus Mesembryanthemum of the family Aizoaceae, native to Southern Africa. Methods We performed shotgun genome paired-end sequencing using the Illumina platform to determine the genome sequence of the ice plants. We assembled the whole genome sequences using the genome assembler “ALGA” and “Redundans”, then released them as available genomic information. Finally, we mainly estimated the potential genomic function by the homology search method. Results A draft genome was generated with a total length of 286 Mb corresponding to 79.2% of the estimated genome size (361 Mb), consisting of 49,782 contigs. It encompassed 93.49% of the genes of terrestrial higher plants, 99.5% of the ice plant transcriptome, and 100% of known DNA sequences. In addition, 110.9 Mb (38.8%) of repetitive sequences and untranslated regions, 971 tRNA, and 100 miRNA loci were identified, and their effects on stress tolerance and photosynthesis were investigated. Molecular phylogenetic analysis based on ribosomal DNA among 26 kinds of plant species revealed genetic similarity between the ice plant and poplar, which have salt tolerance. Overall, 35,702 protein-coding regions were identified in the genome, of which 56.05% to 82.59% were annotated and submitted to domain searches and gene ontology (GO) analyses, which found that eighteen GO terms stood out among five plant species. These terms were related to biological defense, growth, reproduction, transcription, post-transcription, and intermembrane transportation, regarded as one of the fundamental results of using the utilized ice plant genome. Conclusions The information that we characterized is useful for elucidation of the mechanism of growth promotion under salinity and reversible conversion of the photosynthetic type from C3 to Crassulacean Acid Metabolism (CAM).

Whole-genome analysis revealed the growth-promoting and biological control mechanism of the endophytic bacterial strain Bacillus halotolerans Q2H2, with strong antagonistic activity in potato plants.

Endophytes are colonizers of healthy plants and they normally exhibit biocontrol activities, such as reducing the occurrence of plant diseases and promoting plant growth. The endophytic bacterium Bacillus halotolerans Q2H2 (Q2H2) was isolated from the roots of potato plants and was found to have an antagonistic effect on pathogenic fungi. Q2H2 was identified by morphological observations, physiological and biochemical identification, and 16S rRNA gene sequence analysis. Genes related to the anti-fungal and growth-promoting effects were analyzed using whole-genome sequencing and comparative genomic analysis. Finally, we analyzed the growth-promoting and biocontrol activities of Q2H2 in potato plants using pot experiments. Antagonism and non-volatile substance plate tests showed that Q2H2 had strong antagonism against Fusarium oxysporum, Fusarium commune, Fusarium graminearum, Fusarium brachygibbosum, Rhizoctonia solani and Stemphylium solani. The plate test showed that Q2H2 had the ability to produce proteases, cellulases, β-1,3-glucanase, dissolved organic phosphate, siderophores, indole-3-acetic acid (IAA), ammonia and fix nitrogen. The suitable growth ranges of Q2H2 under different forms of abiotic stress were pH 5-9, a temperature of 15-30°C, and a salt concentration of 1-5%. Though whole-genome sequencing, we obtained sequencing data of approximately 4.16 MB encompassed 4,102 coding sequences. We predicted 10 secondary metabolite gene clusters related to antagonism and growth promotion, including five known products surfactin, bacillaene, fengycin, bacilysin, bacillibactin, and subtilosin A. Average nucleotide identity and comparative genomic analyses revealed that Q2H2 was Bacillus halotolerans. Through gene function annotation, we analyzed genes related to antagonism and plant growth promotion in the Q2H2 genome. These included genes involved in phosphate metabolism (pstB, pstA, pstC, and pstS), nitrogen fixation (nifS, nifU, salA, and sufU), ammonia production (gudB, rocG, nasD, and nasE), siderophore production (fhuC, fhuG, fhuB, and fhuD), IAA production (trpABFCDE), biofilm formation (tasA, bslA, and bslB), and volatile compound production (alsD, ilvABCDEHKY, metH, and ispE), and genes encoding hydrolases (eglS, amyE, gmuD, ganB, sleL, and ydhD). The potato pot test showed that Q2H2 had an obvious growth-promoting effect on potato roots and better control of Fusarium wilt than carbendazim. These findings suggest that the strain-specific genes identified in bacterial endophytes may reveal important antagonistic and plant growth-promoting mechanisms.

Prospecção de rizobactérias promotoras de crescimento de plantas em videiras no Vale do São Francisco

ABSTRACT Viticulture is the main agricultural production in the São Francisco Valley, Brazil; however, farm soil management systems require large volumes of fertilizer that could contribute to climate change. Therefore, using plant growth-promoting rhizobacteria (PGPR) has been reported to reduce or replace plant input. This study aimed to evaluate the bacteria in the rhizosphere of Vitis vinifera cultivated in the São Francisco Valley in Pernambuco, Brazil, and to characterize the mechanisms that promote plant growth. The PGPR with the greatest biotechnological potential was identified using sequencing. The bacteria were isolated from tryptic soy agar (TSA) culture medium inoculated with 100 µL of a serial dilution. The isolates obtained were characterized phenotypically and tested for their ability to solubilize phosphate, promote biological nitrogen fixation (BNF), and produce indole-3 acetic acid (IAA), biofilms, and antibiotic factors against Xanthomonas campestris pv. viticola. A total of 423 bacteria were obtained, of which 99 presented positive results for at least one of the growth-promotion mechanisms, representing 6.85% for phosphate solubilizers, 0.74% for BNF, 5.7% for IAA synthesizers, 11.27% for biofilm producers, and 4.01% for promoting antibiosis against X. campestris pv. viticola. Isolates 3.19 and 31.14; 3.17 and 17.04; 5.35 and 5.42; and 5.37 identified as Stenotrophomonas, Bacillus, Pseudomonas, and Clostridium, respectively, presented a biotechnological potential for future experiments to promote vine growth.

Integrating transcriptome and metabolome to explore the growth-promoting mechanisms of GABA in blueberry plantlets.

Tissue culture technology is the main method for the commercial propagation of blueberry plants, but blueberry plantlets grow slowly and have long growth cycles under in vitro propagation, resulting in low propagation efficiency. In addition, the long culturing time can also result in reduced nutrient content in the culture medium, and the accumulation of toxic and harmful substances that can lead to weak growth for the plantlets or browning and vitrification, which ultimately can seriously reduce the quality of the plantlets. Gamma-aminobutyric acid (GABA) is a four-carbon non-protein amino acid that can improve plant resistance to various stresses and promote plant growth, but the effects of its application and mechanism in tissue culture are still unclear. In this study, the effects of GABA on the growth of in vitro blueberry plantlets were analyzed following the treatment of the plantlets with GABA. In addition, the GABA-treated plantlets were also subjected to a comparative transcriptomic and metabolomic analysis. The exogenous application of GABA significantly promoted growth and improved the quality of the blueberry plantlets. In total, 2,626 differentially expressed genes (DEGs) and 377 differentially accumulated metabolites (DAMs) were detected by comparison of the control and GABA-treated plantlets. Most of the DEGs and DAMs were involved in carbohydrate metabolism and biosynthesis of secondary metabolites. The comprehensive analysis results indicated that GABA may promote the growth of blueberry plantlets by promoting carbon metabolism and nitrogen assimilation, as well as increasing the accumulation of secondary metabolites such as flavonoids, steroids and terpenes.

Study on the mechanism of salt relief and growth promotion of Enterobacter cloacae on cotton

AimsIn-depth studies on plant ion uptake and plant growth-promoting rhizobacteria (PGPR) at the molecular level will help to further reveal the effects of PGPR on plants and their interaction mechanisms under salt stress.MethodsCotton was inoculated with a PGPR-Enterobacter cloacae Rs-35, and the ion uptake capacity, membrane transporter protein activity, and expression of key genes were determined under salt stress. Changes in the endogenous hormone content of cotton were also determined. Further, the genome-wide metabolic pathway annotation of E. cloacae Rs-35 and its differential enrichment pathway analysis of multi-omics under salinity environments were performed.ResultsIn a pot experiment of saline-alkali soil, E. cloacae Rs-35-treated cotton significantly increased its uptake of K+ and Ca2+ and decreased uptake of Na+, elevated the activity of the H+-ATPase, and increased the sensitivity of the Na+/H+ reverse transporter protein on the vesicle membrane. Meanwhile, inoculation with E. cloacae Rs-35 could promote cotton to maintain the indole-3-acetic acid (IAA) content under salt stress. Genome-wide annotation showed that E. cloacae Rs-35 was respectively annotated to 31, 38, and 130 related genes in osmotic stress, phytohormone and organic acid metabolism, and ion uptake metabolic pathway. Multi-omics differences analysis showed that E. cloacae Rs-35 were enriched to tryptophan metabolism, multiple amino acid biosynthesis, carbon and glucose synthesis, and oxidative phosphorylation metabolic pathways at the transcriptome, proteome, and metabolome.ConclusionE. cloacae Rs-35 can promote cotton balance cell ion concentration, stabilize intracellular IAA changes, stimulate induction of systemic tolerance, and promote the growth of cotton plants under salt stress.

The Promoting Mechanism of the Sterile Fermentation Filtrate of Serratia odorifera on Hypsizygus marmoreus by Means of Metabolomics Analysis.

Hypsizygus marmoreus has become one of the most popular edible mushrooms due to its high nutritional and economic value. Previous researchers found that Serratia odorifera could promote the growth of H. marmoreus by producing and secreting some of its inducers. However, the specific mechanism of action was still unclear. In this study, we found that the exogenous addition of sterile fermentation filtrate (HZSO-1), quorum sensing (QS) signaling molecules, 3-oxo-C6-HSL, cyclo(Pro-Leu), and cyclo(Tyr-Leu) could significantly promote the growth of H. marmoreus, increase the number of clamp junctions, and the diameter of mycelium (p < 0.05). In addition, non-targeted metabolomic analysis revealed that 706 metabolites were detected in the treated group. Of these, 307 metabolites were significantly different (p < 0.05). Compared with the control, 54 and 86 metabolites were significantly increased and decreased in the HZSO-1 group, respectively (p < 0.05). We speculate that the sterile fermentation filtrate of S. odorifera could mediate the carbohydrate and amino acid metabolism of H. marmoreus by influencing the pentose phosphate pathway (PPP) to increase the energy supply for the growth and development of the mycelium. The above results will further reveal the growth-promoting mechanism of S. odorifera on H. marmoreus.

Enhanced microalgal growth and metabolites through co-cultivation with Escherichia coli in algal organic matter solution

Studies of how symbiotic bacteria interact with microalgae have been an area of interest for some time. However, there is still a knowledge gap on the role of algal organic matters in algal growth promotion and adaptive mechanisms of the co-cultures in medium containing high abundancy of dissolved algal organic matters. It remains unclear if high extra- and intra-cellular organic substances concentration influences algal development or subsequent algal organic matter productivity in the presence of bacteria. Therefore, this study aims to co-cultivate Escherichia coli NEB 5-alpha with broad range of marine and freshwater microalgae in fresh medium (T), soluble EPS (sEPS) and internal organic matter solution (IOM). Among screened species, only the growth of Cylindrotheca fusiformis and Chlorella vulgaris was promoted by E. coli at 1.15×106±2.08×104 cells mL−1 and 7.79×106±1.27×105 cells mL−1after 96 h. Xenic algal growth was further enhanced about 10 % more utilizing sEPS and IOM. However, the net EPS accumulation of the cells cultivated in sEPS and IOM was comparatively lower than that of the cells in T medium due to metabolite consumption. Elevation in the transparent exopolymer particles, total chlorophyll, total carbohydrate, total protein and lipid productivity up to 3.54-fold by cultivating the co-cultures in sEPS and IOM indicated an alteration of the microalgae's physiology. This is a new paradigm on how algal extracts promote xenic algal growth and metabolite production which pave a way for cost-effective biotechnological applications by reusing the algae medium with abundant organic matters.

Transcriptome analysis of growth and quality response of chrysanthemum to co-inoculation with Bacillus velezensis and Pseudomonas aeruginosa

The inoculation of plants with plant growth-promoting rhizobacteria (PGPR) has been increasingly discussed as a way to sustainably promote plant growth and soil health. Although some promising results have been achieved in the laboratory, the applications of microbial inoculants in chrysanthemum production greenhouses and co-inoculation with PGPRs in ornamental planting systems have been less investigated. Here, greenhouse experiments were conducted to study the integrated effect of bioagents (Bacillus velezensis and Pseudomonas aeruginosa) on chrysanthemum nutrient use efficiency, plant growth, and quality. The growth-promoting mechanisms were further elucidated by transcriptome analysis. Co-inoculation with the two PGPRs increased the absorption and utilization of nitrogen, phosphorus, and potassium. The quality and growth of chrysanthemum were significantly higher than those of single PGPR inoculation or soil conditioner application. Transcriptome analysis revealed that differentially expressed genes (DEGs) were co-expressed at 30, 60, and 90 days after chrysanthemum co-inoculation with the two PGPRs. DEGs were primarily enriched in metabolic and signal transduction pathways. PDC encoding pyruvate decarboxylase in the glycolysis pathway and SAUR32 and SAUR36 encoding auxin were upregulated in chrysanthemum during the PGPRs inoculation period. Notably, the transcription factors WRKY70 and BHLH35 belonging to signal transduction and defense responses were both upregulated, demonstrating that chrysanthemum system and disease resistance were activated. The results of this study could help to elucidate the mechanism of 2 PGPRs on chrysanthemum growth and development at the transcriptome level, which could lay a theoretical foundation for the highly efficient cultivation of cut chrysanthemum “Qinhuai Yulian”.

Competition and co-association, but not phosphorous availability, shape the benefits of phosphate-solubilizing root bacteria for maize (Zea mays).

Predicting the conditions under which rhizobacteria benefit plant growth remains challenging. Here we tested the hypothesis that benefits from inoculation with phosphate-solubilizing rhizobacteria will depend upon two environmental conditions: phosphate availability and competition between bacteria. We used maize-associated rhizobacteria with varying phosphate solubilization ability in experiments in soil, sterilized soil and gnotobiotic microcosms under conditions of varying orthophosphate availability, while we manipulated the intensity of competition by varying the number of isolates in plant inocula. Growth promotion by microbes did not depend on phosphate availability but was affected by interactions between inoculants: the beneficial effects of one Serratia isolate were only detectable when plants were inoculated with a single strain and the beneficial effects of a competition-sensitive Rhizobium was only detectable in sterilized soil or in microcosms inoculated with single strains. Moreover, microcosm experiments suggested that facilitation of a parasitic isolate, not competitive interactions between bacteria, prevented plants from gaining benefits from a potential mutualist. Competition and facilitation affected colonization of plants in microcosms but growth promotion by Serratia was more affected by inoculation treatment than culturable densities on roots. Experimental manipulation of seed inocula can reveal whether plant growth stimulation is robust with respect to competition, as well as the ecological strategies of different rhizobacteria. From an applied perspective, phosphate solubilization may not provide the mechanism for bacterial growth promotion but may indicate mutualistic potential due to phylogenetic associations. Importantly, benefits to plants are vulnerable to interactions between rhizobacteria and may not persist in mixed inoculations.

Hsa_circ_0001687 Function as a ceRNA to Facilitate Hepatocellular Carcinoma Progression via miR-140- 3p/FOXQ1 Axis.

Increasingly convincing evidence has revealed that circular RNAs (circRNAs) are critical regulatory components of hepatocellular carcinoma (HCC) genesis. However, the expression of circRNAs in HCC and the relevance of circRNAs to HCC progression remain largely unexplained. qRT-PCR or western blotting was utilized to confirm circ_0001687, miR-140-3p, and Forkhead Box q1 (FOXQ1) levels in HCC tissues or cells. Cell proliferation ability was evaluated via CCK-8 and colony formation assay. The correlation of circ_0001687 or FOXQ1 and miR-140- 3p was determined using dual luciferase reporter assay. Nude mice xenograft tumor model was constructed to verify the effect of circ_0001687 on tumor growth. Circ_0001687 was elevated in HCC. Function assays and the nude mice xenograft tumor model indicated that circ_0001687 acts as a promoting gene in HCC to regulate the proliferation of the tumor cell and foster tumor growth. Further mechanistic exploration revealed that the tumor growth-promoting mechanism of circ_0001687 relied on blocking the inhibitory effect of miR-140- 3p on FOXQ1 and activating FOXQ1 expression. This research indicated the role of circ_0001687/miR-140-3p/FOXQ1 network in regulating HCC development. These may provide new insights into the treatment of HCC.

Mechanism of Salt Tolerance and Plant Growth Promotion in Priestia megaterium ZS-3 Revealed by Cellular Metabolism and Whole-Genome Studies

Approximately one-third of agricultural land worldwide is affected by salinity, which limits the productivity and sustainability of crop ecosystems. Plant-growth-promoting rhizobacteria (PGPR) are a potential solution to this problem, as PGPR increases crop yield through improving soil fertility and stress resistance. Previous studies have shown that Priestia megaterium ZS-3(ZS-3) can effectively help plants tolerate salinity stress. However, how ZS-3 regulates its metabolic adaptations in saline environments remains unclear. In this study, we monitored the metabolic rearrangement of compatibilisers in ZS-3 and combined the findings with genomic data to reveal how ZS-3 survives in stressful environments, induces plant growth, and tolerates stress. The results showed that ZS-3 tolerated salinity levels up to 9%. In addition, glutamate and trehalose help ZS-3 adapt to osmotic stress under low NaCl stress, whereas proline, K+, and extracellular polysaccharides regulate the osmotic responses of ZS-3 exposed to high salt stress. Potting experiments showed that applying the ZS-3 strain in saline and neutral soils could effectively increase the activities of soil acid phosphatase, urease, and invertase in both soils, thus improving soil fertility and promoting plant growth. In addition, strain ZS-3-GFP colonised the rhizosphere and leaves of Cinnamomum camphora well, as confirmed by confocal microscopy and resistance plate count analysis. Genomic studies and in vitro experiments have shown that ZS-3 exhibits a variety of beneficial traits, including plant-promoting, antagonistic, and other related traits (such as resistance to saline and heavy metal stress/tolerance, amino acid synthesis and transport, volatile compound synthesis, micronutrient utilisation, and phytohormone biosynthesis/regulatory potential). The results support that ZS-3 can induce plant tolerance to abiotic stresses. These data provide important clues to further reveal the interactions between plants and microbiomes, as well as the mechanisms by which micro-organisms control plant health.