Rhizosphere最新文献

Mimosa caesalpiniifolia, crucial for fencing and firewood in Brazil's Caatinga dry forest, presents a promising avenue for commercial propagation. The challenges faced in seed propagation, such as the scarcity of inputs and the difficulties in overcoming dormancy, highlight the advantages of vegetative methods. These methods emerge as a viable alternative, enabling uniform and large-scale production of clonal plantlets. This technique ensures consistent plant quality, which is crucial given the wide variety of uses for this species. Additionally, the use of plant growth regulators is critical to enhance the success of vegetative propagation, promoting the formation of robust roots and overall development of plants from cuttings of adult trees. Recognizing the significance of creating clonal forests of M. caesalpiniifolia and the necessity for understanding methods to expedite this endeavor, this study was designed to assess the shooting and adventitious rooting of stem cuttings sourced from adult M. caesalpiniifolia trees, examining the effects of auxinic agents. M. caesalpiniifolia cuttings were harvested through vegetative rescue from six randomly selected adult trees, treated with indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) at concentrations of 0, 1,000, 2,000, and 4000 mg L⁻¹, using a completely randomized design in a 2 × 4 factorial arrangement. The evaluations included assessing root presence, number of shoots, vigor of clonal plantlets and plant survival under greenhouse conditions, shade house conditions, and full sun exposure. The study did not reveal any significant interaction between growth regulators and their concentrations under these conditions. IBA at intermediate concentrations enhanced root growth, while cuttings without growth regulators exhibited superior aerial development. A decrease in survival percentages with increasing concentrations of regulators was observed, while cuttings without regulators demonstrated better morphological development. The study suggests for large-scale nurseries, natural rooting and shoot formation in M. caesalpiniifolia cuttings may suffice for successful propagation without IBA or IAA.

Identifying and comparing plant growth-promoting traits (PGPT) within whole-genome and metagenomic sequencing data can significantly advance agricultural research and promote sustainable crop production. This study introduces PGPg_finder, a comprehensive pipeline designed to annotate and compare PGPT from both whole-genome and metagenome sequencing datasets. This pipeline utilizes direct sequence annotation alongside de novo assembly methods to accurately detect PGPT. By cross-referencing sequences from the PLaBAse database, it identifies and quantifies the presence of these genes within the original datasets, facilitating an intuitive comparison of the abundance and distribution of PGPT across various samples. We evaluated the performance of PGPg_finder by analyzing genomes from five rhizobacterial strains: Paenibacillus vini, Paenibacillus polymyxa, Fictibacillus sp., Brevibacillus agri, and Bacillus cereus, and also metagenomic samples from bulk soils subjected to forest-to-pasture conversion in the Amazon rainforest. The genomic workflow revealed several genes associated with substrate utilization, abiotic stress neutralization, phosphate solubilization, and iron acquisition. It also identified genes unique to specific lineages, including those associated with colonization and plant-derived substrate usage in P. polymyxa, quorum sensing response and biofilm formation in P. vini, heavy metal detoxification and nitrogen acquisition in B. agri, and spore production and neutralizing biotic stress in B. cereus. The strain Fictibacillus sp. presented several unique genes related to surface attachment, stress response, xenobiotic degradation, phosphate solubilization, and phytohormone production. The use of PGPg_finder highlights its potential to uncover novel inoculants and strains. The metagenomic workflow distinguished plant-growth promotion gene profiles between soils from the Amazon rainforest and pasture, with the latter showing a profile more aligned with simple carbohydrate consumption, abiotic stress tolerance, motility and chemotaxis, and phosphorus mineralization. Native forests exhibited a profile associated with the degradation of complex organic matter, oxidative stress tolerance, xenobiotic degradation, bactericidal activity, iron acquisition, and volatile pathways. These findings underscore the effectiveness and sensitivity of PGPg_finder in accurately identifying and comparing PGPT genes, highlighting both commonalities and variations across samples. The application of this pipeline has the potential to significantly facilitate the identification of plant growth-promoting microbes.

The rhizosphere is a hotspot of soil phosphorus (P) transformation, which profoundly influences the P status of plants. Although P is projected to limit the ability of forests to serve as a carbon sink, it remains unclear how rhizosphere P availability responds to changing environments in alpine forests. Here, we investigated changes in rhizosphere available P across a series of altitudinal bands (2850 m, 2950 m, 3060 m and 3200 m) in alpine forests and examined the potential regulators of rhizosphere P availability, including temperature and soil biotic and abiotic properties. The results showed that rhizosphere P availability decreased up to the 3060 m site but then increased at the 3200 m site. A structural equation model showed that temperature and soil properties (pH and organic carbon content) indirectly affected rhizosphere available P through amorphous iron/aluminum oxides and microbial biomass P, which had negative and positive effects on rhizosphere available P, respectively. Thus, sorption by soil minerals and turnover of microbial biomass P may be key processes regulating P availability. In contrast, soil organic acids and acid phosphatase, which may promote the release of P by ligand exchange and mineralization, respectively, did not show a positive relationship with rhizosphere available P. Overall, our findings highlight the potential role of microbial biomass as a labile P pool that provides readily available P by turnover and protects P from sorption by soil minerals, which could help in elucidating the mechanisms by which plants maintain their P nutrient supply in alpine ecosystems under environmental changes.

We present the field rapid generation advancement procedure for shortening the crop cycle in rice. The practical protocol developed by us using different maturity groups of rice showed promising early flower induction. We observed a shortening of crop cycle to about 35–40 days depending on the variety. The spacing between the plants was the major influencer for flower induction compared to other interventions tested viz., clipping, potassium di-hydrogen phosphate and paclobutrazol spray. Our raised bed direct seeding strategy completely avoided the transplantation. The work flow for flower induction can be a reference to increase generations of rice breeding. The rhizosphere bacterial dynamics using 16srRNA gene amplicon sequencing showed the Acinetobacter population abundance as a key mediator and marker for flowering time. The alpha diversity at flowered and unflowered stage showed the species richness as Control < Pusa Sugandh 5 < BPT-5204. The rice rhizosphere of this ecosystem had an abundance of Methylotrophs that utilize methane as a carbon source suggesting that the developed method is a green technique suitable for generation advancement that can be replaced for flooded condition assisted breeding in rice. Selective enrichment of functional abundance between varieties suggested the host - influenced microbiome for early flowering in rice. This protocol is expected to greatly accelerate the process of new variety breeding and the construction of mapping populations.

Microbial remediation, a significant research focus in bioremediation, shows promise in addressing pollution. In this study, the optimal medium for acetochlor-degrading bacteria AB1 was determined by the response surface method as 29.94 g L⁻¹ sucrose, 10.06 g L⁻¹ yeast extract, and 20.32 g L⁻¹ NaCl. The single-factor method identified optimum degradation conditions, including a temperature of 30 °C, pH of 7.0, inoculation with 3% AB1, and an initial acetochlor concentration of 10 mg L⁻¹. The strain reached a maximum degradation rate of 79.87% within 5 days. AB1 performed nitrogen fixation, phosphorus dissolution, potassium hydrolysis, siderophore production, and biofilm formation. In the presence of acetochlor, it also induced the upregulation of genes, wza and luxS. Utilizing a green fluorescent protein and rifampicin-resistant strain LAB1-gfp, it demonstrated stable colonization in maize rhizospheres and soils, enhancing growth and degradation. This reduced the acetochlor half-life to 12.77 days and increased soil enzyme activity, providing a theoretical foundation for acetochlor bioremediation.

The search for new biological products with a positive impact on crop performance is typically initiated by laboratory based in vitro assays. However, live plants and their associated microbes are often removed from in vitro testing assays as a way to reduce biological complexity (variation) and facilitate molecular techniques in the pursuit of uncovering mode-of-action (MoA) mechanisms. Nevertheless, when studying biological candidates intended for use in agriculture, it is essential to incorporate this complexity and validate mechanisms under conditions as close to in situ as possible in order to understand the capacities and MoA of the biologicals in the intended application environments. To address this paradox, we have developed a high-capacity early-stage plant assay that incorporates a live non-sterile plant while also enabling molecular MoA investigations, and that can be conducted in laboratories without greenhouse facilities. The high-capacity design features plants grown in 8-chamber transparent boxes to allow for multiplex imaging and increased biological replicates for greater statistical power. The transparent box design allows the visualization of shoots, roots, tagged-microbes, or visible substrates, and further non-destructive access to shoots or roots for sampling. The boxes are held in racks that hold eight plant boxes during growth in a 19 by 17 cm space, further increasing the throughput to >670 plants per m² and easing the logistical challenges of plant assays. Furthermore, the box can support various levels of microbial complexity with the option to select the plant growth medium that meets experimental objectives, as well as using sterile or non-sterile seeds. A script-based post-imaging quantification was developed to automate image processing and allow for individual plant readings, further enabling increased statistical confidence. As proof of concept, we use the high-capacity plant system to evaluate the biocontrol potential of Pseudomonas protegens and the biostimulation potential of Pseudomonas koreensis, and are in both cases able to show statistically significant differing plant biomass between treatments under these closer-to-nature conditions. We further demonstrate that the high-capacity plant system is suitable for paired molecular investigations by performing metabolomics and qPCR DNA quantification directly from the plant box to explore in situ chemical MoA, as well as confirm the survival of the P. protegens strains to validate their role in the improved plant phenotype. In conclusion, the study presents a modular high-capacity plant assay system that enables increased throughput functional testing of microbial biocontrol and biostimulant candidates in planta. This novel assaying system saves time, reduces human error, provides quantitative and non-destructive in planta data, and can be used in laboratories