Bean Roots Research Articles

Innovative Approach in Sustainable Agriculture: Harnessing Microalgae Potential via Subcritical Water Extraction

Microalgae can contribute to sustainable agriculture and wastewater treatment. This study investigated Tetradesmus obliquus, grown in piggery wastewater (To-PWW), as a biostimulant/biofertilizer compared to biomass grown in synthetic medium (To-B). Subcritical water extraction was tested for disruption/hydrolysis of wet biomass, at three temperatures (120, 170, and 220 ºC) and two biomass loads (1:10 and 1:80 (g dry biomass/mL water)). Extracts were evaluated for germination, and root formation/expansion. Residues were quantified for nutrient composition to assess their biofertilizer potential and tested for their affinity to oil compounds for bioremediation.The best germination was achieved by To-B extracts at 170 ºC (1:10: 148% at 0.2g/L, 1:80: 145% at 0.5g/L). Only To-PWW extracts at 0.2g/L had a significant germination effect (120 ºC: 120-123% for both loads; 170 ºC: 115% for 1:80). To-PWW extract at 120 ºC and 1:10 significantly affected cucumber and mung bean root formation (224 and 268%, respectively). Most extracts significantly enhanced root expansion, with all To-B extracts at 1:10 showing the best results (139-181%). The residues contained essential nutrients (NPK), indicating their biofertilizer potential, helping decrease synthetic fertilizers demands. To-B residues had high affinity to toluene and diesel but lower to used cooking and car oils. To-PWW showed very low affinity to all oil compounds. Finally, all residues were only able to form stable emulsions with the used car oil. This study fully exploits the use of microalgal biomass in sustainable agriculture, producing biostimulant extracts, and residues for biofertilizer and bioremediation, from a low-cost wastewater source.

Migration of Plutonium, Micro- and Macroelements in the “Soil–Plant” System at Different Soil Moisture

In the vegetation experiment, the plutonium, micro- and macroelements migration in the “soil–agricultural plant” system depending on soil moisture in the range from 15 to 40٪ of absolute soil moisture were studied. The content of 239Pu was analyzed by α-spectrometry with preliminary radiochemical isolation. The elemental composition was analyzed by the ICP-MS and ICP-AES methods. Beans (Fabaceae) variety “Amber” were used as a test culture. The plutonium transfer factor obtained in the vegetation experiments are in the range of of 5.3×10–4–1.5×10–2, with an average value of 5.4×10–3 for the aboveground part of bean and range of 4.5×10–2–2.7×10–1, with an average of 1.6×10–1 for bean roots. It was determined that the distribution of plutonium, micro and macro elements in the vegetative organs of plants is not equally, the transfer factor of plutonium for the aboveground part of plants is lower than for the root part. It has been established that the accumulation of plutonium, micro- and macroelements, depending on soil moisture, is different for the organs of beans. The dependence of plutonium accumulation by plants on soil moisture is significantly higher than for other considered elements. A decrease in the coefficient of accumulation of plutonium in the aerial part of the beans is recorded with an increase in soil moisture up to two orders of magnitude. There is a trend towards a slight decrease in the accumulation coefficients of Fe, Mg, Mn, Cr, Mo, Ni, Co, Cu. For the root system of beans, a clear dependence of the accumulation of the considered elements on soil moisture is not observed.

Bacillus amyloliquefaciens strain BaNCT02: An antagonist with multiple mechanisms of action against Meloidogyne incognita

AbstractBacillus species are among the most studied and commercially exploited biocontrol agents of plant‐parasitic nematodes. These antagonists may control nematodes by producing toxic or repellent substances, inducing systemic resistance in plants and disrupting nematode chemotaxis. Understanding the mechanism of action of antagonists increases the likelihood of success for microbiological nematicides under field conditions. Therefore, the objective of this work was to elucidate the mechanisms of action of Bacillus amyloliquefaciens strain BaNCT02 against Meloidogyne incognita. We assessed the potential of this strain for forming biofilm in roots and producing volatile and non‐volatile toxic substances. BaNCT02 did not induce systemic resistance in tomato plants against M. incognita. Scanning electron microscopy and chemotaxis analyses revealed that the bacteria form a biofilm on soybean roots and 67% of second‐stage juveniles of M. incognita are repelled by common bean roots treated with the antagonist. Additionally, BaNCT02 produces substances with toxic effects against eggs and juveniles of M. incognita, including volatile organic compounds such as 2‐undecanone and 2‐heptanone, as well as non‐volatile metabolites like proteases and chitinases. The suppressive effect of these substances on hatching and mortality of juveniles varied from approximately 70% to more than 90%. We concluded that B. amyloliquefaciens BaNCT02 forms a biofilm on root surfaces and produces volatile and non‐volatile metabolites with nematicidal and repellent effects against M. incognita.

Identification, Characteristics, and Fungicide Efficacy of Seed-Associated Fungi of Saposhnikovia divaricata in Northeast China.

Saposhnikovia divaricata (Trucz.) Schischk. is one of the traditional medicinal herbs in Northeast China, and its roots are used for medicinal purposes. In 2020, a fungus isolated from S. divaricata seeds was observed to cause root rot of seedlings and leaf and stem spot of adult plants in Shuangyashan, Heilongjiang, China. Based on morphological and molecular data, isolates of all fungi were identified as Alternaria alternata. To our knowledge, this is the first report of A. alternata isolated from S. divaricata seeds in China. The carrying rate of S. divaricata seeds from 20 different collection sites reached 100% in 70% of the sites in Hulunbeier area, Inner Mongolia, China. The A. alternata isolate could infect the roots of cucumber, sorghum, mung bean, and maize seedlings and cause root rot. Considering the control of seed-associated fungal diseases, prochloraz 45% EW had the best control effect of 92.6%, followed by flusilazole 400 g liter-1 EC (88.9%) and azoxystrobin + propiconazole 18.7% SE (70.7%) of 15 fungicides. Further field control efficacy showed that 45% prochloraz EW had an 80% control efficacy on the disease at a dose of 0.225 g liter-1. It is recommended that soaking seeds and spraying are the best treatments for controlling seed-associated fungi and leaf spot on S. divaricata caused by A. alternata. Therefore, the aforementioned methods can effectively prevent the occurrence of fungal diseases of S. divaricata and provide a way to reduce reinfestation in the field.

New emerging Pseudomonads as causal agents of bean blight disease

Common bean (Phaseolus vulgaris) production is negatively affected by several bacterial plant diseases. A severe outbreak of bean blight was observed in the nine major bean-producing provinces of Iran during 2021–2022. Necrotic spots were observed on leaves which become necrotic with chlorosis beyond it. One hundred-sixty bacterial strains with a greyish-white colony appearance were consistently isolated from the one-hundred eighteen symptomatic bean leaf, pod, seed and root samples on nutrient agar. All strains were screened for their ability to cause disease bean leaves among which 134 strains induced chlorosis three days after inoculation on bean leaves of cv. Yaghoot followed by necrotic spots on the inoculated sites one week after inoculation. The pathogenic strains clustered in three groups based on phenotypic characters and multilocus sequencing analyses. Three housekeeping genes including gyrB, rpoB, and rpoD of representative strains were partially sequenced. In the phylogenetic tree based on concatenated sequences of these three genes or each gene individually, the strains were divided into three clusters each with high bootstrap support. The first group of the strains clustered with Pseudomonas simiae CCUG 50988T. This is the first report of this species as causal agent of bean blight. The second group clustered close to Pseudomonas alloputida NMI5768T which apparently belong to a new species. The third group clustered in a separate clade in Pseudomonas chlororaphis species which belongs to a new subspecies based on pathogenicity on bean, phenotypic characters, sequences of five housekeeping genes which named as subsp. phaseoli subsp. nov. with the type strain UT-M315.

Influences of cerium oxide nanoparticles and salinity on common bean (Phaseolus vulgaris) growth, physiology, and root system architectural and anatomical traits

Influences of cerium oxide nanoparticles and salinity on common bean (Phaseolus vulgaris) growth, physiology, and root system architectural and anatomical traits

Morphological, physiological, and transcriptomic analyses indicate that cell wall properties and antioxidant processes are potential targets for improving the aluminium tolerance of broad beans

Aluminium (Al) stress is the second-leading abiotic stress on crops. An improved understanding of the response mechanisms of plants to Al stress will provide scientific guidance for enhancing the crops’ tolerance to Al stress. In this study, Al stress (50–200 μM AlCl3) caused visible damage to broad bean (Vicia faba L.) roots rather than shoots, which was attributed to Al accumulation and distribution in different tissues. Root transcriptomic analysis revealed that Al stress altered cell wall properties by downregulating lignin synthesis and several xyloglucan endotransglucosylase/hydrolase-, expansin- and peroxidase (POD)-encoding genes, which likely weakened cell extensibility to inhibit root growth. Additionally, Al stress impeded reactive oxygen species scavenging pathways involving POD activity and flavonoid biosynthesis, leading to oxidative damage characterised by malondialdehyde accumulation. These results indicate that optimising cell wall properties and/or enhancing antioxidant processes are crucial for alleviating Al toxicity to broad beans. Interestingly, exogenous application (500 and 1000 μM) of the flavonoid apigenin effectively alleviated Al toxicity in broad bean roots by partially improving the total antioxidant capacity of the roots. This study contributes to understanding the interaction between plants and Al and provides new strategies to alleviate Al toxicity in crops.

Euphorbiaceae superoxide dismutase, catalase, and glutathione peroxidase as clues to better comprehend high drought tolerance in castor bean

Superoxide dismutase (SOD), Catalase (CAT), and Glutathione peroxidase (GPX) enzymes exert a central role in reactive oxygen species (ROS) scavenger in plants, being an important part of enzymatic antioxidant system. Despite the importance of these enzymes in ROS metabolism and in different signaling pathways related to plant development and stress response, their gene families have not yet been comprehensively characterized in many crop plants. Among different crops, the Euphorbiaceae family has some species highly tolerant to drought stress. However, the gene families that encode the antioxidant enzymes, as well as their role in this drought stress tolerance, remains not characterized. Here, the SOD, CAT, and GPX genes of castor bean (Ricinus communis), cassava (Manihot esculenta), jatropha (Jatropha curcas), rubber tree (Hevea brasiliensis), petty spurge (Euphorbia peplus), and annual mercury (Mercurialis annua) were identified and characterized. The comprehensive phylogenetic and genomic analyses allowed the classification of the genes into different classes and revealed the duplication events that contribute to the expansion of these families within plant genomes. The expression patterns of SOD, CAT, and GPX genes were examined in castor bean, cassava, jatropha, and rubber tree by RNA-seq analysis revealing differential expression during stress. Additionally, the castor bean gene expression was confirmed by RT-qPCR. Among castor bean genes, RcGPX4 appears to be induced in castor bean roots under drought stress, but the heterologous expression in Arabidopsis thaliana does not improve the drought tolerance. Altogether, this data has significantly contributed to characterizing the expression patterns and conducting evolutionary assessment of these genes in Euphorbiaceae. This bridge a gap in understanding the proposed functions of core components within the antioxidant mechanism in an economically significant group of plants, particularly during stress responses

Differential spatial plasticity response in common bean (Phaseolus vulgaris L.) root architecture under water stress is driven by increased root diameter, surface area and volume at deeper layers

Root plasticity enables plants to adapt to spatial and temporal changes in soil resources. In this study, 40 common bean genotypes evaluated for two root and shoot traits under irrigated and water stress. Three genotypes WB-216, WB-N-2, and WB-966 with contrasting plasticity responses were used for in-depth study. Highest positive plasticity for most root traits was found in case of WB-N2 and WB-216, whereas, WB-966 had negative plasticity for all the traits recorded. In terms of spatial plasticity for root traits in three root length sections, WB-216 was positively plastic for root diameter with progressive decrease from top to bottom sections. WB-N2 had positive plasticity values for root diameter, root surface area and root volume. WB-966 had negative plasticity for all the traits. For WB-216, the root diameter increased under drought in S1 but was almost same in bottom sections. In case of WB-N2, there was increase in root diameter in S2 and S3, but for WB-966, root diameter decreased in all sections. Similar trend was observed in all three genotypes for root surface area and volume. We report that major drivers of spatial plasticity of root architectural traits are increased root diameter, surface area and volume at deeper layers.

Antifungal activity of Neowestiellopsis persica against Rhizoctonia solani in root and crown of Faba bean cultivated under modified BG-110 medium composition

Rhizoctonia solani, a fungal pathogen, affects the quality and yield of Faba bean crops and hinders plant export. Chemical fungicides effectively control fungal pathogens, but their long-term use harms the environment, soil properties, and human health. Cyanobacteria, a promising source of natural bioactive compounds, have shown efficacy against the fungal colony growth of various plant pathogens, highlighting the need for sustainable practices. As a result, this study examined the biological control of the Rhizoctonia solani disease that affects the Faba bean's root and crown. Disease assessments were then done in five groups: (1) healthy control; (2) control infected with Rhizoctonia solani and not treated with cyanobacterial extract; (3) plant infected with Rhizoctonia solani and treated with cyanobacterial extract suspension of 0.02, (4) 0.04, and (5) 0.08 g/L phosphate during 20 and 34 days. The results of the antioxidant activity by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay showed that with increasing phosphate concentration, the activity increased significantly. The results of enzymatic activity indicated that time did not significantly impact the enzymatic activity of glutathione peroxidase (GPx), catalase (CAT), and guaiacol peroxidase (GPX), with the highest and lowest activity being related to codes 2 and control, respectively. However, time had a significant effect on superoxidase dismutase (SOD) activity, with the highest activity reported on day 35. Moreover, the results showed that increasing the concentration of the extract significantly decreased cell viability in hepatoblastoma (HepG-2) cell lines. The cyanobacterial extract treatment caused over 66 % damage to plants infected with Rhizoctonia solani. The overall results indicated that Neowestiellopsis persica, grown under higher phosphate concentrations, can be used as an effective antifungal biocontrol against Rhizoctonia solani in Faba bean roots and crowns.

Root growth and belowground interactions in spring wheat /faba bean intercrops

Abstract Background and aims Intercrops offer multiple advantages over sole crops. The aim of our study was to characterize root growth and interactions in spring wheat/faba bean intercrops to better understand belowground interactions that govern resource capture. Materials and methods A field experiment was conducted with one faba bean cultivar and two spring wheat cultivars sown at three sowing densities, defining three intercropping designs. Destructive root coring was conducted (0–100 cm) in the intercrops and sole crops at two development stages. FTIR spectroscopy was used to discriminate the species’ root masses. The plant-plant interaction index was calculated to represent the belowground interactions. Results A negative impact of intercropping on total root mass was observed in the treatment with high sowing density in both stages. For the fully and partial replacement design treatments, plant-plant facilitation was more pronounced than competition in all layers. Competition dominated root growth in the treatment with high sowing density in both stages. Lower sowing densities encouraged deep root growth of wheat (both cultivars) in intercropping. The early root growth in depth and in density of one spring wheat cultivar impacted negatively faba bean root growth. Intercropping resulted in a grain yield advantage in both fully and only one partial replacement design treatment. Conclusion In the intercrops, total root mass and plant-plant interactions were affected more by sowing density than by the spring wheat cultivar. Understanding the effect of sowing density on root growth in intercropping can help to support the design of sustainable intercropping systems.

Bioaccumulation and transferreing for impacts on Cd and Pb by aphid consumption of the broad bean, Vicia faba L, in soil heavy metal pollution

Heavy metal pollution threatens human and ecological health. Heavy metals can exist in the soil for a long time and migrate to organisms along the food chain. However, only a few studies have investigated the effects of a single stress on broad beans. Here, we aimed to characterize Cd and Pb bioaccumulation, at varying concentrations, in the broad bean, Vicia faba L. We also determined how the bioaccumulated metals are impacted by aphids that consume the plant. No significant difference was noted in the germination rates of broad beans at the early stage of planting (after 8 days), but eventually, the germination rates of broad beans at all time points first decreased and then increased, and the highest inhibition efficiency was observed in the T3 group (12.5 mg/L Cd2+ + 50 mg/L Pb2+). Fourteen days after planting, there was no significant difference in seedling height between the T5 (50 mg/L Cd2+ + 200 mg/L Pb2+) and control groups; however, that in the other groups decreased significantly and there was no dependence between stress concentration and inhibition efficiency. In addition, both Cd and Pb in the soil could be transferred to broad beans, and the concentration of Pb in the roots of broad beans was greater than that of Cd, whereas the opposite was observed in the stems and leaves. Notably, under mixed stress, aphids could significantly reduce the content of Cd in broad beans; similarly, the Pb content in the roots and stems of broad beans decreased significantly after being infested with aphids but increased significantly in the leaves. Further, the aphid infestation decreased the Pb content in the soil and the soil Cd content in the highest concentration group (T5 group) (50 mg/L Cd2+ + 200 mg/L Pb2+). These results highlight the necessity of focusing on the effect of insects on heavy metal remediation in plants and provide a new perspective for reducing plant Cd toxicity.

Morphological and pathogenic characterization of Fusarium species causing common bean root rot in Uganda

Fusarium root rot (FRR) of common bean occurs in Africa, Central and South America, and causes yield losses of up to 86%. Recently, FRR-like wilt symptoms were observed in Uganda’s agroecology zones. To identify the causal pathogen, we conducted surveys in seven agroecology zones to determine the prevalence and incidence of the reported disease. During the surveys, diseased roots were collected for pathogen isolation. Fungal strains were characterized using colony color, mycelial growth rate and microscopic structures such as conidia and microconidia. The pathogenicity of 99 strains on five bean varieties was determined in artificially inoculated soils in the screenhouse. Based on field symptoms, the observed wilting was identified to be Fusarium root rot, the prevalence of which varied across agroecologies, with the highest (95%) in the Karamoja pastoral zone (KP) and the lowest (40%) in West Nile farming system (WN). Similarly, the incidence of FRR was highest (87%) in KP, and lowest (20%) in WN. Fusarium strains differed in growth rate, colony color, shape and size of microscopic structures. All evaluated strains were pathogenic on common bean and caused severities of 0.9 to 98.3%. Further studies are required to identify the isolated strains at the species level using molecular tools.

Assessing Aluminum Stress Resilience in Common Bean Roots: Phenotypic, Histochemical, and PvGST/PvPOD Gene Expression Analysis

Common bean (Phaseolus vulgaris L.) is grown in various parts of the world. Aluminum (Al) toxicity poses a significant and widespread challenge in marginal areas with unfavorable soil qualities where common bean is grown. In acidic soils, stable forms of Al dissolve into the soil solution and inhibit root growth and function by injuring the root apex with phytotoxic ions. This leads to the development of a smaller root system, adversely affecting crop yield. In this study, the phenotypic evaluation for relative root elongation of 10 common bean genotypes/cultivars under Al stress (50 µM), the impact of Al toxicity using different histochemical dyes (Evan’s blue and Schiff’s reagent) and the expression levels of PvGST (Glutathione S-transferases) and PvPOD (peroxidase) genes in the root tissues of the most resistant/sensitive common beans under Al stress (50 µM) and control conditions (0 µM) were investigated. The maximum relative root elongation value (71.9%) was found in Önceler-98 cultivar, while the lowest value (14.1%) was obtained from Blksr-19 genotype. Histochemical applications used in the study supported phenotypic results. The cracks at the root tip and high blue color intensity were detected in Schiff’s reagent and Evan’s blue dyes in the Blksr-19, respectively. The expression levels of PvGST and PvPOD genes in the root tissue of the Blksr-19 (Al-sensitive) were highly upregulated at 24 h of Al stress treatment. The results revealed that these genes might be involved in the common bean root tissue's defense mechanism against Al stress for the first time. The findings herein will help plant breeders develop common bean cultivars tolerant to Al toxicity.

Production and characterization of bacterial cellulose by Rhizobium sp. isolated from bean root

Bacterial cellulose (BC) is a natural polymer renowned for its unique physicochemical and mechanical attributes, including notable water-holding capacity, crystallinity, and a pristine fiber network structure. While BC has broad applications spanning agriculture, industry, and medicine, its industrial utilization is hindered by production costs and yield limitations. In this study, Rhizobium sp. was isolated from bean roots and systematically assessed for BC synthesis under optimal conditions, with a comparative analysis against BC produced by Komagataeibacter hansenii. The study revealed that Rhizobium sp. exhibited optimal BC synthesis when supplied with a 1.5% glucose carbon source and a 0.15% yeast extract nitrogen source. Under static conditions at 30 °C and pH 6.5, the most favorable conditions for growth and BC production (2.5 g/L) were identified. Modifications were introduced using nisin to enhance BC properties, and the resulting BC-nisin composites were comprehensively characterized through various techniques, including FE-SEM, FTIR, porosity, swelling, filtration, and antibacterial activity assessments. The results demonstrated that BC produced by Rhizobium sp. displayed properties comparable to K. hansenii-produced BC. Furthermore, the BC-nisin composites exhibited remarkable inhibitory activity against Escherichia coli and Pseudomonas aeruginosa. This study contributes valuable insights into BC’s production, modification, and characterization utilizing Rhizobium sp., highlighting the exceptional properties that render it efficacious across diverse applications.

Genome-wide characterization of MATE family members in common bean (Phaseolus vulgaris Linn.) and their expression profiles in response to abiotic stress

Multidrug and toxic compound extrusion (MATE) family plays an important role in the detoxification process of plants under various stresses. Nevertheless, a comprehensive study on MATE family members has thus far not been performed in common bean (Phaseolus vulgaris Linn.), limiting our understanding of its functions in common bean acclimation to stressful environments. In this study, a total of 56 PvMATEs members with uneven distribution on all chromosomes were identified from the common bean genome, with the most on chromosome 4 (10 members) and the least on chromosome 6 and 10 (1 members). Based on their orthologous relationship with those from Arabidopsis and rice, PvMATEs were classified into Clades I, II, III and Ⅳ, wherein 19, 15, 14, and 8 members were included, respectively. Gene ontology (GO) term and cis-regulatory element (CRE) analyses results indicated that the potential functions of PvMATEs were involved in hormonal response, developmental regulation and multiple stress response of common bean. The results of Phytozome and qRT-PCR analyze showed that the expression of PvMATEs in common bean are tissue specificity, with the most in root. Furthermore, 75 mM NaCl, 75 mM CuCl2, 0.35uM HgCl2, 16uM CdCl2, 4.38uM Benzo[c]-phenanthrene (C18H12) and 10 % PEG6000 treatments significantly up-regulated the expression levels of some PvMATEs in common bean roots, indicating that these genes are involved in multiple abiotic stresses respond of common bean. Taken together, these observations enriched our knowledge of MATE family in the common bean and benefit for breeding improved cultivars.

GATA transcription factor in common bean: A comprehensive genome-wide functional characterization, identification, and abiotic stress response evaluation

The GATA transcription factors (TFs) have been extensively studied for its regulatory role in various biological processes in many plant species. The functional and molecular mechanism of GATA TFs in regulating tolerance to abiotic stress has not yet been studied in the common bean. This study analyzed the functional identity of the GATA gene family in the P. vulgaris genome under different abiotic and phytohormonal stress. The GATA gene family was systematically investigated in the P. vulgaris genome, and 31 PvGATA TFs were identified. The study found that 18 out of 31 PvGATA genes had undergone duplication events, emphasizing the role of gene duplication in GATA gene expansion. All the PvGATA genes were classified into four significant subfamilies, with 8, 3, 6, and 13 members in each subfamily (subfamilies I, II, III, and IV), respectively. All PvGATA protein sequences contained a single GATA domain, but subfamily II members had additional domains such as CCT and tify. A total of 799 promoter cis-regulatory elements (CREs) were predicted in the PvGATAs. Additionally, we used qRT-PCR to investigate the expression profiles of five PvGATA genes in the common bean roots under abiotic conditions. The results suggest that PvGATA01/10/25/28 may play crucial roles in regulating plant resistance against salt and drought stress and may be involved in phytohormone-mediated stress signaling pathways. PvGATA28 was selected for overexpression and cloned into N. benthamiana using Agrobacterium-mediated transformation. Transgenic lines were subjected to abiotic stress, and results showed a significant tolerance of transgenic lines to stress conditions compared to wild-type counterparts. The seed germination assay suggested an extended dormancy of transgenic lines compared to wild-type lines. This study provides a comprehensive analysis of the PvGATA gene family, which can serve as a foundation for future research on the function of GATA TFs in abiotic stress tolerance in common bean plants.

Impact of microbial consortium of Rhizobium tropici and Rhizobium mayense on the growth of Phaseolus vulgaris L.

The main objectives of the present investigation was to characterize and recognize potential indigenous Rhizobium spp. associated with red clover nodules, as well as to evaluate the influence of prospective rhizobia inoculation (individual and consortia) on common bean plant growth. Total of 8 rhizobia like bacteria were isolated and were investigated for their specific PGP traits, production of hydrolytic enzymes. Results revealed, four isolates synthesize IAA (22.3 ± 1.45 to 88.6 ± 1.45 μg mL−1), three isolates solubilized phosphate (40.69 ± 1.25 to 216.3 ± 1.31 μg mL−1), three isolates solubilized potassium, produced siderophore, and showed chitinase production, two isolates possess ACC deaminase activity, one isolate was able to solubilize zinc, 5 isolates produced β- 1, 3-glucanase (0.38 ± 0.005 to 2.82 ± 0.011 % units) and four isolates produced cellulase. Two bacterial isolates found to exhibit most of the PGP activities, were selected and identified on the basis of phenotypic, biochemical tests and 16S rRNA sequencing, as Rhizobium tropici IHTF-1 and Rhizobium mayense IHTF-2. Interaction of these potential rhizobium strains individually and consortia with common bean plants under greenhouse conditions boosted root and shoot length, fresh and dry biomass compared to un-inoculated control plants. SEM study revealed that both the strains, IHTF-1 and IHTF-2 colonized common bean roots. These results imply that Rhizobium spp., identified in this work, can be used as bio-inoculants to increase common bean plant production in a sustainable way.

Management of bean root rots by intercropping and legume diversification

Management of bean root rots by intercropping and legume diversification

Impacts of nano-acetamiprid pesticide on faba bean root metabolic response and soil health

The associated benefits and potential environmental risks of nanopesticides on plant and soil health, particularly in comparison with traditional pesticides, have not been systematically elucidated. Herein, we investigated the impacts of the as-synthesized nano-acetamiprid (Nano-Ace, 20 nm) at low (10 mg/L), medium (50 mg/L), high (100 mg/L) doses and the corresponding high commercial acetamiprid (Ace, 100 mg/L) on the physiological and metabolic response of faba bean (Vicia faba L.) plants, as well as on rhizosphere bacterial communities and functions over short-, medium- and long-term exposures. Overall, Nano-Ace exposure contributed to basic metabolic pathways (e.g., flavonoids, amino acids, TCA cycle intermediate, etc.) in faba bean roots across the whole exposure period. Moreover, Nano-Ace exposure enriched rhizosphere beneficial bacteria (e.g., Streptomyces (420.7%), Pseudomonas (33.8%), Flavobacterium (23.3%)) and suppressed pathogenic bacteria (e.g., Acidovorax (44.5%)). Additionally, Nano-Ace exposure showed a trend of low promotion and high inhibition of soil enzyme activities (e.g., invertase, urease, arylsulfatase, alkaline phosphatase) involved in soil C, N, S, and P cycling, while the inhibition was generally weaker than that of conventional Ace. Altogether, this study indicated that the redox-responsive nano-acetamiprid pesticide possessed high safety for host plants and soil health.