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Salinity stress significantly threatens seed germination, plant growth, and agricultural productivity, necessitating effective mitigation strategies. This study evaluates the potential of salicylic acid (SA) pretreatment to alleviate the detrimental effects of salinity on common bean ( Phaseolus vulgaris ) genotypes. SA, a phenolic plant hormone, is crucial for regulating growth, stress responses, and essential physiological processes, including seed germination and ion transport. Previous research has established the general benefits of SA in enhancing stress tolerance, but the specific mechanisms and effects on common bean genotypes remain underexplored. This research focuses on the impact of salinity on the germination and seedling growth of various common bean genotypes, the efficacy of SA pretreatment in enhancing these genotypes' tolerance to salinity stress, and the underlying physiological and biochemical mechanisms, particularly involving the antioxidant defense system. The research was conducted in two phases: germination and seedling growth. Ten genotypes and two commercial varieties were exposed to varying salinity levels alongside SA concentrations to assess germination performance. Subsequently, six genotypes and one variety were evaluated for seedling growth under controlled and salt stress conditions (100 mM and 200 mM NaCl), with SA treatments at 0, 0.5, and 1 mM. Results revealed that salinity severely impaired germination traits, which were significantly enhanced by SA pretreatment. During the seedling growth phase, salinity stress resulted in reduced protein, chlorophyll, and carotenoid content, decreased potassium (K⁺) levels, and diminished water content, while increasing electrolyte leakage, malondialdehyde (MDA) levels, sodium (Na⁺) concentrations, enzyme activities, and proline levels. Importantly, SA pretreatment elevated chlorophyll and protein concentrations, improved water retention, and moderated K⁺ and Na⁺ levels, including their ratios under stress conditions. SA pretreatment also significantly enhanced the antioxidant defense system, reducing oxidative damage induced by salinity stress. Principal component analysis (PCA) successfully categorized the genotypes into semi-tolerant, tolerant, semi-sensitive, and sensitive classes based on their stress responses. Notably, the Jules variety exhibited exceptional resilience during both germination and seedling growth stages, indicating its potential as a superior candidate for cultivation in salt-affected regions. This study highlights SA pretreatment as an effective strategy to enhance salinity stress resilience in common bean genotypes. The novelty of this work lies in the detailed elucidation of SA's role in modulating antioxidant defenses and ion homeostasis in different genotypes, providing new insights into breeding programs and agricultural practices aimed at improving crop resilience and productivity in increasingly saline environments.

Essential oils (EO) of several plant species have the potential to combat plant and fungal diseases. However, the effects of Achillea millefolium EO on the development of common bean ( Phaseolus vulgaris L.), is still unknown. Moreover, its effect on N 2 -fixing bacteria, and in general on soil properties has not been studied yet. A greenhouse trial was set up to evaluate both the influence that Achillea millefolium EO and the inoculation with three different Rhizobium strains have on the bean plant and on the chemical and microbiological properties of an agriculturally used Cambisol. Non-inoculated pots were used as control. Our findings showed a decrease in bacterial colony forming units due to EO application and an increase following the Rhizobium inoculation compared to the control. The EO application decreased soil basal respiration and activities of dehydrogenase, urease, β-glucosidase and acid phosphatase. Such effects were stronger with higher oil concentrations. Moreover, the treatments combining Rhizobium inoculation with EO showed a positive effect on nodulation and plant height. Overall, the combined application of Achillea millefolium EO and rhizobia works as an efficient biocide that could be applied in organic agriculture without hampering the activity of nodule-forming N-fixing bacteria and the development of common bean.

The reactive oxygen species (ROS) generated by respiratory burst oxidative homologs (Rbohs) are involved in numerous plant cell signaling processes, and have critical roles in the symbiosis between legumes and nitrogen‐fixing bacteria. Previously, down‐regulation of RbohB in Phaseolus vulgaris was shown to suppress ROS production and abolish Rhizobium infection thread (IT) progression, but also to enhance arbuscular mycorrhizal fungal (AMF) colonization. Thus, Rbohs function both as positive and negative regulators. Here, we assessed the effect of enhancing ROS concentrations, by overexpressing PvRbohB, on the P. vulgaris–rhizobia and P. vulgaris–AMF symbioses. We estimated superoxide concentrations in hairy roots overexpressing PvRbohB, determined the status of early and late events of both Rhizobium and AMF interactions in symbiont‐inoculated roots, and analyzed the nodule ultrastructure of transgenic plants overexpressing PvRbohB. Overexpression of PvRbohB significantly enhanced ROS production, the formation of ITs, nodule biomass, and nitrogen‐fixing activity, and increased the density of symbiosomes in nodules, and the density and size of bacteroides in symbiosomes. Furthermore, PvCAT, early nodulin, PvSS1, and PvGOGAT transcript abundances were elevated in these nodules. By contrast, mycorrhizal colonization was reduced in roots that overexpressed RbohB. Overexpression of PvRbohB augmented nodule efficiency by enhancing nitrogen fixation and delaying nodule senescence, but impaired AMF colonization.

The cultivation of common beans ( Phaseolus vulgaris L.) in semi-arid regions is affected by drought. To explore potential alleviation strategies, we investigated the impact of inoculation with Bacillus velezensis , and the application of acetylsalicylic acid (ASA) via foliage application (FA), which promote plant growth and enhance stress tolerance. A split-split-plot experiment with four replications was conducted, featuring two irrigation levels: full watering (FW, 100% of plant water requirements) and deficit watering (DW, 70% of plant water requirements) as a main plot, two ASA levels (No foliage application (NFA) 0 and 0.5 mM) as sub plot, and bacterial inoculation (BI) versus non-bacterial inoculation (NBI) as sub-sub plot. Results showed that the highest grain yield was achieved with the ASA + BI under FW (3270 kg ha − ¹), a 56% increase compared to the control (2094 kg ha − ¹). Under DW, the ASA + BI increased yield by approximately 30%. ASA significantly increased relative water content under deficit watering, achieving 84% with BI. Chlorophyll a content peaked at 3.11 mg g − 1 with full watering, and chlorophyll b content increased by up to 23.8% under deficit watering, indicating improved photosynthetic capacity. Malondialdehyde and hydrogen peroxide levels were reduced to 10.88 and 14.81 µmol g − ¹ fresh weight, respectively, in ASA + BI treatments, demonstrating reduced oxidative stress. Antioxidant enzyme activities were significantly elevated in treated plants under DW. This study demonstrates the potential of microbial and hormonal treatments in boosting drought tolerance in common beans, providing a viable approach for sustaining crop performance under stress conditions.

Premise of the study: The soil-inhabiting insect-pathogenic fungus Metarhizium robertsii also colonizes plant roots endophytically, thus showing potential as a plant symbiont. Metarhizium robertsii is not randomly distributed in soils but preferentially associates with the plant rhizosphere when applied in agricultural settings. Root surface and endophytic colonization of switchgrass (Panicum virgatum) and haricot beans (Phaseolus vulgaris) by M. robertsii were examined after inoculation with fungal conidia. Methods: We used light and confocal microscopy to ascertain the plant endophytic association with GFP-expressing M. robertsii. Root lengths, root hair density, and lateral roots emerged were also observed. Key results: Initially, M. robertsii conidia adhered to, germinated on, and colonized roots. Furthermore, plant roots treated with Metarhizium grew faster and the density of plant root hairs increased when compared with control plants. The onset of plant root hair proliferation was initiated before germination of M. robertsii on the root (within 1-2 d). Plants inoculated with M.robertsii AMAD2 (plant adhesin gene) took significantly longer to show root hair proliferation than the wild type. Cell free extracts of M. robertsii did not stimulate root hair proliferation. Longer-term (60 d) associations showed that M. robertsii endophytically colonized cortical cells within bean roots. Metarhizium appeared as a mycelial aggregate within root cortical cells as well as between the intercellular spaces with no apparent damage to the plant. Conclusions: These results suggest that M. robertsii is not only rhizosphere competent but also displays a beneficial endophytic association with plant roots that results in the proliferation of root hairs.

The use of agricultural fertilizers is one of the methods to beat the desired enormous increase in universal food production. The application of nanotechnology in agriculture is regarded as one of the promising approaches to elevate crop production. Whereas mineral nutrients play a crucial role in the growth and yield of the common bean. The experiments were conducted to investigate the application effect of micronutrients as nanoparticles (MN-NPs) on the common ben plants. The trial was performed in the field in El-Menofya, Egypt, through two seasons (2019 & 2020) in a randomized complete block design with three replicates and four combinations of MN-NPs (ZnO, MnO 2 and MoO 3 ) with concentrations 0, 10, 20, 30, 40 mg/L as a foliar application. The data exhibited that the foliar application of MN-NPs significantly upgraded the vegetative growth characters, flower number/plant, photosynthetic pigments, and yield. The concentration of 40 mg/L of MN-NPs leads to improving the vegetative growth, flowering number, and yield characteristics of the common bean. While the biochemical components varied in their response to MN-NPs combinations. The recommended MN-NPs concentration to ameliorate the common bean growth and yield was 40 mg/L.

Background Physical seed dormancy is an important trait in legume domestication. Although seed dormancy is beneficial in wild ecosystems, it is generally considered to be an undesirable trait in crops due to reduction in yield and / or quality. The physiological mechanism and underlying genetic factor(s) of seed dormancy is largely unknown in several legume species. Here we employed an integrative approach to understand the mechanisms controlling physical seed dormancy in common bean ( Phaseolus vulgaris L.). Results Using an innovative CT scan imaging system, we were able to track water movements inside the seed coat. We found that water uptake initiates from the bean seed lens. Using a scanning electron microscopy (SEM) we further identified several micro-cracks on the lens surface of non-dormant bean genotypes. Bulked segregant analysis (BSA) was conducted on a bi-parental RIL (recombinant inbred line) population, segregating for seed dormancy. This analysis revealed that the seed water uptake is associated with a single major QTL on Pv03. The QTL region was fine-mapped to a 118 Kb interval possessing 11 genes. Coding sequence analysis of candidate genes revealed a 5-bp insertion in an ortholog of pectin acetylesterase 8 that causes a frame shift, loss-of-function mutation in non-dormant genotype. Gene expression analysis of the candidate genes in the seed coat of contrasting genotypes indicated 21-fold lower expression of pectin acetylesterase 8 in non-dormant genotype. An analysis of mutational polymorphism was conducted among wild and domesticated beans. Although all the wild beans possessed the functional allele of pectin acetylesterase 8 , the majority (77%) of domesticated beans had the non-functional allele suggesting that this variant was under strong selection pressure through domestication. Conclusions In this study, we identified the physiological mechanism of physical seed dormancy and have identified a candidate allele causing variation in this trait. Our findings suggest that a 5-bp insertion in an ortholog of pectin acetylesterase 8 is likely a major causative mutation underlying the loss of seed dormancy during domestication. Although the results of current study provide strong evidences for the role of pectin acetylesterase 8 in seed dormancy, further confirmations seem necessary by employing transgenic approaches.

Over the past century, plant breeding programs have substantially improved plant growth and health, but have not yet considered the potential effects on the plant microbiome. Here, we conducted metatranscriptome analysis to determine if and how breeding for resistance of common bean against the root pathogen Fusarium oxysporum ( Fox ) affected gene expression in the rhizobacterial community. Our data revealed that the microbiome of the Fox -resistant cultivar presented a significantly higher expression of genes associated with nutrient metabolism, motility, chemotaxis, and the biosynthesis of the antifungal compounds phenazine and colicin V. Network analysis further revealed a more complex community for Fox -resistant cultivar and indicated Paenibacillus as a keystone genus in the rhizosphere microbiome. We suggest that resistance breeding in common bean has unintentionally co-selected for plant traits that strengthen the rhizosphere microbiome network structure and enrich for specific beneficial bacterial genera that express antifungal traits involved in plant protection against infections by root pathogens.

Common bean productivity in arid and semi-arid regions is frequently constrained by water deficit and micronutrient limitations. This study aimed to (i) quantify the effects of deficit irrigation and foliar micronutrient application on growth, yield, and water productivity, and (ii) elucidate the physiological and biochemical mechanisms underlying genotype-specific drought tolerance. Field experiments were conducted over two growing seasons on sandy soil using three common bean varieties (Nebraska, Giza 3, and Giza 6). Treatments were arranged in a split–split-plot randomized complete block design, with varieties as main plots, irrigation regimes [full irrigation (F100%), moderate deficit (D80%), and severe deficit (D70%)] as subplots, and foliar-applied micronutrients (Fe, Zn, and Mn at three rates) as sub-subplots. Measurements at mid- and late-growth stages included chlorophyll content, antioxidant enzyme activity, leaf micronutrient concentrations, growth traits, grain quality, yield, and water productivity. Giza 6 exhibited superior early physiological responses, with significantly higher chlorophyll content and antioxidant enzyme activity under the highest micronutrient rate (T 3 : 15 Fe : 30 Zn : 20 Mn). Under prolonged deficit irrigation, the combination of moderate stress (D80%) and T 2 –T 3 applications sustained higher leaf Fe, Zn, and Mn concentrations, supporting continued growth and nutrient translocation. Clear genotypic differences were observed, with Giza 6 maintaining higher grain quality, yield, and water productivity under water-limited conditions, whereas Nebraska showed greater sensitivity despite micronutrient supplementation. These findings demonstrate that integrated water–nutrient management enhances drought resilience through improved physiological stability and nutrient homeostasis. Combining moderate deficit irrigation with targeted micronutrient application is an effective strategy to optimize productivity and water use efficiency in drought-prone environments.

Nitrogen management and harvest timing are critical determinants of fresh bean ( Phaseolus vulgaris L.) pod quality; however, their combined effects on morphological, colorimetric and biochemical characteristics during pod development remain insufficiently characterized. This study evaluated the effects of four nitrogen top-dressing fertilizers (ammonium sulfate [AS], slow-release fertilizer [SRF], nitropower [NP], and urea) and five pod development stages (BBCH 72–81) on pod morphology, color parameters, antioxidant capacity, phenolic compounds, flavonoids, and protein content under field conditions. Nitrogen top-dressing significantly prolonged days to 50% flowering and pod setting times, with the latest flowering observed under urea treatment compared to basal fertilization. Pod length and width increased with advancing development stages, while pod water content declined from early stages to physiological maturity. Colorimetric analysis revealed a marked increase in lightness (L*), yellowness (b*) and chroma values with maturation, accompanied by a decrease in hue angle, indicating reduction in greenness and increase in yellowness. Antioxidant capacity exhibited a stage-dependent pattern, with lower values at intermediate stages and higher values at late development stages, particularly under urea treatment. Total phenolic, flavonoid and protein content increased significantly at the final development stage. Strong positive correlations were detected between antioxidant capacity, phenolic, flavonoid and protein content, whereas pod water content showed significant negative correlations with these quality traits. Overall, the results demonstrate that development stage plays a key role in determining pod quality, while nitrogen source influences the magnitude of these responses. Late harvest stages (BBCH 79–81), together with stable nitrogen sources such as SRF and AS, could be employed to improve nutritional and antioxidant properties of fresh bean pods.