Evaluation of Polyphenols Synthesized in Mature Seeds of Common Bean (Phaseolus vulgaris L.) Advanced Mutant Lines.

This study aimed to investigate the availability of flavonoids, anthocyanins, and phenolic acids in mutant bean seeds, focusing on M7 mutant lines, and their corresponding initial and local cultivars. HPLC-DAD-MS/MS and HPLC-MS/MS were used to analyze twenty-eight genotypes of common bean. The obtained results suggest that the mutations resulted in four newly synthesized anthocyanins in the mutant bean seeds, namely, delphinidin 3-O-glucoside, cyanidin 3-O-glucoside, pelargonidin 3-O-glucoside, and petunidin 3-O-glucoside, in 20 accessions with colored seed shapes out of the total of 28. Importantly, the initial cultivar with white seeds, as well as the mutant white seeds, did not contain anthocyanins. The mutant lines were classified into groups based on their colors as novel qualitative characteristics. Five phenolic acids were further quantified: ferulic, p-coumaric, caffeic, sinapic, and traces of chlorogenic acids. Flavonoids were represented by epicatechin, quercetin, and luteolin, and their concentrations in the mutant genotypes were several-fold superior compared to those of the initial cultivar. All mutant lines exhibited higher concentrations of phenolic acids and flavonoids. These findings contribute to the understanding of the genetics and biochemistry of phenolic accumulation and anthocyanin production in common bean seeds, which is relevant to health benefits and might have implications for common bean breeding programs and food security efforts.

Common Bean (Phaseolus vulgaris L.) NAC Transcriptional Factor PvNAC52 Enhances Transgenic Arabidopsis Resistance to Salt, Alkali, Osmotic, and ABA Stress by Upregulating Stress-Responsive Genes.

The NAC family of transcription factors includes no apical meristem (NAM), Arabidopsis thaliana transcription activator 1/2 (ATAF1/2), and cup-shaped cotyledon (CUC2) proteins, which are unique to plants, contributing significantly to their adaptation to environmental challenges. In the present study, we observed that the PvNAC52 protein is predominantly expressed in the cell membrane, cytoplasm, and nucleus. Overexpression of PvNAC52 in Arabidopsis strengthened plant resilience to salt, alkali, osmotic, and ABA stresses. PvNAC52 significantly (p < 0.05) reduced the degree of oxidative damage to cell membranes, proline content, and plant water loss by increasing the expression of MSD1, FSD1, CSD1, POD, PRX69, CAT, and P5CS2. Moreover, the expression of genes associated with abiotic stress responses, such as SOS1, P5S1, RD29A, NCED3, ABIs, LEAs, and DREBs, was enhanced by PvNAC52 overexpression. A yeast one-hybrid assay showed that PvNAC52 specifically binds to the cis-acting elements ABRE (abscisic acid-responsive elements, ACGTG) within the promoter. This further suggests that PvNAC52 is responsible for the transcriptional modulation of abiotic stress response genes by identifying the core sequence, ACGTG. These findings provide a theoretical foundation for the further analysis of the targeted cis-acting elements and genes downstream of PvNAC52 in the common bean.

Light-independent pathway of STN7 kinase activation under low temperature stress in runner bean (Phaseolus coccineus L.).

BACKGROUND: The phosphorylation of the Light-Harvesting Complex of photosystem II (LHCII) driven by STATE TRANSITION 7 (STN7) kinase is a part of one of the crucial regulatory mechanisms of photosynthetic light reactions operating in fluctuating environmental conditions, light in particular. There are evidenced that STN7 can also be activated without light as well as in dark-chilling conditions. However, the biochemical mechanism standing behind this complex metabolic pathway has not been deciphered yet. RESULTS: In this work, we showed that dark-chilling induces light-independent LHCII phosphorylation in runner bean (Phaseolus coccineus L.). In dark-chilling conditions, we registered an increased reduction of the PQ pool which led to activation of STN7 kinase, subsequent LHCII phosphorylation, and possible LHCII relocation inside the thylakoid membrane. We also presented the formation of a complex composed of phosphorylated LHCII and photosystem I typically formed upon light-induced phosphorylation. Moreover, we indicated that the observed steps were preceded by the activation of the oxidative pentose phosphate pathway (OPPP) enzymes and starch accumulation. CONCLUSIONS: Our results suggest a direct connection between photosynthetic complexes reorganization and dark-chilling-induced activation of the thioredoxin system. The proposed possible pathway starts from the activation of OPPP enzymes and further NADPH-dependent thioredoxin reductase C (NTRC) activation. In the next steps, NTRC simultaneously activates ADP-glucose pyrophosphorylase and thylakoid membrane-located NAD(P)H dehydrogenase-like complex. These results in starch synthesis and electron transfer to the plastoquinone (PQ) pool, respectively. Reduced PQ pool activates STN7 kinase which phosphorylates LHCII. In this work, we present a new perspective on the mechanisms involving photosynthetic complexes while efficiently operating in the darkness. Although we describe the studied pathway in detail, taking into account also the time course of the following steps, the biological significance of this phenomenon remains puzzling.

Ultrasound-assisted germination of red kidney beans: Enhancements in physicochemical and nutritional profiles.

To improve the conventional germination process and improve the nutritional quality of red kidney beans, this study employed high-intensity ultrasound (HIU) supplemented with hydrogen peroxide as a pre-germination treatment. The results showed that the 350 W-10 min treatment yielded the highest germination rate (77.09%), with its sprout length 81.13% greater than that of the control group. The 350 W-10 min treatment increased total protein, soluble protein, and ash content, while simultaneously reducing the fat, starch, and soluble sugar content. The HIU treatment accelerated the accumulation of phenolic and flavonoid compounds, ascorbic acid, and γ-aminobutyric acid. The 350 W-10 min treatment also decreased the levels of phytic acid, trypsin inhibitor activity, and tannin by 42.71%, 65.58%, and 53.18%, respectively. Furthermore, ultrasonic cavitation enhanced antioxidative capacity and improved amino acid composition and protein digestibility. Consequently, HIU serves as a cost-efficient method to accelerate the germination process and enhance their nutritional composition.

Improving the antinutritional profiles of common beans (Phaseolus vulgaris L.) moderately impacts carotenoid bioaccessibility but not mineral solubility.

Common beans are a common staple food with valuable nutritional qualities, but their high contents in antinutritional factors (ANFs) can decrease the bioavailability of (i) fat-soluble micronutrients including carotenoids and (ii) minerals. Our objective was to select ANF-poor bean lines that would not interfere with carotenoid and mineral bioavailability. To achieve this objective, seeds of commercial and experimental Phaseolus vulgaris L. bean lines were produced for 2 years and the bean's content in ANFs (saponins, phytates, tannins, total polyphenols) was assessed. We then measured carotenoid bioaccessibility and mineral solubility (i.e. the fraction of carotenoid and mineral that transfer into the aqueous phase of the digesta and is therefore absorbable) from prepared beans using in vitro digestion. All beans contained at least 200 mg/100 g of saponins and 2.44 mg/100 g tannins. The low phytic acid (lpa) lines, lpa1 and lpa12 exhibited lower phytate levels (≈ - 80%, p = 0.007 and p = 0.02) than their control BAT-93. However, this decrease had no significant impact on mineral solubility. HP5/1 (lpa + phaseolin and lectin PHA-E free) bean line, induced an improvement in carotenoid bioaccessibility (i.e., + 38%, p = 0.02, and + 32%, p = 0.005, for phytofluene bioaccessibility in 2021 and 2022, respectively). We conclude that decrease in the phytate bean content should thus likely be associated to decreases in other ANFs such as tannins or polyphenols to lead to significant improvement of micronutrient bioaccessibility.

Non-toxic orange carbon dots stimulate photosynthesis and CO2 assimilation in hydroponically cultivated green beans (Phaseolus vulgaris).

Continuous increasing leaf photosynthesis may enhance plant yield. As an evolutionary property, plants use less photosynthetic capacity than is theoretically possible. Plant nanobionics is a bioengineering field that improves plant functions using nanoparticles. We applied orange carbon dots (o-CDs) onto the foliage of green beans (Phaseolus vulgaris ) grown in hydroponics to improve their photosynthetic performance and CO2 assimilation. Photosynthesis parameters, photosynthetic pigments content, total phenolic content (TPC) and antioxidative activity (TAA) were measured. Results show that photosynthetic pigments remained unchanged, while photosynthesis was improved. Both o-CDs concentrations decreased TPC and TAA. The light response curve showed higher CO2 assimilation at both o-CDs concentrations, particularly at lower light intensity. Correlation analysis confirmed increased CO2 binding and assimilation at 1mg L-1 . This study demonstrated the potential of using o-CDs as a safe biostimulator through photosynthesis increase and CO2 assimilation without toxic effects on plants. This may stimulate yield increase that paves the way for their agricultural application.

Measurement of O2 Uptake and Evolution in Leaves In Vivo Using Stable Isotopes and Membrane Inlet Mass Spectrometry.

Oxygen is both product and substrate of photosynthesis and metabolism in plants, by oxygen evolution through water splitting and uptake by photorespiration and respiration. It is important to investigate these processes simultaneously in leaves, especially in response to environmental variables, such as light and temperature. To distinguish between processes that evolve or take up O2 in leaves in the light, in vivo gas exchange of stable isotopes of oxygen and membrane inlet mass spectrometry is used. A closed-cuvette system for gas exchange of leaf discs is described, using the stable isotopes 16O2 and 18O2, with a semi-permeable membrane gas inlet and isotope mass separation and detection by mass spectrometry. Measurement of evolution and uptake, as well as CO2 uptake, at a range of light levels allows composition of a light response curve, here described for French bean (Phaseolus vulgaris) and maize (Zea mays) leaf discs.

Phytohemagglutinin from Phaseolus vulgaris enhances the lung cancer cell chemotherapy sensitivity by changing cell membrane permeability.

Chemotherapy is still a prevalent strategy for clinical lung cancer treatment. However, the inevitable emerged drug resistance has become a great hurdle to therapeutic effect. Studies have demonstrated that the primary cause of drug resistance is a decrease in the chemotherapeutic medicine concentration. Several lectins have been confirmed to be effective as chemotherapy adjuvants, enhancing the anti-tumor effects of chemotherapy drugs. Here, we combined phytohemagglutinin (PHA), which has been reported possess anti-tumor effects, with chemotherapy drugs Cisplatin (DDP) and Adriamycin (ADM) on lung cancer cells to detect the sensitivities of PHA as a chemotherapy adjuvant. Our results demonstrated that the PHA significantly enhanced the sensitivity of lung cancer cells to DDP and ADM, and Western blot showed that PHA combined with DDP or ADM enhance cytotoxic effects by inhibiting autophagy and promoting apoptosis. More importantly, we found PHA enhanced the chemotherapeutic drugs cytotoxicity by changing the cell membrane to increase the intracellular chemotherapeutic drugs concentration. Besides, the combination of PHA and ADM increased the ADM concentration in the multidrug-resistant strain A549-R cells and achieved the drug sensitization effect. Our results suggest that PHA combined with chemotherapy can be applied in the treatment of lung cancer cells and lung cancer multidrug-resistant strains, and provide a novel strategy for clinical tumor chemotherapy and a new idea to solve the problem of drug resistance in clinical lung cancer.

Impact of Chlorella vulgaris, Nannochloropsis salina, and Arthrospira platensis as bio-stimulants on common bean plant growth, yield and antioxidant capacity.

The use of bio-stimulants in agriculture has emerged as a promising strategy to improve crop growth and yield. One type of bio-stimulant that has gained attention is microalgae extracts, which are known for their high metabolic activity, bioactive compounds, and ability to enhance plant growth and development. To investigate their effectiveness, a pot experiment was conducted at the Experimental Farm of Helwan University in Egypt during the 2022 season. The experiment aimed to evaluate the efficacy of Chlorella vulgaris, Nannochloropsis salina, and Arthrospira platensis (Spirulina platensis) extracts as bio-stimulants, applied through foliar spray at concentrations ranging from 0.25 to 2.0%, on common bean plants. Analysis of algal extract showed that . N. salina had the highest content of promotive growth hormones gibberellins (GA3) (74.85 ± 2.7mg100 g-1 d.wt). and auxins (IAA) (34.57 ± 2.7µg 100 g-1 d.wt.) compared to Chlorella and Arthrospira..The results revealed that the application of C. vulgaris, N. salina, and A. platensis extracts at concentrations up to 1.0% significantly improved various growth parameters, such as root, and shoot length, number of leaves and flowers per plant, leaf area, and total fresh and dry weight per plant. These extracts also positively affected yield attributes, including the number and fresh weight of pods per plant, seed index, seed yield per plant, and per feddan [a unit of land area]. Furthermore, the application of these extracts increased the chlorophyll content index with the maximum values of CCI (17.95. and 17.81%) was obtained at 0.50% N. salina, followed by 0.50% C.vulgaris. In addition to increase in the capacity of both non-enzymatic antioxidants [such as total antioxidant capacity, phenolics, and flavonoids] and enzymatic antioxidants [including catalase and ascorbic oxidase]. The most promising results were observed with the application of N. salina, and C. vulgaris extracts at a concentration of 0.5%. Additionally, the extracts significantly reduced the content of oxidative stress markers, such as malondialdehyde, percentage of electrolyte leakage, and hydrogen peroxide, in common bean plants compared to the control group. Contrarily, the measured parameters were reduced, while the levels of oxidative stress markers and some antioxidants including peroxidase, ascorbic peroxidase, superoxide dismutase, glutathione peroxidase, and glutathione transferase were increased by three algal extracts at a concentration of 2.0%, compared to control plants. Additionally, the application of these microalgae extracts improved the quality parameters, proximate composition, seed energy, and mineral contents of the harvested seeds, with the most significant positive impact was observed at 0.5% concentration of algal extract. These findings demonstrate the successful and safe utilization of extracts from C. vulgaris, N. salina, and A. platensis at concentrations up to 1.0% as bio-stimulants to enhance common bean yields and improve the nutritional quality of dried beans for consumers.

A novel pectin methylesterase inhibitor, PMEI3, in common bean suggests a key role of pectin methylesterification in Pseudomonas resistance.

The mechanisms underlying susceptibility to and defense against Pseudomonas syringae (Pph) of the common bean (Phaseolus vulgaris) have not yet been clarified. To investigate these, 15-day-old plants of the variety Riñón were infected with Pph and the transcriptomic changes at 2 h and 9 h post-infection were analysed. RNA-seq analysis showed an up-regulation of genes involved in defense/signaling at 2 h, most of them being down-regulated at 9 h, suggesting that Pph inhibits the transcriptomic reprogramming of the plant. This trend was also observed in the modulation of 101 cell wall-related genes. Cell wall composition changes at early stages of Pph infection were associated with homogalacturonan methylation and the formation of egg boxes. Among the cell wall genes modulated, a pectin methylesterase inhibitor 3 (PvPMEI3) gene, closely related to AtPMEI3, was detected. PvPMEI3 protein was located in the apoplast and its pectin methylesterase inhibitory activity was demonstrated. PvPMEI3 seems to be a good candidate to play a key role in Pph infection, which was supported by analysis of an Arabidopsis pmei3 mutant, which showed susceptibility to Pph, in contrast to resistant Arabidopsis Col-0 plants. These results indicate a key role of the degree of pectin methylesterification in host resistance to Pph during the first steps of the attack.

The effect of heat moisture treatment times on physicochemical and digestibility properties of adzuki bean, pea, and white kidney bean flours and starches.

The effects of heat moisture treatment (HMT) times on the physicochemical properties of three bean flours and their starch were analyzed. The colors of L*, b* and ΔE values increased significantly with time. The adzuki bean and pea flours showed better WAI and SP, and better gelation of starch at 2 h. The rheological properties of mixed HMT dough (3:7) exhibited the typical solid-like weak gel behavior. HMT had a significantly decreased on the pasting viscosity of bean flour starch with treated time. HMT caused the starch granules damage, but did not radically change the crystal type. FTIR results showed more proteins attached to the surface of starch granules, and the short-range molecular order decreased the DO at 2 h. In vitro digestibility inferred that RDS converted into SDS and RS. These results indicated that HMT significantly affected the digestibility and physicochemical properties of bean flours.

Genome wide identification, structural characterization and phylogenetic analysis of High-Affinity potassium (HAK) ion transporters in common bean (Phaseolus vulgaris L.).

BACKGROUND: High-Affinity Potassium ions represent one of the most important and large group of potassium transporters. Although HAK genes have been studied in a variety of plant species, yet, remain unexplored in common bean. RESULTS: In the current study, 20 HAK genes were identified in common bean genome. Super-family "K_trans" domain was found in all PvHAK genes. Signals for localization of PvHAK proteins were detected in cell membrane. Fifty three HAKs genes, across diverse plant species, were divided into 5 groups based on sequential homology. Twelve pairs of orthologs genes were found in various plant species. PvHAKs genes were distributed unequally on 7 chromosomes with maximum number (7) mapped on chromosome 2 while only 1 PvHAK found on each chromosome 1, 4, and 6. Tandem gene duplication was witnessed in 2 paralog pairs while 1 pair exhibited segmental gene duplication. Five groups were made in PvHAK gene family based on Phylogeny. Maximum PvHAKs (10) were detected in Group-V while group-II composed of only 1 PvHAK gene. Variation was witnessed in number and size of motifs, and structure of PvHAKs associated with different groups. Light and hormone responsive elements contributed 57 and 24% share, respectively, to cis regulatory elements. qRT-PCR based results revealed significant increase in expression of all 4 PvHAK genes under low-potassium stress. CONCLUSION: The current study provides valuable information for further functional characterization and uncovering the molecular mechanism associated with Potassium transportation in plants.

Iron and zinc biofortification of rice by synergistic expression of OsNAS2 gene with monocot (Pennisetum glaucum) and dicot (Phaseolus vulgaris) ferritins.

Iron and zinc deficiencies are the most prevalent cause of global hidden hunger. Rice, being one of the most consumed crops worldwide, is suitable to target for Fe and Zn biofortification. In present study, we generated rice transgenic lines to meet the recommended dietary requirement of iron and zinc through endosperm specific expression of dicot (kidney bean) and monocot (pearl millet) Ferritins along with constitutive expression of rice nicotianamine synthase 2 (OsNAS2) gene. Visualization through perls' prussian staining and quantification by ICP-MS showed significant improvement in grain iron content in all the transgenic lines. The transgenic lines expressing any of the three selected gene combinations (PvFerrtin-OsNAS2, feedPgFerrtin-OsNAS2 and foodPgFerritin-OsNAS2), showed the potential to surpass the 30% of the estimated average requirement (13 µg/g Fe and 28 µg/g Zn) proposed for rice in HarvestPlus breeding program. Though the expression of PvFerritin along with OsNAS2 gene in IET10364 (indica) variety showed the best result, providing up to 4.2- and 3.5-fold increase in iron (30.56 µg/g) and zinc (60.1 µg/g) content, respectively; in polished grains compared to non-transgenic control. Thus, the lines developed in our study can be used for further breeding purpose to enhance the iron and zinc content in commercial rice varieties.

Impact of foliar spray with Se, nano-Se and sodium sulfate on growth, yield and metabolic activities of red kidney bean.

Sulfur (S) is an essential microelement for plants. Based on the chemical similarity between Se and S, selenium may affects sulphur uptake by plants. This work aimed at investigating the effect of foliar spray with sodium selenate, gum arabic coated selenium nanoparticles (GA-SeNPs ≈ 48.22 nm) and sodium sulfate on red kidney bean (Phaseolus vulgaris L.) plants. Each treatment was used at 0.0, 1, 5, 10 and 50 µM, alone or combination of sodium sulfate with either Se or nano-Se, each at 0.5, 2.5 and 5 µM concentrations. The effect of foliar spray on vegetative growth, seed quality, and some metabolic constituents of red kidney bean (Phaseolus vulgaris L.) plants were investigated. Selenium nanoparticles have been synthesized through the green route using gum arabic (as a stabilizing and coating agent. Foliar application of different concentrations of Se, nano-Se, Na2SO4 up to 10 µM and their interaction were effective in increasing the growth criteria (i.e. shoot and root lengths, plant fresh and dry weights, number of leaves and photosynthetic area (cm2 plant-1).There was also a significant increase in photosynthetic pigment contents, yield (i.e., 100-seed weight), total carbohydrate, crude proteins and mineral contents in both leaf as compared to their untreated control plants. Furthermore, interaction between sodium sulfate with nano-Se or Se, each at 5 µM significantly increased the vegetative growth, 100-seed weight, and pigment contents in leaves and improved the nutritional value and quality of red kidney bean seeds.

Genome-wide analysis of the SMXL gene family in common bean and identification of karrikin-responsive PvSMXL2 as a negative regulator of PEG-induced drought stress.

Common bean (Phaseolus vulgaris L.) is a major legume crop worldwide, but its growth and development frequently face challenges due to abiotic stresses, particularly drought. Proper supplement of copper could mitigate the adverse effects of drought, but excessive accumulation of this metal in plants can be harmful. The suppressor of MAX2 1-like (SMXL) gene family, which plays important roles in various plant processes, including stress responses, remains poorly understood in common bean. In this study, we identified nine orthologues of SMXL genes in common bean, which are located on six chromosomes and classified into four subgroups. Basic molecular properties, including theoretical isoelectric point (PI), molecular weight (MW), grand average of hydropathicity (GVIO), gene structure, and conserved motifs were characterized, and numerous cis-elements in promoters were predicted. The expression patterns of PvSMXL genes were found to be distinct under 10% polyethylene glycol (PEG)-induced drought stress and 200 µM Cu treatments. Most PvSMXLs showed reduced expression in response to Cu treatment, whereas nearly half PvSMXLs exhibited inducible expression under drought stress. PvSMXL2, which exhibited a rapid response to karrikin 1 (KAR1), an active form of the plant growth regulators newly found in the smoke of burning plant material, was down-regulated by both PEG-induced drought and Cu stresses. Transient silencing of PvSMXL2 resulted in enhanced drought stress tolerance without conferring Cu tolerance. These findings provide valuable insights into the functions of SMXL genes in common bean under abiotic stress conditions.

Metabolomic analysis reveals stress tolerance mechanisms in common bean (Phaseolus vulgaris L.) related to treatment with a biostimulant obtained from Corynebacterium glutamicum.

Microbial biostimulants have emerged as a sustainable alternative to increase the productivity and quality of important crops. Despite this, the effects of the treatment on plant metabolism are poorly understood. Thus, this study investigated the metabolic response of common bean (Phaseolus vulgaris) related to the treatment with a biostimulant obtained from the extract of Corynebacterium glutamicum that showed positive effects on the development, growth, and yield of crops previously. By untargeted metabolomic analysis using UHPLC-MS/MS, plants and seeds were subjected to treatment with the biostimulant. Under ideal growth conditions, the plants treated exhibited higher concentration levels of glutamic acid, nicotiflorin and glycosylated lipids derived from linolenic acid. The foliar application of the biostimulant under water stress conditions increased the chlorophyll content by 17% and induced the accumulation of flavonols, mainly quercetin derivatives. Also, germination seed assays exhibited longer radicle lengths for seeds treated compared to the untreated control even in the absence of light (13-18% increase, p-value <0.05). Metabolomic analysis of the seeds indicated changes in concentration levels of amino acids (tryptophan, phenylalanine, tyrosine, glutamine, and arginine) and their derivatives. The results point out the enhancement of abiotic stress tolerance and the metabolic processes triggered in this crop associated with the treatment with the biostimulant, giving the first insights into stress tolerance mechanisms in P. vulgaris.

Jasmonic acid boosts the salt tolerance of kidney beans (Phaseolus vulgaris L.) by upregulating its osmolytes and antioxidant mechanism.

As a lipid-derived compound, jasmonic acid (JA) regulates growth and defense against environmental stresses. An exogenous foliar JA application was investigated in our study (HA; 0.5 mM) on kidney bean plants (Phaseolus vulgaris L.) grown under different salinity stress concentrations (0, 75, and 150 mM NaCl). According to the results, salt concentrations were related to an increase in malondialdehyde (MDA) levels, whereas they declined the chlorophyll content index. In contrast, JA application decreased the level of MDA but increased the chlorophyll content index. Moreover, increasing salinity levels increased proline, phenolic compounds, flavonoids, free amino acid concentrations, and shikimic acid concentrations, as well as the activities of polyphenol oxidase (PPO), ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD). In addition, JA applications further increased their concentrations with increasing salinity stress levels. JA application increases salt-induced osmolytes and non-enzymatic antioxidants while increasing enzymatic antioxidant activity, suggesting kidney beans have a strong antioxidant mechanism, which can adapt to salinity stress. Our results showed that exogenous JA foliar applications could enhance the salt tolerance ability of kidney bean plants by upregulating their antioxidant mechanism and osmolytes.

CRK12: A Key Player in Regulating the Phaseolus vulgaris-Rhizobium tropici Symbiotic Interaction.

Cysteine-rich receptor-like kinases (CRKs) are a type of receptor-like kinases (RLKs) that are important for pathogen resistance, extracellular reactive oxygen species (ROS) signaling, and programmed cell death in plants. In a previous study, we identified 46 CRK family members in the Phaseolus vulgaris genome and found that CRK12 was highly upregulated under root nodule symbiotic conditions. To better understand the role of CRK12 in the Phaseolus-Rhizobia symbiotic interaction, we functionally characterized this gene by overexpressing (CRK12-OE) and silencing (CRK12-RNAi) it in a P. vulgaris hairy root system. We found that the constitutive expression of CRK12 led to an increase in root hair length and the expression of root hair regulatory genes, while silencing the gene had the opposite effect. During symbiosis, CRK12-RNAi resulted in a significant reduction in nodule numbers, while CRK12-OE roots showed a dramatic increase in rhizobial infection threads and the number of nodules. Nodule cross sections revealed that silenced nodules had very few infected cells, while CRK12-OE nodules had enlarged infected cells, whose numbers had increased compared to controls. As expected, CRK12-RNAi negatively affected nitrogen fixation, while CRK12-OE nodules fixed 1.5 times more nitrogen than controls. Expression levels of genes involved in symbiosis and ROS signaling, as well as nitrogen export genes, supported the nodule phenotypes. Moreover, nodule senescence was prolonged in CRK12-overexpressing roots. Subcellular localization assays showed that the PvCRK12 protein localized to the plasma membrane, and the spatiotemporal expression patterns of the CRK12-promoter::GUS-GFP analysis revealed a symbiosis-specific expression of CRK12 during the early stages of rhizobial infection and in the development of nodules. Our findings suggest that CRK12, a membrane RLK, is a novel regulator of Phaseolus vulgaris-Rhizobium tropici symbiosis.

Glutathione-mediated changes in productivity, photosynthetic efficiency, osmolytes, and antioxidant capacity of common beans (Phaseolus vulgaris) grown under water deficit.

Globally, salinity and drought are severe abiotic stresses that presently threaten vegetable production. This study investigates the potential exogenously-applied glutathione (GSH) to relieve water deficits on Phaseolus vulgaris plants cultivated in saline soil conditions (6.22 dS m-1) by evaluating agronomic, stability index of membrane, water satatus, osmolytes, and antioxidant capacity responses. During two open field growing seasons (2017 and 2018), foliar spraying of glutathione (GSH) at 0.5 (GSH1) or 1.0 (GSH1) mM and three irrigation rates (I100 = 100%, I80 = 80% and I60 = 60% of the crop evapotranspiration) were applied to common bean plants. Water deficits significantly decreased common bean growth, green pods yield, integrity of the membranes, plant water status, SPAD chlorophyll index, and photosynthetic capacity (Fv/Fm, PI), while not improving the irrigation use efficiency (IUE) compared to full irrigation. Foliar-applied GSH markedly lessened drought-induced damages to bean plants, by enhancing the above variables. The integrative I80 + GSH1 or GSH2 and I60 + GSH1 or GSH2 elevated the IUE and exceeded the full irrigation without GSH application (I100) treatment by 38% and 37%, and 33% and 28%, respectively. Drought stress increased proline and total soluble sugars content while decreased the total free amino acids content. However, GSH-supplemented drought-stressed plants mediated further increases in all analyzed osmolytes contents. Exogenous GSH enhanced the common bean antioxidative machinery, being promoted the glutathione and ascorbic acid content as well as up-regulated the activity of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase. These findings demonstrate the efficacy of exogenous GSH in alleviating water deficit in bean plants cultivated in salty soil.

NMR-Based Metabolomic Study on Phaseolus vulgaris Flour Fermented by Lactic Acid Bacteria and Yeasts.

In recent years, fermented foods have attracted increasing attention due to their important role in the human diet, since they supply beneficial health effects, providing important sources of nutrients. In this respect, a comprehensive characterization of the metabolite content in fermented foods is required to achieve a complete vision of physiological, microbiological, and functional traits. In the present preliminary study, the NMR-based metabolomic approach combined with chemometrics has been applied, for the first time, to investigate the metabolite content of Phaseolus vulgaris flour fermented by different lactic acid bacteria (LAB) and yeasts. A differentiation of microorganisms (LAB and yeasts), LAB metabolism (homo- and heterofermentative hexose fermentation), LAB genus (Lactobacillus, Leuconostoc, and Pediococcus), and novel genera (Lacticaseibacillus, Lactiplantibacillus, and Lentilactobacillus) was achieved. Moreover, our findings showed an increase of free amino acids and bioactive molecules, such as GABA, and a degradation of anti-nutritional compounds, such as raffinose and stachyose, confirming the beneficial effects of fermentation processes and the potential use of fermented flours in the production of healthy baking foods. Finally, among all microorganisms considered, the Lactiplantibacillus plantarum species was found to be the most effective in fermenting bean flour, as a larger amount of free amino acids were assessed in their analysis, denoting more intensive proteolytic activity.