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Endophytic bacteria are the association of bacterial microbe resides inside the plant tissues. They are reported to alleviate several biotic and abiotic stresses of plant. They are also found to be promote growth of plant through their several functional attributes viz., nitrogen fixation, phosphate solubilization, siderophore production and by pro...
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In agriculture, Bacillus species are efficient and ecologically tool for promote the growth of the plant.
Purpose: This study obtains the plant growth-promoting (PGP) ability of endophytic bacteria isolated from the potato tubers.
Methods: Using endophytic bacteria to promote potato growth, achieve the purpose of increasing production. In this expe...
Dongxiang wild rice (Oryza rufipogon Griff.) germplasm is a precious resource for the improvement of agronomic traits in rice. Rice seeds also harbor a diverse endophytic bacterial community, and their interactions with their hosts and each other can influence plant growth and adaptability. Here, we investigated the community composition of cultiva...
In order to study the growth promoting potential of endophytic bacteria from Rehmannia glutinosa Libosch, a total of 25 different bacteria belonging to 7 genera were identified by 16S rRNA gene sequencing, including Bacillus, Micrococcus, Lysinibacillus, Brevibacterium, Halomonas, Kocuria and Terribacillus. In this study, thirteen bacterial strains...
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... It is known that the colonization of endophytes is the first and most crucial step in providing benefits to host plants [34,35]. It involves the penetration, growth, and reproduction of endophyte populations within the plant. ...
This study examined the potential of using the endophytic bacteria Bacillus subtilis (10-4 and 26D) to enrich hydroponically grown potato seed minitubers (Solanum tuberosum L. cv. Bashkirsky) to improve plant growth, photosynthetic pigments, yield, and quality parameters, including nutritional value (i.e., macro-/microelements, vitamin C, anthocyanins). Potato seed minitubers, obtained from in-vitro-grown microplants in a hydroponic system, were inoculated with endophytic B. subtilis and subsequently grown in pots under controlled conditions. The results demonstrated the successful colonization of seed minitubers by B. subtilis, with subsequent distribution into growing plants (roots, shoots). The endophytes accelerated the plant’s phenological shifts, resulting in earlier emergence of sprouts, budding, and flowering compared with control plants. They also had increased leaf photosynthetic pigments (chlorophyll (Chl) a, Chl b, and carotenoids), total leaf area, and positively influenced leaf proline contents. The height of plants and number of stems per plant did not change significantly upon endophyte treatment, but improved root growth was observed throughout the experiment. As a result of endophyte application, there was an increase in stolon weight, number and size of tubers, and overall tuber yield. There were no significant differences in terms of total dry matter and starch content of the tubers compared to the control group, but the sugar levels decreased and the size of the starch grains was larger in endophyte-treated tubers. Furthermore, endophyte treatment resulted in an increased accumulation of nutrients including N, P, K, Cu, and Fe, as well as vitamin C and anthocyanins in harvested tubers. These findings indicate that colonization of hydroponically grown potato seed minitubers with endophytic B. subtilis (10-4 and 26D) before planting has great potential as an eco-friendly approach to obtain higher-quality seeds and to increase tuber yield and nutritional value in field conditions.
... "A wide range of biologically active compounds are synthesized by Bacillus spp., including antibiotics, siderophores, lipopeptides, enzymes, and 1aminocyclopropane-1-carboxylate deaminase. They are known to affect the regulation of phytohormone biosynthesis pathways, modulate ethylene levels in plants and influence the emission of volatile organic compounds (VOCs) and the launch of host plants' systemic resistance/tolerance" [14,15,16,17]. ...
... Endophytic Bacillus strains have been developed as a key part of bio-control, since they colonize plant tissues and live in ecological niches similar to pathogens. Consequently, they can survive without external environmental influences while conferring economically useful properties on host plants [17,38]. Endophytic bacteria (B. ...
Bacillus subtilis non-pathogenic beneficial bacteria, promotes plant growth, disease resistance and tolerance to abiotic stresses. It produces bioactive substances with antibiotic properties and induces physiological features in plant metabolism without adverse effects on the environment or human health. Bacillus subtilis has been used to treat various postharvest diseases during handling, transportation and storage of various fresh fruits and vegetables. It is the first microorganism patented as a postharvest bio control agent for Brown rot of stone fruits, improving the post-harvest physiology of various fruit/vegetables. Bacillus strains AG1 and H110 have been shown to be effective against Vine wood fungal pathogens and post-harvest pathogens. They have been shown to reduce symptoms of Anthracnose in fruit caused by fungal pathogens Colletotrichum gloeosporioides and C. acutatum and White rot caused by Botryosphaeria dothidea. Endophytic Bacillus strains have been developed that can colonize plant tissues and live in the same ecological niches as pathogens, thus preventing post-harvest diseases and improving preservation during storage. Bacillus strains induce auxins, cytokinins, gibberellins, ABA, JA and SA in plants, which can stimulate plant growth under stressful conditions. Endophytic bacteria can induce ISR against pathogens and abiotic stressors, extending the shelf life of stored fruits and vegetables. Microbial antagonists can be applied after harvest to control fruit and vegetable diseases, but a single microbial strain cannot prevent all fruits/vegetables from decaying during storage. Combining diverse antagonistic microorganisms with diverse microbial activity and combining various bio-controlling characteristics can prevent post-harvest decay on fruits/vegetables.
... Last but not least, the colonization of endophytic bacilli in the plant interior provides an added benefit of sharing the similar niche as most pathogens. In addition, the stable environment inside the plant reduces competition from soil microbiome and protects against fluctuating environmental abiotic stresses [152]. ...
Nearly all plants and their organs are inhabited by endophytic microbes which play a crucial role in plant fitness and stress resilience. Harnessing endophytic services can provide effective solutions for a sustainable increase in agriculture productivity and can be used as a complement or alternative to agrochemicals. Shifting agriculture practices toward the use of nature-based solutions can contribute directly to the global challenges of food security and environmental sustainability. However, microbial inoculants have been used in agriculture for several decades with inconsistent efficacy. Key reasons of this inconsistent efficacy are linked to competition with indigenous soil microflora and inability to colonize plants. Endophytic microbes provide solutions to both of these issues which potentially make them better candidates for microbial inoculants. This article outlines the current advancements in endophytic research with special focus on endophytic bacilli. A better understanding of diverse mechanisms of disease control by bacilli is essential to achieve maximum biocontrol efficacy against multiple phytopathogens. Furthermore, we argue that integration of emerging technologies with strong theoretical frameworks have the potential to revolutionize biocontrol approaches based on endophytic microbes.
... Among the PGP bacteria associated with cereals, species belonging to such genera as Bacillus, Azospirillum, Arthrobacter, Acinetobacter, Azotobacter, Citricoccus, Lysinibacillus, Burkholderia, Paenibacillus, Serratia, Pseudomonas, etc. have been identified [31,35,38,39]. Beneficial endophytic PGP bacteria or endobacteria are of particular advantage as their vital activities of proceed asymptomatically inside the plant and have a positive effect on plant metabolism from the inside, thus providing protection of the host plant from adverse external conditions [20,37,40]. In addition, once introduced into the plant, endobacteria contribute to the formation of long-term plant protection, both during the entire ontogeny and in the postharvest period during storage of products [16,33,36,[41][42][43][44]. ...
... In addition, once introduced into the plant, endobacteria contribute to the formation of long-term plant protection, both during the entire ontogeny and in the postharvest period during storage of products [16,33,36,[41][42][43][44]. Endophytic microorganisms are widespread among plants and are found in different parts of plants [20,40,45,46]. The growth of endophytes in plant tissues is under the control of their host. ...
This review is devoted to the analysis and systematization of modern data on the participation of endophytic plant growth-promoting (PGP) bacteria in the regulation of growth, development, yield formation, and stress resistance of cultivated plants, mainly spring wheat as the main bread crop. The present data on the interaction of plants with PGP bacteria under normal and drought conditions are described. Particular attention is paid to the molecular mechanisms of regulation of plant metabolism by PGP bacteria, as well as their role in reducing the negative effects of drought, achieved by modulating various processes in plants, for example, improving the supply of moisture and mineral nutrients, and activating the antioxidant and osmoprotective plant systems. A key role in the adaptation and resistance/tolerance of plants caused by PGP bacteria is played by their ability to produce various metabolites with the properties of biologically active substances, including substances with antimicrobial and hormonal activity, enzymes and other compounds. Information about the endophytic microbiome of wheat is given and the elucidation of its role and functions in the plant stress response and adaptation that are necessary for the development of effective and safe strategies for their practical application in order to maximize the adaptation and productive potential of wheat under changing environmental conditions.
... Competition for scarce shared resources like iron may also lead to asymmetrical currency exchange, which could help to explain why some plant-microbe interactions are hostile (Hong and Park, 2016). Furthermore, because the rhizosphere is open, the free diffusion of resources derived from plants may promote higher levels of cheating in which mutant bacterial genotypes take benefit of "public goods" without producing substances that aid plant growth (Pandey et al., 2017). Because of this, mutualistic plant-microbe interactions may need additional enforcement from the plant, such as penalizing dishonest bacterial genotypes or positively identifying genotypes that promote plant growth (Ryan et al., 2008).Intriguing research would also be done to see whether endophytic bacteria and plants may coevolve from first neutral interaction and whether plants can coevolve in response to rhizosphere bacteria (Santos et al., 2018). ...
Endophytic bacteria are mainly present in the plant’s root systems. Endophytic bacteria improve plant health and are sometimes necessary to fight against adverse conditions. There is an increasing trend for the use of bacterial endophytes as bio-fertilizers. However, new challenges are also arising regarding the management of these newly discovered bacterial endophytes. Plant growth-promoting bacterial endophytes exist in a wide host range as part of their microbiome, and are proven to exhibit positive effects on plant growth. Endophytic bacterial communities within plant hosts are dynamic and affected by abiotic/biotic factors such as soil conditions, geographical distribution, climate, plant species, and plant-microbe interaction at a large scale. Therefore, there is a need to evaluate the mechanism of bacterial endophytes’ interaction with plants under field conditions before their application. Bacterial endophytes have both beneficial and harmful impacts on plants but the exact mechanism of interaction is poorly understood. A basic approach to exploit the potential genetic elements involved in an endophytic lifestyle is to compare the genomes of rhizospheric plant growth-promoting bacteria with endophytic bacteria. In this mini-review, we will be focused to characterize the genetic diversity and dynamics of endophyte interaction in different host plants.
... The efficacy of microbial inoculants depends on a variety of strain-dependent factors such as the ability to produce multiple plant growth-promoting traits and the ability to colonize the surface (epiphytes) or interior (endophytes) of the plant. Endophytic B. subtilis strains may be more effective at protecting plant growth under long-term stress conditions because the conditions inside the plant (stable pH, humidity, nutrient flux, and a lack of competition from many microorganisms) offer a stable host environment, allowing the bacteria to thrive and manifest their positive effects [28,29]. However, the behavior of any bacterial strain is at least partially dependent on the host species or varietal characteristics, geographic origin, environment, and stress type/level during growth [30][31][32][33][34][35]. ...
... The colonization of the inner tissues of the plant by endophytes plays a major role in forming effective microbial-plant interactions and is the factor influencing biological activity [8,28,58]. The finding demonstrated that the co-application of B. subtilis 10-4 and ABT did not prevent the bacterial capacity to colonize inner wheat tissues. ...
Endophytic Bacillus subtilis is a non-pathogenic beneficial bacterium which promotes plant growth and tolerance to abiotic stresses, including drought. However, the underlying physiological mechanisms are not well understood. In this study, the potential role that endogenous salicylic acid (SA) plays in regulating endophytic B. subtilis-mediated drought tolerance in wheat (Triticum aestivum L.) was examined. The study was conducted on genotypes with contrasting levels of intrinsic drought tolerance (drought-tolerant (DT) cv. Ekada70; drought-susceptible (DS) cv. Salavat Yulaev). It was revealed that B. subtilis 10-4 promoted endogenous SA accumulation and increased the relative level of transcripts of the PR-1 gene, a marker of the SA-dependent defense pathway, but two wheat cultivars responded differently, with the highest levels exhibited in DT wheat seedlings. These had a positive correlation with the ability of strain 10-4 to effectively protect DT wheat seedlings against drought injury by decreasing osmotic and oxidative damages (i.e., proline, water holding capacity (WHC), and malondialdehyde (MDA)). However, the use of the SA biosynthesis inhibitor 1-aminobenzotriazole prevented endogenous SA accumulation under normal conditions and the maintenance of its increased level under stress as well as abolished the effects of B. subtilis treatment. Particularly, the suppression of strain 10-4-induced effects on proline and WHC, which are both contributing factors to dehydration tolerance, was found. Moreover, the prevention of strain 10-4-induced wheat tolerance to the adverse impacts of drought, as judged by the degree of membrane lipid peroxidation (MDA) and plant growth (length, biomass), was revealed. Thus, these data provide an argument in favor of a key role of endogenous SA as a hormone intermediate in triggering the defense responses by B. subtilis 10-4, which also afford the foundation for the development of the bacterial-induced tolerance of these two different wheat genotypes under dehydration.
... Endophytic PGPMs play a major role in plant growth and development via multiple direct or indirect mechanisms. It is widely reported that endophyte-mediated plant growth improvement occurs through biofertilization and biostimulation: (i) providing the hosts with water and essential nutrients, such as N and P, by transforming them into effortless types, being digestible (using N fixatives, P solubilizers, siderophore producers, etc.) [19][20][21]91]; (ii) the synthesis of growth phytohormones (auxins (IAA), cytokinins (CKs), and gibberellins (GBs)) or alter the synthesis of stress and signaling phytohormones (i.e., abscisic acid (ABA), salicylic acid (SA), ethylene, and jasmonates) [19,21,23,[92][93][94]; and (iii) the synthesis of many compounds with protective and signaling functions (i.e., antibiotics, enzymes, siderophores, LPs, hydrogen cyanide and others) [30,31,82,90,94,95] Endophytes are capable of dissolving water-insoluble and other inaccessible forms of P, K, Mg and other essential compounds through the production of organic and inorganic acids, protons, hydroxyl ions and CO2 that facilitate their uptake by plants [96][97][98][99][100]. Some PGPMs produce organic compounds, such as gluconate, citrate, ketogluconate, tartrate, oxalate and lactate, which also helps solubilize inorganic P [101]. ...
... Gene-based evidence was provided for the aerobic (nitrification), microaerobic (N fixation) and anaerobic (denitrification) parts of the N cycle [102]. To meet the Fe requirements of endophytes, very specific pathways have developed with the participation of low-molecular Fe chelates-siderophores, which, by converting Fe into a form accessible to the cells, increase its availability for plants and digestibility [97]. Siderophore-producing endophytic PGPMs aid in Fe 3+ transport within the plant cell. ...
... They also contribute to plant growth and productivity by synthesizing ATP, DNA precursor and the heme. Moreover, siderophores give endophytes competitive advantages in the colonization of plant tissues, and exclusion of phytopathogenic microorganisms from the same ecological niche [97]. Endophytes also help to accumulate in plants of both significant (N, P, K, Na, Mg, etc.) and minor elements (Zn, Mn, Co, etc.) [100]. ...
Reduction of plant growth, yield and quality due to diverse environmental constrains along with climate change significantly limit the sustainable production of horticultural crops. In this review, we highlight the prospective impacts that are positive challenges for the application of beneficial microbial endophytes, nanomaterials (NMs), exogenous phytohormones strigolactones (SLs) and new breeding techniques (CRISPR), as well as controlled environment horticulture (CEH) using artificial light in sustainable production of horticultural crops. The benefits of such applications are often evaluated by measuring their impact on the metabolic, morphological and biochemical parameters of a variety of cultures, which typically results in higher yields with efficient use of resources when applied in greenhouse or field conditions. Endophytic microbes that promote plant growth play a key role in the adapting of plants to habitat, thereby improving their yield and prolonging their protection from biotic and abiotic stresses. Focusing on quality control, we considered the effects of the applications of microbial endophytes, a novel class of phytohormones SLs, as well as NMs and CEH using artificial light on horticultural commodities. In addition, the genomic editing of plants using CRISPR, including its role in modulating gene expression/transcription factors in improving crop production and tolerance, was also reviewed.
... For the biocontrol of postharvest pathogens, researchers have shown their interest mostly in endophytic strains of Bacillus spp. as they can colonize the internal plant tissues and can be found in close vicinity to the pathogens (Table 15.3). These are the reasons for their independent survival while conferring economically "useful" properties in host plants (Maksimov & Khairullin, 2016;Pandey et al., 2017;Rahman et al., 2019). ...
Genetic and environmental factors affect the crop productivity and health. Beneficial microorganisms are useful in increasing yields and used to minimize the use of synthetic pesticides and fertilizers. Currently, the most successful plant growth–enhancing bacteria belong to the genus Bacillus as they produce endospores that can withstand adverse climatic conditions. They produce various metabolites that inhibit pathogen by favoring plant growth. There is limited literature regarding mechanisms induced in plants by Bacillus spp. to combat biotic and abiotic stresses. Bacillus spp. secrete a wide variety of cell wall degrading enzymes that are related to the inhibition of many plant pathogenic bacteria, fungi, and viruses. These enzymes include chitosanase, protease, cellulase, glucanase, lipopeptides, and hydrogen cyanide. Unfavorable environmental stimuli affects the normal plant metabolism which reduces the health and crop yield. Bacillus-induced physiological changes, such as the activation of the antioxidant and defense systems, resemble the harmful effects of pathogens on crops. Interaction between Bacillus and plants triggers plant defenses against infections by influencing resistance genes, proteins, phytohormones, and metabolites. This chapter describes the current understanding of the mitigation mechanism of Bacillus spp. to pathogen-based biotic stress on horticultural crop plants.
... Biochemical pathways and genes have been identified that control bacterial IAA synthesis; it is assumed that L-tryptophan is the main precursor for IAA formation in microorganisms [77]. However, there may be other pathways for IAA biosynthesis (indole-3-acetamide, indole-3-pyruvate, and tryptamine), and sometimes a bacterial strain possesses more than one pathway for IAA synthesis [77,78]. It is believed that the ability to produce IAA is most widespread among soil bacteria [75] and is more common among endophytic bacteria than among epiphytic ones [77]. ...
... With a moisture deficit under the influence of treatment with the endophytic bacterium B. subtilis B26, in the shoots and roots of timothy, the accumulation of GABA increased and the drought resistance of plants increased [87]. The non-protein amino acid GABA, which rapidly accumulates in plant tissues in response to biotic and abiotic stresses, plays a significant role in plant adaptation to stress and is involved in the regulation of physiological and biochemical pathways that ensure plant resistance to stress, including water shortage [78]. GABA is associated with the maintenance of carbon-nitrogen balance, with the metabolism of amino acids, carbohydrates, and growth regulation [86]. ...
Environmental abiotic factors leading to water deficiency significantly limit the production of major crops worldwide (Z. Ahmad et al., 2018). In the face of rapid population growth and climate change, it is important to ensure food security, which is mainly possible by increasing the productivity of strategically important crops, including wheat, which is used for human consumption in manyregions of the world and provides more than 50 % of food energy needs (S. Asseng et al., 2019). Application of beneficial growth-stimulating bacteria Bacillus spp. are effective, environmentally friendly and safe natural strategy for protecting plants from stresses resulting in water deficiency (M. Kaushal et al., 2019; A. Hussain et al., 2020; M. Camaille et al., 2021). To date, the growth-stimulating and protective effect of Bacillus spp. under various abiotic stresses are indicated for a wide range of plants (S. Moon et al., 2017; H.G. Gowtham et al., 2020; N. Shobana et al., 2020), including wheat (G. Sood et al., 2020; U. Rashid et al., 2021). The mechanisms of this physiological action of Bacillus spp. on host plants remain largely unknown. Presumably, it is due to i) competition for space and nutrients with plant pathogens and increased availability of macro- and micronutrients (S. Danish et al., 2019; D. Miljakovic et al., 2020; А. Kumar et al., 2021), ii) production of a wide range of bioactive components and protective compounds (M. Saha et al., 2016; R. Çakmakçı et al., 2017; N. Ilyas et al., 2020), and iii) induction of plant systemic tolerance to stresses (I.A. Abd El-Daim et al., 2019; C. Blake et al., 2021; U. Rashid et al., 2021). The efficacy of the same Bacillus strain may vary, depending on many factors including a spectrum of the synthesized compounds, strains, plant species, ecological and geographical origin, varietal characteristics, the types of stresses during the growing season, etc. (A. Khalid et al., 2004; G. Salem et al., 2018; O. Lastochkina et al., 2020). This review summarizes an information on the current state of research and the latest available information on plant-microbe interactions with a focus on protecting wheat against drought. In particular, the mech-anisms underlying Bacillus-mediated adaptation and tolerance of wheat plants to drought are under consideration. It is shown that Bacillus spp. can induce wheat drought tolerance due to i) synthesis of compounds which provide protection against osmotic and oxidative stresses (D. Miljakovic et al., 2020; R. Çakmakçı et al., 2017), ii) intracellular transmission and enhancement of protective signals by a cascade of mediators, iii) regulation of the protective protein gene expression and interorgan transduc-tion with the participation of the main phytohormones, their biosynthesis in the whole plant (U. Rashid et al., 2021), and iv) numerous compounds involved in increasing the bioavailability of macro- and microelements and productivity (А. Hussain et al., 2020; А. Kumar et al., 2021). Bacillus spp. can positively influence plant photosynthesis and water exchange (I.A. Abd El-Daim et al., 2019), as well as drought tolerance of wheat genotypes of different agroecological groups (L.I. Pusenkova et al., 2020). The joint use of Bacillus bacteria with other natural growth regulators enhance their effectiveness and stability of action (M. Zafar-ul-Hye et al., 2019). The listed commercial bacillary biologicals are effective on wheats
. The review contributes to the understanding of the fundamental mechanisms of wheat—Bacillus spp. interactions under drought, the development of Bacillus-based biologicals and their use in ecologically oriented technologies for wheat growing under changing climate conditions.
... The effectiveness of bacteria may depend on various characteristics of each strain, including the capacity to confer multiple plant growth-promoting (PGP) traits and the ability to colonize either plant's surface (epiphytes) or interior tissues (endophytes). Endophytic B. subtilis are the most successful bacteria for plant growth and development under long-term stress conditions, due to stable pH, humidity, nutrient flow, lack of competition from a large number of microorganisms and the ability to influence plants from the inside (Sessitsch et al., 2012;Pandey et al., 2017). With that, the same bacterial strain may act differently depending, for example, on the type of host plant species, its varietal characteristics, ecological and geographical origin, etc. (Lastochkina et al., 2017(Lastochkina et al., , 2019. ...
... However, under high stress (2%NaCl) we observed that in bacterial primed plants the LRN, as well as root length, were significantly increased in comparison with non-primed plants (Fig. 3D), which indicates a triggering bacterial-mediated protective mechanism in plants. 10-4 and 26D have an intrinsic ability to colonize internal plant tissues (Fig. 1) and positively affect plant metabolism from there (Sessitsch et al., 2012;Pandey et al., 2017;Lastochkina et al., 2019). Strain 10-4 likely colonizes internal plant tissues better due to increased IAA production in comparison with 26D, since Bacillus spp. ...
Bacillus subtilis is one of the non-pathogenic beneficial bacteria that promote plant growth and stress tolerance. In the present study, we revealed that seed priming with endophytic B. subtilis (strains 10-4, 26D) improved Phaseolus vulgaris L. (common bean) seed germination and plant growth under both saline and non-saline conditions. 10-4 and 26D decreased oxidative and osmotic damage to the plant cells since bacterial inoculations reduced lipid peroxidation and proline accumulation in plants under salinity. 26D and especially 10-4 preserved different elevated levels of chlorophyll (Chl) a and Chl b in bean leaves under salinity, while carotenoids (Car) increased only by 10-4 and slightly decreased by 26D. Under normal conditions, 10-4 and 26D did not affect Chl a and Car concentrations, while Chl b decreased in the same plants. Under non-saline and especially saline conditions, 10-4 and 26D significantly increased lignin accumulation in plant roots and the highest lignin content along with better growth and oxidative damages reduction was observed after 10-4 inoculation under salinity, indicating a major role of B. subtilis-induced strengthening the root cell walls in the implementation protective effect of studied bacteria on plants. Therefore, B. subtilis 10-4 and 26D exerts protective effects on the growth of common bean plants under salinity by regulating plant defense mechanisms and the major role in tolerance development may contribute through the activation by B. subtilis lignin deposition in roots. The obtained data also indicates a strain-dependent efficiency of endophytic B. subtilis since strains 10-4 and 26D differently improved growth attributes and modulates cellular response reactions of the same common bean plants both under normal and salinity conditions, that generates interest for further investigations in this direction.
