Combination Of Abiotic Stresses Research Articles

Correlation between plant cell wall stiffening and root extension arrest phenotype in the combined abiotic stress of Fe and Al.

The plasticity and growth of plant cell walls (CWs) remain poorly understood at the molecular level. In this work, we used atomic force microscopy (AFM) to observe elastic responses of the root transition zone of 4-day-old Arabidopsis thaliana wild-type and almt1-mutant seedlings grown under Fe or Al stresses. Elastic parameters were deduced from force-distance curve measurements using the trimechanic-3PCS framework. The presence of single metal species Fe2+ or Al3+ at 10 µM exerts no noticeable effect on the root growth compared with the control conditions. On the contrary, a mix of both the metal ions produced a strong root-extension arrest concomitant with significant increase of CW stiffness. Raising the concentration of either Fe2+ or Al3+ to 20 µM, no root-extension arrest was observed; nevertheless, an increase in root stiffness occurred. In the presence of both the metal ions at 10 µM, root-extension arrest was not observed in the almt1 mutant, which substantially abolishes the ability to exude malate. Our results indicate that the combination of Fe2+ and Al3+ with exuded malate is crucial for both CW stiffening and root-extension arrest. However, stiffness increase induced by single Fe2+ or Al3+ is not sufficient for arresting root growth in our experimental conditions.

Silicon modifies leaf nutriome and improves growth of oak seedlings exposed to phosphorus deficiency and Phytophthora plurivora infection.

Beneficial effects of silicon (Si) on plants have primarily been studied in crop species under single stress. Moreover, nutrient acquisition-based responses to combination of biotic and abiotic stresses (a common situation in natural habitats) have rarely been reported, in particular in conjunction with soil amendments with Si. Pedunculate oak (Quercus robur L.), one of the ecologically and economically most important tree species in Europe, is facing a severe decline due to combined stresses, but also problems in assisted regeneration in nurseries. Here, we studied the effect of Si supply on the leaf nutriome, root traits and overall growth of 12-weeks-old oak seedlings exposed to abiotic stress [low phosphorus (P) supply], biotic stress (Phytophthora plurivora root infection), and their combination. The application of Si had the strongest ameliorative effect on growth, root health and root phenome under the most severe stress conditions (i.e., combination of P deficiency and P. plurivora root infection), where it differentially affected the uptake and leaf accumulation in 11 out of 13 analysed nutrients. Silicon supply tended to reverse the pattern of change of some, but not all, leaf nutrients affected by stresses: P, boron (B) and magnesium (Mg) under P deficiency, and P, B and sulphur (S) under pathogen attack, but also nickel (Ni) and molybdenum (Mo) under all three stresses. Surprisingly, Si affected some nutrients that were not changed by a particular stress itself and decreased leaf Mg levels under all the stresses. On the other hand, pathogen attack increased leaf accumulation of Si. This exploratory work presents the complexity of nutrient crosstalk under three stresses, and opens more questions about genetic networks that control plant physiological responses. Practically, we show a potential of Si application to improve P status and root health in oak seedlings, particularly in nurseries.

OsCM regulates rice defence system in response to UV light supplemented with drought stress.

Studies on plant responses to combined abiotic stresses are very limited, especially in major crop plants. The current study evaluated the response of chorismate mutase overexpressor (OxCM) rice line to combined UV light and drought stress. The experiments were conducted in pots in a growth chamber, and data were assessed for gene expression, antioxidant and hormone regulation, flavonoid accumulation, phenotypic variation, and amino acid accumulation. Wild-type (WT) rice had reduced the growth and vigour, while transgenic rice maintained growth and vigour under combined UV light and drought stress. ROS and lipid peroxidation analysis revealed that chorismate mutase (OsCM) reduced oxidative stress mediated by ROS scavenging and reduced lipid peroxidation. The combined stresses reduced biosynthesis of total flavonoids, kaempferol and quercetin in WT plants, but increased significantly in plants with OxCM. Phytohormone analysis showed that SA was reduced by 50% in WT and 73% in transgenic plants, while ABA was reduced by 22% in WT plants but increased to 129% in transgenic plants. Expression of chorismate mutase regulates phenylalanine biosynthesis, UV light and drought stress-responsive genes, e.g., phenylalanine ammonia lyase (OsPAL), dehydrin (OsDHN), dehydration-responsive element-binding (OsDREB), ras-related protein 7 (OsRab7), ultraviolet-B resistance 8 (OsUVR8), WRKY transcription factor 89 (OsWRKY89) and tryptophan synthase alpha chain (OsTSA). Moreover, OsCM also increases accumulation of free amino acids (aspartic acid, glutamic acid, leucine, tyrosine, phenylalanine and proline) and sodium (Na), potassium (K), and calcium (Ca) ions in response to the combined stresses. Together, these results suggest that chorismate mutase expression induces physiological, biochemical and molecular changes that enhance rice tolerance to combined UV light and drought stresses.

Comparison of metabolomic reconfiguration between Columbia and Landsberg ecotypes subjected to the combination of high salinity and increased irradiance

BackgroundPlants growing in the field are subjected to combinations of abiotic stresses. These conditions pose a devastating threat to crops, decreasing their yield and causing a negative economic impact on agricultural production. Metabolic responses play a key role in plant acclimation to stress and natural variation for these metabolic changes could be key for plant adaptation to fluctuating environmental conditions.ResultsHere we studied the metabolomic response of two Arabidopsis ecotypes (Columbia-0 [Col] and Landsberg erecta-0 [Ler]), widely used as genetic background for Arabidopsis mutant collections, subjected to the combination of high salinity and increased irradiance. Our findings demonstrate that this stress combination results in a specific metabolic response, different than that of the individual stresses. Although both ecotypes displayed reduced growth and quantum yield of photosystem II, as well as increased foliar damage and malondialdehyde accumulation, different mechanisms to tolerate the stress combination were observed. These included a relocation of amino acids and sugars to act as potential osmoprotectants, and the accumulation of different stress-protective compounds such as polyamines or secondary metabolites.ConclusionsOur findings reflect an initial identification of metabolic pathways that differentially change under stress combination that could be considered in studies of stress combination of Arabidopsis mutants that include Col or Ler as genetic backgrounds.

From challenges to solutions: The impact of melatonin on abiotic stress synergies in horticultural plants via redox regulation and epigenetic signaling

In the face of escalating environmental challenges, plants encounter complex combinations of abiotic stresses that pose severe threats to their growth and survival. Recent advancements have shed light on the multifaceted role of melatonin, revealing its intricate interplay with redox regulation and epigenetic signaling in plant stress responses. As a versatile ally, melatonin orchestrates a cascade of redox regulatory events that counteract the oxidative damage caused by abiotic stress synergies. Melatonin strengthens plant defenses by fine-tuning antioxidant systems and directly scavenging reactive oxygen species (ROS), mitigating oxidative stress, and preserving cellular homeostasis. Moreover, melatonin interacts with epigenetic mechanisms, exerting control over gene expression through DNA methylation, histone modifications, and miRNA regulation. These epigenetic modifications have far-reaching implications in shaping stress-responsive gene networks and enabling plants to adapt to complex stress scenarios. However, understanding the intricate crosstalk by which melatonin coordinates redox regulation and epigenetic signaling to develop novel strategies to enhance plant resilience against a wide range of abiotic stresses remains unclear. This review delves into the current advancements, knowledge gaps, and charting future directions of melatonin-induced redox regulation and epigenetic signaling as the key mechanisms underlying abiotic stress resilience in plants. This study will pave the way for the future development of sustainable agricultural production of major horticulture crops, offering a beacon of hope amid mounting environmental challenges.

Natural variation in Brachypodium distachyon responses to combined abiotic stresses.

The demand for agricultural production is becoming more challenging as climate change increases global temperature and the frequency of extreme weather events. This study examines the phenotypic variation of 149 accessions of Brachypodium distachyon under drought, heat, and the combination of stresses. Heat alone causes the largest amounts of tissue damage while the combination of stresses causes the largest decrease in biomass compared to other treatments. Notably, Bd21-0, the reference line for B. distachyon, did not have robust growth under stress conditions, especially the heat and combined drought and heat treatments. The climate of origin was significantly associated with B. distachyon responses to the assessed stress conditions. Additionally, a GWAS found loci associated with changes in plant height and the amount of damaged tissue under stress. Some of these SNPs were closely located to genes known to be involved in responses to abiotic stresses and point to potential causative loci in plant stress response. However, SNPs found to be significantly associated with a response to heat or drought individually are not also significantly associated with the combination of stresses. This, with the phenotypic data, suggests that the effects of these abiotic stresses are not simply additive, and the responses to the combined stresses differ from drought and heat alone.

Modeling the interactions between inter-correlated variables of plant and soil micro-ecology responses under simultaneous cadmium stress and drought

Cadmium and water stress are considered two important prevalent abiotic stresses which may occur simultaneously in many parts of the world. The occurrence of different stress factors in nature is often simultaneous and the effect of multiple stress factors on living organisms cannot be investigated separately. Although it is essential to evaluate plant and microbial community responses to the combination of different abiotic stresses simultaneously, many scientists have used a single evaluative approach to study the effect of cadmium and/or water stress on the response of plant and/or soil microorganisms. The purpose of this study is to assess the effects of water stress and cadmium together on the development and growth of Medicago scutellata L. and soil biological activity. To investigate potential relationships among inter-correlated variables and comprehend potential mechanisms, predictive regression modeling, principal component analysis, and path analysis were implemented. Considering the outcomes, cadmium at low concentrations stimulates nodule growth and the fungi population. Moderate water stress (50%) decreased the bacteria population while it did not affect the fungi population. The obtained results of this study suggest that soil microsymbiont such as fungi might have a significant role in maintaining (as well as increasing) the nitrogen fixation ability of Medicago under low cadmium stress. Except for the removal rate (0.683), all predictive equation models showed strong linear fitness of the regression models, with adjusted R2 values ranging from 0.838 to 0.987. Based on the path analysis, urease has a significant positive direct effect on phosphatase activity. Due to the high removal rate and bioconcentration factor, M. scutellata can be considered as a potential cadmium hyperaccumulator.

Differences in Physiological Responses of Two Tomato Genotypes to Combined Waterlogging and Cadmium Stresses.

Waterlogging and heavy mental (e.g., cadmium) stress are two primary threats to crop growth. The combination of abiotic stresses was common and frequent, especially in the field condition. Even though the effects of individual waterlogging and cadmium on tomato plants have been widely investigated, the response of tomatoes under combined waterlogging and cadmium stress remains unclear. This study aimed to clarify and compare physiological, biochemical characteristics and plant growth of two tomato genotypes under individual and combined stress. Two tomato genotypes ('MIX-002' and 'LA4440') were treated under control, waterlogging, cadmium stress and their combination. The results showed that chloroplast ultrastructure of tomatoes under individual and combined stress was damaged with disordered stroma and grana lamellae. The H2O2 (hydrogen peroxide) content and O2·- (superoxide anion radical) production rate of plants under all the three stresses was not significantly higher than the control except for 'LA4440' under the combined stress. Antioxidant enzymes actively responded in the two tomato genotypes, as shown by significant increase in SOD activity from 'MIX-002' under waterlogging and combined stress and from 'LA4440' under cadmium. Meanwhile, CAT activity of 'MIX-002' under waterlogging and 'LA4440' under combined stress significantly decreased, and the POD activity of 'MIX-002' under combined stress significantly increased as compared with the respective control. The APX activity of 'MIX-002' and 'LA4440' under combined stress was significantly lower and higher than the respective controls. This indicated that tomato plants were able to secure redox homeostasis and protect plants from oxidative damage through the synergetic regulation of antioxidant enzymes. Plant height and biomass of the two genotypes under individual and combined stress significantly decreased, which could be a direct result from the chloroplast alteration and resource re-allocation. Overall, the effects of combined waterlogging and cadmium stress were not simply the sum of individual effects on two tomato genotypes. Distinct ROS (reactive oxygen species) scavenging systems of two tomato genotypes under stresses suggest a genotype-dependent antioxidant enzymes regulation.

Pre-Treatment of Rice Plants with ABA Makes Them More Tolerant to Multiple Abiotic Stress.

Multiple abiotic stress is known as a type of environmental unfavourable condition maximizing the yield and growth gap of crops compared with the optimal condition in both natural and cultivated environments. Rice is the world's most important staple food, and its production is limited the most by environmental unfavourable conditions. In this study, we investigated the pre-treatment of abscisic acid (ABA) on the tolerance of the IAC1131 rice genotype to multiple abiotic stress after a 4-day exposure to combined drought, salt and extreme temperature treatments. A total of 3285 proteins were identified and quantified across the four treatment groups, consisting of control and stressed plants with and without pre-treatment with ABA, with 1633 of those proteins found to be differentially abundant between groups. Compared with the control condition, pre-treatment with the ABA hormone significantly mitigated the leaf damage against combined abiotic stress at the proteome level. Furthermore, the application of exogenous ABA did not affect the proteome profile of the control plants remarkably, while the results were different in stress-exposed plants by a greater number of proteins changed in abundance, especially those which were increased. Taken together, these results suggest that exogenous ABA has a potential priming effect for enhancing the rice seedlings' tolerance against combined abiotic stress, mainly by affecting stress-responsive mechanisms dependent on ABA signalling pathways in plants.

Omics analyses in citrus reveal a possible role of RNA translation pathways and Unfolded Protein Response regulators in the tolerance to combined drought, high irradiance, and heat stress.

Environmental changes derived from global warming and human activities increase the intensity and frequency of stressful conditions for plants. Multiple abiotic factors acting simultaneously enhance stress pressure and drastically reduce plant growth, yield, and survival. Stress combination causes a specific stress situation that induces a particular plant response different to the sum of responses to the individual stresses. Here, by comparing transcriptomic and proteomic profiles to different abiotic stress combinations in two citrus genotypes, Carrizo citrange (Citrus sinensis×Poncirus trifoliata) and Cleopatra mandarin (Citrus reshni), with contrasting tolerance to different abiotic stresses, we revealed key responses to the triple combination of heat stress, high irradiance and drought. The specific transcriptomic response to this stress combination in Carrizo was directed to regulate RNA metabolic pathways and translation processes, potentially conferring an advantage with respect to Cleopatra. In addition, we found endoplasmic reticulum stress response as common to all individual and combined stress conditions in both genotypes and identified the accumulation of specific groups of heat shock proteins (HSPs), such as small HSPs and HSP70s, and regulators of the unfolded protein response, BiP2 and PDIL2-2, as possible factors involved in citrus tolerance to triple stress combination. Taken together, our findings provide new insights into the acclimation process of citrus plants to multiple stress combination, necessary for increasing crop tolerance to the changing climatic conditions.

Current advances in the molecular regulation of abiotic stress tolerance in sorghum via transcriptomic, proteomic, and metabolomic approaches.

Sorghum (Sorghum bicolor L. Moench), a monocot C4 crop, is an important staple crop for many countries in arid and semi-arid regions worldwide. Because sorghum has outstanding tolerance and adaptability to a variety of abiotic stresses, including drought, salt, and alkaline, and heavy metal stressors, it is valuable research material for better understanding the molecular mechanisms of stress tolerance in crops and for mining new genes for their genetic improvement of abiotic stress tolerance. Here, we compile recent progress achieved using physiological, transcriptome, proteome, and metabolome approaches; discuss the similarities and differences in how sorghum responds to differing stresses; and summarize the candidate genes involved in the process of responding to and regulating abiotic stresses. More importantly, we exemplify the differences between combined stresses and a single stress, emphasizing the necessity to strengthen future studies regarding the molecular responses and mechanisms of combined abiotic stresses, which has greater practical significance for food security. Our review lays a foundation for future functional studies of stress-tolerance-related genes and provides new insights into the molecular breeding of stress-tolerant sorghum genotypes, as well as listing a catalog of candidate genes for improving the stress tolerance for other key monocot crops, such as maize, rice, and sugarcane.

Molecular Cloning, Subcellular Localization, and Abiotic Stress Induction Analysis of a Polyamine Oxidase Gene from Oryza sativa

Abiotic stress is a major bottleneck for crop productivity. To counter abiotic stresses, plants have developed several strategies, and the accumulation of polyamine (PA) serving as an osmolyte is one of them. The cellular pool of PAs is primarily regulated by polyamine oxidases (PAOs) either by terminal catabolism or by back conversion (BC) of polyamines. The role of PAO in abiotic stress tolerance has also been reported. Polyamine oxidases are primarily localized in the cytosol, cell wall, and apoplastic regions; however, lately, their peroxisomal localization has also been demonstrated. In this study, we reported the detection of polyamine oxidase isoform 3 from Oryza sativa (OsPAO3) in peroxisome as early as 12 h post-transformation under in vitro conditions using fluorescent microscopy. The gene was also found to be significantly upregulated by salinity, dehydration, cold, and heat stress. We have also demonstrated that the expression of OsPAO3 gene was mediated by a second messenger, calcium. The upregulation of OsPAO3 by salinity, dehydration, cold, and heat stresses suggests that it could be a suitable candidate for providing tolerance to plants against abiotic stress combination or stress matrix, which is a common feature in agricultural field conditions. Furthermore, the data provided here would be valuable in understanding the abiotic stress-mediated signal transduction network of PAOs.

Multitraits evaluation of a Solanum pennellii introgression tomato line challenged by combined abiotic stress.

Rising daily temperatures and water shortage are two of the major concerns in agriculture. In this work we analysed the tolerance traits in a tomato line carrying a small region of the S. pennellii wild genome (IL12-4-SL) when grown under prolonged conditions of single and combined high temperature and water stress. When exposed to stress, IL12-4-SL showed higher heat tolerance than the cultivated line M82 at morphological, physiological, and biochemical levels. Moreover, under stress IL12-4-SL produced more flowers than M82, also characterized by higher pollen viability. In both lines, water stress negatively affected photosynthesis more than heat alone, whereas the combined stress did not further exacerbate the negative impacts of drought on this trait. Despite an observed decrease in carbon fixation, the quantum yield of PSII linear electron transport in IL12-4-SL was not affected by stress, thereby indicating that photochemical processes other than CO2 fixation acted to maintain the electron chain in oxidized state and prevent photodamage. The ability of IL12-4-SL to tolerate abiotic stress was also related to the intrinsic ability of this line to accumulate ascorbic acid. The data collected in this study clearly indicate improved tolerance to single and combined abiotic stress for IL12-4-SL, making this line a promising one to be cultivated in a climate scenario characterized by frequent and long-lasting heat waves and low rainfall.

The Combination of Both Heat and Water Stresses May Worsen Botryosphaeria Dieback Symptoms in Grapevine

(1) Background: Grapevine trunk diseases (GTDs) have become a global threat to vineyards worldwide. These diseases share three main common features. First, they are caused by multiple pathogenic micro-organisms. Second, these pathogens often maintain a long latent phase, which makes any research in pathology and symptomatology challenging. Third, a consensus is raising to pinpoint combined abiotic stresses as a key factor contributing to disease symptom expression. (2) Methods: We analyzed the impact of combined abiotic stresses in grapevine cuttings artificially infected by two fungi involved in Botryosphaeria dieback (one of the major GTDs), Neofusicoccum parvum and Diplodia seriata. Fungal-infected and control plants were subjected to single or combined abiotic stresses (heat stress, drought stress or both). Disease intensity was monitored thanks to the measurement of necrosis area size. (3) Results and conclusions: Overall, our results suggest that combined stresses might have a stronger impact on disease intensity upon infection by the less virulent pathogen Diplodia seriata. This conclusion is discussed through the impact on plant physiology using metabolomic and transcriptomic analyses of leaves sampled for the different conditions.

Molecular cloning of glutathione reductase from Oryza sativa, demonstrating its peroxisomal localization and upregulation by abiotic stresses.

Abiotic stress is a major constraint on crop productivity and in the agricultural field, multiple abiotic stresses act synchronously leading to substantial damage to plants. A common after-effect of abiotic stress-induced damage in plants is an increased concentration of reactive oxygen species (ROS) leading to oxidative damage. Glutathione reductase (GR) plays a significant role in curtailing ROS. Apart from the GR enzyme, the peroxisome as an organelle also plays a significant role in ROS homeostasis. Here, we report a peroxisome localized GR, whose expression was found to be upregulated by various abiotic stresses. The in silico analysis also revealed that the peroxisomal localization of GR could be a common phenomenon in angiosperms, suggesting that it could be a suitable candidate against abiotic stress combinations.

GENETIC ENGINEERING: AN EMERGING METHOD IN PLANT BREEDING

Abiotic stresses like drought, heat, and salinity are major causes of agricultural production losses worldwide. However, progress in developing genetically modified crops with better tolerance to these stresses has been slow. Modern agriculture faces various challenges, such as the complex field environment, diverse abiotic stress combinations, and global climatic changes. A combination of approaches is required to improve crop tolerance to abiotic stress significantly. These include understanding stress response and acclimation networks, testing under different growth conditions, using innovative techniques considering genetic and physiological variations in crops, and incorporating enzymes and proteins from other organisms.

Influence of Osmotic, Salt, and Combined Stress on Morphophysiological Parameters of Chenopodium quinoa Photosynthetic Organs

Chenopodium quinoa Willd. is an annual facultative halophytic pseudocereal widely studied for its physiology and grain yield owing to its great tolerance to unfavorable growing conditions. However, the morphophysiological and anatomical characteristics of plants’ photosynthetic organs under various and combined abiotic stresses during the early stages of development have not been thoroughly studied. Therefore, the current study compared the influence of osmotic, salt, and combined stress at different intensities on the morphology and anatomy of photosynthetic organs in young quinoa plants. The main findings demonstrate that salt stress at an intensity between 100 and 200 mM NaCl is not critical for the growth of young quinoa plants and that the young plants can withstand salt stress at an intensity of 300 mM NaCl. However, it can be concluded that some adaptation mechanisms of the plants were already violated at a salt stress intensity of 200 mM NaCl, while significant changes in the water balance of the plants were observed at an intensity of 300 mM NaCl, possibly caused by damage to the cell structures.

Heat and drought induced transcriptomic changes in barley varieties with contrasting stress response phenotypes.

Drought and heat stress substantially impact plant growth and productivity. When subjected to drought or heat stress, plants exhibit reduction in growth resulting in yield losses. The occurrence of these two stresses together intensifies their negative effects. Unraveling the molecular changes in response to combined abiotic stress is essential to breed climate-resilient crops. In this study, transcriptome profiles were compared between stress-tolerant (Otis), and stress-sensitive (Golden Promise) barley genotypes subjected to drought, heat, and combined heat and drought stress for five days during heading stage. The major differences that emerged from the transcriptome analysis were the overall number of differentially expressed genes was relatively higher in Golden Promise (GP) compared to Otis. The differential expression of more than 900 transcription factors in GP and Otis may aid this transcriptional reprogramming in response to abiotic stress. Secondly, combined heat and water deficit stress results in a unique and massive transcriptomic response that cannot be predicted from individual stress responses. Enrichment analyses of gene ontology terms revealed unique and stress type-specific adjustments of gene expression. Weighted Gene Co-expression Network Analysis identified genes associated with RNA metabolism and Hsp70 chaperone components as hub genes that can be useful for engineering tolerance to multiple abiotic stresses. Comparison of the transcriptomes of unstressed Otis and GP plants identified several genes associated with biosynthesis of antioxidants and osmolytes were higher in the former that maybe providing innate tolerance capabilities to effectively combat hostile conditions. Lines with different repertoire of innate tolerance mechanisms can be effectively leveraged in breeding programs for developing climate-resilient barley varieties with superior end-use traits.

Inhibitory Effects of Antipsychotic Chlorpromazine on the Survival, Reproduction and Population Growth Other Than Neurotransmitters of Zooplankton in Light of Global Warming.

Global warming and environmental pollution have created a unique combination of abiotic and biotic stresses to zooplankton. However, little information is available on the effects of antipsychotic drugs commonly used to treat psychosis, such as chlorpromazine (CPZ), on non-target aquatic organisms in light of global warming. This study investigated how dopamine concentrations (DAC), acute toxicity and chronic toxicity of Brachionus calyciflorus changed in response to CPZ and gradually increasing temperatures. The results showed that the concentration range of rotifer DAC was 1.06~2.51 ng/g. At 18, 25 and 32 °C, the 24 h LC50 was 1.795, 1.242 and 0.833 mg/L, respectively. Compared to the control, exposure to CPZ significantly decreased life expectancy at hatching, the net reproduction rate, generation time, population growth rate and dopamine concentration of B. calyciflorus in all three temperatures (p < 0.05). The toxicity of CPZ to rotifers was increased by high temperature. These findings indicated that CPZ is highly toxic to rotifers, displaying high ecological risks to aquatic ecosystems.

Biotic and Abiotic Stress Factors Induce Microbiome Shifts and Enrichment of Distinct Beneficial Bacteria in Tomato Roots

Crops are often simultaneously threatened by abiotic and biotic stress factors but the stress response of the plant holobiont is not well understood, despite the high importance of this response to ensure future plant production. Therefore, the aim of this study was to assess the impact of individual and combined abiotic (ionic and osmotic) and biotic ( Verticillium dahliae and Fusarium oxysporum) stress factors on plant performance and on the bacterial composition of the root endosphere in tomato. Structure and function of the microbiota was analyzed by 16S ribosomal RNA gene amplicon sequencing and a complementary cultivation approach, including in vitro and in vivo assays. Under all stress conditions, tomato growth and photosynthetic activity was reduced. Combined abiotic stressors with F. oxysporum but not with V. dahliae infection led to an additive negative effect on plant performance. All stress conditions induced a microbiome shift, and changed the relative abundance of phyla such as Firmicutes and classes of Proteobacteria. Endophytes identified as Bacillus, Paenibacillus, and Microbacterium spp. showed tolerance to abiotic stress conditions and plant beneficial effects. Stressor-specific enrichments of beneficial bacteria in the root were discovered (e.g., Paenibacillus in roots infected with F. oxysporum and Microbacterium in roots infected with V. dahliae). Interestingly, endophytes that were able to promote plant growth were obtained only from roots exposed to individual biotic and combined abiotic and biotic stress conditions but not individual abiotic stressors. Our study revealed stressor-specific enrichment of beneficial bacteria in tomato roots, which has implications for novel plant protection strategies.