Proline Accumulation Research Articles

Investigating drought tolerance in four Argania spinosa provenances through morpho-physio-biochemical traits

ABSTRACT Drought stress significantly threatens plant ecosystems, particularly amid climate change. Understanding the mechanisms of plant resilience is essential for developing strategies to mitigate water scarcity effects on agroforestry. This study evaluated morphological, physiological and biochemical traits in Argania spinosa seedlings from four provenances (Berkane (BRK), Essaouira (ESS), Agadir (AGD) and Bouizakarne (BZK)) subjected to severe drought for three weeks. The results showed significant inter-provenance variation in the traits examined. Root dry biomass increased markedly across all provenances, with the highest increase observed in BZK (117.9%). Leaf water potential significantly decreased under drought stress, but relative water content (RWC) remained stable. Proline accumulation was significant in stressed seedlings, especially in ESS (163.4%), while total soluble sugars significantly increased only in BRK (26.6%). All provenances showed a significant reduction in chlorophyll a and b, except for BRK. Correlations among all studied traits varied significantly in both number and significance between drought stress and non-stress conditions. Canonical discriminant analysis revealed distinct separation among the provenances, indicating intra-species variability in drought responses. Key traits like dry biomass, collar diameter, basic leaf water potential, RWC and proline were identified as important indicators of drought tolerance, suggesting their utility in selecting the most resilient A. spinosa provenance.

Multifunctional Transcription Factor YABBY6 Regulates Morphogenesis, Drought and Cold Stress Responses in Rice

The roles of plant-specific transcription factor family YABBY may vary among different members. OsYABBY6 is a rice YABBY gene, whose function is not well elucidated so far. In this paper, we show that OsYABBY6 is a nucleus-localized protein with transcriptional activation activity. OsYABBY6 is predominantly expressed in the palea and lemma, as well as in the sheath, culm and node. OsYABBY6 RNA interference (RNAi) plants exhibited altered plant height and larger grain size. Under cold treatment, OsYABBY6 overexpression (OE) plants had up-regulated expression of cold responsive genes, and accumulated less reactive oxygen species but more proline compared to wild type, resulting in improved cold tolerance. On the other hand, RNAi plants showed enhanced drought tolerance compared to the wild type by slower water loss, less reactive oxygen species but more proline and soluble sugar accumulation. In addition, endogenous abscisic acid (ABA) level was reduced in OsYABBY6 RNAi plants, and RNAi and OE plants were more and less sensitive to ABA treatment, respectively. Accordingly, we deduce that OsYABBY6 positively regulates cold response but negatively regulates drought response through different pathways. Our study reveals the crucial roles of OsYABBY6 in plant architecture and grain development, as well as in abiotic stress response, providing new insights into the functions of YABBYs in rice.

Transcriptome-Based Spatiotemporal Analysis of Drought Response Mechanisms in Two Distinct Peanut Cultivars

Drought tolerance varies among different peanut (Arachis hypogaea L.) cultivars. Here, drought responses of two cultivars, Huayu 22 (HY22) with drought tolerance and Fuhua 18 (FH18) with drought sensitivity, were compared at the morphological, physiological, biochemical, photosynthetic, and transcriptional levels. Drought stress caused wilting and curling of leaves, bending of stems, and water loss in both cultivars. There was an increase in malondialdehyde (MDA) content under prolonged drought stress, more so in FH18. But the levels of reactive oxygen species (H2O2) and lipid peroxidation were low in HY22. The activities of superoxide dismutase (SOD), peroxidase (POD), and glutathione reductase (GR) were considerably elevated, corresponding with rapid increases in the accumulation of soluble proteins, soluble sugars, and proline. Transcriptional sequencing showed gene expression varied seriously in HY22, which was upregulated in both stems of two cultivars, though downregulation was less pronounced in HY22. KEGG pathway analysis revealed significant enrichment in four leaf and six stem pathways. Additionally, core genes relating to photosynthesis, carbon fixation, proline synthesis, and sucrose and starch synthesis pathways were identified by correlation analysis. Those gene expressions were variously upregulated in stems of two cultivars, especially in HY22, giving a novel view of the shoot as a whole participating in stress response.

Impact of Salinity Stress on Morpho-physiology of Four Rice (Oryza sativa L.) Varieties

Abiotic stress, especially salinity, is one of the major restraints for attaining self-sufficiency in the food grain production. The saline soils affect the crop growth both directly and indirectly by interfering with plant metabolism resulting in reduction in yield potential of various crops. Rice (Oryza sativa L.), the staple food of much of the world’s population, is categorized as a salt-susceptible crop. Improving the salt tolerance of rice would increase the potential of saline-alkali land and ensure food security. To investigate the effect of different levels of salinity on morpho-physiological characters and yield of four rice variety viz. Pokkali, Narendra Ushar Dhan 3, IR 28 and IR 29. A pot experiment was conducted during Kharif 2011 and 2012 at the Department of Crop Physiology, Narendra Deva University of Agriculture and Technology, Kumarganj, Faizabad (U.P.) under normal soil and saline conditions with EC 6.0 and EC 10.0 dS/m. Gradual increase on plant height as well as biomass with the advancement in the age of crop up to dough grain in all the varities under both normal and salinity treatment. Maximum grain yield recorded in tolerant varieties Narendra Usar Dhan 3 followed by Pokkali, whereas minimum in IR 28. Under saline conditions regarding sink potential, the tolerant varieties recorded less reduction in yield attributes like length of panicle (cm), number of panicle per plant, number grain panicle-1 and grain yield plant-1 as compared to normal condition. The salinity tolerance capacity of tolerance varieties was associated with increased the activity of catalase and superoxide dismutase enzyme batter accumulation of proline and total carbohydrate as compared to normal condition.

Sink-source driven metabolic acclimation of winter oilseed rape leaves (Brassica napus L.) to drought

The crop cycle of winter oilseed rape (WOSR) incorporates source-to-sink remobilisation during the vegetative stage as a principal factor influencing the ultimate seed yield. These processes are supported by the coordinated activity of the plant’s central metabolism. However, climate change-induced drought will affect the metabolic acclimation of WOSR sink/source relationships at this vegetative stage, with consequences that remain to be determined. In this study, we subjected WOSR to severe soil dehydration for 18 days and analysed the physiological and metabolic acclimation of sink and source leaves along the kinetics in combination with measurements of enzymatic activities and transcript levels. Overall, the acclimation of WOSR to drought led to subtle regulations of central metabolism in relation to leaf growth and Pro-induced osmotic adjustment. Notably, sink leaves drastically reduced their growth and transiently accumulated starch. Subsequent starch degradation correlated with the induction of beta-amylases, sucrose transporters, pyrroline-5-carboxylate synthases and proline accumulation. The functioning of the tricarboxylic acid cycle was also altered in sink leaves, as evidenced by variations in citrate, malate and associated enzymatic activities. The metabolic origin of Pro in sink leaves is discussed in relation to Pro accumulation in source leaves and the up-regulation of amino acid permease 1 and glutamine synthetase genes.

Higher endogenous abscisic acid confers greater tolerance to saline-alkaline stress in Petunia hybrida

Saline-alkaline stress not only leads to reduced crop yields but also diminishes the ornamental value of flowers. While petunia exhibits tolerance to saline-alkaline stress, research on the mechanisms underlying this tolerance remains unreported. We investigated the physiological and molecular mechanisms underlying saline-alkaline stress tolerance using two petunia genotypes (Haishishenlou and Mitchell Diploid) with differing tolerance levels. Haishishenlou exhibited less inhibition of growth under saline-alkaline stress compared to Mitchell Diploid, as indicated by higher biomass. Higher endogenous concentration of abscisic acid (ABA) and greater expression levels of ABA biosynthetic genes and lower expression levels of ABA catabolic genes in Haishishenlou than in Mitchell Diploid were observed when challenged by saline-alkaline stress, suggesting that a higher concentration of ABA may underpin the greater tolerance of Haishishenlou to saline-alkaline stress than that of Mitchell Diploid. Under saline-alkaline conditions, Haishishenlou displayed higher chlorophyll content, photosynthetic rates, Pro and soluble sugars content, as well as higher activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and a lower Na+/K+ ratio. Exogenous application of ABA alleviated the growth inhibition induced by saline-alkaline stress, promoted the accumulation of proline and soluble sugar, reduced reactive oxygen species (ROS) content and Na+/K+ ratio, and improved antioxidative capacity. These results indicated that a higher endogenous concentration of ABA may underpin the greater tolerance of petunia seedlings to saline-alkaline stress, and exogenous ABA improves the saline-alkaline tolerance of petunia seedlings.

Influence of biofertilizers on potato (Solanum tuberosum L.) growth and physiological modulations for water and fertilizers managing

Biofertilizers constitute a safe way to alleviate the impacts of water shortage and the overload of chemical fertilizers. This work focuses on the effects of Arbuscular Mycorrhizal Fungi (AMF) and Plant Growth-Promoting Rhizobacteria (PGPR) on potato's agro-physiological response, beneath the reduction of water, nitrogen (N), phosphorous (P) and potassium (K) fertilizers. Five microbioal treatments (C: Control, AMF: Mycorhizae, B1: Bacillus halotolerans, B2: Bacillus amyloliquefaciens and B1B2: B.halotolerans+ B.amyloliquefaciens) were tested in arrangement with two nitrogen-phosphorous-potassium (NPK) rates (F1: Entire rate, F ½: Half rate) and three irrigation levels (100 % of crop water requirement: 100 % ETc; 75 % ETc; 50 % ETc) in a two year factorial split plot design. We studied vegetative growth, photosynthetic activity, chlorophyll fluorescence, water status, osmoticums, N, P, K and enzymatic antioxidants accumulation. Data obtained in 2019–2022 showed that AMF and B1B2 biofertilizers were beneficial to improve Root/Shoot, Dry Underground Part/Aerial Part, leaf area (LA), water saturation deficit (WSD), chlorophyll index (SPAD) and tuber yield under 75 % ETc. The photosynthetic promoter effect of biofertilizers under 75 % ETc, compared to 50 % ETc was observed in the following trend B1B2>AMF>B1. The efficacy of B1B2 and AMF were coupled to high catalase (CAT) activity. Potatoes treated with B1B2 were found to be efficient for 75 % ETc in terms of proline accumulation. The AMF was more effective in terms of soluble sugars (SS) accumulation and control of osmotic potential (Ψs). Taking together, the B1B2 and AMF could be regarded as efficient biofertilizers under 75 % ETc, alleviating the impacts of water stress and the problem of excessive fertilization in potatoes.

Drought and heat stress interactions: Unveiling the molecular and physiological responses of Persian walnut

While numerous studies explored the response of walnut plants to drought stress (DS), there remains a significant gap in the knowledge regarding the impact of heat stress (HS) and the combined effects of DS and HS on the recovery capacity of walnut trees. This study aimed to investigate the mechanism of Persian walnut (cv. Chandler) response to the combined DS and HS, focusing on various aspects including photosynthesis, water relations, and osmotic regulation. The treatments involved subjecting plants to DS (through a withholding method for 24 d), HS (gradually up to 40 °C for 8 d), and a combined DS and HS, which were compared to a control group (no stress) during the stress and recovery phases. The results showed that DS had significantly more negative effects on chlorophyll content, relative water content (RWC), leaf water potential (WP), osmotic potential (OP) compared to HS. Involvement of osmoregulation mechanism was detected more in DS and HS plants through the accumulation of proline, glycine Betaine and total soluble carbohydrates. The functionality of photosynthesis was significantly impacted by both HS and DS, respectively. While the HS accelerated the change of the abovementioned physiological processes in drought-stressed seedlings. Consistently, more pronounced damage was found in leaves under the combined stress, alongside the decrease RWC, chlorophyll content and fluorescence ratios. Based on the analysis of the linear mixed-effect model, the effects of combined stress and HS on photosynthesis parameters were detected in the early stages of stress compared to DS. Within a range of stresses, the abovementioned physiological processes of individual and combined-stressed plants recovered to levels comparable to those of the control. Our results also showed a substantial reduction in the expression of the photosynthetic genes (Fd, Cyt b6f, and PsbB) in Persian walnut saplings under abiotic stress conditions indicating significant damage to their photosynthetic apparatus. This study highlights that, under scenarios of aggravating drought occurring with heat, walnut seedlings could face a high risk of damage to physiological structures in relation to the synergistically increased hydraulic and thermal impairments.

Proline Accumulation and Drought Tolerance in Green Gram (Vigna radiata L.)

Green gram (Vigna radiata L.), a key legume crop in Asia, contributes to sustainable agriculture by fixing atmospheric nitrogen and providing valuable nutrients. Despite its importance, productivity is hindered by various factors including drought, affecting key physiological and biochemical processes, leading to reduced yields. This study aimed to identify drought-tolerant green gram genotypes by evaluating 50 accessions for root, shoot and biochemical parameters under controlled moisture stress. An increase in root length and diameter under stress was observed, which aids in nutrient uptake and osmoregulation. Conversely, shoot length and dry weight decreased due to moisture limitations, with genotypes like VBN 3 and PLM 38 showing resilience by maintaining higher dry weights. Biochemical analysis revealed that proline accumulation, which correlates positively with drought tolerance, increased in most genotypes, particularly in IC 395518 and ML 1415. This suggests its role in maintaining cell turgor and mitigating stress effects. Chlorophyll content decreased under stress, while total phenolic content increased in some genotypes, further indicating drought tolerance. Correlation and path analysis revealed strong positive relationships between root traits and proline content, emphasizing their importance in drought tolerance. The study concludes that genotypes with robust root systems and higher proline accumulation are more capable of withstanding drought, highlighting the need for breeding programs targeting these traits for improved green gram productivity under changing climates.

Spraying KH2PO4 Alleviates the Damage of Spring Low-Temperature Stress by Improving the Physiological Characteristics of Wheat Flag Leaves.

The low-temperature stress (LTS) in spring results in tremendous yield loss in wheat production, and the application of potassium dihydrogen phosphate (KH2PO4) can alleviate stress-induced damage. However, the underlying effect of spraying KH2PO4 on the physiological characteristics of wheat flag leaves under spring LTS remains unclear. In this study, we investigated the effect of spraying KH2PO4 on flag leaf physiological traits and yield under spring LTS, including treatments at 15 °C and spraying H2O (CK), treatment at -4 °C and spraying H2O (LT1), and treatment at -4 °C and spraying KH2PO4 (LT2). The results showed that spraying KH2PO4 significantly increased the activities of the superoxide dismutase (SOD), the peroxidase (POD), and the catalase (CAT), and reduced malondialdehyde (MDA) content in the flag leaves. Compared to LT1, the SOD, POD, and CAT activities in the flag leaves of the Yangnong19 (YN19) and Xinmai26 (XM26) via LT2 increased by 5.5%, 10.9%, and 3.9%, and 5.4%, 9.2%, and 4.4%, respectively, and the MDA content of the YN19 and XM26 decreased by 10.5% and 9.1%, respectively, at 0-12 d after low temperature treatment (DALTT). Spraying KH2PO4 appreciably alleviated damage to the leaf cell morphology and tissue integrity, and increased the accumulation of proline and soluble protein, the chlorophyll content, and the activities of Ribulose-1,5-bisphosphate carboxylase and phosphoenolpyruvate carboxykinase. The net photosynthetic rate in the flag leaves of the YN19 and XM26 via LT2 increased by 37.9% and 35.9%, respectively, at 0-12 DALTT, compared to LT1. Moreover, spraying KH2PO4 reduced the yield loss rate of the YN19 and XM26 by 13.06% and 16.72%, respectively. The present study demonstrates that spraying KH2PO4 can enhance wheat resistance to spring LTS and maintain the photosynthetic capacity of flag leaves, alleviating the negative effects of LTS on grain yield.

Investigating the influence of selenium and epibrassinolide on antioxidant activity, proline accumulation, and protein expression profiles in wheat plants experiencing heat and drought stress.

In the current investigation, the combination of selenium (Se) and epibrassinolide (EBL) exhibited a promising alleviative response against the concurrent stress of heat and drought in wheat plants. The compromised growth and photosynthetic performance of wheat plants under the combined stress of heat and drought were substantially improved with the treatment involving Se and EBL. This improvement was facilitated through the expression of Q9FIE3 and O04939 proteins, along with enhanced antioxidant activities. The heightened levels of antioxidant enzymes and the accumulation of osmoprotectant proline helped mitigate the overaccumulation of reactive oxygen species (ROS), including electrolyte leakage, H2O2 accumulation, and lipid peroxidation, thus conferring tolerance against the combined stress of heat and drought. Studies have demonstrated that Se and EBL can assist wheat plants in recuperating from the adverse effects of heat and drought. As such, they are essential components of sustainable farming methods that aim to increase crop productivity.

Impact of Plant Growth-Promoting Microorganism (PGPM) Consortium on Biochemical Properties and Yields of Tomato Under Drought Stress.

Drought is the most important abiotic stress that restricts the genetically predetermined yield potential of the crops. In the present study, four tomato varieties: Kashi Vishesh, Kashi Aman, Kashi Abhiman, and Kashi Amrit, were used to study the effect of PGPMs (plant growth-promoting microorganisms). PGPM strains, Bacillus megaterium BHUPSB14, Pseudomonas fluorescens BHUPSB06, Pseudomonas aeruginosa BHUPSB01, Pseudomonas putida BHUPSB0, Paenibacillus polymixa BHUPSB17, and Trichoderma horzianum, were used as the consortium. The control group was irrigated up to 80% of field capacity, while 7-, 14-, and 21-day water-deficit-exposed (DWD) plants' pot soil moisture was maintained to 40, 25, and 15% of the field capacity, both with and without the PGPM inoculation condition. The physiological parameters, such as electrolyte leakage, relative water content, photosynthetic efficiency, and chlorophyll color index, were significantly improved by PGPM application under progressive drought stress, compared to the control. PGPM application enhanced the proline accumulation and reduced the formation of hydrogen peroxide and lipid peroxidation under drought stress. The plant growth attributes were significantly increased by PGPM application. The Kashi Amrit variety showed the highest fruit yield among the four varieties under all the treatments. The PGPM consortium application also improved the soil physico-biological properties and nutrient availability in the soil. The PGPM consortium used in this study can potentially mitigate drought stress on tomato in drought-prone regions and act as a biofertilizer. The present study will open a new avenue of drought stress management in tomato.

Effects of alkaline salt stress on growth, physiological properties and medicinal components of clonal Glechoma longituba (Nakai) Kupr.

BackgroundGlechoma longituba, recognized as a medicinal plant, provides valuable pharmaceutical raw materials for treating various diseases. Saline-alkali stress may effectively enhance the medicinal quality of G. longituba by promoting the synthesis of secondary metabolites. To investigate the changes in the primary medicinal components of G. longituba under saline-alkali stress and improve the quality of medicinal materials, Na2CO3 was applied to induce short-term stress under different conditions and the biomass, physiologically active substances and primary medicinal components of G. longituba were measured in this study.ResultsUnder alkaline salt stress, the activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) were elevated in G. longituba, accompanied by increased accumulation of proline (Pro) and malondialdehyde (MDA). Furthermore, analysis of the medicinal constituents revealed that G. longituba produced the highest levels of soluble sugars, flavonoids, ursolic acid, and oleanolic acid under 0.6% Na2CO3 stress for 48 h, 0.2% Na2CO3 stress for 72 h, 0.4% Na2CO3 stress for 12 h, and 0.4% Na2CO3 stress for 8 h, respectively.ConclusionsShort-term Na2CO3 stress enhances the synthesis of medicinal components in G. longituba. By manipulating stress conditions, the production of various medicinal substances could be optimized. This approach may serve as a basis for the targeted cultivation of G. longituba, offering potential applications in the treatment of diverse diseases.

Stress-Responsive Gene Expression, Metabolic, Physiological, and Agronomic Responses by Consortium Nano-Silica with Trichoderma against Drought Stress in Bread Wheat

The exploitation of drought is a critical worldwide challenge that influences wheat growth and productivity. This study aimed to investigate a synergistic amendment strategy for drought using the single and combined application of plant growth-promoting microorganisms (PGPM) (Trichoderma harzianum) and biogenic silica nanoparticles (SiO2NPs) from rice husk ash (RHA) on Saudi Arabia’s Spring wheat Summit cultivar (Triticum aestivum L.) for 102 DAS (days after sowing). The significant improvement was due to the application of 600 ppm SiO2NPs and T. harzianum + 600 ppm SiO2NPs, which enhanced the physiological properties of chlorophyll a, carotenoids, total pigments, osmolytes, and antioxidant contents of drought-stressed wheat plants as adaptive strategies. The results suggest that the expression of the studied genes (TaP5CS1, TaZFP34, TaWRKY1, TaMPK3, TaLEA, and the wheat housekeeping gene TaActin) in wheat remarkably enhanced wheat tolerance to drought stress. We discovered that the genes and metabolites involved significantly contributed to defense responses, making them potential targets for assessing drought tolerance levels. The drought tolerance indices of wheat were revealed by the mean productivity (MP), stress sensitivity index (SSI), yield stability index (YSI), and stress tolerance index (STI). We employed four databases, such as BAR, InterPro, phytozome, and the KEGG pathway, to predict and decipher the putative domains in prior gene sequencing. As a result, we discovered that these genes may be involved in a range of important biological functions in specific tissues at different developmental stages, including response to drought stress, proline accumulation, plant growth and development, and defense response. In conclusion, the sole and/or dual T. harzianum application to the wheat cultivar improved drought tolerance strength. These findings could be insightful data for wheat production in Saudi Arabia under various water regimes.

Alleviation of NaCl Stress on Growth and Biochemical Traits of Cenchrus ciliaris L. via Arbuscular Mycorrhizal Fungi Symbiosis

Soil salinization, especially in arid and semi-arid regions, is one of the major abiotic stresses that affect plant growth. To mediate and boost plant tolerance against this abiotic stress, arbuscular mycorrhizal fungi (AMF) symbiosis is commonly thought to be an effective tool. So, the main purpose of this study was to estimate the role of AMF (applied as a consortium of Claroideoglomus etunicatum Claroideoglomus eutinicatum, Funneliformis mosseae Funliformis mosseae, Rhizophagus fasciculatum, and R. intraradices species) symbiosis in mitigating deleterious salt stress effects on the growth parameters (shoot length (SL), root length (RL), shoot dry weight (SDW), root dry weight (RDW), root surface area (RSA), total root length (TRL), root volume (RV), root diameter (RD), number of nodes and leaves) of Cenchrus ciliaris L. plants through improved accumulations of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll), proline and phenolic compounds. The results of this experiment revealed that the roots of C. ciliaris plants were colonized by AMF under all the applied salinity levels (0, 75, 150, 225, and 300 mM NaCl). However, the rate of colonization was negatively affected by increasing salinity as depicted by the varied colonization structures (mycelium, vesicles, arbuscules and spores) which were highest under non-saline conditions. This association of AMF induced an increase in the growth parameters of the plant which were reduced by salinity stress. The improved shoot/root indices are likely due to enhanced photosynthetic activities as the AMF-treated plants showed increased accumulation of pigments (chlorophyll a, chlorophyll b and total chlorophyll), under saline as well as non-saline conditions, compared to non-AMF (N-AMF) plants. Furthermore, the AMF-treated plants also exhibited enhanced accumulation of proline and phenolic compounds. These accumulated metabolites act as protective measures under salinity stress, hence explaining the improved photosynthetic and growth parameters of the plants. These results suggest that AMF could be a good tool for the restoration of salt-affected habitats. However, more research is needed to check the true efficacy of different AMF inoculants under field conditions.

The role of SlCHRC in carotenoid biosynthesis and plastid development in tomato fruit

Chromoplasts are specialized plastids in plants involved in carotenoid synthesis, accumulation, and stress resistance. In tomatoes (Solanum lycopersicum), the Chromoplast-associated carotenoid binding protein (CHRC) regulates chromoplast development and carotenoid accumulation, although its precise mechanisms are not yet fully understood. To investigate the role of SlCHRC in carotenoid biosynthesis, we generated transgenic tomatoes using overexpression (oe-SlCHRC) and CRISPR/Cas9-mediated gene editing (cr-SlCHRC) techniques. The results demonstrated inhibited fruit ripening and delayed onset of color break in both transgenic lines. The oe-SlCHRC lines exhibited increased carotenoid accumulation, particularly (E/Z)-phytoene, lycopene, and γ-carotene, with abundant plastoglobules and carotenoid crystals observed via TEM. In contrast, cr-SlCHRC mutants showed a greener phenotype, reduced carotenoid content, and fewer plastoglobules at the BK + 10 stage. Transcriptome analysis indicated that SlCHRC influences key genes in carotenoid biosynthesis, such as SlNCED2, as well as genes related to chloroplast development, photosynthesis, and plastoglobule formation. Additionally, SlCHRC enhances heat stress tolerance in tomato fruits by upregulating heat shock proteins (HSPs), antioxidants, and proline accumulation. These findings indicate that SlCHRC plays a crucial role in improving tomato fruit quality under heat stress conditions.

The Serratia sp. strain C2 confers tomato tolerance to high salt, virus infection and both stresses in combination

Besides increasing plant growth, several Plant Growth Promoting Rhizobacteria (PGPR), can enhance tolerance to biotic and/or abiotic stresses of numerous plant species. While cultivated plants are frequently subject to combined stresses in the field, there is limited knowledge of the effect of PGPR on plants undergoing simultaneous stress conditions. Therefore, we tested the beneficial properties of the halotolerant PGPR Serratia sp. strain C2, previously shown to enhance salt stress tolerance in barley, on tomato plants exposed to salinity, to Potato Virus Y (PVY) infection, and both stresses simultaneously. In our experimental conditions, C2 inoculation improved tomato tolerance to salt stress and positively correlated with a 46–68 % decrease in the level of PVY RNA compared to non-inoculated tomato plants. Morphometric, physiological and biochemical analyses (e.g., chlorophyll, sugar and proline accumulation, oxidative stress status and NDVI) indicated that C2 treatments had beneficial effects on tomato growth under simple and combined stress conditions. This is the first report of a PGPR enhancing tolerance not only to individually induced salinity and PVY infection, but also to both stresses in combination. Moreover, the expression analysis of selected genes involved in stress responses and RNA silencing-mediated antiviral immunity suggests that C2 can interfere with distinct defence response pathways to enhance stress tolerance in tomato. These pioneering results support the perspective of using PGPR as multi-spectrum and multi-host biostimulants for improving plant growth and protection from biotic, abiotic, and combined stresses to promote sustainable crop production in the face of environmental changes.

Tetraspanin 5 orchestrates resilience to salt stress through the regulation of ion and reactive oxygen species homeostasis in rice.

Tetraspanins (TETs) are integral membrane proteins, characterized by four transmembrane domains and a unique signature motif in their large extracellular loop. They form dynamic supramolecular complexes called tetraspanin-enriched microdomains (TEMs), through interactions with partner proteins. In plants, TETs are involved in development, reproduction and immune responses, but their role in defining abiotic stress responses is largely underexplored. We focused on OsTET5, which is differentially expressed under various abiotic stresses and localizes to both plasma membrane and endoplasmic reticulum. Using overexpression and underexpression transgenic lines we demonstrate that OsTET5 contributes to salinity and drought stress tolerance in rice. OsTET5 can interact with itself in yeast, suggesting homomer formation. Immunoblotting of native PAGE of microsomal fraction enriched from OsTET5-Myc transgenic rice lines revealed multimeric complexes containing OsTET5, suggesting the potential formation of TEM complexes. Transcriptome analysis, coupled with quantitative PCR-based validation, of OsTET5-altered transgenic lines unveiled the differential expression patterns of several stress-responsive genes, as well as those coding for transporters under salt stress. Notably, OsTET5 plays a crucial role in maintaining the ionic equilibrium during salinity stress, particularly by preserving an elevated potassium-to-sodium (K+/Na+) ratio. OsTET5 also regulates reactive oxygen species homeostasis, primarily by modulating the gene expression and activities of antioxidant pathway enzymes and proline accumulation. Our comprehensive investigation underscores the multifaceted role of OsTET5 in rice, accentuating its significance in developmental processes and abiotic stress tolerance. These findings open new avenues for potential strategies aimed at enhancing stress resilience and making valuable contributions to global food security.

Plant Beneficial Desert Actinomycete, Modestobacter caceresii KNN 45-2bT, Promote Growth of Tomato (Lycopersicum esculentum Mill.) under Drought Condition

Drought stress is currently the most serious challenge to global food security and agricultural productivity. Desert actinobacteria have gained attention as potential candidates for enhancing plant growth in water stress environments. In this regard, a desert actinomycete, namely Modestobacter caceresii strain KNN 45-2bT, was selected to investigate its plant growth promoting abilities and drought tolerance. Next, this desert strain was inoculated to tomato (Lycopersicum esculentum Mill.) under drought, and the results included increases in root length, shoot and root fresh weight, shoot and root dry weight, total fresh weight and dry weight, fruit weight, proline accumulation, total soluble sugar content and trolox content. Stress treatments on the bacterized tomato plants also resulted in the reduction of hydrogen peroxide accumulation. Putative proteins coding sequences conferring plant growth promoting (PGP) traits (IAA production, phosphate solubilization, siderophore production, nitrogen fixation) and drought response (biosynthesis of proline metabolism, oxidative and osmotic stress response) were also detected from their genomic analyses. In conclusion, these results provide credence to the idea that the inoculation of tomato plants with plant beneficial desert actinomycete is an effective method of combating the negative effects of drought stress.

Fulvic and Salicylic Acids Improve Morpho-Physio-Biochemical Attributes, Yield and Fruit Quality of Two Mango Cultivars Exposed to Dual Salinity and Heat Stress Conditions

Abstract Purpose The present research’s main objective was to explore the potential stimulative effect of fulvic acid (FA) as a soil conditioner and salicylic acid (SA) as foliar spraying on morpho-physio-biochemical attributes, fruit yield, and quality of ‘Sediek’ and ‘Ewais’ mango cultivars (cvs.) grown under saline calcareous soil and heat stress conditions Methods Eight treatments, namely, 200 (FA200) and 400 (FA400) g FA tree−1 as a soil addition, 200 (SA200) or 400 (SA400) mg SA L−1 as foliar spraying, and their bilateral combinations (e.g., FA200 + SA200, FA200 + SA400, FA400 + SA200, and FA400 + SA400) compared to untreated control on morpho-physio-biochemical attributes, yield, and fruit quality of ‘Sediek’ and ‘Ewais’ mango cvs. grown under saline calcareous soil and heat stress conditions were assessed. These treatments were carried out using a split-plot arrangement in a randomized complete block design replicated three times during the 2022 and 2023 seasons. Results Cultivar Sediek had higher SPAD value, leaf proline and phenolic content, leaf area, fruit weight, yield and vitamin C than Ewais which had higher tree water status and shoot length. Saline calcareous and heat-stressed mango trees without FA or/and SA treatment had a significant decline in their water status, photosynthetic traits, biochemical responses that adversely affected growth and yield and fruit quality. However, soil FA addition and foliar SA spraying alone or in combination at any application level attenuated the negative effects of saline calcareous and heat-stress conditions via enhancing the morpho-physio-biochemical attributes, positively reflecting in tree growth, yield, and fruit quality. FA treatment alone improved tree water status (membrane stability index; MSI and relative water content; RWC), photosynthetic traits (SPAD value and maximum photochemical efficiency; Fv/Fm), leaf area, fruit weight, fruit yield, and fruit vitamin C (fruit vit.C), while SA treatment alone enhanced leaf proline and phenolic content, shoot length, and fruit total soluble solids (fruit TSS) compared to the non-FA or SA-treated control. Moreover, co-application of FA400 and SA400 effectively alleviated the harmful impacts of dual stress of heat and salinity on mango trees by improving MSI, RWC, SPAD value, Fv/Fm, proline and phenolic content, fruit weight, fruit yield, fruit TSS, fruit vit.C by 19.7, 26.1, 46.7, 18.7, 101.7, 390.7, 42.7, 6.8, 22.6, 69.6% (averages of the two seasons), respectively, compared to the non-FA or SA-treated trees. Conclusion It is recommended to add 400 g FA tree−1 to soil integrated with 400 mg SA L−1 foliar spraying four times at 30-day intervals for improving water status and photosynthetic traits, proline and phenolic accumulation, thereby growth, yield, and fruit quality of mango trees exposed to dual stress of heat and salinity under arid conditions.