Untreated Plants Research Articles

Analysis of the cytohistological phenotype of anthers in sunflower with ASI-AG3 in the context of the PET1 mytotype and the allelic genotype for the Rf1 gene

Microsporogenesis and male gametogenesis are processes that, although under tight morphogenetic control, can often be affected by deviations of internal or external stimuli causing androsterility. The article examines the cytohistological phenotypes of sunflower anthers with gibberellin induced androsterility in plants with different mitotype and allelic genotype for the Rf1 gene, in comparison with the cytohistological phenotypes of fertile and sterile anthers (ASC-PET1). The treatment with gibberellic acid (AG3, 0.01%) was carried out by spraying the inflorescence at the budding stage. Cytological samples and those with semi-thin anther sections were analysed by light microscopy. It was determined that the gametocidal effects induced by AG3 associated with degenerative and early apoptotic events in tapetum cells were more severe in plants with sterile cytoplasm and nuclear Rf1 genes compared to those with fertile cytoplasm and no fertility-restoring genes. In plants with ASC, the exogenous gibberellin stimulus does not cause any visible compensatory events of the sterile phenotype, on the contrary, the effects of microsporogenesis inhibition are more temporally advanced, with sporogenous and sporophytic tissue cells showing various lesions in the premeiosis. The general common and differentiation characteristics found at the androsteril phenotypes suggest interactions between orfH522 and Rf1 gene expression products of negative feedback type in untreated plants and positive feedback type in AG3-treated ones. The research is relevant in the context of elucidating the physiological regulatory processes of the sensitivity of male gametophyte development to various stress conditions, which prospectively makes possible regulatory intervention in plants with different androsterility/androfertility control systems.

More efficient nitrogen utilization through wool pellet and soil inoculation

AbstractIn recent years, many alternative bio‐waste‐based fertilizers have been proven to have a beneficial effect on plant nutrition. These also include wool pellet, whose comprehensive evaluation of synergistic effects on plant development and soil biological activity is still a limited field of investigation. To address this, we explored the potential of combining soil inoculations and N‐rich wool pellet as ecologically sound alternatives to N fertilizers. In a pot experiment, we investigated the effect of Azotobacter vinelandii, the Trichoderma harzianum T34, and wool pellet, individually and in combination, on the growth and nitrate uptake of the test plants, as well as on the biological activity and permanganate‐oxidizable carbon of the sandy soil with low organic matter content. The combination of T. harzianum + wool pellet showed the highest biological activity and permanganate‐oxidizable carbon content, while the untreated control plants exhibited the lowest values. The treatment combination of wool pellet and A. vinelandii exhibited the highest nitrate uptake by plants. Measuring the concentration of photosynthetic pigments, net photosynthesis, transpiration rate, stomatal conductance, and total dry biomass, we found that the treatments led to a significant improvement in the photosynthetic intensity of lettuce plants. These results suggest that wool pellet served as a significant source of N and that their biological activity plays a key role in improving plant parameters. Moreover, the combination of microbial inoculants and wool pellet effectively increases N use efficiency in plant growth.

Non-Pathogenic Pythium Induced the Resistance in Hydroponic Lettuce Against Root Rot Disease

Hy droponics is a common soilless type of culture. It is clean and gives high-yield crop production. Lettuce is the most widely grown leafy vegetable in hydroponics. The Pythium species causes root rot, a serious disease in lettuce. In this study, we investigated an effective elicitor to promote resistance in lettuce after pathogen infection. To evaluate the plant defense gene response profile, the expression stability of five candidate genes was studied using RT-qPCR. The LsPR1 and LsLTC2 gene expression were higher in lettuce leaves treated with non-pathogenic Pythium PyASR23 than in roots compared to untreated plants. To assess the disease, the rate of relative gene expression of LsLTC2, LsPR-1b like, LsERF, LsAOS, and LsDEF was associated with Pythium root rot pathogenesis. As a result, it was revealed that alterations in these gene expressions were a defense response to Pythium infection, which increased after pre-treatment with various elicitors for 24 hours. When the chemically stimulated lettuce was infected with pathogenic PySR31, the expression of these genes increased dramatically. These results suggested that non-pathogenic PyASR23 might be employed as an elicitor in lettuce roots and contribute to disease control by activating plant defense gene expression against the Pythium pathogen.

Synergistic impact of Serendipita indica and Zhihengliuella sp. ISTPL4 on the mitigation of arsenic stress in rice.

Arsenic (As) is a highly toxic metal that interferes with plant growth and disrupts various biochemical and molecular processes in plants. In this study, the harmful effects of As on rice were mitigated using combined inoculation of a root endophyte Serendipita indica and an actinobacterium Zhihengliuella sp. ISTPL4. A randomized experiment was conducted, in which rice plants were grown under controlled conditions and As-stressed conditions. The control and treatment groups consisted of untreated and non-stressed plants (C1), treated and non-stressed plants (C2), stressed and untreated plants (T1), and stressed and treated plants (T2). Various phenotypic characteristics such as shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW), and root dry weight (RDW) and biochemical parameters such as chlorophyll content, protein content, and antioxidant enzymatic activities were evaluated. The activity of various antioxidant enzymes was increased in T2 followed by T1 plants. Furthermore, high concentrations of phytohormones such as ethylene (ET), gibberellic acid (GA), and cytokinin (CK) were found at 4.11 μmol mg-1, 2.53 μmol mg-1, and 3.62 μmol mg-1 of FW of plant, respectively. The results of AAS indicated an increased As accumulation in roots of T2 plants (131.5 mg kg-1) than in roots of T1 plants (120 mg kg-1). It showed that there was an increased As accumulation and sequestration in roots of microbial-treated plants (T2) than in uninoculated plants (T1). Our data suggest that this microbial combination can be used to reduce the toxic effects of As in plants by increasing the activity of antioxidant enzymes such as SOD, CAT, PAL, PPO and POD. Furthermore, rice plants can withstand As stress owing to the active synthesis of phytohormones in the presence of microbial combinations.

Enhancing Wheat Growth, Physiology, Yield, and Water Use Efficiency under Deficit Irrigation by Integrating Foliar Application of Salicylic Acid and Nutrients at Critical Growth Stages.

Transitioning from full to deficit irrigation (DI) has become a key strategy in arid regions to combat water scarcity and enhance irrigation water use efficiency (IWUE). However, implementing DI requires additional approaches to counter its negative effects on wheat production. One effective approach is the foliar application of salicylic acid (SA), micronutrients (Mic; zinc and manganese), and macronutrients (Mac; nitrogen, phosphorus, and potassium). However, there is a lack of knowledge on the optimal combinations and timing of foliar application for these components to maximize their benefits under arid conditions, which is the primary focus of this study. A two-year field study was conducted to assess the impact of the foliar application of SA alone and in combination with Mic (SA + Mic) or Mic and Mac (SA + Mic + Mac) at various critical growth stages on wheat growth, physiology, productivity, and IWUE under DI conditions. Our result demonstrated that the foliar application of different components, the timing of application, and their interaction had significant effects on all investigated wheat parameters with few exceptions. Applying different components through foliar application at multiple growth stages, such as tillering and heading or tillering, heading, and grain filling, led to significant enhancements in various wheat parameters. The improvements ranged from 7.7% to 23.2% for growth parameters, 8.7% to 24.0% for physiological traits, 1.4% to 21.0% for yield and yield components, and 14.8% to 19.0% for IWUE compared to applying the components only at the tillering stage. Plants treated with different components (SA, Mic, Mac) exhibited enhanced growth, production, and IWUE in wheat compared to untreated plants. The most effective treatment was SA + Mic, followed by SA alone and SA + Mic + Mac. The foliar application of SA, SA + Mic, and SA + Mic + Mac improved growth parameters by 1.2-50.8%, 2.7-54.6%, and 2.5-43.9%, respectively. Yield parameters were also enhanced by 1.3-33.0%, 2.4-37.2%, and 3.0-26.6% while IWUE increased by 28.6%, 33.0%, and 18.5% compared to untreated plants. A heatmap analysis revealed that the foliar application of SA + Mic at multiple growth stages resulted in the highest values for all parameters, followed by SA alone and SA + Mic + Mac applications at multiple growth stages. The lowest values were observed in untreated plants and with the foliar application of different components only at the tillering stage. Thus, this study suggested that the foliar application of SA + Mic at various growth stages can help sustain wheat production in arid regions with limited water resources.

Methylobacterium symbioticum Applied as a Foliar Inoculant Was Little Effective in Enhancing Nitrogen Fixation and Lettuce Dry Matter Yield

Nitrogen (N) is a limiting ecological factor for plant growth in most agroecosystems. Biological N fixation, especially from nodulated legumes, has been promoted in recent decades as an alternative or complement to industrially synthesized N fertilizers. The possibility of utilizing N-fixing organisms from the phyllosphere that demonstrate effectiveness across a wide range of crops is particularly exciting. In this study, we examined the N-fixing capacity and the impact on lettuce growth of an inoculant recently introduced to the market, which contains the microorganism Methylobacterium symbioticum and is recommended for various cultivated species. A pot experiment was conducted using a factorial design, which included the inoculant (No and Yes) and four N rates (0 (N0), 25 (N25), 50 (N50), and 100 (N100) kg ha−1 of N), with four replicates, over four lettuce growing cycles. The inoculant had a significant effect on dry matter yield (DMY) only during the second of the four growing cycles. The mean values of the four growing cycles ranged from 9.9 to 13.7 g pot−1 and 9.9 to 12.6 g kg−1 in pots that received and did not receive the inoculant, respectively. On the other hand, plants exhibited a robust response to N applied to the soil, showing significant increases in both DMY and tissue N concentration across all growing cycles. Mean values of DMY in the treatments N0 and N100 ranged from 5.6 to 8.9 g pot−1 and 12.5 to 16.1 g pot−1, respectively. N concentration in tissues varied inversely with DMY, indicating a concentration/dilution effect. The difference in N concentration between treated and untreated plants, used as an estimate of fixed N, was very low for each of the soils’ applied N rates, assuming average values for the four growing cycles of −1.5, −0.9, 2.4, and 6.3 kg ha−1 for N0, N25, N50, and N100, respectively. This study emphasized the low amount of N supplied to lettuce by the inoculant and its limited effect on DMY. Generally, in biological systems with N-fixing microorganisms, achieving high fixation rates requires a high level of specificity between the microorganism and host plant, a condition that seems not to have been met with lettuce. Considering the importance of the subject, is imperative that further studies be conducted to determine more precisely in which crops and under what growing conditions the inoculant proves to be a valuable input for farmers and an effective method for reducing N mineral fertilization.

Plant growth-promoting rhizobacteria modulate induced corn defense against Spodoptera litura (Lepidoptera: Noctuidae).

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant growth-promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds were analyzed using gas chromatography-mass spectrometry. Larvae fed inoculated corn exhibited lower weights and relative growth rate than noninoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. Volatile organic compound ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura, making it a promising candidate for crop protection strategies.

Control biológico de Ralstonia solanacearum y su efecto en el crecimiento vegetativo de banano orgánico

The banana (Musa AAA) is one of the main economically important crops worldwide. Currently, it faces a serious problem of plant death caused by the bacterium Ralstonia solanacearum (Smith) variety 2. The objective of this research was to evaluate the effect of biological control of Moko disease and its relationship with the vegetative growth of banana seedlings under field conditions. Four treatments were employed: absolute control (T0), Trichoderma spp. (T2), Bacillus spp. (Bio-remedy) (T3), and ADMF® (T4) with three replications in a completely randomized block design. The incubation period, the incidence percentage, and the area under the disease progress curve (AUDPC) were evaluated, along with plant survival and height, pseudostem diameter, and leaf emission rate. At 113 days after transplanting (dat), treatments T1, T2, and T3 showed higher seedling survival. Plant height (111-145 cm), pseudostem diameter (7.43-11.28 cm), and leaf emission rate (11.74-13.15 leaves) exhibited significant differences among treatments. Treated plants showed the lowest AUDPC (between 576.1 and 1435.4 units) compared to untreated plants (3156.55 units). Trichoderma, Bacillus, and ADMF® were demonstrated to reduce disease incidence and promote banana vegetative growth, proving to be viable sustainable alternatives for this crop. Keywords: Musa AAA, Trichoderma, Bacillus, ADMF®, Ralstonia solanacearum, AUDPC.

Utilization of Rhodopseudomonas palustris in Crop Rotation Practice Boosts Rice Productivity and Soil Nutrient Dynamics

Using beneficial microorganisms, such as purple non-sulfur bacteria (PNSB), has shown enormous potential for improving plant growth and agricultural production. However, the full extent of their benefits and interactions with agricultural practices is yet to be fully understood. The present study aimed to investigate the use of PNSB in crop rotation practice, focusing on its impact on rice growth and yield. The experiment was conducted over two rice cropping seasons, with djulis grown between the rice as a rotation crop. The study shows that PNSB treatment increased the concentration of 5-aminolevulinic acid (5-ALA) in plants, indicating enhanced photosynthesis. Moreover, when combined with crop rotation, PNSB remarkably improved soil fertility. These combined benefits resulted in substantial increases in tiller numbers (163%), leaf chlorophyll content (13%), and lodging resistance (66%), compared to the untreated plants. The combined treatment also resulted in higher productive tillers per hill (112%), average grain per hill (65%), and grain fertility (26%). This led to increased grain yield (65%), shoot dry weight (15%), and harvest index (37%). The findings clearly suggest that the incorporation of PNSB in crop rotation strategies can significantly augment the growth and yield of rice crops. These insights, pivotal for sustainable rice cultivation, hold the potential to simultaneously tackle the pressing issues of global food security and climate change.

Relative Expression of Genes Elicited by Clonostachys rosea in Pinus radiata Induces Systemic Resistance

Radiata pine is one of the most commonly planted tree species in Chile due to its fast growth and desirable wood and pulp properties. However, its productivity is hampered by several diseases. Pitch canker disease (PCC) caused by Fusarium circinatum, is considered the most damaging disease to the pine forest industry. Several control measures have been established, with biological control emerging as an environmentally friendly and effective way for F. circinatum control. Previous studies support the value of Clonostachys rosea in reducing PCC damage, with evidence suggesting a potential induced systemic resistance (ISR) triggered in radiata pines by this agent. Ten-month-old radiata pine plants were pre-treated with C. rosea on a substrate at 8 and 1 days before inoculation with F. circinatum on the stem tip, and expression levels were determined for DXS1, LOX, PAL, and PR3 genes 24 h later. Lesion length was 45% lower on plants pre-treated with C. rosea and infected with F. circinatum compared to non-pre-treated and infected plants. Additionally, LOX and PR3 were induced 23 and 62 times more, respectively, in comparison to untreated plants. Our results indicate that C. rosea causes an ISR response in pre-treated plants, significantly increasing the expression of resistance genes and reducing lesion length.

Indirect effects of plasma-activated water irrigation on Tetranychus urticae populations

AbstractPlasma-activated water (PAW) is receiving increased attention as a booster of seed germination and seedling vigor, and some studies have described use of PAW to manage crop pathogens. Here, we examined physicochemical properties of two PAWs (referred to as PAW 6.0 and 9.4 min with atmospheric plasma jet) and assessed “their indirect effects” (applied as supplementary irrigation) on host suitability of tomato plants (Solanum lycopersicum L.) to two-spotted spider mites (Tetranychus urticae Koch). Exposure of water to cold plasma significantly lowered pH and increased concentrations of H2O2, NO2−, and NO3−. Supplementary PAW irrigations elicited significant increases in leaf composition of several elements (N, P, K S, Ca, and Mg), leaf reflectance, plant size, and trichome densities (except non-glandular trichomes on the adaxial surface). Preference bioassays revealed significant avoidance of settling and reduced oviposition by two-spotted spider mites on leaf discs from PAW-irrigated plants compared to those from untreated control plants. Performance bioassays showed a significant decrease in two-spotted spider mite populations on PAW-irrigated plants. Results presented in this study provide comprehensive support to the hypothesis that indirect effects of supplementary PAW irrigation significantly reduce host plant suitability to two-spotted spider mites. PAW 6.0 may be slightly better than PAW 9.4, and this difference in performance is discussed in this study. Applications of PAW as supplementary irrigation are likely highly compatible with other IPM tactics and should be considered an innovative and sustainable component in twenty-first-century pest management.

Assessing the Effectiveness of Neem oil and Microalgae in the Management of Cowpea (Vigna unguiculata L.) Leaf Spot Caused by Alternaria spp.

The current study aimed to assess the effectiveness of neem oil and microalgae in controlling leaf spot caused by Alternaria spp. in cowpea (Vigna unguiculataL.). The research was conducted during the Zaid season of 2022 at the Central Research Field of the Department of Plant Pathology, SHUATS, Prayagraj, Uttar Pradesh, using a Randomized Block Design with three replications and seven treatments. Analysis of variance (ANOVA) was utilized to draw conclusions from the data. Leaf spot disease caused by Alternaria spp poses a significant threat to cowpea crops, resulting in yield losses and decreased plant vigor. An in vivo study was carried out to evaluate the impact of different concentrations of microalgae combined with neem oil at 1% on plant growth parameters and Disease Intensity (%). The application of microalgae @540 grams in various splits and neem oil @1% was done. Among all the treatments, T4 (Microalgae 48gms @5 DAS 96gms@15,45 DAS + Neem oil @1% showed promising results. Notably, the T4 treatment significantly increased plant height (84.63 cm) and the number of branches(10.83) at60DAS. Moreover, an increased numberof nodules per plant (21.44) was observed at 75 DAS, indicating improved root health and nitrogen fixation. Additionally, the treatment led to longer pod length (34.44 cm) in three pickings, suggesting enhanced yield potential. Furthermore, the combined application of microalgae and neem oil resulted in a significant reduction in disease intensity, with a notable decrease of 24.47% compared to untreated plants and those treated with chemicals (Bavistin). This indicates that the use of microalgae and neem oil together effectively suppressed leaf spot disease caused by Alternaria spp. in cowpea, thereby improving plant health and productivity. In conclusion, these findings underscore the potential use of eco-friendly alternatives like microalgae and neem oil for managing leaf spot disease in cowpea cultivation. Further research in this area is recommended for sustainable agricultural practices.

Transcriptome analysis revealed endophytic Beauveria bassiana triggered methyl jasmonate pathway associated with resistance against stem weevil (Apion corchori)

The fungal entomopathogen Beauveria bassiana could be established as an endophyte within jute (Corchorus capsularis) plant through seed inoculation. The highest colonization was observed in ITCC 6063 followed by ITCC 5562 and ITCC 5408 which are statistically at par (p < 0.05). The lowest apion infestation was observed in ITCC 5408, ITCC 6063, ITCC 4512 and ITCC 4563 which are statistically at par (p < 0.05). Highest apion infestation was observed in case of two non-endophytic isolates ITCC 4644 and ITCC 4925. Transcriptome study showed that a significant number of stem-weevil (Apion corchori) resistant genes involved in biosynthesis of plant volatiles viz., oxidative cleavage of fatty acids, LEGO-like building blocks, salicylic acid activation pathway, methyl jasmonic acid synthesis pathway were activated in ten B. bassiana isolate treated plants. RNA Sequencing was used to identify 1017 DEGs between ‘endophyte colonised plant’ and ‘untreated plant’. 1117 genes were up-regulated and 279 genes were down regulated in treated plant.

The novel bacteriocin BacYB1 produced by Leuconostoc mesenteroides YB1: From recent analytical characterization to biocontrol Verticillium dahliae and Agrobacterium tumefaciens

Biocontrol of phytopathogens involving the use of bioactive compounds produced by lactic acid bacteria (LAB), is a promising approach to manage many diseases in agriculture. In this study, a lactic acid bacterium designated YB1 was isolated from fermented olives and selected for its antagonistic activity against Verticillium dahliae (V. dahliae) and Agrobacterium tumefaciens (A. tumefaciens). Based on the 16S rRNA gene nucleotide sequence analysis (1565 pb, accession number: OR714267), the new isolate YB1 bacterium was assigned as Leuconostoc mesenteroides YB1 (OR714267) strain. This bacterium produces an active peptide “bacteriocin” called BacYB1, which was purified in four steps. Matrix-assisted lasers desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) based approach was performed to identify and characterize BacYB1. The exact mass was 5470.75 Da, and the analysis of the N-terminal sequence (VTRASGASTPPGTASPFKTL) of BacYB1 revealed no significant similarity to currently available antimicrobial peptides. The BacYB1 displayed a bactericidal mode of action against A. tumefaciens. The potentiel role of BacYB1 to supress the growth of A. tumefaciens was confirmed by live-dead cells viability assay. In pot experiments, the biocontrol efficacy of BacYB1 against V. dahliae wilt on young olive trees was studied. The percentage of dead plants (PDP) and the final mean symptomes severity (FMS) of plants articifialy infected by V. dahliae and treated with the pre-purified peptide BacYB1 (preventive and curative treatments) were significantly inferior to untreated plants. Biochemical analysis of leaves of the plants has shown that polyophenols contents were highly detected in plants infected by V. dahliae and the highest contents of chlorophyl a, b and total chlorophyll were recorded in plants treated with the combination of BacYB1 with the biofertilisant Humivital. BacYB1 presents a promising alternative for the control of Verticillium wilt and crown gall diseases.

Integrated transcriptome and metabolome analysis reveals the regulation of phlorizin synthesis in Lithocarpus polystachyus under nitrogen fertilization

BackgroundNitrogen (N) is essential for plant growth and development. In Lithocarpus polystachyus Rehd., a species known for its medicinal and food value, phlorizin is the major bioactive compound with pharmacological activity. Research has revealed a positive correlation between plant nitrogen (N) content and phlorizin synthesis in this species. However, no study has analyzed the effect of N fertilization on phlorizin content and elucidated the molecular mechanisms underlying phlorizin synthesis in L. polystachyus.ResultsA comparison of the L. polystachyus plants grown without (0 mg/plant) and with N fertilization (25, 75, 125, 175, 225, and 275 mg/plant) revealed that 75 mg N/plant fertilization resulted in the greatest seedling height, ground diameter, crown width, and total phlorizin content. Subsequent analysis of the leaves using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detected 150 metabolites, including 42 flavonoids, that were differentially accumulated between the plants grown without and with 75 mg/plant N fertilization. Transcriptomic analysis of the L. polystachyus plants via RNA sequencing revealed 162 genes involved in flavonoid biosynthesis, among which 53 significantly differed between the N-treated and untreated plants. Fertilization (75 mg N/plant) specifically upregulated the expression of the genes phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), and phlorizin synthase (PGT1) but downregulated the expression of trans-cinnamate 4-monooxygenase (C4H), shikimate O-hydroxycinnamoyltransferase (HCT), and chalcone isomerase (CHI), which are related to phlorizin synthesis. Finally, an integrated analysis of the transcriptome and metabolome revealed that the increase in phlorizin after N fertilization was consistent with the upregulation of phlorizin biosynthetic genes. Quantitative real-time PCR (qRT‒PCR) was used to validate the RNA sequencing data. Thus, our results indicated that N fertilization increased phlorizin metabolism in L. polystachyus by regulating the expression levels of the PAL, PGT1, 5-O-(4-coumaroyl)-D-quinate 3’-monooxygenase (C3’H), C4H, and HCT genes.ConclusionsOur results demonstrated that the addition of 75 mg/plant N to L. polystachyus significantly promoted the accumulation of flavonoids, including phlorizin, and the expression of flavonoid synthesis-related genes. Under these conditions, the genes PAL, 4CL, and PGT1 were positively correlated with phlorizin accumulation, while C4H, CHI, and HCT were negatively correlated with phlorizin accumulation. Therefore, we speculate that PAL, 4CL, and PGT1 participate in the phlorizin pathway under an optimal N environment, regulating phlorizin biosynthesis. These findings provide a basis for improving plant bioactive constituents and serve as a reference for further pharmacological studies.

Selenium alleviates growth characteristics, plant pigments, photosynthetic and antioxidant capacity of basil (Ocimum basilicum L.) under low temperature

Se in optimal concentrations may help to expand the plant tolerance to the different abiotic stresses. In this regard, the effect of foliar application of sodium selenate (0, 2, 4, and 6 mg of Na2SeO4) at two temperature conditions: 1. Optimal temperature (OT, 26 ± 3 °C) and 2. Cold temperature (CT, 13 ± 3 °C) was compared. The results showed that under CT, fresh and dry weight, leaf area, and length of pre-treated plant with 2 mg.L−1 Se were more suitable than untreated plants, although selenium under OT declined these characteristics. The pre-treatment of 2 mg. L−1 of Se under CT was conducive to, the 6.75% dry weight higher than that non-treated plants with Se under low temperature conditions. Also under CT conditions, pretreatment of plants with 2 mg. L−1 Se increased H2O2 production by 102% compared to non-treated plants with selenium. However, it was about 25.56% lower than the untreated plants with selenium under CT. It is interesting to note that under the CT conditions, pretreatment of 2 mg. L −1 Se reduced the content of MDA by 10.28% compared to the same temperature conditions and no Se pretreatment. Foliar application of 2 mg.L−1 Se is recommended to improve basil endure in CT and biofortification with Se under both OT and CT.

DIAZOTROPHIC ENDOPHYTE Klebsiella sp. N5 FROM SORGHUM SHOWS CROSS-COLONIZATION AND PLANT GROWTH PROMOTION IN RICE

Rice necessitates the highest levels of N fertilizers during its cultivation increasing demand for nitrogen fertilizers as well as negatively affecting the environment. Endophytic diazotrophic bacteria were isolated from sorghum, out of 35 isolates Klebsiella sp. N5 showed maximum potential for biological nitrogen fixation. Primary screening of strain N5 was done with acetylene reduction assay indicating dry root activity of 638.55 nmol C2H4 h-1 g-1. That was further confirmed by nifH gene amplification. The strain was identified morphologically, biochemically and 16S rDNA sequencing analysis and identified as Klebsiella sp. strain N5. This strain exhibited other plant growth-promoting (PGP) traits, such as phosphate solubilization, production of indole acetic acid, siderophore activity, ACC deaminase activity, and anti-fungal activity. PGP endophyte N5 was inoculated into rice seedlings to investigate its interaction under axenic conditions and to characterize its ability to colonize non-native host plant rice. Extensive colonization of rice roots was corroborated by Scanning electron microscopy. In-planta experiments with rice seeds inoculated with Klebsiella sp. N5 showed significant improvements in various agronomic traits such as increase in shoot length, root length, fresh and dry weight of root and shoot, chlorophyll content, and nitrogen content of the plant and soil compared to the untreated plants. Klebsiella sp. N5, a cross colonizer from sorghum (C4 plant) to rice (C3 plant) plays a crucial role in facilitating the acquisition of essential resources such as nitrogen, phosphorus, and iron through direct mechanisms. This study expands the horizon for its potential as a valuable bioinoculant for sustainable agricultural practices, particularly in non-native host rice, paving the way for future field trials.

Carbon Nanoparticles Promoted the Absorption of Potassium Ions by Tobacco Roots via Regulation of K+ Flux and Ion Channel Gene Expression

Background: The regulatory effects of carbon nanomaterials (CNMs) on plant growth and their potential applications in agriculture have attracted a great deal of attention from researchers. CNMs have been shown to promote nutrient absorption and increase plant growth. However, the mechanisms by which CNMs affect plant growth and nutrient absorption are still unknown. Methods: The tobacco seedling biomass, potassium (K+) concentration, and accumulation in hydroponic were investigated to exposure of carbon nanoparticles (CNPs). To directly observe the effect of CNPs on K+ uptake by roots, we employed a noninvasive micro-test technique (NMT) to detect the net flux of K+ on the surface of tobacco roots. The K+-depletion experiment was carried out to explore the kinetic characteristics of K+ absorption, and qRT-PCR was used to monitor the expression levels of the K+ channel gene. Results: The results showed that tobacco seedling biomass significantly improved at 10 mg·L-1 CNP treatments, and K+ concentration and accumulation both in roots and shoots increased with 10 and 20 mg·L-1 CNPs. CNP treatments changed the flow rate of K+ from efflux to influx in tobacco roots; this was observed both in plants cultivated in a CNP-containing medium and after the addition of CNPs to previously untreated plants. A depletion test also showed that CNPs improved the K+ absorption capacity and low-K+ tolerance of tobacco seedlings. Conclusion: CNPs enhanced the K+ absorption capacity and low-K+ tolerance of tobacco seedlings. The promotion of K+ absorption by CNPs was closely related to the activation of K+ influx channel genes and inhibition of the K+ outflow channel gene. The K+ flux response and ion channel gene expression to CNPs in plants reveal the mechanism whereby CNPs promote plant nutrient absorption.

The efficacy of chemical inducers and fungicides in controlling tomato root rot disease caused by Rhizoctoniasolani

Chitosan is an environmentally friendly natural substance that is used in crop disease management as an alternative to chemical pesticides. A significant issue restricting output in Egypt is root rot, which is a disease, caused by Rhizoctonia solani. Therefore, a greenhouse experiment was conducted to assess the effects of R. solani on 60-day-old tomato plants under fungal infection and to determine the antifungal activity of chitosan and Rizolax T fungicide against the pathogenic fungus. The findings demonstrated that 4 g/L of chitosan seed application completely obstructed the radial mycelial growth of R. solani and decreased the disease severity. Pathogenic infection significantly decreased morphological characteristics and total chlorophyll but significantly increased carotenoid, total thiol, non-protein thiol, protein thiol, antioxidant enzymes, oxidative stress, total phenolic, total flavonoid, and isoflavone compared to healthy plants. Tomato plants treated with chitosan exhibited lower rates of oxidative stress, but higher levels of all previously mentioned parameters compared to untreated infected plants. The number and molecular mass of protein banding patterns varied in all treated tomato plants as compared to the healthy control. There are 42 bands in the treatments, and their polymorphism rate is 69.55%. Moreover, the number and density of α- and β-esterase, and peroxidase isozymes in treated tomato plants exhibited varied responses. Moreover, in treated and control plants, chitosan treatment raised the expression levels of phenylalanine ammonia-lyase, pathogenesis-related protein-1, β-1,3-glucanases and chitinase. In conclusions, chitosan reduces R. solani infection by controlling the biochemical and molecular mechanisms in tomato plants during infection.

Effect of Selenium and Garlic Extract Treatments of Seed-Addressed Lettuce Plants on Biofortification Level, Seed Productivity and Mature Plant Yield and Quality.

The enhancement of the plant seed yield and quality represents the basis of the successful productivity of the deriving crop. The effect of single and combined foliar treatments of lettuce plants with sodium selenate and garlic bulb extract on seed yield and quality and on mature plant biochemical characteristics was investigated using four lettuce cultivars (Bouquet, Picnic, Moskovsky parnikovy and Cavalier). The seed production of plants treated with Se increased by 20-41%, compared to the untreated control plants, while the augmentation was as much as 10-23% and 17-27% under garlic extract and the joint application of Se and garlic, respectively. Garlic extract stimulated the accumulation of Se in lettuce seeds, which rose by 1.21-1.29 times compared to the Se-treated plants. The proline levels in lettuce seeds exceeded the corresponding values recorded in the control ones by 1.32-1.64 times in the case of the Se supply, 1.10-1.47 times upon garlic extract application and 1.09-1.31 times under the combined Se/garlic treatment. All the treatments given to lettuce plants increased the leaf weight by 1.10-1.30 times, compared to the untreated control. The seed Se levels positively correlated with the leaf weight (r = 0.621; p < 0.005), chlorophyll (r = 0.672, p < 0.002) and total antioxidant activity (AOA; r = 0.730, p < 0.001) of plants grown from these seeds. Positive correlations were also recorded between the seed proline content and lettuce plant leaf weight, chlorophyll and AOA (r = 0.868, 0.811 and 0.815, respectively, at p < 0.001). Lettuce yield was positively correlated with the leaf AOA, chlorophyll and ascorbic acid content (r = 0.942, 0.921 and 0.665, respectively, at p < 0.001). The results indicate high prospects of Na2SeO4 and garlic extract application to seed-addressed lettuce plants, to improve seed productivity and quality, as well as lettuce yield and quality.