Plant Defense System Research Articles

Repellent and toxic effects of Salvia rosmarinus oil against Liriomyza sativae

AbstractThe vegetable leafminer (VLM) Liriomyza sativae Blanchard is a troublesome pest of vegetable and ornamental plants worldwide. Resistance development and environmental pollution from the overuse of chemical insecticides have driven interest in alternative control strategies for this pest. Secondary metabolites derived from aromatic nonhost plants are recognised components of the plant defence system against herbivores. The essential oils derived from aromatic plants not only repel insects but also have toxic effects against various insect pests, yet little is known about their effects against leafminers. The major constituents of the essential oil extracted from rosemary leaves by hydrodistillation were identified by GC–MS. The behavioural responses of VLM adults to the rosemary essential oil (REO) were explored with Y‐tube olfactometer experiments, and the oviposition and feeding deterrent effects of REO against adults were studied using no‐choice cage tests. Dipping methods were used to determine the toxicity of REO and Matrine (a commercial botanical pesticide) against VLM eggs, larvae and pupae, while glass‐vial bioassays were used for adults. The identified major constituents of the cineoliferum chemotype of REO were 1,8‐cineole (23.53%), pinene (23.45%), (S)‐(−)‐verbenone (12.84%) and borneol (7.47%). REO repelled leafminer adults. Sublethal concentrations of REO deterred oviposition and feeding by adults. Adults were more susceptible than other developmental stages to toxicity of REO and Matrine. Female adults were more sensitive than males, based on EC50 values at 24 and 48 hr after treatment. Rosemary essential oil is a behaviour‐modifying stimulus potentially useful in a “push‐pull” strategy for L. sativae control, and as an alternative to synthetic chemical insecticides due to its low toxicity and high efficacy in the control of VLM.

RNA Interference: Promising Approach to Combat Plant Viruses.

Plant viruses are devastating plant pathogens that severely affect crop yield and quality. Plants have developed multiple lines of defense systems to combat viral infection. Gene silencing/RNA interference is the key defense system in plants that inhibits the virulence and multiplication of pathogens. The general mechanism of RNAi involves (i) the transcription and cleavage of dsRNA into small RNA molecules, such as microRNA (miRNA), or small interfering RNA (siRNA), (ii) the loading of siRNA/miRNA into an RNA Induced Silencing Complex (RISC), (iii) complementary base pairing between siRNA/miRNA with a targeted gene, and (iv) the cleavage or repression of a target gene with an Argonaute (AGO) protein. This natural RNAi pathway could introduce transgenes targeting various viral genes to induce gene silencing. Different RNAi pathways are reported for the artificial silencing of viral genes. These include Host-Induced Gene Silencing (HIGS), Virus-Induced Gene Silencing (VIGS), and Spray-Induced Gene Silencing (SIGS). There are significant limitations in HIGS and VIGS technology, such as lengthy and time-consuming processes, off-target effects, and public concerns regarding genetically modified (GM) transgenic plants. Here, we provide in-depth knowledge regarding SIGS, which efficiently provides RNAi resistance development against targeted genes without the need for GM transgenic plants. We give an overview of the defense system of plants against viral infection, including a detailed mechanism of RNAi, small RNA molecules and their types, and various kinds of RNAi pathways. This review will describe how RNA interference provides the antiviral defense, recent improvements, and their limitations.

Exogenous melatonin improves the resistance to cucumber bacterial angular leaf spot caused by Pseudomonas syringae pv. Lachrymans.

Pseudomonas syringae pv. Lachrymans (Psl) is a bacterial pathogen that causes cucumber bacterial angular leaf spot (BALS). It is known that melatonin (MT), as a pleiotropic signal molecule, can improve plant stress tolerance, but less information is available about the function of MT on plant resistance to bacteria disease. Here, we investigated the effect of MT on cucumber BALS. Our results show that MT inhibited the bacteria Psl growth significantly in vitro and attenuated cucumber BALS remarkably in vivo. The concentration of bacteria in leaves treated with 0.1 mM MT was approximately 10,000 times reduced at 5 days-post-inoculation (dpi), compared to the control without MT. Transcriptomic analysis showed that 225 differentially expressed genes (DEGs) were induced in leaves after just MT treatment for 3h. The functions of these DEGs were mainly associated with hormone signal transduction, mitogen-activated protein kinase (MAPK) signaling pathway, and photosynthesis, suggesting that MT could regulate plant growth and induce plant immunity. Moreover, 665 DEGs were induced when leaves were treated with exogenous MT in combination with the bacteria inoculation for 12 h. The functions of these DEGs were much related to plant-pathogen interaction, hormone signal transduction, and amino acids biosynthesis pathways. Many MT-induced DEGs were involved in some distinct signal transduction pathways, such as calmodulin (CaM), polyamines (PAs), nitric oxide (NO), and salicylic acid (SA). The physiological analysis shows that exogenous MT spray reduced the stomatal aperture and enhanced the activities of antioxidant and defense enzymes, which were in consistent with the results of the transcriptome analysis. In addition, MT may function in regulating the metabolic balance between plant growth and defense. In conclusion, our results demonstrate that MT could alleviate the cucumber BALS via inhibiting propagation and invasion of Psl, activating plant signaling, enhancing antioxidative and defense systems, inducing stress-related genes expression, and regulating the plant growth-defense balance.

Growth and Yield of Purple Kculli Corn Plants under Different Fertilization Schemes.

Globally, corn is the most economically important crop, surpassing other cereals of economic importance. However, the tillage methods, monoculture and the abuse of synthetic agrochemicals used in Mexico have led to the loss of fertility and soil yield. In this sense, the application of alternative fertilization methods based on chemical fertilizer, organic matter and biofertilizer, applied alone or in combination, can stimulate the defense systems of corn plants and increase their yield. Therefore, in this research, some fertilization schemes were tested on purple corn plants of the Kculli race through the evaluation of some growth and yield variables, as well as the subsequent evaluation of the chemical characteristics of the corn grain produced in each fertilization scheme. The results indicate highly significant differences (p ≤ 0.05) between treatments, for the different growth and yield variables studied. Of all the fertilization schemes evaluated, treatment T7 obtained the best grain yield of 6.19 ± 0.07 t ha−1, with respect to treatment T1 of 1.02 ± 0.01 t ha−1, as well as the highest protein content and starch quality. Being clear the positive effect of the adequate contribution of the macro and micronutrients used exerts on the corn crop in each of the fertilization schemes studied. On the other hand, the analysis carried out on the grains was found within the values reported by other authors.

Foliar Spray of Micronutrients Alleviates Heat and Moisture Stress in Lentil (Lens culinaris Medik) Grown Under Rainfed Field Conditions.

The simultaneous occurrence of high temperature and moisture stress during the reproductive stage of lentil (Lens culinaris Medik) constrains yield potential by disrupting the plant defense system. We studied the detrimental outcomes of heat and moisture stress on rainfed lentils under residual moisture in a field experiment conducted on clay loam soil (Aeric Haplaquept) in eastern India from 2018 to 2019 and from 2019 to 2020 in winter seasons. Lentil was sown on two dates (November and December) to expose the later sowing to higher temperatures and moisture stress. Foliar sprays of boron (0.2% B), zinc (0.5% Zn), and iron (0.5% Fe) were applied individually or in combination at the pre-flowering and pod development stages. High temperatures increased malondialdehyde (MDA) content due to membrane degradation and reduced leaf chlorophyll content, net photosynthetic rate, stomatal conductance, water potential, and yield (kg ha–1). The nutrient treatments affected the growth and physiology of stressed lentil plants. The B+Fe treatment outperformed the other nutrient treatments for both sowing dates, increasing peroxidase (POX) and ascorbate peroxidase (APX) activities, chlorophyll content, net photosynthetic rate, stomatal conductance, relative leaf water content (RLWC), seed filling duration, seed growth rate, and yield per hectare. The B+Fe treatment increased seed yield by 35–38% in late-sown lentils (December). In addition, the micronutrient treatments positively impacted physiological responses under heat and moisture stress with B+Fe and B+Fe+Zn alleviating heat and moisture stress-induced perturbations. Moreover, the exogenous nutrients helped in improving physiochemical attributes, such as chlorophyll content, net photosynthetic rate, stomatal conductance, water potential, seed filling duration, and seed growth rate.

EFFECTS OF SECONDARY METABOLITE PRODUCTION AND ANTIOXIDANT ENZYME RESPONSE OF SELECTED MEDICINAL PLANTS LEAF CELL CULTURES

Leaf explants of three medicinally important plants viz., Convolvulus microphyllus Seib., Peltophorum pterocarpum (DC.) Baker ex. K. Heyne and Pergularia daemia (Forsk.) Chiov. were cultured in Murashige and Skoog’s medium with different concentrations of auxins and cytokinins. Callus of each of the plant species was dried, extracted in alcohol and estimated for total levels of phenolics and flavonoids. Antioxidative enzymes such as catalase (CAT) and ascorbate peroxidase (APX), which play important role in plant defense systems, also calculated. The data reveled that with age of the callus, total levels of phenolics and flavonoids increased. Among the test extracts, 8 weeks-old callus of C. microphyllus demonstrated higher levels of total phenolics (20.36 ± 6.67 mg GAE g-1 dw), while flavonoids were higher in 8 weeks-old callus of P. daemia (23.80 ± 0.05 mg QE g-1 dw). However, ascorbate peroxidase and catalase activities decreased with the age of the callus levels of phenolics and flavonoids were found to be higher. The results indicate that, with the age of cultures generated stress leading to the production of secondary metabolites. It is known that, production of phenolics and flavonoids suppresses CAT and APX activities, critical factor for the damage of oxidative stress.

Content of Enzymatic and Nonenzymatic Antioxidants in <i>Salix viminalis</i> L. Grown on the Stebnyk Tailing

Currently, the problem of environmental pollution, especially in contaminated areas, is highly important. The study of the defense mechanisms of plants under salt stress (high salinity) is of considerable importance, given the conditions of current agricultural development and climate change. The aim of this study was to reveal the effect of salinity on <i>Salix viminalis</i> L. under field conditions at the Stebnyk tailing site in Ukraine. After 120 days of growth, the leaves, stems, and roots of <i>S. viminalis</i> were harvested to measure the antioxidant defense system of plants under salinity. Inhibition of <i>S. viminalis</i> growth was observed. We found that peroxidase, ascorbic acid, and proline mainly accumulated in the stems of <i>S. viminalis</i> under salinity conditions. However, in the roots, an increase in catalase activity and soluble sugars content was observed under salinity stress. Thus, the increase in the amount and changes in the activity of enzymes showed the involvement of the antioxidant system in the adaptation of <i>S. viminalis</i> to salinity. The data obtained in this study serve as a starting point for understanding the adaptive mechanisms of <i>S. viminalis</i> to salinity, particularly at the Stebnyk tailing. We believe our findings will support the use of plants in nature-based solutions and eco-engineering projects on saline and industrially polluted lands.

Drenched Silicon Suppresses Disease and Insect Pests in Coffee Plant Grown in Controlled Environment by Improving Physiology and Upregulating Defense Genes.

Plant disease and insect pests are major limiting factors that reduce crop production worldwide. The ornamental indoor cultivation cash crop dwarf coffee Punica arabica ‘Pacas’ is also troubled by these issues. Silicon (Si) is one of the most abundant elements in the lithosphere and positively impacts plant health by effectively mitigating biotic and abiotic stresses. Several studies have shown that Si activates plant defense systems, although the specific nature of the involvement of Si in biochemical processes that lead to resistance is unclear. In our study, Si significantly promoted the growth and development of dwarf coffee seedlings grown in plant growth chambers. More than that, through natural infection, Si suppressed disease and insect pests by improving physiology (e.g., the strong development of the internal structures of roots, stems, and leaves; higher photosynthetic efficiency; more abundant organic matter accumulation; the promotion of root activity; the efficient absorption and transfer of mineral elements; and various activated enzymes) and up-regulating defense genes (CaERFTF11 and CaERF13). Overall, in agriculture, Si may potentially contribute to global food security and safety by assisting in the creation of enhanced crop types with optimal production as well by mitigating plant disease and insect pests. In this sense, Si is a sustainable alternative in agricultural production.

Pseudozyma aphidis Suppresses Microbe-Associated Molecular Pattern (MAMP)-Triggered Callose Deposition and Can Penetrate Leaf Tissue.

ABSTRACTBeneficial microorganisms need to overcome the plant defense system to establish on or within plant tissues. Like pathogens, beneficial microbes can manipulate a plant’s immunity pathways, first by suppressing and hiding to establish on the host and then by inducing resistance to protect the plant. In the current study, we demonstrated that although Pseudozyma aphidis can activate microbe-associated molecular pattern (MAMP)-associated genes, it does not activate MAMP-triggered callose deposition and can, moreover, suppress such deposition triggered by Flg22 or chitin. While MAMP-associated gene activation by P. aphidis was not dependent on salicylic acid, jasmonic acid, or ethylene signaling, suppression of MAMP-triggered callose deposition required the salicylic acid and jasmonic acid signaling factors JAR1-1 and E3 ubiquitin ligase COI1 yet did not rely on EIN2, NPR1, or the transcription factor JIN1/MYC2. We also demonstrated the ability of P. aphidis, known to be an epiphytic yeast-like organism, to penetrate the stomata and establish within plant tissues, as do endophytes. These results thus demonstrate the potential of P. aphidis to suppress MAMP-elicited defenses in order to establish on and within host plant tissues.IMPORTANCE Our study demonstrates the ability of P. aphidis to penetrate into plant tissues, where it avoids and overcomes plant defense systems in order to establish and subsequently protect the plant.

Exposure effects of non-ionizing radiation of radio waves on antimicrobial potential of medicinal plants

The high frequency electromagnetic (EM) waves have been proven as potent environmental polluters. The radio towers are considerably increasing to cater to the growing telecommunication requirements. The presented research focuses on the investigation of EM waves on antimicrobial potential of pharmaceutically important medicinal plants viz. Tulsi (Ocimum sanctum L.) and Brahmi (Bacopa monnieri). The similar work has not been reported till date at the best of our knowledge. The medicinal plants were exposed to EM waves of 900 MHz possessing a 1.9 mG magnetic field. Our former investigation on plant physiology gave deteriorative effects on selected plants physiology in terms of growth, chlorophyll content, protein and carbohydrate content. In the presented article, the antimicrobial activity of two plants was inspected through various bacterial and fungal species. In case of B. monnieri, investigations revealed raise in Zone of Inhibition (ZOI) for both the bacterial and fungal strains in the range of 50%, whereas for O. sanctum increase of 63.26% and 59.42% ZOI for bacterial and fungal strains were noted respectively upon 24 h of exposure. Minimum Inhibitory Concentration (MIC) also decreased for 24 and 48 h of exposure. The transient raise in antimicrobial activity indicated the induction of plant defense system which can be considered as positive influence of short term radiation on medicinal properties of plants. Both plants exhibited the highest antimicrobial potential for E. coli and P. chrysogenum showing a prominent decline after 72 h of exposure. A substantial decline in antimicrobial in MIC of B. monnieri reported was 211% against E. coli and 166% against P. chrysogenum upon 144 h of exposure compared to control plants. The antimicrobial potential of O. sanctum was also decreased upon radiation, which is having a 392% reduction against E. coli and a 225% reduction against P. chrysogenum upon 144 h of exposure. The noteworthy deteriorative effects of radio waves on antimicrobial potential have been observed for both the medicinal plants.

Combined Role of Fe Nanoparticles (Fe NPs) and Staphylococcus aureus L. in the Alleviation of Chromium Stress in Rice Plants.

Chromium (Cr) is a toxic heavy metal whose high concentration in soil badly affects plant growth, photosynthesis, and overall yield. Metal-derived nano-particles and metal-resistant bacteria can strengthen the plant defense system against different abiotic stresses; however, little is known about the use of nanoparticles in conjunction with bacteria. This study examined the combined effect of Fe nanoparticles (Fe NPs) and a chromium-resistant bacterium Staphylococcus aureus, on rice plants grown on chromium saturated medium. Chromium stress reduced rice growth, biomass, and chlorophyll contents by causing oxidative damage leading to overproduction of electrolyte leakage, hydrogen peroxide, and malondialdehyde. Fe NPs significantly improved plant growth, biomass, yield, and photosynthetic activity by enhancing the chlorophyll contents and alleviating oxidative damage. Application of Fe NPs also reduced the uptake and accumulation of Cr in the plants by increasing the bioavailability of micronutrients to the plant. The Fe NPs decreased oxidative damage and enhanced the enzymatic and non-enzymatic activity in the plant to withstand Cr stress compared to the plants without Fe NPs treatments. The inoculation of rice plants with the chromium-resistant bacteria S. aureus further enhanced the positive impact of Fe NPs by transforming the toxic form of chromium (Cr6+) into a less toxic form of chromium (Cr3+). The bacterial inoculation reduced Cr uptake by plants through adsorption of Cr ions, resulting in decreased chromium ion bioavailability. At chromium level 100 mg/kg, the foliar application of Fe NPs from 0 to 20 mg/L increased the total chlorophyll contents from 2.8 to 3.9. The application of S. aureus further enhanced the chlorophyll contents from 4.4 to 5.4, respectively. The current study suggested that combining Fe NPs and S. aureus could be a viable strategy for reducing Cr toxicity and accumulation in rice plants and most likely other plants.

Identification of Potential Cytokinin Responsive Key Genes in Rice Treated With Trans-Zeatin Through Systems Biology Approach.

Rice is an important staple food grain consumed by most of the population around the world. With climate and environmental changes, rice has undergone a tremendous stress state which has impacted crop production and productivity. Plant growth hormones are essential component that controls the overall outcome of the growth and development of the plant. Cytokinin is a hormone that plays an important role in plant immunity and defense systems. Trans-zeatin is an active form of cytokinin that can affect plant growth which is mediated by a multi-step two-component phosphorelay system that has different roles in various developmental stages. Systems biology is an approach for pathway analysis to trans-zeatin treated rice that could provide a deep understanding of different molecules associated with them. In this study, we have used a weighted gene co-expression network analysis method to identify the functional modules and hub genes involved in the cytokinin pathway. We have identified nine functional modules comprising of different hub genes which contribute to the cytokinin signaling route. The biological significance of these identified hub genes has been tested by applying well-proven statistical techniques to establish the association with the experimentally validated QTLs and annotated by the DAVID server. The establishment of key genes in different pathways has been confirmed. These results will be useful to design new stress-resistant cultivars which can provide sustainable yield in stress-specific conditions.

Spatial variations in the biochemical potential of okra [Abelmoschus esculentus L. (Moench)] leaf and fruit under field conditions.

Okra (Abelmoschus esculentus L. (Moench) plays a significant role in humans nutrition because its fresh leaves, stems, flowers, pods and seeds, are used for multiple purposes. The present study attempted to determine the spatial variations in biochemical attributes of osmoprotectants and the oxidative defense system of okra plants. Samples of soil and okra plants (leaves and fruits) were collected from three different locations: Faisalabad region-1 (7 JB-I), Faisalabad region-2 (7 JB-II) and Pindi Bhattian. Chlorophyll contents, glycine betaine (GB), ascorbic acid (AsA), total phenolics, hydrogen peroxide (H2O2), proline, and malondialdehyde (MDA) contents were analyzed in the leaves and fruits of okra plants. Soil analyses showed that pH, electrical conductivity (EC), phosphorus (P), potassium (K), iron (Fe), and saturation of soil were higher in Faisalabad region 2, while organic matter, sand, Zn, and Cu were higher in the Pindi Bhattian region. The results from okra leaves showed that Pindi Bhattian had higher chlorophyll a, GB and H2O2 contents, while Faisalabad region 1 had a higher ratio of chlorophyll a/b compared to the other regions. However, Faisalabad regions 2 and 1 had higher leaf phenolic contents, Faisalabad regions 1 and 2 showed higher leaf proline contents, and Faisalabad region 2 possessed higher AsA and MDA contents. Analyses of okra fruits showed that Faisalabad region 2 had higher chlorophyll a and total chlorophyll contents, while Faisalabad region 1 had higher chlorophyll b contents. Faisalabad region 2 and Pindi Bhattian had higher ratios of chlorophyll a/b, and Faisalabad region 1 showed higher phenolic, AsA, H2O2, and MDA contents of okra fruit, whereas the Faisalabad regions exhibited higher proline and GB contents than the Pindi Bhattian region. Overall, okra leaves and fruits showed better responses in the Faisalabad regions, and these results may be used to screen for okra cultivars with better tolerance under different environmental conditions.

S-Fertilizer (Elemental Sulfur) Improves the Phytoextraction of Cadmium through Solanum nigrum L.

Soil contamination with toxic heavy metals [such as cadmium (Cd)] is becoming a serious global problem due to the rapid development of the social economy. This study was carried out to assess the beneficial role of two different kinds of (S)-fertilizer in the phytoremediation of Cd contaminated soil through Solanum nigrum L. Gypsum (Gyp) and Elemental sulfur (ES) was applied alone and in combination with different ratios (0, 100:0, 0:100, 50:50 mg kg−1) accompanied by different Cd levels (0, 25, 50 mg kg−1). After seventy days of sowing, plants were harvested for determination of growth, physiological characteristics, oxidants and antioxidants, along with Cd uptake from different parts of the plant. Cd toxicity significantly inhibited growth, physiology and plant defence systems, and also increased Cd uptake in the roots and shoots of Solanum nigrum L. The application of Gyp 100 mg kg−1 boosted plant growth and physiology along with oxidants and antioxidants activity as compared to ES 100 mg kg−1 alone, and combine application of GYP+ES 50 + 50 mg kg−1. The application of ES 100 mg kg−1 showed an effective approach to decreasing Cd uptake as compared to Gyp 100 mg kg−1. Overall results showed that the combined application of GYP+ES 50 + 50 mg kg−1 significantly enhanced the phytoremediation potential of S. nigrum in Cd contaminated soil. Thus, it is highly recommended to apply the combined application of GYP+ES for phytoremediation of Cd contaminated soil.

Anti-Herbivore Resistance Changes in Tomato with Elevation.

Local adaptations of host plants to climatic conditions along an elevation gradient can affect insect-plant interactions. Using local accessions sampled from different elevations within South America, plant defense responses and herbivore growth were evaluated on two host plants: a) cherry tomato, Solanum lycopersicum var. cerasiforme, and b) wild tomato, Solanum pimpinellifolium. The elevational origin of the accessions ranged from 100 to 3000m above sea level. We hypothesized a higher level of defensive compounds in plants originating from lower elevations and, consequently, stronger resistance to insect herbivory. Interestingly, plant resistance to insect herbivory, as demonstrated by a reduction in Helicoverpa zea growth, was stronger for middle and high-elevation accessions. Total phenolic content increased with elevation in both herbivore-damaged and undamaged leaves, augmenting plant resistance. However, an elevational gradient was not evident for plant defensive proteins (polyphenol oxidase and trypsin protease inhibitors) or the density of leaf trichomes. Tradeoffs between constitutive and induced defenses were evident in both tomato genotypes. Future studies should test the role of plasticity in plant defense systems in restricting or facilitating range expansion of insect herbivores with climate change.

The ability of Meloidogyne javanica to suppress salicylic acid-induced plant defence responses

Summary Suppression of the defence system of plants by some plant pathogens is an important mechanism of their parasitism, and plant-parasitic nematodes use several mechanisms to affect different parts of the plant defence system. This study was designed to investigate the ability of a root-knot nematode, Meloidogyne javanica, to reduce or suppress the plant (tomato) immune system, before or after activation by a strong inducer, salicylic acid (SA). The experimental treatments were tomato plants inoculated with nematodes alone, plants pre-treated with SA and then nematodes (‘SA then nematode’), plants treated with SA after nematode inoculation (‘nematode then SA’), plants treated with SA alone, and plants treated with sterile distilled water. The results showed that treatment of the plants with SA before or after nematode infection reduced nematode disease indices compared to the control (nematode alone). The number of eggs per individual egg mass, in ‘nematode then SA’ treatment was significantly greater than the control, which shows the effect of nematodes on reducing the plant defence mechanism in this treatment. Evaluation of the activity of some defence enzymes such as chitinase, protease, phenylalanine ammonia lyase, catalase and density of hydrogen peroxide also showed that M. javanica is able to suppress these compounds in the ‘SA then nematode’ treatment, and to a greater extent in the ‘nematode then SA’ treatment. Suppression of plant defence responses by phytonematodes is of great importance in their synergistic relationship with secondary pathogens and plants.

Dirigent gene family is involved in the molecular interaction between Panax notoginseng and root rot pathogen Fusarium solani

Root rot, mainly caused by Fusarium solani, severely reduces the yield and quality of Panax notoginseng (Burk) F.H. Chen. Dirigent (DIR) proteins catalyze the coupling of lignin monomers during lignin biosynthesis, making them important components of plant defense systems. In this study, a small P. notoginseng DIR gene family was isolated from P. notoginseng. A phylogenetic analysis indicated that PnDIR1 belongs to the DIR-a subfamily, whereas the other six PnDIRs belong to the DIR-b/d subfamily. The expression patterns determined by real-time PCR revealed that PnDIR transcription was up-regulated by F. solani and modulated by some hormone signals (except PnDIR5). The PnDIR1 was a cell wall localized protein, and the PnDIR1 promoter activity was induced by several plant hormones and multiple stress stimuli. The recombinant PnDIR1 protein inhibited the growth of Sclerotinia sclerotiorum and F. solani in vitro. Moreover, the overexpression of PnDIR1 in tobacco (Nicotiana tabacum) up-regulated the expression of some genes involved in the biosynthesis of lignin and lignan and considerably increased the resistance to F. solani as well as the increase in lignin accumulation. The results of this study suggest that PnDIRs may facilitate the molecular interaction between P. notoginseng and F. solani through be involved in lignin biosynthesis.

Protective role of antifusarial eco-friendly agents (Trichoderma and salicylic acid) to improve resistance performance of tomato plants

Fusarium wilt triggered great losing in tomato plants quality and quantity in all worlds. In the recent experiment, physiological resistance performance in tomato seedlings using Trichoderma harzianum and salicylic acid (SA) either (individual or combination) anti Fusarium had been studied. In vitro antifungal prospective of T. harzianum and SA againstF. oxysporumwere also examined. A noticeable antifungal capacity with highest activity of 10 and 8 mm ZOI after the treatment with the T. harzianum and SA. Also, Trichoderma have great ability to decreasing Fusarium growth by 25% inhibition at dual culture method. The MIC of SA was 1.5 mM to reduce Fusarium growth. For more ultrastructure by TEM of Fusarium treated with SA and Trichoderma showed alteration of cell wall as well as cytoplasmic components of mycelium, macroconidia and microconida. In the current experiment, ameliorative potentials of T. harzianum and SA either (individual or combination) via soil or foliar application were administered to the Fusarium- infected tomato plants and then disease index, growth indicators, photosynthetic pigments, metabolic markers, and antioxidant isozymes were assessed. The achieved result indicates that T. harzianum and SA through two modes (foliar and soil) lowered PDI by 12.50 and 20.83% and produced great protecting ability by 86.36 and 72.2%. The results revealed, infected seedlings exhibited high decrement in all tested growth characters, photosynthetic pigment contents, contents of total carbohydrate and protein, whereas proline, phenols and enzymes’ activity were elevated under Fusarium infectivity. It was concluded that use of combination (T. harzianum and SA) acted as a commercially eco-friendly instrument for intensifying the defense system of tomato plants against Fusarium wilt.

Heat shock transcription factor (Hsf) gene family in common bean (Phaseolus vulgaris): genome-wide identification, phylogeny, evolutionary expansion and expression analyses at the sprout stage under abiotic stress

BackgroundCommon bean (Phaseolus vulgaris) is an essential crop with high economic value. The growth of this plant is sensitive to environmental stress. Heat shock factor (Hsf) is a family of antiretroviral transcription factors that regulate plant defense system against biotic and abiotic stress. To date, few studies have identified and bio-analyzed Hsfs in common bean.ResultsIn this study, 30 Hsf transcription factors (PvHsf1–30) were identified from the PFAM database. The PvHsf1–30 belonged to 14 subfamilies with similar motifs, gene structure and cis-acting elements. The Hsf members in Arabidopsis, rice (Oryza sativa), maize (Zea mays) and common bean were classified into 14 subfamilies. Collinearity analysis showed that PvHsfs played a role in the regulation of responses to abiotic stress. The expression of PvHsfs varied across different tissues. Moreover, quantitative real-time PCR (qRT-PCR) revealed that most PvHsfs were differentially expressed under cold, heat, salt and heavy metal stress, indicating that PvHsfs might play different functions depending on the type of abiotic stress.ConclusionsIn this study, we identified 30 Hsf transcription factors and determined their location, motifs, gene structure, cis-elements, collinearity and expression patterns. It was found that PvHsfs regulates responses to abiotic stress in common bean. Thus, this study provides a basis for further analysis of the function of PvHsfs in the regulation of abiotic stress in common bean.

Lavender sensitivity to water stress: Comparison between eleven varieties across two phenological stages

Essential oils from Lavandula angustifolia Mill. and Lavandula x intermedia Emeric x Loisel composed of concentrated terpene mixtures, and are highly produced due to their economic value. In the Mediterranean area, the production is threatened by the increasing frequency and intensity of drought events, leading to the loss of crops. Thus, we aimed to evaluate the response to water stress and the tolerance of the main French cultivated varieties of L. angustifolia and L. x intermedia during flowering period, based on the response of their primary metabolic traits (e.g. growth, photosynthesis, stomatal conductance) and specialized metabolic traits (terpene storage and emissions related to the plant defense system). Two treatments were applied: a control where plants received 300 mL every day (≈75% of substrate field capacity) and a stress where plants received 100 mL every two days (≈25% of substrate field capacity). Our results showed that both species featured a drought-tolerant strategy to cope with water stress with a more competitive strategy in L. angustifolia. Water deficit modified the amounts of stored terpenes in both species which could be economically harmful for the sector related to essential oil production. Moreover, some compounds such as bornyl acetate were highlighted as potential defense compounds. The study also highlighted that the varieties ‘Rapido’ (L. angustifolia), arecent variety developed in France, and ‘Sumian’ (L. x intermedia), could be the best candidates to cultivate under intense drought.