Pepper defense against Ralstonia solanacearum and High-temperature stress is positively regulated by CaMYB59.

We have functionally evaluated a transcription factor CaMYB59 for its role in pepper immune responses to Ralstonia solanacearum attack and high temperature-high humidity (HTHH). Exposure to R. solanacearum inoculation (RSI) and HTHH resulted in up-regulation of this nucleus-localized TF. Function of this TF was confirmed by performing loss of function assay of CaMYB59 by VIGS (virus-induced gene silencing). Plants with silenced CaMYB59 displayed not only compromised pepper immunity against RSI but also impaired tolerance to HTHH along with decreased hypersensitive response (HR). This impairment in defense function was fully linked with low induction of stress-linked genes like CaPO2, CaPR1, CaAcc and thermo-tolerance linked CaHSP24 as well as CaHsfB2a. Conversely, transient overexpression of CaMYB59 enhanced pepper immunity. This reveals that CaMYB59 positively regulated host defense against RSI and HTHH by means of HR like mimic cell death, H2O2 production and up-regulation of defense as well as thermo-tolerance associated genes. These changes in attributes collectively confirm the role of CaMYB59 as a positive regulator of pepper immunity against R. solanacearum. We recommend that such positive regulation of pepper defense is dynamically supported by phyto-hormone signaling and transcriptional web of defense genes. These integrated and interlinked events stabilize plant growth and survival under abiotic and biotic stresses.

Interplay between edaphic and climatic factors unravels plant and microbial diversity along an altitudinal gradient.

Altitude influences biodiversity and physiochemical soil attributes in terrestrial ecosystems. It is of immense importance to know the patterns of how interactions among climatic and edaphic factors influence plant and microbial diversity in various ecosystems, particularly along the gradients. We hypothesize that altitudinal variation determines the distribution of plant and microbial species as well as their interactions. To test the hypothesis, different sites with variable altitudes were selected. Analyses of edaphic factors revealed significant (p < 0.001) effects of the altitude. Soil ammonium and nitrate were strongly affected by it contrary to potassium (K), soil organic matter and carbon. The response patterns of individual taxonomic groups differed across the altitudinal gradient. Plant species and soil fungal diversity increased with increasing altitude, while soil archaeal and bacterial diversity decreased with increasing altitude. Plant species richness showed significant positive and negative interactions with edaphic and climatic factors. Fungal species richness was also significantly influenced by the soil ammonium, nitrate, available phosphorus, available potassium, electrical conductivity, and the pH of the soil, but showed non-significant interactions with other edaphic factors. Similarly, soil variables had limited impact on soil bacterial and archaeal species richness along the altitude gradient. Proteobacteria, Ascomycota, and Thaumarchaeota dominate soil bacterial, fungal, and archaeal communities, with relative abundance of 27.4%, 70.56%, and 81.55%, respectively. Additionally, Cynodon dactylon is most abundant plant species, comprising 22.33% of the recorded plant taxa in various study sites. RDA revealed that these communities influenced by certain edaphic and climatic factors, e.g., Actinobacteria strongly respond to MAT, EC, and C/N ratio, Ascomycota and Basidiomycota show strong associations with EC and MAP, respectively. Thaumarcheota are linked to pH, and OM, while Cyperus rotundus are sensitive to AI and EC. In conclusion, the observed variations in microbial as well as plant species richness and changes in soil properties at different elevations provide valuable insights into the factors determining ecosystem stability and multifunctionality in different regions.

Differential capacity of phragmites ecotypes in remediation of inorganic contaminants in coastal ecosystems: Implications for climate change.

Remediating inorganic pollutants is an important part of protecting coastal ecosystems, which are especially at risk from the effects of climate change. Different Phragmites karka (Retz) Trin. ex Steud ecotypes were gathered from a variety of environments, and their abilities to remove inorganic contaminants from coastal wetlands were assessed. The goal is to learn how these ecotypes process innovation might help reduce the negative impacts of climate change on coastal environments. The Phragmites karka ecotype E1, found in a coastal environment in Ichkera that was impacted by residential wastewater, has higher biomass production and photosynthetic pigment content than the Phragmites karka ecotypes E2 (Kalsh) and E3 (Gatwala). Osmoprotectant accumulation was similar across ecotypes, suggesting that all were able to successfully adapt to polluted marine environments. The levels of both total soluble sugars and proteins were highest in E2. The amount of glycine betaine (GB) rose across the board, with the highest levels being found in the E3 ecotype. The study also demonstrated that differing coastal habitats significantly influenced the antioxidant activity of all ecotypes, with E1 displaying the lowest superoxide dismutase (SOD) activity, while E2 exhibited the lowest peroxidase (POD) and catalase (CAT) activities. Significant morphological changes were evident in E3, such as an expansion of the phloem, vascular bundle, and metaxylem cell areas. When compared to the E3 ecotype, the E1 and E2 ecotypes showed striking improvements across the board in leaf anatomy. Mechanistic links between architectural and physio-biochemical alterations are crucial to the ecological survival of different ecotypes of Phragmites karka in coastal environments affected by climate change. Their robustness and capacity to reduce pollution can help coastal ecosystems endure in the face of persistent climate change.

Genetic modification strategies for enhancing plant resilience to abiotic stresses in the context of climate change.

Enhancing the resilience of plants to abiotic stresses, such as drought, salinity, heat, and cold, is crucial for ensuring global food security challenge in the context of climate change. The adverse effects of climate change, characterized by rising temperatures, shifting rainfall patterns, and increased frequency of extreme weather events, pose significant threats to agricultural systems worldwide. Genetic modification strategies offer promising approaches to develop crops with improved abiotic stress tolerance. This review article provides a comprehensive overview of various genetic modification techniques employed to enhance plant resilience. These strategies include the introduction of stress-responsive genes, transcription factors, and regulatory elements to enhance stress signaling pathways. Additionally, the manipulation of hormone signaling pathways, osmoprotectant accumulation, and antioxidant defense mechanisms is discussed. The use of genome editing tools, such as CRISPR-Cas9, for precise modification of target genes related to stress tolerance is also explored. Furthermore, the challenges and future prospects of genetic modification for abiotic stress tolerance are highlighted. Understanding and harnessing the potential of genetic modification strategies can contribute to the development of resilient crop varieties capable of withstanding adverse environmental conditions caused by climate change, thereby ensuring sustainable agricultural productivity and food security.

Morpho-physiological characterization and metabolic profiling of rice lines for immunity to counter Helminthosporiumoryzae.

Heliminthosporium oryzae is a necrotrophic fungal pathogen that effect rice crops grown on millions of hectares. We evaluated nine newly establishing rice lines and one local variety for resistance against H. oryzae. Significant (P ≤ 0.05) differences in response to pathogen attack were recorded in all rice lines. Maximum disease resistance was recorded in Kharamana under pathogen attack as compared to uninfected plants. A comparison of decline in shoot length revealed that Kharamana and Sakh experienced minimum lost (9.21%, 17.23%) in shoot length respectively against control while Binicol exhibited highest reduction (35.04%) in shoot length due to H. oryzae attack. Post-infection observations of shoot fresh weight revealed 63% decline in Binicol and declared it as the most susceptible rice line. Sakh, Kharamana and Gervex exhibited minimum fresh weight decrease (19.86%, 19.24% and 17.64% respectively) as compared to other lines under pathogen attack. Maximum chlorophyll-a contents were recorded in Kharamana under control and post pathogen attackconditions. Following the inoculation of H. oryzae, SOD was increased up to 35% and 23% in Kharamana and Sakh. However, minimum POD activity was recorded in Gervex followed by Swarnalata, Kaosen and C-13 in non-inoculated and pathogen-inoculated plants. Significant decrease in ascorbic acid contents (73.7% and 70.8%) was observed in Gervex and Binicol that later contributed in their susceptibility to H. oryzae attack. Pathogen attack caused Significant (P ≤ 0.05) changes in secondary metabolites in all rice lines but minimum total flavonoids, anthocyanin and lignin were observed in Binicol in uninfected plants and attested its susceptibility to pathogen. In post-pathogen attack conditions, Kharamana showed best resistance against pathogen by exhibiting a significantly high and maximum value of morpho-physiological, and biochemical attributes. Our findings suggest that tested resistant lines can be further explored for multiple traits including molecular regulation of defense responses to breed immunity in rice varieties.

Relative biochemical and physiological docking of cucumber varieties for supporting innate immunity against Podosphaera xanthii.

Powdery mildew in cucumber is caused by the Podosphaera xanthii. No strategy for improving disease resistance can be successful in the absence of thorough insights into the physiological and biochemical responses of cucumber plants to powdery mildew. Therefore, a field experiment was executed to evaluate five commercial cucumber varieties (V1: Dynasty, V2: Long green, V3:Desi Kheera, V4:Thamin II, V5:Cucumber 363) for their inherent immunity to powdery mildew. Upon inoculating cucumber plants with Podosphaera xanthii, we noted differential responses among the varieties. Compared to other varieties, V1 and V2 showed higher values (P ≤ 0.05) for chlorophyll-a under control and pathogen-attacked plants respectively. The minimum value of anthocyanin content (-53.73%) was recorded in V3 as compared to other varieties post pathogen infection. All pathogen-infected cucumber varieties showed a considerable (P ≤ 0.05) loss in flavonoid content except V2. The maximum destruction for Phenolics under powdery mildew (179%) were recorded in V4, whereas V1 exhibited maximum phenolic content under control conditions. In pathogen-infected plants, the minimum AsA was recorded in V5 as compared to all other varieties. Pathogen invasion impacted significantly (P ≤ 0.05) the activity of superoxide dismutase (SOD). Besides, cucumber plants after pathogen inoculation resulted in a considerable (P ≤ 0.05) increase of peroxidase (POD) activity in V1 (5.02%), V2 (7.5%), and V3 (11%) in contrast to V4. Our results confirmed that cucumber varieties perform differently, which was brought on by distinct metabolic and physiological modifications that have an impact on growth and development. The changes in different attributes were correlated with cucumber resistance against powdery mildew. The results would help us fully harness the potential of these varieties to trigger disease management initiatives and defense responses.

Integrative Evaluation of the Ecological Hazards by Microplastics and Heavy Metals in Wetland Ecosystem.

This study was performed to evaluate the impact of microplastics and heavy metals (Pb, Cd, Cr, Cu, Zn, Ni) on sediments, water, aquatic plants (Pistia stratiotes, Alternanthera philoxeroides, and Ipomoea carnea), and fish (Labeo rohita) samples collected from five different sites in the Bajwat wetlands in Sialkot, Pakistan. The concentrations of Pb, Cd, and Cr were above the permissible limits devised by WHO in all the ecosystem components (i.e. sediments, water, plants, and fish) at all sites. The maximum amount of microplastic particles (2317 microplastic particles per kg of sediments) was recorded at Site 1. The filaments were the most commonly found type of microplastics. Plants and fish samples also showed considerable concentration of metals. The multivariate statistical analysis revealed anthropogenic sources of elevated concentrations of metal elements which could cause adverse biological effects in the ecosystem.

Transcriptome profiling in rice reveals a positive role for OsNCED3 in defense against the brown planthopper, Nilaparvata lugens.

9-cis-epoxycarotenoid dioxygenase (NCED) is the rate-limiting enzyme for abscisic acid (ABA) biosynthesis in higher plants. In rice, OsNCED3 was shown to promote ABA synthesis, and improve abiotic stress tolerance, but the function of OsNCED3 in regulating rice defense against the brown planthopper (Nilaparvata lugens; BPH) has been unclear. In this study, several parameters were used to assess rice resistance to BPH, including the average injury level, the functional plant loss index, and electrical penetration graph analysis. Rice lines overexpressing OsNCED3 (OE) were more resistant to BPH than the wild-type cv. Zhonghua11 (WT). Transcriptome analysis was performed on WT, OE, and a RNAi transgenic line silenced for OsNCED3; these three lines were either infested or non-infested with BPH. Seventeen RNA libraries were compared, and most of the differentially expressed genes (DEGs) were upregulated. The number of DEGs in the RNAi line infested with BPH was significantly higher than the OE, and WT lines, and many DEGs were related to the stress response, and biosynthesis of jasmonic acid. This study shows that overexpression of OsNCED3 in rice improves resistance to BPH, and has potential merit in rice breeding programs.

Goethite modified biochar simultaneously mitigates the arsenic and cadmium accumulation in paddy rice (Oryza sativa) L.

Cadmium (Cd) and arsenic (As) contamination of paddy soils is a serious global issue because of the opposite geochemical behavior of Cd and As in paddy soils. Rice plant (Oryza sativa L.) cultivation in Cd- and As- contaminated paddy soil is regarded as one of the main dietary cause of Cd and As entry in human beings. This study aimed to determine the impact of goethite-modified biochar (GB) on bioavailability of both Cd and As in Cd- and As- polluted paddy soil. Contrary to control and biochar (BC) amendments, the application of GB amendments significantly impeded the accumulation of both Cd and As in rice plants. The results confirmed an obvious reduction in Cd and As content of rice grains by 85% and 77%, respectively after soil supplementation with GB 2% amendment. BC 3% application minimized the Cd uptake by 59% in the rice grains as compared to the control but exhibited a little impact on As accumulation in rice grains. Sequential extraction results displayed an increase in immobile Cd and As fractions of the soil by decreasing the bioavailable fractions of both elements after GB treatments. Fe-plaque formation on the root surfaces was significantly variable (P Ë‚ 0.05) among all the amendments. GB 2% treatment significantly increased the Fe content (10 g kg-1) of root Fe-plaque by 48%, which ultimately enhanced the sequestration of Cd and As by Fe-plaque and minimized the transport of Cd and As in rice plants. Moreover, GB treatments significantly changed the relative abundance of the microbial community in the rice rhizosphere and minimized the metal(loid)s mobility in the soil. The relative abundance of Acidobacteria, Firmicutes and Verrucomicrobia increased with GB 2% treatment while those of Bacteroidetes and Choloroflexi decreased. Our findings confirmed improvement in the rice grains quality regarding enhanced amino acid contents with GB application. Overall, the results of this study demonstrated that GB amendment simultaneously alleviated the Cd and As concentrations in edible parts of rice plant and provided a new valuable method to protect the public health by effectively remediating the co-occurrence of Cd and As in paddy soils.

N-Methyltransferase CaASHH3 Acts as a Positive Regulator of Immunity against Bacterial Pathogens in Pepper.

Proteins with conserved SET domain play a critical role in plant immunity. However, the means of organization and functions of these proteins are unclear, particularly in non-model plants such as pepper (Capsicum annum L.). Herein, we functionally characterized CaASHH3, a member of class II (the ASH1 homologs H3K36) proteins in pepper immunity against Ralstonia solanacearum and Pseudomonas syringae pv tomato DC3000 (Pst DC3000). The CaASHH3 was localized in the nucleus, and its transcript levels were significantly enhanced by R. solanacearum inoculation (RSI) and exogenous application of salicylic acid (SA), methyl jasmonate (MeJA), ethephon (ETH), and abscisic acid (ABA). Knockdown of CaASHH3 by virus-induced gene silencing (VIGS) compromised peppers' resistance to RSI. Furthermore, silencing of CaASHH3 impaired hypersensitive-response (HR)-like cell death response due to RSI and downregulated defense-associated marker genes, including CaPR1, CaNPR1, and CaABR1. The CaASHH3 protein was revealed to affect the promoters of CaNPR1, CaPR1, and CaHSP24. Transiently over-expression of CaASHH3 in pepper leaves elicited HR-like cell death and upregulated immunity-related marker genes. To further study the role of CaASHH3 in plant defense in vivo, CaASHH3 transgenic plants were generated in Arabidopsis. Overexpression of CaASHH3 in transgenic Arabidopsis thaliana enhanced innate immunity against Pst DC3000. Furthermore, CaASHH3 over-expressing transgenic A. thaliana plants exhibited upregulated transcriptional levels of immunity-associated marker genes, such as AtNPR1, AtPR1, and AtPR2. These results collectively confirm the role of CaASHH3 as a positive regulator of plant cell death and pepper immunity against bacterial pathogens, which is regulated by signaling synergistically mediated by SA, JA, ET, and ABA.

Entailing the Next-Generation Sequencing and Metabolome for Sustainable Agriculture by Improving Plant Tolerance.

Crop production is a serious challenge to provide food for the 10 billion individuals forecasted to live across the globe in 2050. The scientists' emphasize establishing an equilibrium among diversity and quality of crops by enhancing yield to fulfill the increasing demand for food supply sustainably. The exploitation of genetic resources using genomics and metabolomics strategies can help generate resilient plants against stressors in the future. The innovation of the next-generation sequencing (NGS) strategies laid the foundation to unveil various plants' genetic potential and help us to understand the domestication process to unmask the genetic potential among wild-type plants to utilize for crop improvement. Nowadays, NGS is generating massive genomic resources using wild-type and domesticated plants grown under normal and harsh environments to explore the stress regulatory factors and determine the key metabolites. Improved food nutritional value is also the key to eradicating malnutrition problems around the globe, which could be attained by employing the knowledge gained through NGS and metabolomics to achieve suitability in crop yield. Advanced technologies can further enhance our understanding in defining the strategy to obtain a specific phenotype of a crop. Integration among bioinformatic tools and molecular techniques, such as marker-assisted, QTLs mapping, creation of reference genome, de novo genome assembly, pan- and/or super-pan-genomes, etc., will boost breeding programs. The current article provides sequential progress in NGS technologies, a broad application of NGS, enhancement of genetic manipulation resources, and understanding the crop response to stress by producing plant metabolites. The NGS and metabolomics utilization in generating stress-tolerant plants/crops without deteriorating a natural ecosystem is considered a sustainable way to improve agriculture production. This highlighted knowledge also provides useful research that explores the suitable resources for agriculture sustainability.

Spike glycoproteins: Their significance for corona viruses and receptor binding activities for pathogenesis and viral survival.

The recent outbreak of Covid-19 is posing a severe threat to public health globally. Coronaviruses (CoVs) are the largest known group of positive-sense RNA viruses surviving on an extensive number of natural hosts. CoVs are enveloped and non-segmented viruses with a size between 80 and 120 nm. CoV attachment to the surface receptor and its subsequent entrance into cells is mediated by Spike glycoprotein (S). For enhanced CoV entry and successful pathogenesis of CoV, proteolytic processing and receptor-binding act synergistically for induction of large-scale S conformational changes. The shape, size and orientation of receptor-binding domains in viral attachment proteins are well conserved among viruses of different classes that utilize the same receptor. Therefore, investigations unraveling the distribution of cellular receptors with respect to CoV entry, structural aspects of glycoproteins and related conformational changes are highly significant for understanding virus invasion and infection spread. We present the characteristic features of CoV S-Proteins, their significance for CoVs and related receptor binding activities for pathogenesis and viral survival. We are analyzing the novel role of S-protein of CoVs along with their interactive receptors for improving host immunity and decreasing infection spread. This is hoped that presented information will open new ways in tackling coronavirus, especially for the ongoing epidemic.

Insect-fungal-interactions: A detailed review on entomopathogenic fungi pathogenicity to combat insect pests.

Global food security is threatened by insect pests of economically important crops. Chemical pesticides have been used frequently for the last few decades to manage insect pests throughout the world. However, these chemicals are hazardous for human health as well as the ecosystem. In addition, several pests have evolved resistance to many chemicals. Finding environment friendly alternatives lead the researchers to introduce biocontrol agents such as entomopathogenic fungi (EPF). These fungi include various genera that can infect and kill insects efficiently. Moreover, EPFs have considerable host specificity with a mild effect on non-target organisms and can be produced in bulk quantity quickly. However, insights into the biology of EPF and mechanism of action are of prime significance for their efficient utilization as a biocontrol agent. This review focuses on EPF-mediated insect management by explaining particular EPF strains and their general mode of action. We have comprehensively discussed which criteria should be used for the selection of pertinent EPF, and which aspects can impact the EPF efficiency. Finally, we have outlined various advantages of EPF and their limitations. The article summarizes the prospects related to EPF utilization as biocontrol agents. We hope that future strategies for the management of insects will be safer for our planet.

A basic helix-loop-helix transcription factor CabHLH113 positively regulate pepper immunity against Ralstonia solanacearum.

Pepper's (Capsicum annum) response to bacterial pathogen Ralstonia solanacearm inoculation (RSI) and abiotic stresses is known to be synchronized by transcriptional network; however, related molecular mechanisms need extensive experimentation. We identified and characterized functions of CabHLH113 -a basic helix-loop-helix transcription factor-in pepper immunity to R. solanacearum infection. The RSI and foliar spray of phytohormones, including salicylic acid (SA), methyl jasmonate (MeJA), ethylene (ETH), and absicic acid (ABA) induced transcription of CabHLH113 in pepper. Loss of function of CabHLH113 by virus-induced-gene-silencing (VIGS) compromised defense of pepper plants against RSI and suppressed relative expression levels of immunity-associated marker genes, i.e., CaPR1, CaNPR1, CaDEF1, CaHIR1 and CaABR1. Pathogen growth was significantly increased after loss of function of CabHLH113 compared with un-silenced plants with remarkable increase in pepper susceptibility. Besides, transiently over-expression of CabHLH113 induced HR-like cell death, H2O2 accumulation and up-regulation of defense-associated marker genes, e.g. CaPR1, CaNPR1, CaDEF1, CaHIR1 and CaABR1. Additionally, transient over-expression of CabHLH113 enhanced the transcriptional levels of CaWRKY6, CaWRKY27 and CaWRKY40. Conversely, transient over-expression of CaWRKY6, CaWRKY27 and CaWRKY40 enhanced the transcriptional levels of CabHLH113. Collectively, our results indicate that newly characterized CabHLH113 has novel defense functions in pepper immunity against RSI via triggering HR-like cell death and cellular levels of defense linked genes.

Rising Metals Concentration in the Environment: A Response to Effluents of Leather Industries in Sialkot.

Many leather processing industries in Sialkot, Pakistan, discharge their wastes freely into the environment which then enters nearby water bodies. Irrigation practices with these polluted waters pose a great threat to the soil quality. Hence, the soils and effluent waters of five famous leather processing sites were evaluated for the presence of As, Cr, Cd, Ni, Zn, Mn, Mg, Na, K, and Ca. High mean concentrations of As (112.6 mg kg-1), Cr (45.9 mg kg-1), Cd (2.0 mg kg-1), Ni (58.2 mg kg-1), Zn (117.6 mg kg-1), Mn (12.8 mg kg-1), Mg (34,511 mg kg-1), Na (16,292 mg kg-1), K (1765 mg kg-1), and Ca (4387 mg kg-1) were found in soils at our study sites. Effluents were found to be highly acidic with high TDS content and high EC values. Index of Geoaccumulation (Igeo) confirmed the extremely toxic nature of these soils. Plants growing at these sites also showed high concentrations of As, Cr, and Cd in their leaves.

Physiological homeostasis for ecological success of Typha (Typha domingensis Pers.) populations in saline soils.

The natural capacity of plants to endure salt stress is largely regulated by multifaceted structural and physio-biochemical modulations. Salt toxicity endurance mechanism of six ecotypes of Typha domingensis Pers. was evaluated by analyzing photosynthesis, ionic homeostasis, and stomatal physiology under different levels of salinity (0, 100, 200 and 300 mM NaCl). Typha populations were collected across different areas of Punjab, an eastern province in Pakistan. All studied attributes among ecotypes presented differential changes as compared to control. Different salt treatments not only affected gas exchange attributes but also shown significant modifications in stomatal anatomical changes. As compared to control, net photosynthetic rate, transpiration rate, total chlorophyll contents and carotenoids were increased by 111%, 64%, 103% and 171% respectively, in Sahianwala ecotype among all other ecotypes. Similarly, maximum water use efficiency (WUE), sub stomatal CO2 concentration, sodium (Na+) and chloride (Cl-) contents were observed in Sahianwala (191%, 93%, 168%, 158%) and Knotti (162%, 75%, 146%, 182%) respectively, as compared to the others ecotypes. Adaxial and abaxial stomatal areas remained stable in Sahianwala and Knotti. The highest abaxial stomatal density was observed in Gatwala ecotype (42 mm2) and maximum adaxial stomatal density was recorded in Sahianwala ecotype (43 mm2) at 300 mM NaCl salinity. The current study showed that Typha ecotypes responded varyingly to salinity in terms of photosynthesis attributes to avoid damages due to salinity. Overall, differential photosynthetic activity, WUE, and changes in stomatal attributes of Sahianwala and Knotti ecotypes contributed more prominently in tolerating salinity stress. Therefore, Typha domingensis is a potential species to be used to rehabilitate salt affected lands for agriculture and aquatic habitat. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-00963-x.

Host plants alter their volatiles to help a solitary egg parasitoid distinguish habitats with parasitized hosts from those without.

When attacked by herbivores, plants emit volatiles to attract parasitoids and predators of herbivores. However, our understanding of the effect of plant volatiles on the subsequent behaviour of conspecific parasitoids when herbivores on plants are parasitized is limited. In this study, rice plants were infested with gravid females of the brown planthopper (BPH) Nilaparvata lugens for 24 hr followed by another 24 hr in which the BPH eggs on plants were permitted to be parasitized by their egg parasitoid, Anagrus nilaparvatae; volatiles from rice plants that underwent such treatment were less attractive to subsequent conspecific parasitoids compared to the volatiles from plants infested with gravid BPH females alone. Chemical analysis revealed that levels of JA and JA-Ile as well as of four volatile compounds-linalool, MeSA, α-zingiberene and an unknown compound-from plants infested with BPH and parasitized by wasps were significantly higher than levels of these compounds from BPH-infested plants. Laboratory and field bioassays revealed that one of the four increased chemicals-α-zingiberene-reduced the plant's attractiveness to the parasitoid. These results suggest that host plants can fine-tune their volatiles to help egg parasitoids distinguish host habitats with parasitized hosts from those without.

Plant hypersensitive response vs pathogen ingression: Death of few gives life to others.

The hypersensitive response (HR) is a defense action against pathogen ingression. Typically, HR is predictable with the appearance of the dead, brown cells along with visible lesions. Although death during HR can be limited to the cells in direct contact with pathogens, yet cell death can also spread away from the infection site. The variety in morphologies of plant cell death proposes involvement of different pathways for triggering HR. It is considered that, despite the differences, HR in plants performs the resembling functions like that of animal programmed cell death (PCD) for confining pathogen progression. HR, in fact, crucially initiates systemic signals for activation of defense in distal plant parts that ultimately results in systemic acquired resistance (SAR). Therefore, HR can be separated from other local immune actions/responses at the infection site. HR comprises of serial events inclusive of transcriptional reprograming, Ca2+ influx, oxidative bursts and phyto-hormonal signaling. Although a lot of work has been done on HR in plants but many questions regarding mechanisms and consequences of HRs remain unaddressed.We have summarized the mechanistic roles and cellular events of plant cells during HR in defense regulation. Roles of different genes during HR have been discussed to clarify genetic control of HR in plants. Generally existing ambiguities about HR and programmed cell death at the reader level has been addressed.

Q-SNARE protein FgSyn8 plays important role in growth, DON production and pathogenicity of Fusarium graminearum.

SNAREs (Soluble N-ethylmaleimide-sensitive factor attachment protein receptors) help intracellular vesicle trafficking and membrane fusion among eukaryotes. They are vital for growth and development of phyto-pathogenic fungi such as Fusarium graminearum which causes Fusarium Head Blight (FHB) of wheat and barley. The SNARE protein Syn8 and its homologues play many roles among different organisms. Here, we have characterized FgSyn8 in F. graminearum as a homologue of Syn8. We have integrated biochemical, microbiological and molecular genetic approaches to investigate the roles of this protein. Our results reveal that FgSyn8 is indispensable for normal vegetative growth, conidiation, conidial morphology and pathogenicity of F. graminearum. Deoxynivalenol (DON) biochemical assay reveals active participation of this protein in DON production of F. graminearum. This has further been confirmed by the production of bulbous structures among the intercalary hyphae. FgSyn8 mutant strain produced defects in perithecia formation which portrays its role in sexual reproduction. In summary, our results support that the SNARE protein FgSyn8 is required for vegetative growth, sexual reproduction, DON production and pathogenicity of F. graminearum.

Elicitins as molecular weapons against pathogens: consolidated biotechnological strategy for enhancing plant growth.

To fight against pathogens, defense systems in plants mainly depend upon preformed as well as induced responses. Pathogen detection activates induced responses and signals are transmitted for coordinated cellular events in order to restrict infection and spread. In spite of significant developments in manipulating genes, transcription factors and proteins for their involvement in immunity, absolute tolerance/resistance to pathogens has not been seen in plants/crops. Defense responses, among diverse plant types, to different pathogens involve modifications at the physio-biochemical and molecular levels. Secreted by oomycetes, elicitins are small, highly conserved and sterol-binding extracellular proteins with PAMP (pathogen associated molecular patterns) functions and are capable of eliciting plant defense reactions. Belonging to multigene families in oomycetes, elicitins are different from other plant proteins and show a different affinity for binding sterols and other lipids. These function for sterols binding to catalyze their inter-membrane and intra- as well as inter-micelle transport. Importantly, elicitins protect plants by inducing HR (hypersensitive response) and systemic acquired resistance. Despite immense metabolic significance and the involvement in defense activities, elicitins have not yet been fully studied and many questions regarding their functional activities remain to be explained. In order to address multiple questions associated with the role of elicitins, we have reviewed the understanding and topical advancements in plant defense mechanisms with a particular interest in elicitin-based defense actions and metabolic activities. This article offers potential attributes of elicitins as the biological control of plant diseases and can be considered as a baseline toward a more profound understanding of elicitins.