Cajanus platycarpus Flavonoid 3'5' Hydroxylase_2 (CpF3'5'H_2) Confers Resistance to Helicoverpa armigera by Modulating Total Polyphenols and Flavonoids in Transgenic Tobacco.

Pod borer Helicoverpa armigera, a polyphagus herbivorous pest, tremendously incurs crop damage in economically important crops. This necessitates the identification and utility of novel genes for the control of the herbivore. The present study deals with the characterization of a flavonoid 3'5' hydroxylase_2 (F3'5'H_2) from a pigeonpea wild relative Cajanus platycarpus, possessing a robust chemical resistance response to H. armigera. Though F3'5'H_2 displayed a dynamic expression pattern in both C. platycarpus (Cp) and the cultivated pigeonpea, Cajanus cajan (Cc) during continued herbivory, CpF3'5'H_2 showed a 4.6-fold increase vis a vis 3-fold in CcF3'5'H_2. Despite similar gene copy numbers in the two Cajanus spp., interesting genic and promoter sequence changes highlighted the stress responsiveness of CpF3'5'H_2. The relevance of CpF3'5'H_2 in H. armigera resistance was further validated in CpF3'5'H_2-overexpressed transgenic tobacco based on reduced leaf damage and increased larval mortality through an in vitro bioassay. As exciting maiden clues, CpF3'5'H_2 deterred herbivory in transgenic tobacco by increasing total flavonoids, polyphenols and reactive oxygen species (ROS) scavenging capacity. To the best of our knowledge, this is a maiden attempt ascertaining the role of F3'5'H_2 gene in the management of H. armigera. These interesting leads suggest the potential of this pivotal branch-point gene in biotic stress management programs.

Reactive oxygen species in plants: an invincible fulcrum for biotic stress mitigation.

Climate change-associated environmental vagaries have amplified the incidence of pests and pathogens on plants, thus imparting the increased quest for management strategies. Plants respond to stresses through intricate signaling networks that regulate diverse cellular mechanisms. Reactive oxygen species (ROS) are cardinal towards the maintenance of normal plant activities as well as improving stress management. Plants that exhibit a fine balance between ROS levels and its management apparently mitigate stresses better. There have been very many compendiums on signaling and management of ROS during several abiotic stresses. However, expansion of knowledge related to ROS induction and homeostasis during biotic stresses is pertinent. Hence, considering its importance, we provide insights in this review on how plants signal and manage ROS upon an oxidative burst during their interaction with pathogens and herbivores. Substantial degree of molecular changes and pivotal roles of ROS have been detected during phyto-pathogen/herbivore interactions, opening novel platforms to understand signaling/management of events under varied biotic stresses. It is interesting to know that, though plants react to biotic stresses through oxidative burst, receptors and elicitors involved in the signal transduction differ across stresses. The review provides explicit details about the specific signaling of ROS production in plants under pathogen and herbivore attack. Furthermore, we also provide an update about tackling the accumulated ROS under biotic stresses as another pivotal step. ROS signaling and homeostasis can be exploited as critical players and a fulcrum to tackle biotic stresses, thus paving the way for futuristic combinatorial stress management strategies. KEY POINTS: • The review is a comprehension of redox signaling and management in plants during herbivory and pathogen infection • Reactive oxygen species (ROS) is an important factor during normal plant activities as well as in their response to stresses. Diverse modes of ROS signaling and management have been observed during both biotic stresses independently • Exploration of plant biology in multi-stress resistant plants like the crop wild relatives could pave the way for combinatorial management of stress for a better tomorrow.

A comprehensive review on the influence of light on signaling cross-talk and molecular communication against phyto-microbiome interactions.

Generally, plant growth, development, and their productivity are mainly affected by their growth rate and also depend on environmental factors such as temperature, pH, humidity, and light. The interaction between plants and pathogens are highly specific. Such specificity is well characterized by plants and pathogenic microbes in the form of a molecular signature such as pattern-recognition receptors (PRRs) and microbes-associated molecular patterns (MAMPs), which in turn trigger systemic acquired immunity in plants. A number of Arabidopsis mutant collections are available to investigate molecular and physiological changes in plants under the presence of different light conditions. Over the past decade(s), several studies have been performed by selecting Arabidopsis thaliana under the influence of red, green, blue, far/far-red, and white light. However, only few phenotypic and molecular based studies represent the modulatory effects in plants under the influence of green and blue lights. Apart from this, red light (RL) actively participates in defense mechanisms against several pathogenic infections. This evolutionary pattern of light sensitizes the pathologist to analyze a series of events in plants during various stress conditions of the natural and/or the artificial environment. This review scrutinizes the literature where red, blue, white, and green light (GL) act as sensory systems that affects physiological parameters in plants. Generally, white and RL are responsible for regulating various defense mechanisms, but, GL also participates in this process with a robust impact! In addition to this, we also focus on the activation of signaling pathways (salicylic acid and jasmonic acid) and their influence on plant immune systems against phytopathogen(s).

Unraveling the proteomic changes involved in the resistance response of Cajanus platycarpus to herbivory by Helicoverpa armigera.

The pigeonpea wild relative Cajanus platycarpus is resistant to Helicoverpa armigera, one of the major pests responsible for yield losses in Cajanus cajan. Deciphering the molecular mechanism underlying host plant resistance is pertinent to identify proteins that aid in the mitigation of the insect pest. The present study adopted comparative proteomics as a tool to interpret the resistance mechanism(s) in C. platycarpus vis-à-vis C. cajan during continued herbivory (up to 96 h). Over-representation analysis of the differentially expressed proteins implicated a multi-dimensional resistance response accomplished by both physical and chemical barriers in C. platycarpus. While the chemical basis for resistance was depicted by the upregulation of proteins playing a rate limiting role in the phenylpropanoid pathway, the physical basis was provided by the regulation of proteins involved in microtubule assembly and synthesis of lignins. Upregulation of proteins in the polyamine pathway indicated the role of metabolite conjugates to be negatively affecting herbivore growth. Reallocation of resources and diversion of metabolic flux to support the production of secondary metabolites could be the probable approach in the wild relative against herbivory. Our study provided deeper insights into the pod borer resistance mechanism in C. platycarpus for utility in crop improvement. KEY POINTS: • Pod borer resistance in Cajanus platycarpus is multi-dimensional. • Pod borer resistance has been arbitrated to cell wall rigidity and secondary metabolites. • Phenylpropanoid pathway derivatives apparently shaped the plant chemical defense against pod borer.

Genome-wide identification and characterization of DIRIGENT gene family (CcDIR) in pigeonpea (Cajanus cajan L.) provide insights on their spatial expression pattern and relevance to stress response.

This study is a thorough characterization of pigeonpea dirigent gene (CcDIR) family, an important component of the lignin biosynthesis pathway. Genome-wide analysis identified 25 CcDIR genes followed by a range of analytical approaches employed to unravel their structural and functional characteristics. Structural examination revealed a classic single exon and no intron arrangement in CcDIRs contributing to our understanding on evolutionary dynamics. Phylogenetic analysis elucidated evolutionary relationships among CcDIR genes with six DIR sub-families, while motif distribution analysis displayed and highlighted ten conserved protein motifs in CcDIRs. Promoter analyses of all the dirigent genes detected 18 stress responsive cis-acting elements offering insights into transcriptional regulation. While spatial expression analyses across six plant tissues showed preferential expression of CcDIR genes, exposure to salt (CcDIR2 and CcDIR9) and herbivory (CcDIR1, CcDIR2, CcDIR3 and CcDIR11), demonstrated potential roles of specific DIRs in plant defense. Interestingly, increased gene expression during herbivory, also correlated with increased lignin content authenticating the specific response. Furthermore, exogenous application of stress hormones, SA and MeJA on leaves significantly induced the expression of CcDIRs that responded to herbivory. Taken together, these findings contribute to a comprehensive understanding of CcDIR genes impacting development and stress response in the important legume pigeonpea.

A Prospective Comparison of Octyl-2-Cyanoacrylate and Suture in Facial Wounds.

The study aimed to evaluate the efficacy of octyl-2-cyanoacrylate as well as sutures as a wound closure material. Whether octyl-2-cyanoacrylate can be used as an alternative to suture in the closure of facial wounds. Out of total of 19 wounds, 11 wounds were closed with sutures and tissue adhesive both, out of rest 8 wounds, 4 wounds were closed using sutures alone and in 4 wounds, closure was done with tissue adhesive alone. Therefore, a total of 15 facial wounds were divided into two groups: Group-I Cases in whom 3-0 Black silk suture was used for closure of the wound and Group-II Cases in whom Dermabond (Octyl-2-Cyanoacrylate) was used for closure of the wound. Results showed that Octyl-2-cyanoacrylate offered the benefit of decreased procedure time with less pain, no need for its removal, and better cosmetic outcome compared to sutures.

Comparative Evaluation of Compressive and Diametral Tensile Strength in Die Stone Reinforced With Different Types of Nanoparticles: An In Vitro Study.

AIM: To investigate the effect of different types of nanoparticles on the compressive strength (CS) and diametral tensile strength (DTS) of type IV dental stones. MATERIALS AND METHODS: A total of 100 specimens were made from the mould for all five groups. Four commercially available nanoparticles (aluminium oxide (Al2O3), silicon dioxide (SiO2), zinc oxide (ZnO), and zirconium oxide (ZrO2)) were used in this study in a concentration of 10%. CS and DTS tests were performed in a universal test machine. The data were statistically analysed using ANOVA and Student's t-test. RESULTS: The interaction between nanoparticles and the type of dental stone was found to be statistically significant (p < 0.05). CS and DTS values decreased by adding all four nanoparticles. The lowest CS and DTS were observed in 10% ZnO nanoparticles when added to type IV dental stone. CONCLUSION: It was concluded that the addition of nanoparticles (Al2O3, SiO2, ZnO, and ZrO2) to die stone significantly decreased the CS and DTS for all groups. Among all groups, the incorporation of 10% ZrO2 nanoparticles (group E) to die stone showed significantly less decrease in CS and DTS compared to Al2O3, SiO2, and ZnO. Incorporation of ZnO nanoparticles, on the other hand, showed a significantly more amount of decrease in the CS and DTS compared to Al2O3, SiO2, and ZrO2.

The plant specialized metabolite epicatechin- 3-gallate (EC3G) perturbs lipid metabolism and attenuates fat accumulation in pigeonpea pod borer, Helicoverpa armigera.

Control of pod borer Helicoverpa armigera, a notorious polyphagous pest requires paramount attention with focus on environment-friendly management approaches. Overproduction of catechins (epigallocatechin-EGC and epicatechin-3-gallate-EC3G) in the pod borer-resistant pigeonpea wild relative, Cajanus platycarpus during continued herbivory prodded us to assess their underlying molecular effect on H. armigera. Significant reduction in larval and pupal growth parameters was observed when reared on artificial diet incorporated with 100 ppm EC3G vis a vis 100 ppm EGC and EGC + EC3G. Comparative RNAseq analyses of larvae that fed on normal and EC3G-incorporated diet revealed 62 differentially expressed genes dominated by detoxification and lipid metabolism. While lipase and fatty acid-binding protein 2-like were up-regulated, delta9-FADS-like involved in fatty acid synthesis was downregulated, indicating effect of EC3G on fat metabolism. Validation of RNAseq data by qPCR; midgut glutathione-S-transferase and esterase assays depicted increased lipolysis and reduced lipogenesis in EC3G-fed larvae. Additionally, differential accumulation of stearic acid and oleic acid in EC3G-fed and control larvae/adults ascertained perturbation in lipogenesis. Supported by modelling, molecular docking and simulations, we demonstrate the possible involvement of the insect adipokinetic hormone receptor (AKHR) in the EC3G-mediated response. The study demonstrates plant specialized metabolite EC3G as a potential candidate for H. armigera control.

Deciphering of Pod Borer [Helicoverpa armigera (Hübner)] Resistance in Cajanus platycarpus (Benth.) Offers Novel Insights on the Reprogramming and Role of Flavonoid Biosynthesis Pathway

Management of pod borer, Helicoverpa armigera in pigeonpea (Cajanus cajan L.), an important legume crop, has been a pertinent endeavor globally. As with other crops, wild relatives of pigeonpea are bestowed with various resistance traits that include the ability to deter the H. armigera. Understanding the molecular basis of pod borer resistance could provide useful leads for the management of this notorious herbivore. Earlier studies by our group in deciphering the resistance response to herbivory through multiomics approaches in the pigeonpea wild relative, Cajanus platycarpus, divulged the involvement of the flavonoid biosynthesis pathway, speculating an active chemical response of the wild relative to herbivory. The present study is a deeper understanding of the chemical basis of pod borer (H. armigera) resistance in, C. platycarpus, with focus on the flavonoid biosynthesis pathway. To substantiate, quantification of transcripts in H. armigera-challenged C. platycarpus (8 h, 24 h, 48 h, 96 h) showed dynamic upregulation (up to 11-fold) of pivotal pathway genes such as chalcone synthase, dihydroflavonol-4-reductase, flavonoid-3'5'-hydroxylase, flavonol synthase, leucoanthocyanidin reductase, and anthocyanidin synthase. Targeted LC-MS analyses demonstrated a concomitant increase (up to 4-fold) in naringenin, kaempferol, quercetin, delphinidin, cyanidin, epigallocatechin, and epicatechin-3-gallate. Interestingly, H. armigera diet overlaid with the over-produced flavonoids (100 ppm) showed deleterious effects on growth leading to a prolonged larval period demonstrating noteworthy coherence between over-accumulation of pathway transcripts/metabolites. The study depicts novel evidence for the directed metabolic reprogramming of the flavonoid biosynthesis pathway in the wild relative to pod borer; plant metabolic potential is worth exploiting for pest management.

Relevance of methionine sulfoxide reductase(s) (MSR) as candidate proteins in redox homeostasis-mediated resistance response to Helicoverpa armigera (Hübner) in the pigeonpea wild relative Cajanus platycarpus (Benth.) Maesen.

Pod borer, Helicoverpa armigera, a polyphagus herbivore causes extensive economic losses to crops, including pigeonpea. Exploitation of pod borer resistance in wild relatives is pertinent due to the absence of resistance sources in cultivated pigeonpea and crossing-incompatibility with the resistant wild relatives. We present leads obtained in deeper understanding of pod borer resistance mechanism in Cajanus platycarpus, a pigeonpea wild relative. Surge in cellular ROS during herbivory leads to redox-PTMs (post translational modifications) of methionine-rich proteins including antioxidant enzymes, causing oxidative damage. Plants then officiate methionine sulfoxide reductases (MSRs), that maintain the redox status of methionine and hence homeostasis. We demonstrate functionality of MSRs (MSRA and MSRB) in the resistance response of the wild relative to pod borer. Among 5 MSRA and 3 MSRB genes, CpMSRA2 and CpMSRB1 were herbivore-responsive based on expression during herbivory. Clues about the stress-responsiveness were obtained upon analyses of cis-elements and co-expressing genes. Apparently, the wild relative followed a non-canonical mode of redox management, as divulged by antioxidant enzymes and the scavenging capacity. Differential lipid peroxidation as an early response provided evidences for an effective redox management in the wild relative. This is the first report signifying redox homeostasis in the resistance response towards herbivory.

Characterization and in planta validation of a CHI4 chitinase from Cajanus platycarpus (Benth.) Maesen for its efficacy against pod borer, Helicoverpa armigera (Hübner).

BACKGROUND: Pigeonpea, Cajanus cajan is one of the economically important legume food crops and a major source of dietary proteins. Management of pod borer, Helicoverpa armigera has been prominent among crop improvement programs. Lack of resistance sources in the cultivated germplasm and crossing incompatibility with pod borer-resistant wild relatives have prompted biotechnological interventions. Identification and exploitation of genes from pigeonpea wild relatives in host plant resistance towards the pod borer assumes pertinence. Dynamic transcriptome analysis of the wild relative vis a vis cultivated pigeonpea identified a CHI4 chitinase as one of the putative insect resistance genes. RESULTS: The study presents variations in important amino acids in CHI4 chitinases from C. cajan and its wild relative C. platycarpus. Comparative protein modeling and docking analysis of the two proteins demonstrated differences in substrate binding efficacy of the chitinase from C. platycarpus which resulted in a minimum binding energy of -8.7 kcal mol-1 . Furthermore, we successfully evaluated the insecticidal activity of the chitinase from C. platycarpus against H. armigera challenge through heterologous expression in tobacco. Molecular characterization of transgenic plants confirmed that their efficacy against H. armigera was a result of the integration of CHI4 from C. platycarpus. CONCLUSION: Docking analysis demonstrated effective substrate interaction as a possible reason for efficacy against pod borer in the chitinase from C. platycarpus. This was authenticated by successful overexpression and bioefficacy assessment against H. armigera in tobacco. The CHI4 gene from C. platycarpus can be useful in the mitigation of H. armegira in pigeonpea as well as in other crops. © 2021 Society of Chemical Industry.

Genome Editing for Resistance to Insect Pests: An Emerging Tool for Crop Improvement.

Plants are challenged incessantly by several biotic and abiotic stresses during their entire growth period. As with other biotic stress factors, insect pests have also posed serious concerns related to yield losses due to which agricultural productivity is at stake. In plants, trait modification for crop improvement was initiated with breeding approaches followed by genetic engineering. However, stringent regulatory policies for risk assessment and lack of social acceptance for genetically modified crops worldwide have incited researchers toward alternate strategies. Genome engineering or genome editing has emerged as a new breeding technique with the ability to edit the genomes of plants, animals, microbes, and human beings. Several gene editing strategies are being executed with continuous emergence of variants. The scientific community has unraveled the utility of various editing tools from endonucleases to CRISPR/Cas in several aspects related to plant growth, development, and mitigation of stresses. The categorical focus on the development of tools and techniques including designing of binary vectors to facilitate ease in genome engineering are being pursued. Through this Review, we embark upon the conglomeration of various genome editing strategies that can be and are being used to design insect pest resistance in plants. Case studies and novel crop-based approaches that reiterate the successful use of these tools in insects as well as in plants are highlighted. Further, the Review also provides implications for the requirement of a specific regulatory framework and risk assessment of the edited crops. Genome editing toward insect pest management is here to stay, provided uncompromising efforts are made toward the identification of amiable target genes.

An Apical Meristem-Targeted in planta Transformation Method for the Development of Transgenics in Flax (Linum usitatissimum): Optimization and Validation.

Efficient regeneration of explants devoid of intrinsic somaclonal variations is a cardinal step in plant tissue culture, thus, a vital component of transgenic technology. However, recalcitrance of economically important crops to tissue culture-based organogenesis ensues a setback in the use of transgenesis in the genetic engineering of crop plants. The present study developed an optimized, genotype-independent, nonconventional tissue culture-independent in planta strategy for the genetic transformation of flax/linseed. This apical meristem-targeted in planta transformation protocol will accelerate value addition in the dual purpose industrially important but recalcitrant fiber crop flax/linseed. The study delineated optimization of Agrobacterium tumefaciens-mediated transformation and stable T-DNA (pCambia2301:GUS:nptII) integration in flax. It established successful use of a stringent soilrite-based screening in the presence of 30 mg/L kanamycin for the identification of putative transformants. The amenability, authenticity, and reproducibility of soilrite-based kanamycin screening were further verified at the molecular level by GUS histochemical analysis of T0 seedlings, GUS and nptII gene-specific PCR, genomic Southern hybridization for stable integration of T-DNA, and expression analysis of transgenes by sqRT-PCR. This method resulted in a screening efficiency of 6.05% in the presence of kanamycin, indicating amenability of in planta flax transformation. The strategy can be a promising tool for the successful development of transgenics in flax.