Publications of NIPGR Scientists
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Item Secret weapon of insects: The oral secretion cocktail and its modulation of host immunity(Oxford University Press, 2024) Prajapati, Vinod Kumar; Vijayan, Vishakh; Vadassery, JyothilakshmiPlants and insects have co-existed for almost 400 million years and their interactions can be beneficial or harmful, thus reflecting their intricate co-evolutionary dynamics. Many herbivorous arthropods cause tremendous crop loss, impacting the agro-economy worldwide. Plants possess an arsenal of chemical defenses that comprise diverse secondary metabolites that help protect against harmful herbivorous arthropods. In response, the strategies that herbivores use to cope with plant defenses can be behavioral, or molecular and/or biochemical of which salivary secretions are a key determinant. Insect salivary secretions/oral secretions (OSs) play a crucial role in plant immunity as they contain several biologically active elicitors and effector proteins that modulate plants’ defense responses. Using this oral secretion cocktail, insects overcome plant natural defenses to allow successful feeding. However, a lack of knowledge of the nature of the signals present in oral secretion cocktails has resulted in reduced mechanistic knowledge of their cellular perception. In this review, we discuss the latest knowledge on herbivore oral secretion derived elicitors and effectors and various mechanisms involved in plant defense modulation. Identification of novel herbivore-released molecules and their plant targets should pave the way for understanding the intricate strategies employed by both herbivorous arthropods and plants in their interactions.Item Deciphering the regulation of transporters and mitogen-activated protein kinase in arsenic and iron exposed rice(Elsevier B.V., 2024) Panthri, Medha; Saini, Himanshu; Banerjee, Gopal; Bhatia, Priyanka; Verma, Neetu; Sinha, Alok Krishna; Gupta, MeetuThis study investigates the influence of arsenic (As) and iron (Fe) on the molecular aspects of rice plants. The mRNA-abundance of As (OsLsi, OsPHT, OsNRAMP1, OsABCC1) and Fe (OsIRT, OsNRAMP1, OsYSL, OsFRDL1, OsVIT2, OsSAMS1, OsNAS, OsNAAT1, OsDMAS1, OsTOM1, OsFER) related genes has been observed in 12-d old As and Fe impacted rice varieties. Analyses of phytosiderophores synthesis and Fe-uptake genes affirm the existence of specialized Fe-uptake strategies in rice with varieties PB-1 and Varsha favouring strategy I and II, respectively. Expression of OsNAS3, OsVIT2, OsFER and OsABCC1 indicated PB-1′s tolerance towards Fe and As. Analysis of mitogen-activated protein kinase cascade members (OsMKK3, OsMKK4, OsMKK6, OsMPK3, OsMPK4, OsMPK7, and OsMPK14) revealed their importance in the fine adjustment of As/Fe in the rice system. A conditional network map was generated based on the gene expression pattern that unfolded the differential dynamics of both rice varieties. The mating based split ubiquitin system determined the interaction of OsIRT1 with OsMPK3, and OsLsi1 with both OsMPK3 and OsMPK4. In-silico tools also confirmed the binding affinities of OsARM1 with OsLsi1, OsMPK3 and OsMPK4, and of OsIDEF1/OsIRO2 with OsIRT1 and OsMPK3, supporting our hypothesis that OsARM1, OsIDEF1, OsIRO2 were active in the connections discovered by mbSUS.Item The war for apoplastic water: stomatal control as a key strategy in bacterial pathogenesis(Springer Nature Publishing AG, 2023) Choudhary, Aanchal; Senthil-Kumar, MuthappaIn this commentary, important recent discoveries on effector-mediated manipulation of apoplast hydration and the involvement of ABA machinery that are targeted in later stages of bacterial infection culminating in stomatal closure are highlighted. This article also sheds light on the differences in early and later stages of infection wherein the COR signaling in the initial phase promotes stomatal opening while in later stages ABA signaling overrides and forces the stomata to close. Also, the current understanding of pathogen-driven modulation of leaf water status during infection, in which stomata act as a crucial battleground between pathogens and plants at the post-invasive stage is summarized.Item The multifaceted roles of heterotrimeric G-proteins: lessons from models and crops(Springer Nature Publishing AG, 2022) Tiwari, Ruchi; Bisht, Naveen C.Heterotrimeric G-proteins (hereafter G-proteins), consisting of G-alpha (Gα), G-beta (Gβ) and G-gamma (Gγ) subunits, are key signal transducers conserved across different forms of life. The discovery of plant lineage-specific G-protein components (extra-large G-proteins and type-C Gγ subunits), inherent polyploidy in angiosperms, and unique modes of G-protein cycle regulation in plants pointed out to a few fundamental differences of plant G-protein signaling from its animal counterpart. Over the last 2 decades, extensive studies in the model plant Arabidopsis thaliana have confirmed the involvement of G-proteins in a wide range of plant growth and development, and stress adaptation processes. The G-protein research in crop species, however, is still in its infancy, and a handful of studies suggest important roles of G-proteins in regulating plant architectural and key agronomical traits including plant’s response to abiotic and biotic factors. We propose that the advancement made in plant G-proteins research will facilitate the development of novel approaches to manage plant yield and fitness in changing environments.Item In silico identification of effector proteins from generalist herbivore Spodoptera litura(BioMed Central Ltd, 2020) Prajapati, Vinod Kumar; Varma, Mahendra; Vadassery, JyothilakshmiBackground: The common cutworm, Spodoptera litura Fabricius is a leaf and fruit feeding generalist insect of the order Lepidoptera and a destructive agriculture pest. The broad host range of the herbivore is due to its ability to downregulate plant defense across different plants. The identity of Spodoptera litura released effectors that downregulate plant defense are largely unknown. The current study aims to identify genes encoding effector proteins from salivary glands of S. litura (Fab.). Results: Head and salivary glands of Spodoptera litura were used for de-novo transcriptome analysis and effector prediction. Eight hundred ninety-nine proteins from the head and 330 from salivary gland were identified as secretory proteins. Eight hundred eight proteins from the head and 267 from salivary gland proteins were predicted to be potential effector proteins. Conclusions: This study is the first report on identification of potential effectors from Spodoptera litura salivary glands.Item Chlorogenic acid-mediated chemical defense of plants against insect herbivores(John Wiley & Sons, 2019) Kundu, Anish; Vadassery, JyothilakshmiChlorogenic acid is one of the most abundant beneficial polyphenols in plants and is well known as nutritional anti‐oxidant in plant based foods. Apart from its dietary antioxidant activity, it has been proven to be an efficient defense molecule against a broad range of insect herbivores. In the last two decades, several reports have shown the effectiveness of chlorogenic acid for insect's growth deterrence. Biosynthetic pathway for chlorogenic acid biosynthesis in plants was previously elucidated and metabolic engineering of the principal pathway showed high chlorogenic acid production in tomato plants. Herbivore mediated induction of chlorogenic acid biosynthesis was also demonstrated both at metabolite and transcript level, though herbivore‐mediated molecular regulation of chlorogenic acid biosynthesis is not fully elucidated yet. In this communication, we present our views on the efficacy of chlorogenic acid as anti‐herbivore defense molecule in plants and also discuss its future outlook.Item Regulation of glucosinolate metabolism: From model plant Arabidopsis thaliana to Brassica crops(Springer, 2017) Augustine, Rehna; Bisht, Naveen C.Brassicaceae are blessed with secondary metabolites called glucosinolates which form the defense arsenal of these plants. Glucosinolates and its degradation products are also proved to be beneficial in agriculture and human health even though some are known to be detrimental. The type of glucosinolates and its content displays huge diversity across different species. The glucosinolate diversity is primarily genetically controlled. The profile of glucosinolates also varies depending on the growth stages and external environment of the plant. The environmental factors include type of pest/pathogen attack, nutrient status of the plant, and other abiotic stress factors. The glucosinolate pathway is also linked to other major metabolic and signaling pathways resulting in a complex mechanism of regulation. Even though the regulatory mechanism is not completely understood, the current chapter integrates the knowledge available from the model plant Arabidopsis and related Brassica crops.Item Tissue water status and bacterial pathogen infection: how they are correlated?(Springer, 2017) Fatima, Urooj; Senthil-Kumar, MuthappaTissue water status plays an important role in determining the fate of plant-pathogen interaction. Water availability is one of the factors that determine the multiplication of bacteria on the surface and inside the plants. Plant-water relations are highly influenced by soil water status, and drought stress is known to severely impact plant-pathogen interaction. Water, as a limiting factor, is differentially manipulated by both plants and pathogens during compatible and incompatible interactions. Plants stimulate the localized loss of water at the site of infection for limiting the bacterial multiplication. On the other hand, foliar and vascular bacterial pathogens employ different strategies to alter the plant water status and eventually establish the infection in plants. Foliar pathogens manipulate their own machinery in response to water-limited condition in plants. They also modulate the plant machinery in order to promote disease by increasing the water soaking between the cells. Similarly, vascular pathogens use different strategies such as clogging of vessels and embolism of xylem elements that leads to wilting of plant. Here, we discuss the current knowledge on impact of drought stress during plant interaction with foliar or vascular pathogen interactions.Item Biotic elicitors and mechanical damage modulate glucosinolate accumulation by co-ordinated interplay of glucosinolate biosynthesis regulators in polyploid Brassica juncea(Elsevier B.V., 2015) Augustine, Rehna; Bisht, Naveen C.Glucosinolates are nitrogen and sulfur containing secondary metabolites found mainly in the Brassicaceae. They function as plant defense compounds against a broad spectrum of pathogens and pests. Since these molecules form part of the plant defense mechanism, glucosinolate biosynthesis may be modulated by environmental signals leading to activation of a biological stress response. In the current study, we have mimicked such conditions by exogenously applying biotic elicitors such as methyl jasmonate, salicylic acid, glucose and mechanical injury in Brassica juncea seedling over a time course experiment. We found that total glucosinolates over-accumulated under these stress conditions with maximum accumulation observed 24h post treatment. Indole glucosinolates like 1-methoxy-indol-3-ylmethyl and its precursor indol-3-methyl glucosinolates showed a more significant induction compared to aliphatic glucosinolates thereby suggesting a prominent role of indole glucosinolates during plant defense response in B. juncea seedlings. In contrast, the higher amounts of aliphatic glucosinolates were less regulated by the tested biotic elicitors in B. juncea. Expression profiling of multiple homologs of key transcriptional regulators of glucosinolate biosynthesis further showed that a complex interplay of these regulators exists in polyploid B. juncea where they exert co-ordinated and overlapping effects toward altering glucosinolate accumulation. This study has a significant role toward understanding and augmenting plant defense mechanisms in B. juncea, a globally important oilseed crop of genus Brassica.