Institutional Publications

Permanent URI for this collectionhttps://ndkr-library.nipgr.ac.in/handle/123456789/11

Browse

Author: search.filters.author.Meena, Mukesh KumarSubject: search.filters.subject.Arabidopsis

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Insect herbivory simulation and insect bioassays to study plant stress memory response
    (Springer Nature Publishing AG, 2026) Meena, Mukesh Kumar
    Plant stress memory response is an emerging field in plant–insect interaction. Recent reports indicate phytohormone jasmonic acid (JA) triggers long-term effects on the defense phenotype, transcriptome, and DNA methylome of Arabidopsis. Long-term JA-mediated induced resistance required MYC2/3/4 transcription factors and epigenetic regulatory components that prepare plants for future insect herbivore threats. Three weeks after transient JA signaling, 5-week-old plants retained induced resistance against herbivory but showed increased susceptibility to pathogens. This mechanism is linked with long-term priming and/or upregulation of JA-dependent defense genes but repression of ethylene- and salicylic acid-dependent genes. Still more research is required to fully understand plant stress memory response in plant–insect interaction. Here, a detailed and reproducible protocol for simulated herbivory and sample collection for transcriptomic and metabolomic studies is described to investigate involved defense signaling pathways. Furthermore, the insect bioassay protocol is described to study insect performance on various plant genotypes. Both protocols are robust and could be useful to study plant stress memory response in plant defense mechanisms through simulated herbivory and direct insect performance and feeding behavior by insect bioassays.
  • Thumbnail Image
    Item
    Jasmonic acid (JA) induced-calcium elevation in Arabidopsis is highly variable due to time of day and conversion to JA-Ile
    (Springer Nature Publishing AG, 2020) Prajapati, Ramgopal; Mittal, Deepika; Meena, Mukesh Kumar; Vadassery, Jyothilakshmi
    Plants have evolved mechanisms to effectively anticipate environmental changes via diurnal rhythmicity (day/night) maintained by the circadian clock. Jasmonic acid biosynthesis and signalling are known to be under the control of the circadian clock. Both JA and its bioactive form jasmonoyl-L-isoleucine (JA-Ile) when externally added can induce a cytosolic Ca2? influx in Arabidopsis thaliana. JA and JA-Ile induced Ca2? is poorly understood and often used interchangeably to study Ca2? regulation of jasmonates. We attempted to understand if they are similar and if diurnal rhythms or time of day regulate them. JA induced Cacyt 2? signature is variable according to time-of-day in Arabidopsis. JA is sensed in two ways according to the time-of-day (a) directly sensed as JA and induces Cacyt 2? elevation (b) JA gets converted into the JA-Ile by JAR1 and is sensed as JA-Ile, which we proved using jar1-1*aequorin. This twin sensing mode is responsible for variability in JA induced Cacyt 2? signature. We further suggest caution when using JA as a stimulant for Cacyt 2? elevation measurements to compare wild-type (Col-0 transformed with pMAQ2; transgenic aequorin) and effect of different mutations. On the other hand bioactive JA-Ile induced Cacyt 2? signature is constant diurnally with maximum amplitude at dawn which coincides with maximum sensitivity of JA-Ile receptor, COI1 and increased VSP2 expression. From the above study we conclude that JA-Ile induced Cacyt 2? elevation is a better read-out than the highly variable JA-induced Cacyt 2? elevations to study the output pathways.
  • Thumbnail Image
    Item
    The Ca2+ channel CNGC19 regulates Arabidopsis defense against spodoptera herbivory
    (American Society of Plant Biologists, 2019) Meena, Mukesh Kumar; Prajapati, Ramgopal; Krishna, Deepthi; Divakaran, Keerthi; Pandey, Yogesh; Reichelt, Michael; Mathew, M.K.; Boland, Wilhelm; Mithöfer, Axel; Vadassery, Jyothilakshmi
    Cellular calcium elevation is an important signal used by plants for recognition and signaling of environmental stress. Perception of the generalist insect, Spodoptera litura, by Arabidopsis thaliana activates cytosolic Ca2+ elevation, which triggers downstream defense. However, not all the Ca2+ channels generating the signal have been identified, nor are their modes of action known. We report on a rapidly activated, leaf vasculature- and plasma membrane-localized, CYCLIC NUCLEOTIDE GATED CHANNEL19 (CNGC19), which activates herbivory-induced Ca2+ flux and plant defense. Loss of CNGC19 function results in decreased herbivory defense. The cngc19 mutant shows aberrant and attenuated intra-vascular Ca2+ fluxes. CNGC19 is a Ca2+ permeable channel, as hyperpolarization of CNGC19-expressing Xenopus oocytes in the presence of both cAMP and Ca2+ results in Ca2+ influx. Breakdown of Ca2+-based defence in cngc19 mutants leads to a decrease in herbivory-induced JA-Ile biosynthesis and expression of JA responsive genes. cngc19 mutants are deficient in aliphatic glucosinolate accumulation and hyperaccumulate its precursor, methionine. CNGC19 modulates aliphatic glucosinolate biosynthesis in tandem with BRANCHED-CHAIN AMINO ACID TRANSAMINASE4 (BCAT4), which is involved in the chain elongation pathway of Met-derived glucosinolates. Furthermore, CNGC19 interacts with herbivory-induced CALMODULIN2 (CaM2) in planta. Together, our work reveals a key mechanistic role for the Ca2+ channel CNGC19 in the recognition of herbivory and the activation of defense signaling.