scholarly journals Negative regulation of plastidial isoprenoid pathway by herbivore-induced β-cyclocitral in Arabidopsis thaliana

2021 ◽  
Vol 118 (10) ◽  
pp. e2008747118
Author(s):  
Sirsha Mitra ◽  
Roger Estrada-Tejedor ◽  
Daniel C. Volke ◽  
Michael A. Phillips ◽  
Jonathan Gershenzon ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Insect Herbivory ◽  
Carbon Assimilation ◽  
Mep Pathway ◽  
Simulated Herbivory ◽  
Transcript Accumulation ◽  
Generalist Herbivore ◽  
Defense Signaling ◽  
Steady State Levels

Insect damage to plants is known to up-regulate defense and down-regulate growth processes. While there are frequent reports about up-regulation of defense signaling and production of defense metabolites in response to herbivory, much less is understood about the mechanisms by which growth and carbon assimilation are down-regulated. Here we demonstrate that insect herbivory down-regulates the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway in Arabidopsis (Arabidopsis thaliana), a pathway making primarily metabolites for use in photosynthesis. Simulated feeding by the generalist herbivore Spodoptera littoralis suppressed flux through the MEP pathway and decreased steady-state levels of the intermediate 1-deoxy-D-xylulose 5-phosphate (DXP). Simulated herbivory also increased reactive oxygen species content which caused the conversion of β-carotene to β-cyclocitral (βCC). This volatile oxidation product affected the MEP pathway by directly inhibiting DXP synthase (DXS), the rate-controlling enzyme of the MEP pathway in Arabidopsis and inducing plant resistance against S. littoralis. βCC inhibited both DXS transcript accumulation and DXS activity. Molecular models suggested that βCC binds to DXS at the binding site for the thymine pyrophosphate cofactor and blocks catalysis, which was confirmed by direct assays of βCC with the purified DXS protein in vitro. Another intermediate of the MEP pathway, 2-C-methyl-D-erythritol-2, 4-cyclodiphosphate, which is known to stimulate salicylate defense signaling, showed greater accumulation and enhanced export out of the plastid in response to simulated herbivory. Together, our work implicates βCC as a signal of herbivore damage in Arabidopsis that increases defense and decreases flux through the MEP pathway, a pathway involved in growth and carbon assimilation.

scholarly journals Identification and Characterization of trans-Isopentenyl Diphosphate Synthases Involved in Herbivory-Induced Volatile Terpene Formation in Populus trichocarpa

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2408 ◽  
Author(s):  
Nathalie D. Lackus ◽  
Nora P. Petersen ◽  
Raimund Nagel ◽  
Axel Schmidt ◽  
Sandra Irmisch ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Populus Trichocarpa ◽  
Insect Herbivory ◽  
Isopentenyl Diphosphate ◽  
Transcript Accumulation ◽  
Sequence Comparisons ◽  
Geranyl Diphosphate ◽  
Genes Encoding

In response to insect herbivory, poplar releases a blend of volatiles that plays important roles in plant defense. Although the volatile bouquet is highly complex and comprises several classes of compounds, it is dominated by mono- and sesquiterpenes. The most common precursors for mono- and sesquiterpenes, geranyl diphosphate (GPP) and (E,E)-farnesyl diphosphate (FPP), respectively, are in general produced by homodimeric or heterodimeric trans-isopentenyl diphosphate synthases (trans-IDSs) that belong to the family of prenyltransferases. To understand the molecular basis of herbivory-induced terpene formation in poplar, we investigated the trans-IDS gene family in the western balsam poplar Populus trichocarpa. Sequence comparisons suggested that this species possesses a single FPP synthase gene (PtFPPS1) and four genes encoding two large subunits (PtGPPS1.LSU and PtGPPS2.LSU) and two small subunits (PtGPPS.SSU1 and PtGPPS.SSU2) of GPP synthases. Transcript accumulation of PtGPPS1.LSU and PtGPPS.SSU1 was significantly upregulated upon leaf herbivory, while the expression of PtFPPS1, PtGPPS2.LSU, and PtGPPS.SSU2 was not influenced by the herbivore treatment. Heterologous expression and biochemical characterization of recombinant PtFPPS1, PtGPPS1.LSU, and PtGPPS2.LSU confirmed their respective IDS activities. Recombinant PtGPPS.SSU1 and PtGPPS.SSU2, however, had no enzymatic activity on their own, but PtGPPS.SSU1 enhanced the GPP synthase activities of PtGPPS1.LSU and PtGPPS2.LSU in vitro. Altogether, our data suggest that PtGPPS1.LSU and PtGPPS2.LSU in combination with PtGPPS.SSU1 may provide the substrate for herbivory-induced monoterpene formation in P. trichocarpa. The sole FPP synthase PtFPPS1 likely produces FPP for both primary and specialized metabolism in this plant species.

scholarly journals The Arabidopsis thaliana chloroplast division protein FtsZ1 counterbalances FtsZ2 filament stability in vitro

2021 ◽  
pp. 100627
Author(s):  
Katie J. Porter ◽  
Lingyan Cao ◽  
Yaodong Chen ◽  
Allan D. TerBush ◽  
Cheng Chen ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Chloroplast Division

Alteration in the expression of genes for cholesterol side-chain cleavage enzyme and 21-hydroxylase by hypophysectomy and ACTH administration in the rat adrenal

1990 ◽  
Vol 4 (3) ◽  
pp. 239-245 ◽  
Author(s):  
T. Imai ◽  
H. Seo ◽  
Y. Murata ◽  
M. Ohno ◽  
Y. Satoh ◽  
...  
Keyword(s):  
Steady State ◽  
Adrenal Weight ◽  
Side Chain ◽  
Total Rna ◽  
Side Chain Cleavage ◽  
Chain Cleavage ◽  
Acth Treatment ◽  
Steady State Levels ◽  
Cytochrome P 450

ABSTRACT The changes in steady-state levels of mRNA for cholesterol side-chain cleavage cytochrome P-450 (P-450scc) and steroid 21-hydroxylase cytochrome P-450 (P-450c21) caused by hypophysectomy and ACTH treatment were determined in rat adrenals. Hypophysectomy caused marked decreases in adrenal weight and total RNA per gland. Administration of ACTH resulted in increases in adrenal weight and total RNA. A significant correlation between the amount of RNA and adrenal weight was observed. Both P-450scc and P-450c21 mRNAs were decreased by hypophysectomy and increased by ACTH treatment. P-450scc mRNA decreased to 20% and P-450c21 mRNA to 76% of control values 1 day after hypophysectomy. ACTH caused a significant increase in P-450scc mRNA after 3 h. However, a significant increase in P-450c21 mRNA was observed 12 h after administration of ACTH. These results are concordant with previous studies in vitro utilizing cultured adrenocortical cells. Moreover, the induction of steady-state levels of P-450scc mRNA was faster than that observed by other investigators in studies in vitro. These results may indicate that integrity of the adrenal gland in vivo is important for the action of ACTH.

Transcription of the histone H5 gene is not S-phase regulated

1986 ◽  
Vol 6 (2) ◽  
pp. 601-606
Author(s):  
S Dalton ◽  
J R Coleman ◽  
J R Wells
Keyword(s):  
Cell Cycle ◽  
Steady State ◽  
Northern Blotting ◽  
S Phase ◽  
Erythroid Cells ◽  
Dividing Cells ◽  
Steady State Levels ◽  
Avian Erythroblastosis Virus ◽  
Histone H5

Levels of the tissue-specific linker histone H5 are elevated in mature erythroid cells as compared with levels in dividing cells of the same lineage. We examined levels of H5 mRNA in relation to the cell cycle in early erythroid cells transformed by avian erythroblastosis virus to determine whether the gene for this unusual histone is S-phase regulated. Northern blotting analyses revealed that during the cell cycle steady-state levels of H5 mRNA remained relatively constant in contrast to levels of the major core and H1 mRNAs which increased approximately 15-fold during S phase. In vitro pulse-labeling experiments involving nuclei isolated from synchronized cells at various stages of the cell cycle revealed that transcription of the H5 gene was not initiated at any particular stage of the cell cycle but was constitutive. In contrast, transcription of the H2A gene(s) initiated in early S phase, was present throughout the DNA replicative phase, and was essentially absent in G1 and G2 phases.

scholarly journals Transcriptome and translatome changes in germinated pollen under heat stress uncover roles of transporter genes involved in pollen tube growth

2020 ◽  
Author(s):  
Laetitia Poidevin ◽  
Javier Forment ◽  
Dilek Unal ◽  
Alejandro Ferrando
Keyword(s):  
Arabidopsis Thaliana ◽  
Heat Stress ◽  
High Temperature ◽  
Heat Shock ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Tube Growth ◽  
Heat Shock Genes ◽  
Germinated Pollen

ABSTRACTPlant reproduction is one key biological process very sensitive to heat stress and, as a consequence, enhanced global warming poses serious threats to food security worldwide. In this work we have used a high-resolution ribosome profiling technology to study how heat affects both the transcriptome and the translatome of Arabidopsis thaliana pollen germinated in vitro. Overall, a high correlation between transcriptional and translational responses to high temperature was found, but specific regulations at the translational level were also present. We show that bona fide heat shock genes are induced by high temperature indicating that in vitro germinated pollen is a suitable system to understand the molecular basis of heat responses. Concurrently heat induced significant down-regulation of key membrane transporters required for pollen tube growth, thus uncovering heat-sensitive targets. We also found that a large subset of the heat-repressed transporters is specifically up-regulated, in a coordinated manner, with canonical heat-shock genes in pollen tubes grown in vitro and semi in vivo, based on published transcriptomes from Arabidopsis thaliana. Ribosome footprints were also detected in gene sequences annotated as non-coding, highlighting the potential for novel translatable genes and translational dynamics.

scholarly journals Characterization of the early response of Arabidopsis thaliana to Dickeya dadantii infection using expression profiling

2018 ◽  
Author(s):  
Frédérique Van Gijsegem ◽  
Frédérique Bitton ◽  
Anne-Laure Laborie ◽  
Yvan Kraepiel ◽  
Jacques Pédron
Keyword(s):  
Arabidopsis Thaliana ◽  
Early Stage ◽  
Plant Defence ◽  
Plant Responses ◽  
Type I ◽  
In Planta ◽  
Secretion Systems ◽  
Dickeya Dadantii ◽  
A Genome

AbstractTo draw a global view of plant responses to interactions with the phytopathogenic enterobacterale Dickeya dadantii, a causal agent of soft rot diseases on many plant species, we analysed the early Arabidopsis responses to D. dadantii infection. We performed a genome-wide analysis of the Arabidopsis thaliana transcriptome during D. dadantii infection and conducted a genetic study of identified responses.A limited set of genes related to plant defence or interactions with the environment were induced at an early stage of infection, with an over-representation of genes involved in both the metabolism of indole glucosinolates (IGs) and the jasmonate (JA) defence pathway. Bacterial type I and type II secretion systems are required to trigger the induction of IG and JA-related genes while the type III secretion system appears to partially inhibit these defence pathways. Using Arabidopsis mutants impaired in JA biosynthesis or perception, we showed that induction of some IG metabolism genes was COI1-dependent but, surprisingly, JA-independent. Moreover, characterisation of D. dadantii disease progression in Arabidopsis mutants impaired in JA or IG pathways showed that JA triggers an efficient plant defence response that does not involve IGs.The induction of the IG pathway by bacterial pathogens has been reported several times in vitro. This study shows for the first time, that this induction does indeed occur in planta, but also that this line of defence is ineffective against D. dadantii infection, in contrast to its role to counteract herbivorous or fungal pathogen attacks.

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