RNAi-mediated suppression of isoprene emission in poplar transiently impacts phenolic metabolism under high temperature and high light intensities: a transcriptomic and metabolomic analysis.
In plants, isoprene plays a dual role: (a) as thermo-protective agent proposed to prevent degradation of enzymes/membrane structures involved in photosynthesis, and (b) as reactive molecule reducing abiotic oxidative stress. The present work addresses the question whether suppression of isoprene emission interferes with genome wide transcription rates and metabolite fluxes in grey poplar (Populus x canescens) throughout the growing season. Gene expression and metabolite profiles of isoprene emitting wild type plants and RNAi-mediated non-isoprene emitting poplars were compared by using poplar Affymetrix microarrays and non-targeted FT-ICR-MS (Fourier transform ion cyclotron resonance mass spectrometry). We observed a transcriptional down-regulation of genes encoding enzymes of phenylpropanoid regulatory and biosynthetic pathways, as well as distinct metabolic down-regulation of condensed tannins and anthocyanins, in non-isoprene emitting genotypes during July, when high temperature and light intensities possibly caused transient drought stress, as indicated by stomatal closure. Under these conditions leaves of non-isoprene emitting plants accumulated hydrogen peroxide (H(2)O(2)), a signaling molecule in stress response and negative regulator of anthocyanin biosynthesis. The absence of isoprene emission under high temperature and light stress resulted transiently in a new chemo(pheno)type with suppressed production of phenolic compounds. This may compromise inducible defenses and may render non-isoprene emitting poplars more susceptible to environmental stress.
Behnke
Katja
K
Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany.
Kaiser
Andreas
A
Zimmer
Ina
I
Brüggemann
Nicolas
N
Janz
Dennis
D
Polle
Andrea
A
Hampp
Rüdiger
R
Hänsch
Robert
R
Popko
Jennifer
J
Schmitt-Kopplin
Philippe
P
Ehlting
Barbara
B
Rennenberg
Heinz
H
Barta
Csengele
C
Loreto
Francesco
F
Schnitzler
Jörg-Peter
JP
D001483:Base Sequence; D002070:Butadienes / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D017931:DNA Primers / Q000235:genetics; D015536:Down-Regulation; D055864:Droughts; D020869:Gene Expression Profiling; D017343:Genes, Plant; D045782:Hemiterpenes / Q000235:genetics* / Q000378:metabolism*; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000378:metabolism; D008027:Light; D055442:Metabolome; D008954:Models, Biological; D010420:Pentanes / Q000378:metabolism*; D010636:Phenols / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics* / Q000378:metabolism*; D034622:RNA Interference; D012621:Seasons; D013312:Stress, Physiological; D013729:Terpenes / Q000378:metabolism
D002070:Butadienes; D017931:DNA Primers; D045782:Hemiterpenes; D010420:Pentanes; D010636:Phenols; D013729:Terpenes; C005059:isoprene; D006861:Hydrogen Peroxide