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A jasmonate ZIM-domain protein NaJAZd regulates floral jasmonic acid levels and counteracts flower abscission in Nicotiana attenuata plants.

Oh Y, Baldwin IT, Galis I - PLoS ONE (2013)

Bottom Line: Although NaJAZd transcripts were strongly and transiently up-regulated in the rosette leaves by simulated herbivory treatment, we did not observe strong defense-related phenotypes, such as altered herbivore performance or the constitutive accumulation of defense-related secondary metabolites in irJAZd plants compared to wild type plants, both in the glasshouse and the native habitat of Nicotiana attenuata in the Great Basin Desert, Utah, USA.The early- and mid-developmental stages of irJAZd flowers had reduced levels of jasmonic acid and jasmonoyl-L-isoleucine, while fully open flowers had normal levels, but these were impaired in NaMYB305 transcript accumulations.This novel insight into the function of JAZ proteins in flower and seed development highlights the diversity of functions played by jasmonates and JAZ proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany.

ABSTRACT
Jasmonic acid is an important regulator of plant growth, development and defense. The jasmonate-ZIM domain (JAZ) proteins are key regulators in jasmonate signaling ubiquitously present in flowering plants but their functional annotation remains largely incomplete. Recently, we identified 12 putative JAZ proteins in native tobacco, Nicotiana attenuata, and initiated systematic functional characterization of these proteins by reverse genetic approaches. In this report, Nicotiana attenuata plants silenced in the expression of NaJAZd (irJAZd) by RNA interference were used to characterize NaJAZd function. Although NaJAZd transcripts were strongly and transiently up-regulated in the rosette leaves by simulated herbivory treatment, we did not observe strong defense-related phenotypes, such as altered herbivore performance or the constitutive accumulation of defense-related secondary metabolites in irJAZd plants compared to wild type plants, both in the glasshouse and the native habitat of Nicotiana attenuata in the Great Basin Desert, Utah, USA. Interestingly, irJAZd plants produced fewer seed capsules than did wild type plants as a result of increased flower abscission in later stages of flower development. The early- and mid-developmental stages of irJAZd flowers had reduced levels of jasmonic acid and jasmonoyl-L-isoleucine, while fully open flowers had normal levels, but these were impaired in NaMYB305 transcript accumulations. Previously, NaMYB305-silenced plants were shown to have strong flower abscission phenotypes and contained lower NECTARIN 1 transcript levels, phenotypes which are copied in irJAZd plants. We propose that the NaJAZd protein is required to counteract flower abscission, possibly by regulating jasmonic acid and jasmonoyl-L-isoleucine levels and/or expression of NaMYB305 gene in Nicotiana attenuata flowers. This novel insight into the function of JAZ proteins in flower and seed development highlights the diversity of functions played by jasmonates and JAZ proteins.

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Regulation of NaJAZd transcripts and silencing efficiency in irJAZd plants.(A) NaJAZd transcript abundances ± SE were determined by quantitative real-time PCR (qPCR, n = 3) in samples from WT N. attenuata leaves treated with wounding and water (W+W), wounding and M. sexta oral secretions (W+OS) harvested at 0, 1, 2, 3, and 24 h after treatment (control leaves remained untreated). (B) Transcript abundances ± SE of NaJAZd determined in untreated (control) and 1 h W+OS-treated leaves of three independent inverted repeat (ir)-NaJAZd-silenced genotypes (irJAZd-4, -8, and -10) by qPCR (n = 3). Signals in A and B were normalized by housekeeping EF1α transcript abundances determined by qPCR in the same samples. Different letters in B indicate significant differences among the combination of identically treated genotypes (WT vs. independent NaJAZd silenced lines, irJAZd-4, -8, 10 by one-way-ANOVA (P≤0.05).
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pone-0057868-g001: Regulation of NaJAZd transcripts and silencing efficiency in irJAZd plants.(A) NaJAZd transcript abundances ± SE were determined by quantitative real-time PCR (qPCR, n = 3) in samples from WT N. attenuata leaves treated with wounding and water (W+W), wounding and M. sexta oral secretions (W+OS) harvested at 0, 1, 2, 3, and 24 h after treatment (control leaves remained untreated). (B) Transcript abundances ± SE of NaJAZd determined in untreated (control) and 1 h W+OS-treated leaves of three independent inverted repeat (ir)-NaJAZd-silenced genotypes (irJAZd-4, -8, and -10) by qPCR (n = 3). Signals in A and B were normalized by housekeeping EF1α transcript abundances determined by qPCR in the same samples. Different letters in B indicate significant differences among the combination of identically treated genotypes (WT vs. independent NaJAZd silenced lines, irJAZd-4, -8, 10 by one-way-ANOVA (P≤0.05).

Mentions: Previously, we reported 12 JAZ genes in N. attenuata[31], including the NaJAZd gene characterized in this study. First, we examined NaJAZd expression in the rosette leaves of N. attenuata plants after wound and water treatment (puncturing leaves with a fabric pattern wheel and supplying with 20 µL of water; W+W), simulated herbivore attack (wounds treated with 20 µL of 1∶10 diluted oral secretions isolated from specialist herbivore Manduca sexta (M. sexta) larvae; W+OS), and in untreated leaves by quantitative real-time PCR (qPCR). While both treatments strongly increased NaJAZd transcript accumulations compared to the levels in untreated leaves, W+OS-treatment dramatically amplified these increases (Figure 1A). The gene transcripts rapidly returned to basal levels within 3 h after treatment. To further explore the function of NaJAZd, we generated the inverted-repeat (ir) RNAi-mediated NaJAZd-silenced plants (irJAZd; Figure S1A and S1B) and selected the three best-silenced lines (irJAZd-4, -8, and -10; Figure 1B) for functional analysis. A single copy T-DNA insertion status of each line was confirmed by Southern blot analysis (Figure S1C).


A jasmonate ZIM-domain protein NaJAZd regulates floral jasmonic acid levels and counteracts flower abscission in Nicotiana attenuata plants.

Oh Y, Baldwin IT, Galis I - PLoS ONE (2013)

Regulation of NaJAZd transcripts and silencing efficiency in irJAZd plants.(A) NaJAZd transcript abundances ± SE were determined by quantitative real-time PCR (qPCR, n = 3) in samples from WT N. attenuata leaves treated with wounding and water (W+W), wounding and M. sexta oral secretions (W+OS) harvested at 0, 1, 2, 3, and 24 h after treatment (control leaves remained untreated). (B) Transcript abundances ± SE of NaJAZd determined in untreated (control) and 1 h W+OS-treated leaves of three independent inverted repeat (ir)-NaJAZd-silenced genotypes (irJAZd-4, -8, and -10) by qPCR (n = 3). Signals in A and B were normalized by housekeeping EF1α transcript abundances determined by qPCR in the same samples. Different letters in B indicate significant differences among the combination of identically treated genotypes (WT vs. independent NaJAZd silenced lines, irJAZd-4, -8, 10 by one-way-ANOVA (P≤0.05).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585257&req=5

pone-0057868-g001: Regulation of NaJAZd transcripts and silencing efficiency in irJAZd plants.(A) NaJAZd transcript abundances ± SE were determined by quantitative real-time PCR (qPCR, n = 3) in samples from WT N. attenuata leaves treated with wounding and water (W+W), wounding and M. sexta oral secretions (W+OS) harvested at 0, 1, 2, 3, and 24 h after treatment (control leaves remained untreated). (B) Transcript abundances ± SE of NaJAZd determined in untreated (control) and 1 h W+OS-treated leaves of three independent inverted repeat (ir)-NaJAZd-silenced genotypes (irJAZd-4, -8, and -10) by qPCR (n = 3). Signals in A and B were normalized by housekeeping EF1α transcript abundances determined by qPCR in the same samples. Different letters in B indicate significant differences among the combination of identically treated genotypes (WT vs. independent NaJAZd silenced lines, irJAZd-4, -8, 10 by one-way-ANOVA (P≤0.05).
Mentions: Previously, we reported 12 JAZ genes in N. attenuata[31], including the NaJAZd gene characterized in this study. First, we examined NaJAZd expression in the rosette leaves of N. attenuata plants after wound and water treatment (puncturing leaves with a fabric pattern wheel and supplying with 20 µL of water; W+W), simulated herbivore attack (wounds treated with 20 µL of 1∶10 diluted oral secretions isolated from specialist herbivore Manduca sexta (M. sexta) larvae; W+OS), and in untreated leaves by quantitative real-time PCR (qPCR). While both treatments strongly increased NaJAZd transcript accumulations compared to the levels in untreated leaves, W+OS-treatment dramatically amplified these increases (Figure 1A). The gene transcripts rapidly returned to basal levels within 3 h after treatment. To further explore the function of NaJAZd, we generated the inverted-repeat (ir) RNAi-mediated NaJAZd-silenced plants (irJAZd; Figure S1A and S1B) and selected the three best-silenced lines (irJAZd-4, -8, and -10; Figure 1B) for functional analysis. A single copy T-DNA insertion status of each line was confirmed by Southern blot analysis (Figure S1C).

Bottom Line: Although NaJAZd transcripts were strongly and transiently up-regulated in the rosette leaves by simulated herbivory treatment, we did not observe strong defense-related phenotypes, such as altered herbivore performance or the constitutive accumulation of defense-related secondary metabolites in irJAZd plants compared to wild type plants, both in the glasshouse and the native habitat of Nicotiana attenuata in the Great Basin Desert, Utah, USA.The early- and mid-developmental stages of irJAZd flowers had reduced levels of jasmonic acid and jasmonoyl-L-isoleucine, while fully open flowers had normal levels, but these were impaired in NaMYB305 transcript accumulations.This novel insight into the function of JAZ proteins in flower and seed development highlights the diversity of functions played by jasmonates and JAZ proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany.

ABSTRACT
Jasmonic acid is an important regulator of plant growth, development and defense. The jasmonate-ZIM domain (JAZ) proteins are key regulators in jasmonate signaling ubiquitously present in flowering plants but their functional annotation remains largely incomplete. Recently, we identified 12 putative JAZ proteins in native tobacco, Nicotiana attenuata, and initiated systematic functional characterization of these proteins by reverse genetic approaches. In this report, Nicotiana attenuata plants silenced in the expression of NaJAZd (irJAZd) by RNA interference were used to characterize NaJAZd function. Although NaJAZd transcripts were strongly and transiently up-regulated in the rosette leaves by simulated herbivory treatment, we did not observe strong defense-related phenotypes, such as altered herbivore performance or the constitutive accumulation of defense-related secondary metabolites in irJAZd plants compared to wild type plants, both in the glasshouse and the native habitat of Nicotiana attenuata in the Great Basin Desert, Utah, USA. Interestingly, irJAZd plants produced fewer seed capsules than did wild type plants as a result of increased flower abscission in later stages of flower development. The early- and mid-developmental stages of irJAZd flowers had reduced levels of jasmonic acid and jasmonoyl-L-isoleucine, while fully open flowers had normal levels, but these were impaired in NaMYB305 transcript accumulations. Previously, NaMYB305-silenced plants were shown to have strong flower abscission phenotypes and contained lower NECTARIN 1 transcript levels, phenotypes which are copied in irJAZd plants. We propose that the NaJAZd protein is required to counteract flower abscission, possibly by regulating jasmonic acid and jasmonoyl-L-isoleucine levels and/or expression of NaMYB305 gene in Nicotiana attenuata flowers. This novel insight into the function of JAZ proteins in flower and seed development highlights the diversity of functions played by jasmonates and JAZ proteins.

Show MeSH