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Targeting Hormone-Related Pathways to Improve Grain Yield in Rice: A Chemical Approach.

Tamaki H, Reguera M, Abdel-Tawab YM, Takebayashi Y, Kasahara H, Blumwald E - PLoS ONE (2015)

Bottom Line: NDGA inhibited the expression of ABA-responsive gene, but did not significantly decrease ABA content.Instead, NDGA significantly decreased jasmonic acid and jasmonic acid-isoleucine.Our results support the notion that the specific inhibition of jasmonic acid and ethylene biosynthesis resulted in grain yield increase in rice.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of California Davis, Davis, California 95616, United States of America; Health and Crop Sciences Research Laboratory, Sumitomo Chemical Co. Ltd., Hyogo 665-8555, Japan.

ABSTRACT
Sink/source relationships, regulating the mobilization of stored carbohydrates from the vegetative tissues to the grains, are of key importance for grain filling and grain yield. We used different inhibitors of plant hormone action to assess their effects on grain yield and on the expression of hormone-associated genes. Among the tested chemicals, 2-indol-3-yl-4-oxo-4-phenylbutanoic acid (PEO-IAA; antagonist of auxin receptor), nordihydroguaiaretic acid (NDGA; abscisic acid (ABA) biosynthesis inhibitor), and 2-aminoisobutyric acid (AIB; ethylene biosynthesis inhibitor) improved grain yield in a concentration dependent manner. These effects were also dependent on the plant developmental stage. NDGA and AIB treatments induced an increase in photosynthesis in flag leaves concomitant to the increments of starch content in flag leaves and grains. NDGA inhibited the expression of ABA-responsive gene, but did not significantly decrease ABA content. Instead, NDGA significantly decreased jasmonic acid and jasmonic acid-isoleucine. Our results support the notion that the specific inhibition of jasmonic acid and ethylene biosynthesis resulted in grain yield increase in rice.

No MeSH data available.


Effects of NDGA on the expression of JA synthesis-related genes.Effects of NDGA on the expression of JA synthesis-related genes (OsPLDα4 [LOC_Os06g40170], OsPLDα5 [LOC_Os06g40180], OsLOX1 [LOC_Os03g49380], OsHI-LOX [LOC_Os08g39840], OsAOS2 [LOC_Os03g12500], OsAOC [LOC_Os03g32314], OsOPR7 [LOC_Os08g35740], OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 days after treatment at pre-anthesis stage. (A) Scheme of the main steps in the JA synthesis pathway indicating (in colored boxes) the genes that were differently expressed in NDGA treated plants with respect to UTC plants. White indicates genes not significantly different and Blue indicates genes with a significantly lower gene expression. (B) Relative gene expression values setting UTC as 0. Values are Mean ± SE (n = 6). * indicating significance at P ≤ 0.05.
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pone.0131213.g004: Effects of NDGA on the expression of JA synthesis-related genes.Effects of NDGA on the expression of JA synthesis-related genes (OsPLDα4 [LOC_Os06g40170], OsPLDα5 [LOC_Os06g40180], OsLOX1 [LOC_Os03g49380], OsHI-LOX [LOC_Os08g39840], OsAOS2 [LOC_Os03g12500], OsAOC [LOC_Os03g32314], OsOPR7 [LOC_Os08g35740], OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 days after treatment at pre-anthesis stage. (A) Scheme of the main steps in the JA synthesis pathway indicating (in colored boxes) the genes that were differently expressed in NDGA treated plants with respect to UTC plants. White indicates genes not significantly different and Blue indicates genes with a significantly lower gene expression. (B) Relative gene expression values setting UTC as 0. Values are Mean ± SE (n = 6). * indicating significance at P ≤ 0.05.

Mentions: We also evaluated the effects of 0.12 mM NDGA on the expression of JA synthesis-related genes including, rice Phospholipase D alpha 4 (OsPLDα4) [LOC_Os06g40170], rice Phospholipase D alpha 5 (OsPLDα5) [LOC_Os06g40180], rice lipoxygenases (OsLOX1 [LOC_Os03g49380] and OsHI-LOX [LOC_Os08g39840]), rice allen oxide synthase (OsAOS2 [LOC_Os03g12500]), rice allen oxide cyclase (OsAOC [LOC_Os03g32314]), rice 12-oxophytodienoate reductase 7 (OsOPR7 [LOC_Os08g35740]), rice jasmonic acid resistance 1 and 2 (OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 d after treatment at pre-anthesis ([52] and references therein). The decreased expression of OsPLDα4, OsPLDα5, OsLOX1, OsAOC, and OsOPR7, following the NDGA treatment, suggested the NDGA-induced inhibition of the JA synthesis pathway (Fig 4). These results indicated that the repression of JA synthesis-related genes expressions might contribute to the reduction of JA and JA-Ile contents.


Targeting Hormone-Related Pathways to Improve Grain Yield in Rice: A Chemical Approach.

Tamaki H, Reguera M, Abdel-Tawab YM, Takebayashi Y, Kasahara H, Blumwald E - PLoS ONE (2015)

Effects of NDGA on the expression of JA synthesis-related genes.Effects of NDGA on the expression of JA synthesis-related genes (OsPLDα4 [LOC_Os06g40170], OsPLDα5 [LOC_Os06g40180], OsLOX1 [LOC_Os03g49380], OsHI-LOX [LOC_Os08g39840], OsAOS2 [LOC_Os03g12500], OsAOC [LOC_Os03g32314], OsOPR7 [LOC_Os08g35740], OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 days after treatment at pre-anthesis stage. (A) Scheme of the main steps in the JA synthesis pathway indicating (in colored boxes) the genes that were differently expressed in NDGA treated plants with respect to UTC plants. White indicates genes not significantly different and Blue indicates genes with a significantly lower gene expression. (B) Relative gene expression values setting UTC as 0. Values are Mean ± SE (n = 6). * indicating significance at P ≤ 0.05.
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pone.0131213.g004: Effects of NDGA on the expression of JA synthesis-related genes.Effects of NDGA on the expression of JA synthesis-related genes (OsPLDα4 [LOC_Os06g40170], OsPLDα5 [LOC_Os06g40180], OsLOX1 [LOC_Os03g49380], OsHI-LOX [LOC_Os08g39840], OsAOS2 [LOC_Os03g12500], OsAOC [LOC_Os03g32314], OsOPR7 [LOC_Os08g35740], OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 days after treatment at pre-anthesis stage. (A) Scheme of the main steps in the JA synthesis pathway indicating (in colored boxes) the genes that were differently expressed in NDGA treated plants with respect to UTC plants. White indicates genes not significantly different and Blue indicates genes with a significantly lower gene expression. (B) Relative gene expression values setting UTC as 0. Values are Mean ± SE (n = 6). * indicating significance at P ≤ 0.05.
Mentions: We also evaluated the effects of 0.12 mM NDGA on the expression of JA synthesis-related genes including, rice Phospholipase D alpha 4 (OsPLDα4) [LOC_Os06g40170], rice Phospholipase D alpha 5 (OsPLDα5) [LOC_Os06g40180], rice lipoxygenases (OsLOX1 [LOC_Os03g49380] and OsHI-LOX [LOC_Os08g39840]), rice allen oxide synthase (OsAOS2 [LOC_Os03g12500]), rice allen oxide cyclase (OsAOC [LOC_Os03g32314]), rice 12-oxophytodienoate reductase 7 (OsOPR7 [LOC_Os08g35740]), rice jasmonic acid resistance 1 and 2 (OsJAR1 [LOC_Os05g50890] and OsJAR2 [LOC_Os01g12160]) 2 d after treatment at pre-anthesis ([52] and references therein). The decreased expression of OsPLDα4, OsPLDα5, OsLOX1, OsAOC, and OsOPR7, following the NDGA treatment, suggested the NDGA-induced inhibition of the JA synthesis pathway (Fig 4). These results indicated that the repression of JA synthesis-related genes expressions might contribute to the reduction of JA and JA-Ile contents.

Bottom Line: NDGA inhibited the expression of ABA-responsive gene, but did not significantly decrease ABA content.Instead, NDGA significantly decreased jasmonic acid and jasmonic acid-isoleucine.Our results support the notion that the specific inhibition of jasmonic acid and ethylene biosynthesis resulted in grain yield increase in rice.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of California Davis, Davis, California 95616, United States of America; Health and Crop Sciences Research Laboratory, Sumitomo Chemical Co. Ltd., Hyogo 665-8555, Japan.

ABSTRACT
Sink/source relationships, regulating the mobilization of stored carbohydrates from the vegetative tissues to the grains, are of key importance for grain filling and grain yield. We used different inhibitors of plant hormone action to assess their effects on grain yield and on the expression of hormone-associated genes. Among the tested chemicals, 2-indol-3-yl-4-oxo-4-phenylbutanoic acid (PEO-IAA; antagonist of auxin receptor), nordihydroguaiaretic acid (NDGA; abscisic acid (ABA) biosynthesis inhibitor), and 2-aminoisobutyric acid (AIB; ethylene biosynthesis inhibitor) improved grain yield in a concentration dependent manner. These effects were also dependent on the plant developmental stage. NDGA and AIB treatments induced an increase in photosynthesis in flag leaves concomitant to the increments of starch content in flag leaves and grains. NDGA inhibited the expression of ABA-responsive gene, but did not significantly decrease ABA content. Instead, NDGA significantly decreased jasmonic acid and jasmonic acid-isoleucine. Our results support the notion that the specific inhibition of jasmonic acid and ethylene biosynthesis resulted in grain yield increase in rice.

No MeSH data available.