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Title: Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response

Abstract

Abstract Endogenous levels and signaling of gibberellin plant hormones such as gibberellic acid (GA) have been genetically down-regulated to create semi-dwarf varieties of poplar. The potential benefits of semi-dwarf stature include reduced risk of wind damage, improved stress tolerance, and improved wood quality. Despite these benefits, modification of growth traits may have consequences for non-target traits that confer defense against insect herbivores. According to the growth-differentiation balance hypothesis, reductions in growth may shift allocation of carbon from growth to chemical resistance traits, thereby altering plant defense. To date, host-plant suitability and pest response have not been comprehensively evaluated in GA down-regulated plants. We quantified chemical resistance and nitrogen (an index of protein) in GA down-regulated and wild-type poplar (Populus alba × P. tremula) genotypes. We also evaluated performance of both generalist (Lymantria dispar) and specialist (Chrysomela scripta) insect pests reared on these genotypes. Our evaluation of resistance traits in four GA down-regulated genotypes revealed increased phenolic glycosides in one modified genotype and reduced lignin in two modified genotypes relative to the non-transgenic wild type. Nitrogen levels did not vary significantly among the experimental genotypes. Generalists reared on the four GA down-regulated genotypes exhibited reduced performance on only one modified genotypemore » relative to the wild type. Specialists, however, performed similarly across all genotypes. Results from this study indicate that although some non-target traits varied among GA down-regulated genotypes, the differences in poplar pest susceptibility were modest and highly genotype-specific.« less

Authors:
 [1];  [2];  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
  2. Oregon State Univ., Corvallis, OR (United States). Dept. of Forest Ecosystems and Society
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1174151
Grant/Contract Number:
FG02-06ER64185; FG02-05ER64113
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Arthropod-Plant Interactions
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 1872-8855
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Genetically modified plants; Gibberellic acid; Non-target plant defense; Plant–insect interactions; Cottonwood leaf beetle; Gypsy moth; populus-tremuloides michx; intraspecific variation; herbivore interactions; phytochemistry; phenolic glycosides; foliar quality

Citation Formats

Buhl, Christine, Strauss, Steven H., and Lindroth, Richard L.. Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response. United States: N. p., 2015. Web. doi:10.1007/s11829-014-9351-y.
Buhl, Christine, Strauss, Steven H., & Lindroth, Richard L.. Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response. United States. doi:10.1007/s11829-014-9351-y.
Buhl, Christine, Strauss, Steven H., and Lindroth, Richard L.. 2015. "Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response". United States. doi:10.1007/s11829-014-9351-y. https://www.osti.gov/servlets/purl/1174151.
@article{osti_1174151,
title = {Down-regulation of gibberellic acid in poplar has negligible effects on host-plant suitability and insect pest response},
author = {Buhl, Christine and Strauss, Steven H. and Lindroth, Richard L.},
abstractNote = {Abstract Endogenous levels and signaling of gibberellin plant hormones such as gibberellic acid (GA) have been genetically down-regulated to create semi-dwarf varieties of poplar. The potential benefits of semi-dwarf stature include reduced risk of wind damage, improved stress tolerance, and improved wood quality. Despite these benefits, modification of growth traits may have consequences for non-target traits that confer defense against insect herbivores. According to the growth-differentiation balance hypothesis, reductions in growth may shift allocation of carbon from growth to chemical resistance traits, thereby altering plant defense. To date, host-plant suitability and pest response have not been comprehensively evaluated in GA down-regulated plants. We quantified chemical resistance and nitrogen (an index of protein) in GA down-regulated and wild-type poplar (Populus alba × P. tremula) genotypes. We also evaluated performance of both generalist (Lymantria dispar) and specialist (Chrysomela scripta) insect pests reared on these genotypes. Our evaluation of resistance traits in four GA down-regulated genotypes revealed increased phenolic glycosides in one modified genotype and reduced lignin in two modified genotypes relative to the non-transgenic wild type. Nitrogen levels did not vary significantly among the experimental genotypes. Generalists reared on the four GA down-regulated genotypes exhibited reduced performance on only one modified genotype relative to the wild type. Specialists, however, performed similarly across all genotypes. Results from this study indicate that although some non-target traits varied among GA down-regulated genotypes, the differences in poplar pest susceptibility were modest and highly genotype-specific.},
doi = {10.1007/s11829-014-9351-y},
journal = {Arthropod-Plant Interactions},
number = 1,
volume = 9,
place = {United States},
year = 2015,
month = 1
}

Journal Article:
Free Publicly Available Full Text
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  • The effects of gibberellic acid (GA/sub 3/) and calcium ions on the production of ..cap alpha..-amylase and acid phosphatase by isolated aleurone layers of barley (Hordeum vulgare L. cv Himalaya) were studied. Aleurone layers not previously exposed to GA/sub 3/ or CA/sup 2 +/ show qualitative and quantitative changes in hydrolase production following incubation in either GA/sub 3/ or CA/sup 2 +/ or both. In cubation in H/sub 2/O or CA/sup 2 +/ results in the production of low levels of ..cap alpha..-amylase or acid phosphatase. The addition of GA/sub 3/ to the incubation medium causes 10- to 20-fold increasemore » in the amounts of these enzymes released from the tissue, and addition of CA/sup 2 +/ at 10 millimolar causes a further 8- to 9-fold increase in ..cap alpha..-amylase release and a 75% increase in phosphatase release. Production of ..cap alpha..-amylase isoenzymes is also modified by the levels of GA/sub 3/ and CA/sup 2 +/ in the incubation medium. ..cap alpha..-amylase 2 is produced under all conditions of incubation, while ..cap alpha..-amylase 1 appears only when layers are incubated in GA/sub 3/ or GA/sub 3/ plus CA/sup 2 +/. The synthesis of ..cap alpha..-amylases 3 and 4 requires the presence of both GA/sub 3/ and CA/sup 2 +/ in the incubation medium. Laurell rocket immunoelectrophoresis shows that two distinct groups of ..cap alpha..-amylase antigens are present in incubation media of aleurone layers incubated with both GA/sub 3/ and CA/sup 2 +/, while only one group of antigens is found in media of layers incubated in GA/sub 3/ alone. Strontium ions can be substituted for CA/sup 2 +/ in increasing hydrolase production, although higher concentrations of Sr/sup 2 +/ are requried for maximal response. We conclude that GA/sub 3/ is required for the production of ..cap alpha..-amylase 1 and that both GA/sub 3/ and either CA/sup 2 +/ or Sr/sup 2 +/ are required for the production of isoenzymes 3 and 4 of barley aleurone ..cap alpha..-amylase. 22 references, 8 figures, 1 tables.« less
  • Treatment of aleurone layers of barley seed with gibberellic acid increases the observable phosphorylcholine glyceride transferase activity in a membrane fraction prepared from extracts of the aleurone cells. This gibberellic acid-dependent increase in glyceride transferase activity requires neither RNA synthesis nor protein synthesis. Membrane fractions prepared from mixtures of extracts of gibberellic acid-treated layers and control layers have a specific activity of glyceride transferase higher than expected on the basis of simple addition of the activities from the two sources. Therefore, some kind of activation is occurring. (auth)