Abstract
We used in situ hybridization to localize two classes of auxin-regulated transcripts, GH3 and SAURs, within organs and tissues of soybean seedlings and flowers. GH3 transcripts occurred in the inner cortex and protoxylem ridges of roots and were expressed transiently during flower and pod development. SAUR transcripts were expressed in the epidermis, cortex, and starch sheath of epicotyls and immature hypocotyls. SAUR transcripts became more abundant on the bottom side of hypocotyls that were undergoing gravitropic curvature. SAURs were also expressed in developing xylem elements of the hypocotyl hook. When soybean organ sections were treated with 50 micromolar 2,4-dichlorophenoxyacetic acid (2,4-D), GH3 transcripts became more abundant in the vascular regions of all organs analyzed. High levels of GH3 transcripts were also found in developing palisade mesophyll cells of leaves, cotyledons, and flowers treated with 2,4-D. SAUR transcripts became more abundant in the epidermis, cortex, starch sheath, and pith of epicotyls and hypocotyls after 2,4-D treatment. Our results showed that a variety of tissues and cell types express auxin-responsive transcripts and that different tissues respond rapidly to exogenous auxin by expressing different hormone-responsive genes.
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- Ainley W. M., Walker J. C., Nagao R. T., Key J. L. Sequence and characterization of two auxin-regulated genes from soybean. J Biol Chem. 1988 Aug 5;263(22):10658–10666. [PubMed] [Google Scholar]
- Alliotte T., Tiré C., Engler G., Peleman J., Caplan A., Van Montagu M., Inzé D. An Auxin-Regulated Gene of Arabidopsis thaliana Encodes a DNA-Binding Protein. Plant Physiol. 1989 Mar;89(3):743–752. doi: 10.1104/pp.89.3.743. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Conner T. W., Goekjian V. H., LaFayette P. R., Key J. L. Structure and expression of two auxin-inducible genes from Arabidopsis. Plant Mol Biol. 1990 Oct;15(4):623–632. doi: 10.1007/BF00017836. [DOI] [PubMed] [Google Scholar]
- Franco A. R., Gee M. A., Guilfoyle T. J. Induction and superinduction of auxin-responsive mRNAs with auxin and protein synthesis inhibitors. J Biol Chem. 1990 Sep 15;265(26):15845–15849. [PubMed] [Google Scholar]
- Hagen G., Guilfoyle T. J. Rapid induction of selective transcription by auxins. Mol Cell Biol. 1985 Jun;5(6):1197–1203. doi: 10.1128/mcb.5.6.1197. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Klämbt D. A view about the function of auxin-binding proteins at plasma membranes. Plant Mol Biol. 1990 Jun;14(6):1045–1050. doi: 10.1007/BF00019401. [DOI] [PubMed] [Google Scholar]
- Kutschera U., Briggs W. R. Differential effect of auxin on in vivo extensibility of cortical cylinder and epidermis in pea internodes. Plant Physiol. 1987 Aug;84(4):1361–1366. doi: 10.1104/pp.84.4.1361. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Löbler M., Klämbt D. Auxin-binding protein from coleoptile membranes of corn (Zea mays L.). I. Purification by immunological methods and characterization. J Biol Chem. 1985 Aug 15;260(17):9848–9853. [PubMed] [Google Scholar]
- Maurel C., Brevet J., Barbier-Brygoo H., Guern J., Tempé J. Auxin regulates the promoter of the root-inducing rolB gene of Agrobacterium rhizogenes in transgenic tobacco. Mol Gen Genet. 1990 Aug;223(1):58–64. doi: 10.1007/BF00315797. [DOI] [PubMed] [Google Scholar]
- Takahashi Y., Niwa Y., Machida Y., Nagata T. Location of the cis-acting auxin-responsive region in the promoter of the par gene from tobacco mesophyll protoplasts. Proc Natl Acad Sci U S A. 1990 Oct;87(20):8013–8016. doi: 10.1073/pnas.87.20.8013. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Theologis A., Huynh T. V., Davis R. W. Rapid induction of specific mRNAs by auxin in pea epicotyl tissue. J Mol Biol. 1985 May 5;183(1):53–68. doi: 10.1016/0022-2836(85)90280-3. [DOI] [PubMed] [Google Scholar]
- Walker J. C., Key J. L. Isolation of cloned cDNAs to auxin-responsive poly(A)RNAs of elongating soybean hypocotyl. Proc Natl Acad Sci U S A. 1982 Dec;79(23):7185–7189. doi: 10.1073/pnas.79.23.7185. [DOI] [PMC free article] [PubMed] [Google Scholar]