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. 1994 Feb;104(2):505–513. doi: 10.1104/pp.104.2.505

Investigation of Gene Expression, Growth Kinetics, and Wall Extensibility during Brassinosteroid-Regulated Stem Elongation.

D M Zurek 1, D L Rayle 1, T C McMorris 1, S D Clouse 1
PMCID: PMC159224  PMID: 12232099

Abstract

Brassinosteroids promote stem elongation in a variety of plants but little is known about the mechanism of action of these plant growth regulators. We investigated a number of physiological and molecular parameters associated with brassinosteroid-enhanced elongation. Continuous growth recordings of soybean (Glycine max L. cv Williams 82) epicotyls showed that there was a 45-min lag before 0.1 [mu]M brassinolide (BR) exerted a detectable effect on elongation. BR caused a marked increase in Instron-measured plastic extensibility, suggesting that BR may promote elongation in part by altering mechanical properties of the cell wall (wall loosening). Structure-function studies suggested that the dimensions of the brassinosteroid side chain were critical for promotion of elongation and expression of BRU1, a gene regulated specifically by active brassinosteroids. Auxin-BR interactions were examined by using small auxin up RNA (SAUR) gene probes and the auxin-insensitive diageotropica (dgt) mutant of tomato (Lycopersicon esculentum Mill.). We have shown that in wild-type tomato, which elongates in response to exogenous auxin, a transcript of identical size to the soybean SAUR 15A is strongly induced within 1 h by 50 [mu]M 2,4-dichlorophenoxyacetic acid or indoleacetic acid, whereas in the dgt mutant, which does not elongate in response to auxin, no transcript is expressed. Furthermore, BR promotes equal elongation of hypocotyls in both wild-type and dgt tomatoes but does not rapidly induce the SAUR 15A homolog in either genotype. BR does not cause rapid induction of SAUR 6B in elongating soybean epicotyls but does lead to increased expression after 18 h. This late BR activation of SAUR 6B is controlled, at least in part, at the transcriptional level and is not accompanied by an increase of free indoleacetic acid in the tissue. We conclude that although both BR and auxin affect wall relaxation processes, BR-promoted elongation in soybean and tomato stems acts via a mechanism that most likely does not proceed through the auxin signal transduction pathway.

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Selected References

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  1. Behringer F. J., Cosgrove D. J., Reid J. B., Davies P. J. Physical basis for altered stem elongation rates in internode length mutants of Pisum. Plant Physiol. 1990;94:166–173. doi: 10.1104/pp.94.1.166. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Clouse S. D., Zurek D. M., McMorris T. C., Baker M. E. Effect of brassinolide on gene expression in elongating soybean epicotyls. Plant Physiol. 1992 Nov;100(3):1377–1383. doi: 10.1104/pp.100.3.1377. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cohen J. D., Meudt W. J. Investigations on the Mechanism of the Brassinosteroid Response: I. Indole-3-acetic Acid Metabolism and Transport. Plant Physiol. 1983 Jul;72(3):691–694. doi: 10.1104/pp.72.3.691. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Daniel S. G., Rayle D. L., Cleland R. E. Auxin physiology of the tomato mutant diageotropica. Plant Physiol. 1989;91:804–807. doi: 10.1104/pp.91.3.804. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Fry S. C., Smith R. C., Renwick K. F., Martin D. J., Hodge S. K., Matthews K. J. Xyloglucan endotransglycosylase, a new wall-loosening enzyme activity from plants. Biochem J. 1992 Mar 15;282(Pt 3):821–828. doi: 10.1042/bj2820821. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Kovatz S., Rathaus M., Aderet N. B., Bernheim J. Increased renal prostaglandins in normal pregnancy and in pregnancy with hypertension. Nephron. 1982;32(3):239–243. doi: 10.1159/000182852. [DOI] [PubMed] [Google Scholar]
  7. Lawton M. A., Lamb C. J. Transcriptional activation of plant defense genes by fungal elicitor, wounding, and infection. Mol Cell Biol. 1987 Jan;7(1):335–341. doi: 10.1128/mcb.7.1.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Lincoln C., Britton J. H., Estelle M. Growth and development of the axr1 mutants of Arabidopsis. Plant Cell. 1990 Nov;2(11):1071–1080. doi: 10.1105/tpc.2.11.1071. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Luthe D. S., Quatrano R. S. Transcription in Isolated Wheat Nuclei: I. ISOLATION OF NUCLEI AND ELIMINATION OF ENDOGENOUS RIBONUCLEASE ACTIVITY. Plant Physiol. 1980 Feb;65(2):305–308. doi: 10.1104/pp.65.2.305. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. McClure B. A., Hagen G., Brown C. S., Gee M. A., Guilfoyle T. J. Transcription, organization, and sequence of an auxin-regulated gene cluster in soybean. Plant Cell. 1989 Feb;1(2):229–239. doi: 10.1105/tpc.1.2.229. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. McQueen-Mason S., Durachko D. M., Cosgrove D. J. Two endogenous proteins that induce cell wall extension in plants. Plant Cell. 1992 Nov;4:1425–1433. doi: 10.1105/tpc.4.11.1425. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Medford J. I., Elmer J. S., Klee H. J. Molecular cloning and characterization of genes expressed in shoot apical meristems. Plant Cell. 1991 Apr;3(4):359–370. doi: 10.1105/tpc.3.4.359. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Nairn C. J., Winesett L., Ferl R. J. Nucleotide sequence of an actin gene from Arabidopsis thaliana. Gene. 1988 May 30;65(2):247–257. doi: 10.1016/0378-1119(88)90461-1. [DOI] [PubMed] [Google Scholar]
  14. 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]
  15. Wang T. W., Cosgrove D. J., Arteca R. N. Brassinosteroid Stimulation of Hypocotyl Elongation and Wall Relaxation in Pakchoi (Brassica chinensis cv Lei-Choi). Plant Physiol. 1993 Mar;101(3):965–968. doi: 10.1104/pp.101.3.965. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Zurek D. M., Clouse S. D. Molecular cloning and characterization of a brassinosteroid-regulated gene from elongating soybean (Glycine max L.) epicotyls. Plant Physiol. 1994 Jan;104(1):161–170. doi: 10.1104/pp.104.1.161. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. de Silva J., Jarman C. D., Arrowsmith D. A., Stronach M. S., Chengappa S., Sidebottom C., Reid J. S. Molecular characterization of a xyloglucan-specific endo-(1-->4)-beta-D-glucanase (xyloglucan endo-transglycosylase) from nasturtium seeds. Plant J. 1993 May;3(5):701–711. [PubMed] [Google Scholar]

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