Skip to main content
PMC home page
The Plant Cell logoLink to The Plant Cell
. 1998 Dec;10(12):2115–2126. doi: 10.1105/tpc.10.12.2115

Phytochrome regulation and differential expression of gibberellin 3beta-hydroxylase genes in germinating Arabidopsis seeds.

S Yamaguchi 1, M W Smith 1, R G Brown 1, Y Kamiya 1, T Sun 1
PMCID: PMC143973  PMID: 9836749

Abstract

Despite extensive studies on the roles of phytochrome in photostimulated seed germination, the mechanisms downstream of the photoreceptor that promote germination are largely unknown. Previous studies have indicated that light-induced germination of Arabidopsis seeds is mediated by the hormone gibberellin (GA). Using RNA gel blot analyses, we studied the regulation of two Arabidopsis genes, GA4 and GA4H (for GA4 homolog), both of which encode GA 3beta-hydroxylases that catalyze the final biosynthetic step to produce bioactive GAs. The newly isolated GA4H gene was expressed predominantly during seed germination. We show that expression of both GA4 and GA4H genes in imbibed seeds was induced within 1 hr after a brief red (R) light treatment. In the phytochrome B-deficient phyB-1 mutant, GA4H expression was not induced by R light, but GA4 expression still was, indicating that R light-induced GA4 and GA4H expression is mediated by different phytochromes. In contrast to the GA4 gene, the GA4H gene was not regulated by the feedback inhibition mechanism in germinating seeds. Our data demonstrate that expression of GA 3beta-hydroxylase genes is elevated by R light, which may result in an increase in biosynthesis of active GAs to promote seed germination. Furthermore, our results suggest that each GA 3beta-hydroxylase gene plays a unique physiological role during light-induced seed germination.

Full Text

The Full Text of this article is available as a PDF (583.4 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Altschul S. F., Gish W., Miller W., Myers E. W., Lipman D. J. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. doi: 10.1016/S0022-2836(05)80360-2. [DOI] [PubMed] [Google Scholar]
  2. Bewley J. D. Seed Germination and Dormancy. Plant Cell. 1997 Jul;9(7):1055–1066. doi: 10.1105/tpc.9.7.1055. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Chiang H. H., Hwang I., Goodman H. M. Isolation of the Arabidopsis GA4 locus. Plant Cell. 1995 Feb;7(2):195–201. doi: 10.1105/tpc.7.2.195. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Chory J. Light modulation of vegetative development. Plant Cell. 1997 Jul;9(7):1225–1234. doi: 10.1105/tpc.9.7.1225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Clack T., Mathews S., Sharrock R. A. The phytochrome apoprotein family in Arabidopsis is encoded by five genes: the sequences and expression of PHYD and PHYE. Plant Mol Biol. 1994 Jun;25(3):413–427. doi: 10.1007/BF00043870. [DOI] [PubMed] [Google Scholar]
  6. Fujioka S., Yamane H., Spray C. R., Gaskin P., Macmillan J., Phinney B. O., Takahashi N. Qualitative and Quantitative Analyses of Gibberellins in Vegetative Shoots of Normal, dwarf-1, dwarf-2, dwarf-3, and dwarf-5 Seedlings of Zea mays L. Plant Physiol. 1988 Dec;88(4):1367–1372. doi: 10.1104/pp.88.4.1367. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Hedden Peter, Kamiya Yuji. GIBBERELLIN BIOSYNTHESIS: Enzymes, Genes and Their Regulation. Annu Rev Plant Physiol Plant Mol Biol. 1997 Jun;48(NaN):431–460. doi: 10.1146/annurev.arplant.48.1.431. [DOI] [PubMed] [Google Scholar]
  8. Hilhorst H. W., Karssen C. M. Dual Effect of Light on the Gibberellin- and Nitrate-Stimulated Seed Germination of Sisymbrium officinale and Arabidopsis thaliana. Plant Physiol. 1988 Feb;86(2):591–597. doi: 10.1104/pp.86.2.591. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Lange T., Robatzek S., Frisse A. Cloning and expression of a gibberellin 2 beta,3 beta-hydroxylase cDNA from pumpkin endosperm. Plant Cell. 1997 Aug;9(8):1459–1467. doi: 10.1105/tpc.9.8.1459. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Lester D. R., Ross J. J., Davies P. J., Reid J. B. Mendel's stem length gene (Le) encodes a gibberellin 3 beta-hydroxylase. Plant Cell. 1997 Aug;9(8):1435–1443. doi: 10.1105/tpc.9.8.1435. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Martin D. N., Proebsting W. M., Hedden P. Mendel's dwarfing gene: cDNAs from the Le alleles and function of the expressed proteins. Proc Natl Acad Sci U S A. 1997 Aug 5;94(16):8907–8911. doi: 10.1073/pnas.94.16.8907. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Nagatani A., Reed J. W., Chory J. Isolation and Initial Characterization of Arabidopsis Mutants That Are Deficient in Phytochrome A. Plant Physiol. 1993 May;102(1):269–277. doi: 10.1104/pp.102.1.269. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Nambara E., Akazawa T., McCourt P. Effects of the gibberellin biosynthetic inhibitor uniconazol on mutants of Arabidopsis. Plant Physiol. 1991 Oct;97(2):736–738. doi: 10.1104/pp.97.2.736. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Phillips A. L., Ward D. A., Uknes S., Appleford N. E., Lange T., Huttly A. K., Gaskin P., Graebe J. E., Hedden P. Isolation and expression of three gibberellin 20-oxidase cDNA clones from Arabidopsis. Plant Physiol. 1995 Jul;108(3):1049–1057. doi: 10.1104/pp.108.3.1049. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Poppe C., Schäfer E. Seed germination of Arabidopsis thaliana phyA/phyB double mutants is under phytochrome control. Plant Physiol. 1997 Aug;114(4):1487–1492. doi: 10.1104/pp.114.4.1487. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Reed J. W., Nagatani A., Elich T. D., Fagan M., Chory J. Phytochrome A and Phytochrome B Have Overlapping but Distinct Functions in Arabidopsis Development. Plant Physiol. 1994 Apr;104(4):1139–1149. doi: 10.1104/pp.104.4.1139. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Reed J. W., Nagpal P., Poole D. S., Furuya M., Chory J. Mutations in the gene for the red/far-red light receptor phytochrome B alter cell elongation and physiological responses throughout Arabidopsis development. Plant Cell. 1993 Feb;5(2):147–157. doi: 10.1105/tpc.5.2.147. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Sharrock R. A., Quail P. H. Novel phytochrome sequences in Arabidopsis thaliana: structure, evolution, and differential expression of a plant regulatory photoreceptor family. Genes Dev. 1989 Nov;3(11):1745–1757. doi: 10.1101/gad.3.11.1745. [DOI] [PubMed] [Google Scholar]
  20. Shinomura T., Nagatani A., Chory J., Furuya M. The Induction of Seed Germination in Arabidopsis thaliana Is Regulated Principally by Phytochrome B and Secondarily by Phytochrome A. Plant Physiol. 1994 Feb;104(2):363–371. doi: 10.1104/pp.104.2.363. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Shinomura T., Nagatani A., Hanzawa H., Kubota M., Watanabe M., Furuya M. Action spectra for phytochrome A- and B-specific photoinduction of seed germination in Arabidopsis thaliana. Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):8129–8133. doi: 10.1073/pnas.93.15.8129. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Silverstone A. L., Ciampaglio C. N., Sun T. The Arabidopsis RGA gene encodes a transcriptional regulator repressing the gibberellin signal transduction pathway. Plant Cell. 1998 Feb;10(2):155–169. doi: 10.1105/tpc.10.2.155. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Silverstone A. L., Mak P. Y., Martínez E. C., Sun T. P. The new RGA locus encodes a negative regulator of gibberellin response in Arabidopsis thaliana. Genetics. 1997 Jul;146(3):1087–1099. doi: 10.1093/genetics/146.3.1087. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Somers D. E., Sharrock R. A., Tepperman J. M., Quail P. H. The hy3 Long Hypocotyl Mutant of Arabidopsis Is Deficient in Phytochrome B. Plant Cell. 1991 Dec;3(12):1263–1274. doi: 10.1105/tpc.3.12.1263. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Sun T. P., Kamiya Y. The Arabidopsis GA1 locus encodes the cyclase ent-kaurene synthetase A of gibberellin biosynthesis. Plant Cell. 1994 Oct;6(10):1509–1518. doi: 10.1105/tpc.6.10.1509. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Talon M., Koornneef M., Zeevaart J. A. Endogenous gibberellins in Arabidopsis thaliana and possible steps blocked in the biosynthetic pathways of the semidwarf ga4 and ga5 mutants. Proc Natl Acad Sci U S A. 1990 Oct;87(20):7983–7987. doi: 10.1073/pnas.87.20.7983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Toyomasu T., Kawaide H., Mitsuhashi W., Inoue Y., Kamiya Y. Phytochrome regulates gibberellin biosynthesis during germination of photoblastic lettuce seeds. Plant Physiol. 1998 Dec;118(4):1517–1523. doi: 10.1104/pp.118.4.1517. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Von Arnim Albrecht, Deng Xing-Wang. LIGHT CONTROL OF SEEDLING DEVELOPMENT. Annu Rev Plant Physiol Plant Mol Biol. 1996 Jun;47(NaN):215–243. doi: 10.1146/annurev.arplant.47.1.215. [DOI] [PubMed] [Google Scholar]
  29. Williams J., Phillips A. L., Gaskin P., Hedden P. Function and substrate specificity of the gibberellin 3beta-hydroxylase encoded by the Arabidopsis GA4 gene. Plant Physiol. 1998 Jun;117(2):559–563. doi: 10.1104/pp.117.2.559. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Xu Y. L., Li L., Wu K., Peeters A. J., Gage D. A., Zeevaart J. A. The GA5 locus of Arabidopsis thaliana encodes a multifunctional gibberellin 20-oxidase: molecular cloning and functional expression. Proc Natl Acad Sci U S A. 1995 Jul 3;92(14):6640–6644. doi: 10.1073/pnas.92.14.6640. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Yamaguchi S., Saito T., Abe H., Yamane H., Murofushi N., Kamiya Y. Molecular cloning and characterization of a cDNA encoding the gibberellin biosynthetic enzyme ent-kaurene synthase B from pumpkin (Cucurbita maxima L.). Plant J. 1996 Aug;10(2):203–213. doi: 10.1046/j.1365-313x.1996.10020203.x. [DOI] [PubMed] [Google Scholar]
  32. Yamaguchi S., Sun T. p., Kawaide H., Kamiya Y. The GA2 locus of Arabidopsis thaliana encodes ent-kaurene synthase of gibberellin biosynthesis. Plant Physiol. 1998 Apr;116(4):1271–1278. doi: 10.1104/pp.116.4.1271. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Yang Y. Y., Nagatani A., Zhao Y. J., Kang B. J., Kendrick R. E., Kamiya Y. Effects of gibberellins on seed germination of phytochrome-deficient mutants of Arabidopsis thaliana. Plant Cell Physiol. 1995 Oct;36(7):1205–1211. [PubMed] [Google Scholar]

Articles from The Plant Cell are provided here courtesy of Oxford University Press

RESOURCES