The Roles of Phytohormones and AtEXPA3 Gene in Gravitropic Response of Arabidopsis thaliana

애기장대 굴중성 반응에 있어서 식물호르몬과 AtEXPA3 유전자의 역할

  • Yun, Hye-Sup (Department of Life Science, Chung-Ang University) ;
  • Lee, Yew (Department of Biological Science and Technology, Yonsei University) ;
  • Kim, Seong-Ki (Department of Life Science, Chung-Ang University)
  • 윤혜섭 (중앙대학교 생명과학과) ;
  • 이유 (연세대학교 생명과학기술학부) ;
  • 김성기 (중앙대학교 생명과학과)
  • Received : 2011.02.07
  • Accepted : 2011.06.24
  • Published : 2011.07.30


We focused on relationship between phytohormones and AtEXPA3 gene in gravitropic response of A. thaliana. RT-PCR analysis shows that AtEXPA3 was highly expressed in actively developing tissues such as leaf, rosette, root and flower tissues. AtEXPA3 gene expression was enhanced by gravistimulation, BR and IAA. Furthermore, decreased gravitropism was observed when treatment of AVG, an ethylene biosynthetic inhibitor, suggesting that ethylene has a gravistimulating effect itself as well as BRs and IAA. Inhibition of gravitropism in AtEXPA3 RNAi mutant suggests that BR, auxin and ethylene are playing roles as regulators of AtEXPA3. In addition, altered gravitropism in BRs signaling mutant (decreased in bri1-301, bak1, and increased BRI-GFP) indicated that BRs signaling mediated the gravitropism. In conclusion, gravitropic responses of Arabidopsis root resulting from root growth were mediated by increased expression of AtEXPA3 gene, which is stimulated by phytohormones.


Supported by : 중앙대학교


  1. Catala, C., J. K. C. Rose, and A. B. Bennett. 2000. Auxin-regulated genes encoding cell wall-modifying proteins are expressed during early tomato fruit growth. Plant Physiol. 122, 527-534.
  2. Cho, H. T. and H. Kende. 1997. Expression of expansin genes correlated with growth in deepwater rice. Plant Cell 9, 1661-1671.
  3. Cho, H. T. and D. J. Cosgrove. 2000. Altered expression of expansin modulates leaf growth and pedical abscission in Arabidopsis thaliana. Proc. Natl. Acad. Sci. USA 97, 9783-9788.
  4. Cho, H. T. and H. Kende. 1997. Expansins in deepwater rice internodes. Plant Physiol. 113, 1137-1143.
  5. Civello, P. M., A. L. Powell, A. Sabehat, and A. B. Bennett. 1999. An Expansin gene expressed in ripening strawberry fruit. Plant Physiol. 121, 1273-1279.
  6. Clough, S. J. and A. F. Bent. 1998. Floral dip: a simplified method for agrobacterium-mediated transformation of Arabidopsis thaliana. Plant J. 16, 735-743.
  7. Cosgrove, D. J. 1989. Characterization of long-term expression of isolated cell walls from growing cucumber hypocotyls. Planta 177, 121-130.
  8. Cosgrove, D. J. 1993. Water uptake by growing cells; an assessment of the controlling roles of wall relaxation, solute uptake and hydraulic conductance. Int. J. Plant Sci. 154, 10-21.
  9. Cosgrove, D. J. 1997. Cellular mechanisms underlying growth asymmetry during stem gravitropism. Planta 203, 130-135.
  10. Cosgrove, D. J. 2000. Loosening of plant cell walls by expansins. Nature 407, 321-326.
  11. Cosgrove, D. J. 2000. New genes and new biological roles for expansins. Curr. Opin. Plant Biol. 3, 73-78.
  12. Downes, B. P., C. R. Steinbaker, and D. N. Crowell. 1998. Expression and processing of a hormonally regulated beta- expansin from Soybean. Plant Physiol. 126, 244-252.
  13. Fleming, A. J., S. McQueen-Mason, T. Mandel, and C. Kuhlemeier. 1997. Induction of leaf primordia by the cell wall protein expansin. Science 27, 1414-1418.
  14. Fry, S. C. 1995. Polysaccharide modifying enzymes in the plant cell wall. Annu. Rev. Plant Physiol. Plant Mol. Biol. 46, 497-520.
  15. Hruz, T., O. Laule, G. Szabo, F. Wessendorp, S. Bleuler, L. Oertle, P. Widmayer, W. Gruissem, and P. Zimmermann. 2008. Genevestigator V3: a reference expression database for the meta-analysis of transcriptomes. Adv. Bioinformatics 2008, Article ID 420747, 5.
  16. Huchison, K. W., P. B. Singer, C. Diaz-Sala, and M. S. Greenwood. 1999. Expansin are conserved in conifers and expression in response to exogenous auxin. Plant Physiol. 120, 827-832.
  17. Kim, S. K., S. C. Chang, E. J. Lee, W. S. Chung, Y. S. Kim, S. Hwang, and J. S Lee. 2000. Involvement of brassinosteroids in the gravitropic response of primary root of maize. Plant Physiol. 123, 997-1004.
  18. Kim, T. W. 2003. Mechanism of homeostatic regulation and action of plant steroidal hormones, brassinosteroids. Ph. D Thesis, Chung-Ang University, Seoul. Korea.
  19. Lee, Y., D. Choi, and H. Kende. 2001. Expansin: ever-expanding numbers and functions. Curr. Opin. Plant Biol. 4, 527-532.
  20. McQueen-Mason, S. J., D. M. Durachko, and D. J. Cosgrove. 1992. Two endogenous proteins that induce cell wall extension in plants. Plant Cell 4, 1425-1433.
  21. Meudt, W. T. 1987. Investigations on mechanism of brassinosteroid response. Plant Physiol. 83, 195-198.
  22. Nishitani, K. 1997. The role of endoxyloglucan transferase in the organization of plant cell walls. Int. Rev. Cytol. 173, 157-206.
  23. Nishitani, K. 1998. Construction and re-structuring of the cellulose-xyloglucan framework in the apoplast as mediated by the xyloglucan-related protein family-a hypothetical scheme. J. Plant Res. 111, 1-8.
  24. Park, W. J. 1998. Effect of epibrassinolide on hypocotyl growth of the tomato mutant diageotropica. Planta 207, 120-124.
  25. Rose, J. K. C., H. H. Lee, and A. B. Bennett. 1997. Expression of a divergent expansin gene is fruit-specific and ripening-regulated. Proc. Natl. Acad. Sci. USA 94, 5955-5960.
  26. Shcherban, T. Y., J. Shi, D. M. Durachko, M. J. Guiltinam, S. McQueen-Mason, M. Shieh, and D. J. Cosgrove. 1995. Molecular cloning and sequence analysis of expansins-a highly conserved, multigene family of proteins that mediate cell wall extension in plants. Proc. Natl. Acad. Sci. USA 92, 9245-9249.
  27. Varner, J. E. and L. S. Lin. 1989. Plant cell wall architecture. Cell 56, 231-239.
  28. Wieczorek, K., B. Golecki, L. Gerdes, P. Heinen, D. Szakasits, D. M. Durachko, D. J. Cosgrove, D. P. Kreil, P. S. Puzio, H. Bohlmann, and F. M. W. Grundler. 2006. Expansins are involved in the formation of nematode-induced syncytia in roots of Arabidopsis thaliana. Plant J. 48, 98-112.