Abstract
Brassinosteroids are plant growth-promoting compounds that exhibit structural similarities to animal steroid hormones. Recent studies have indicated that brassinosteroids are essential for proper plant development. In addition to a role in development, several lines of evidence suggest that brassinosteroids exert anti-stress effects on plants. However, the mechanism by which they modulate plant stress responses is not understood. We show here that Brassica napus and tomato seedlings grown in the presence of 24-epibrassinolide (EBR) are significantly more tolerant to a lethal heat treatment than are control seedlings grown in the absence of the compound. Since a preconditioning treatment of seedlings was not required to observe this effect, we conclude that EBR treatment increases the basic thermotolerance of seedlings. An analysis of heat shock proteins (HSPs) in B. napus seedlings by western blot analysis indicated that the HSPs did not preferentially accumulate in EBR-treated seedlings at the control temperature. However, after heat stress, HSP accumulation was higher in EBR-treated than in untreated seedlings. The results of the present study provide the first direct evidence for EBR-induced expression of HSPs. The higher accumulation of HSPs in EBR-treated seedlings raises the possibility that HSPs contribute, at least in part, to thermotolerance in EBR-treated seedlings. A search for factors other than HSPs, which may directly or indirectly contribute to brassinosteroid-mediated increase in thermotolerance, is underway.
Similar content being viewed by others
References
Apuya, N.R. and Zimmerman, J.L. 1992. Heat shock gene expression is controlled primarily at the translational level in carrot cells and somatic embryos. Plant Cell 4: 657–665.
Chomczynski, P. and Sacchi, N. 1987. Single step method of RNA isolation by acid guanidium extraction. Anal. Biochem. 162: 156–159 (1987).
Chory, J., Nagpal, P. and Peto, C.A. 1991. Phenotypic and genetic analysis of det2, a new mutant that affects light-regulated seedling development in Arabidopsis. Plant Cell 3: 445–459.
Cloney, L.P., Bekkaoui, D.R., Feist, G.L., Lane, W.S. and Hemmingsen, S.M. 1994. Brassica napus plastid and mitochondrial chaperonin-60 proteins contain multiple distinct polypeptides. Plant Physiol. 105: 233–241.
Clouse, S.D. 1996. Molecular genetic studies confirm the role of brassinosteroids in plant growth and development. Plant J. 10: 1–8.
Clouse, S.D. and Sasse, J.M. 1998. Brassinosteroids: essential regulators of plant growth and development. Annu. Rev. Plant Physiol. Plant Mol. Biol. 49: 427–451.
Clouse, S.D., Zurek, D.M., McMorris, T.C. and Baker, M.E. 1992. Effects of brassinolide on gene expression in elongating soybean epicotyls. Plant Physiol. 100: 1377–1383.
Clouse, S.D., Hall, A.F., Langford, M., McMorris, T.C. and Baker, M.E. 1993. Physiological and molecular effects of brassinosteroids on Arabidopsis thaliana. J. Plant Growth Regul. 12: 61–66.
Cutler, G.C. 1991. Brassinosteroids through the looking glass: an appraisal. In: H.G. Cutler, T. Yokota and G. Adam (Eds.), Brassinosteroids: Chemistry, Bioactivity and Applications, American Chemical Society Symposium Series 474, American Chemical Society, Washington, DC, pp. 334–345.
Feder, J.H., Rossi, J.M., Solomon, J., Solomon, N. and Lindquist, S. 1992. The consequences of expressing hsp70 in Drosophila cells at normal temperatures. Genes Dev. 6: 1402–1413 (1992).
Guan, M. and Roddick, J.G. 1988. Epibrassinolide-inhibition of development of excised, adventitious and intact roots of tomato (Lycopersicon esculentum): comparison with the effects of steroidal estrogens. Physiol. Plant. 74: 720–726.
He, R.Y., Wang, G.J. and Wang, X.S. 1991. Effects of brassinolide on growth and chilling resistance of maize seedlings. In: H.G. Cutler, T. Yokota and G. Adam (Eds.), Brassinosteroids: Chemistry, Bioactivity and Applications, American Chemical Society Symposium Series 474, American Chemical Society, Washington, DC, pp. 220–230.
Kamuro, Y. and Takatsuto, S. 1991. Capability for and problems of practical uses of brassinosteroids. In: H.G. Cutler, T. Yokota and G. Adam (Eds.), Brassinosteroids: Chemistry, Bioactivity and Applications, American Chemical Society Symposium Series 474, American Chemical Society, Washington, DC, pp. 292–297.
Katsumi, M. 1991. Physiological modes of brassinolide action in cucumber hypocotyl growth. In: H.G. Cutler, T. Yokota and G. Adam (Eds.), Brassinosteroids: Chemistry, Bioactivity and Applications, American Chemical Society Symposium Series 474, American Chemical Society, Washington, DC, pp. 246–254.
Kauschmann, A., Jessop, A., Koncz, C., Szekeres, M., Willmitzer, L. and Altmann, T. 1996. Genetic evidence for an essential role of brassinosteroids in plant development. Plant J 9: 701–713.
Ko, K., Bornemisza, O., Kourtz, Z.W., Plaxton, W.C. and Cashmore, A.R. 1992. Isolation and characterization of a cDNA clone encoding a cognate 70 kDa heat shock protein of the chloroplast envelope. J. Biol. Chem. 267: 2986–2993.
Krishna, P., Sacco, M., Cherutti, J.F. and Hill, S. 1995. Coldinduced accumulation of hsp90 transcripts in Brassica napus. Plant Physiol. 107: 915–923.
Krishna, P., Reddy, R.K., Sacco, M., Frappier, J.R. and Felsheim, R.F. 1997. Analysis of the native forms of the 90 kDa heat shock protein (hsp90) in plant cytosolic extracts. Plant Mol. Biol. 33: 457–466.
Kulaeva, O.N., Burkhanova, E.A., Fedina, A.B., Khokhlova, V.A., Bokebayeva, G.A., Vorbrodt, H.M. and Adam, G. 1991. Effect of brassinosteroids on protein synthesis and plant-cell ultrastructure under stress conditions. In: H.G. Cutler, T. Yokota and G. Adam (Eds.), Brassinosteroids: Chemistry, Bioactivity and Applications, American Chemical Society Symposium Series 474, American Chemical Society, Washington, DC, pp. 141–155.
Laemmli, U.K. 1970. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227: 680–685.
Lee, Y.J., Nagao, R.T. and Key, J.L. 1994. Soybean 101-kD heat shock protein complements a yeast HSP104 deletion mutant in acquiring thermotolerance. Plant Cell 6: 1889–1897.
Lee, G.J., Pokala, N. and Vierling, E. 1995. Structure and in vitro molecular chaperone activity of cytosolic small heat shock proteins from pea. J. Biol. Chem. 270: 10432–10438.
Lee, G.J., Roseman, A.M., Saibil, H.R. and Vierling, E. 1997. A small heat shock protein stably binds heat-denatured model substrates and can maintain a substrate in a folding-competent state. EMBO J. 16: 659–671.
Li, J., Nagpal, P., Vitart, V., McMorris, T.C. and Chory, J. 1996. A role for brassinosteroids in light-dependent development of Arabidopsis. Science 272: 398–401.
Lindquist, S. 1986. The heat-shock response. Annu. Rev. Biochem. 55: 1151–1191.
Lindquist, S. and Craig, E.A. 1988. The heat-shock proteins. Annu. Rev. Genet. 22: 631–677.
Lindquist, S. and Kim, G. 1996. Heat-shock protein 104 expression is sufficient for thermotolerance in yeast. Proc. Natl. Acad. Sci. USA 93: 5301–5306.
Mandava, N.B. 1998. Plant growth-promoting brassinosteroids. Annu. Rev. Plant Physiol. Plant Mol. Biol. 39: 23–52.
Man-Ho, O., Romanow, W.G., Smith, R.C., Zamski, E., Sasse, J. and Clouse, S.D. 1998. Soybean BRU1 encodes a functional xyloglucan endotransglycosylase that is highly expressed in inner epicotyl tissues during brassinosteroid-promoted elongation. Plant Cell Physiol. 39: 124–130.
Murashige, T. and Skoog, F. 1962. A revised medium for rapid growth and bioassay with tobacco tissue cultures. Physiol. Plant. 15: 473–497.
Nomura, T., Nakayama, M., Reid, J.B., Takeuchi, Y. and Yokota, T. 1997. Blockage of brassinosteroid biosynthesis and sensitivity causes dwarfism in garden pea. Plant Physiol. 113: 31–37.
Parsell, D.A. and Lindquist, S. 1993. The functions of heat-shock proteins in stress tolerance: degradation and reactivation of damaged proteins. Annu. Rev. Genet. 27: 437–496.
Roddick, J.G., Rijnenberg, A.L. and Ikekawa, N. 1993. Developmental effects of 24-epibrassinolide in excised roots of tomato grown in vitro. Physiol. Plant. 87: 453–458.
Sanchez, Y. and Lindquist, S. 1990. Hsp104 required for induced thermotolerance. Science 248: 1112–1115.
Schirmer, E.C., Lindquist, S. and Vierling, E. 1994. An Arabidopsis heat shock protein complements a thermotolerance defect in yeast. Plant Cell 6: 1899–1909.
Solomon, J.M., Rossi, J.M., Golic, K., McGarry, T. and Lindquist, S. 1991. Changes in hsp70 alter the acquisition of thermotolerance and the regulation of the heat shock response in Drosophila. New Biol. 3: 1106–1120.
Szekeres, M., Nemeth, K., Koncz-Kalman, Z., Mathur, J., Kauschmann, A., Altmann, T., Redei, G.P., Nagy, F., Schell, J. and Koncz, C. 1996. Brassinosteroids rescue the deficiency of CYP90, a cytochrome P450, controlling cell elongation and de-etiolation in Arabidopsis. Cell 85: 171–182.
Vierling, E. 1991. The roles of heat shock proteins in plants. Annu. Rev. Plant Physiol. Plant Mol. Biol. 42: 579–620.
Wilen, R.W., Sacco, M., Gusta, L.V. and Krishna, P. 1995. Effects of 24-epibrassinolide on freezing and thermotolerance of bromegrass (Bromus inermis) cell cultures. Physiol Plant. 95: 195–202.
Wilson, M.I., Ghosh, S., Gerhardt, K.E., Holland, N., Babu, T.S., Edelman, M., Dumbroff, E.B. and Greenberg, B.M. 1995. In vivo photomodification of ribulose-1,5 bisphosphate carboxylase/ oxygenase holoenzyme by ultraviolet-B radiation: formation of a 66 kD variant of the large subunit. Plant Physiol. 109: 221–229.
Zurek, D.M. and Clouse, S.D. 1994. Molecular cloning and characterization of a brassinosteroid-regulated gene from elongating soybean epicotyls. Plant Physiol. 104: 161–170.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Dhaubhadel, S., Chaudhary, S., Dobinson, K.F. et al. Treatment with 24-epibrassinolide, a brassinosteroid, increases the basic thermotolerance of Brassica napus and tomato seedlings. Plant Mol Biol 40, 333–342 (1999). https://doi.org/10.1023/A:1006283015582
Issue Date:
DOI: https://doi.org/10.1023/A:1006283015582