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Different effects of two brassinosteroids on growth, auxin and cytokinin content in tobacco callus tissue

Different effects of two brassinosteroids on growth, auxin and cytokinin content in tobacco... Two synthetic brassinosteroids, 24-epibrassinolide (24-epiBR) and 2α,3α, 17β-trihydroxy-5α-androstan-6-one (THA-BR), exhibit different effects on growth of tobacco callus tissue. When added to a culture medium containing growth-limiting amounts of auxin, 24-epiBR reduced and THA-BR increased the fresh weight yield of tissue up to 53% and 207%, respectively, after 6 weeks of cultivation. The stimulatory and inhibitory effects of the two brassinosteroids on tissue growth occurred over a broad range of concentrations without a pronounced maximum corresponding to the ‘yes or no’ type of response. Different effects of 24-epiBR and THA-BR on tissue growth were inversely proportional to the content of endogenous cytokinins. Maximum contents of predominant cytokinins N6-(△2-isopentenyl)adenine (iP) and trans-zeatin (Z) in tissues supplied with 24-epiBR in growth-inhibiting concentrations were up to 3.7 fold and 3.4 fold higher, respectively, as compared to tissues grown on media containing growth-stimulating concentrations of THA-BR. Stimulation of tissue growth by THA-BR correlated with content of endogenous IAA and an inverse correlation was found between the content of endogenous IAA and cytokinins in tissues supplied with 24-epiBR. THA-BR exhibited weak cytokinin-like activity in a bioassay based on stimulation of growth of lateral buds of pea while 24-epiBR was inactive. Results indicate that the qualitatively different effects of the two brassinosteroids on growth of tobacco tissue may reflect their different influence on content of endogenous cytokinin. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Growth Regulation Springer Journals

Different effects of two brassinosteroids on growth, auxin and cytokinin content in tobacco callus tissue

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References (31)

Publisher
Springer Journals
Copyright
Copyright
Subject
Life Sciences; Plant Sciences; Plant Anatomy/Development; Plant Physiology; Agriculture
ISSN
0167-6903
eISSN
1573-5087
DOI
10.1007/BF00024171
Publisher site
See Article on Publisher Site

Abstract

Two synthetic brassinosteroids, 24-epibrassinolide (24-epiBR) and 2α,3α, 17β-trihydroxy-5α-androstan-6-one (THA-BR), exhibit different effects on growth of tobacco callus tissue. When added to a culture medium containing growth-limiting amounts of auxin, 24-epiBR reduced and THA-BR increased the fresh weight yield of tissue up to 53% and 207%, respectively, after 6 weeks of cultivation. The stimulatory and inhibitory effects of the two brassinosteroids on tissue growth occurred over a broad range of concentrations without a pronounced maximum corresponding to the ‘yes or no’ type of response. Different effects of 24-epiBR and THA-BR on tissue growth were inversely proportional to the content of endogenous cytokinins. Maximum contents of predominant cytokinins N6-(△2-isopentenyl)adenine (iP) and trans-zeatin (Z) in tissues supplied with 24-epiBR in growth-inhibiting concentrations were up to 3.7 fold and 3.4 fold higher, respectively, as compared to tissues grown on media containing growth-stimulating concentrations of THA-BR. Stimulation of tissue growth by THA-BR correlated with content of endogenous IAA and an inverse correlation was found between the content of endogenous IAA and cytokinins in tissues supplied with 24-epiBR. THA-BR exhibited weak cytokinin-like activity in a bioassay based on stimulation of growth of lateral buds of pea while 24-epiBR was inactive. Results indicate that the qualitatively different effects of the two brassinosteroids on growth of tobacco tissue may reflect their different influence on content of endogenous cytokinin.

Journal

Plant Growth Regulation – Springer Journals

Published: Apr 16, 2004

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