Involvement of gibberellin in tracheary element differentiation and lignification in Zinnia elegans xylogenic culture |
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Authors: | Naohito Tokunaga Nami Uchimura Yasushi Sato |
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Institution: | (1) Department of Biology, Faculty of Science, Ehime University, Matsuyama |
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Abstract: | Summary. Gibberellin (GA) is considered an important growth regulator involved in many aspects of plant development. However, little
is known about the relationship between GA and lignification. In this study, we analyzed the role of GA in tracheary element
(TE) differentiation and lignification using a Zinnia elegans xylogenic culture. When gibberellic acid-3 (GA3) was exogenously supplied, a slight increase in the frequency of TE differentiation and a remarkable increase in lignin content
were observed. Computer image analysis of individual TEs showed that the lignification level of each TE was significantly
increased in the culture treated with GA3 compared with those of the control. In contrast, suppression of TE differentiation and lignification was observed when GA
biosynthesis was inhibited by ancymidol, paclobutrazol, or uniconazole. This suppression was restored by the addition of GA3. These results suggest that GA plays an important role in TE differentiation, and even more so in lignification. When conditioned
medium obtained after 120 h of control culture was analyzed by high-performance liquid chromatography, many lignin precursors
were detected. However, these lignin precursors were greatly reduced in the GA-treated culture. This result suggests that
GA promotes lignification by activating the polymerization of lignin precursors.
Correspondence and reprints: Department of Biology, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan. |
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Keywords: | : Gibberellin Lignin Tracheary element Zinnia elegans |
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