Journal Article

Complete tylosis formation in a latest Permian conifer stem

Zhuo Feng, Jun Wang, Ronny Rößler, Hans Kerp and Hai-Bo Wei

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 111, issue 6, pages 1075-1081
Published in print June 2013 | ISSN: 0305-7364
Published online March 2013 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mct060
Complete tylosis formation in a latest Permian conifer stem

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Our knowledge of tylosis formation is mainly based on observations of extant plants; however, its developmental and functional significance are less well understood in fossil plants. This study, for the first time, describes a complete tylosis formation in a fossil woody conifer and discusses its ecophysiological implications.

Methods

The permineralized stem of Shenoxylon mirabile was collected from the upper Permian (Changhsingian) Sunjiagou Formation of Shitanjing coalfield, northern China. Samples from different portions of the stem were prepared by using the standard thin-sectioning technique and studied in transmitted light.

Key Results

The outgrowth of ray parenchyma cells protruded into adjacent tracheids through pits initially forming small pyriform or balloon-shaped structures, which became globular or slightly elongated when they reached their maximum size. The tracheid luminae were gradually occluded by densely spaced tyloses. The host tracheids are arranged in distinct concentric zones representing different growth phases of tylosis formation within a single growth ring.

Conclusions

The extensive development of tyloses from the innermost heartwood (metaxylem) tracheids to the outermost sapwood tracheids suggests that the plant was highly vulnerable and reacted strongly to environmental stress. Based on the evidence available, the tyloses were probably not produced in response to wound reaction or pathogenic infection, since evidence of wood traumatic events or fungal invasion are not recognizable. Rather, they may represent an ecophysiological response to the constant environmental stimuli.

Keywords: Shenoxylon mirabile; tylose; fossil plant; conifer wood; ecophysiological response; late Permian; China

Journal Article.  4075 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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