Stem gravitropism and tension wood formation in Acacia mangium seedlings inclined at various angles
Stem gravitropism and tension wood formation in Acacia mangium seedlings inclined at various angles
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DOI：
10.1093/aob/mcy056
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发表时间：
2018-06
期刊：
影响因子：
4.2
通讯作者：
W. D. Nugroho;Satoshi Nakaba;Y. Yamagishi;S. Begum;Md Hasnat Rahman;Kayo Kudo;S. N. Marsoem;R. Funada
中科院分区：
文献类型：
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作者：
W. D. Nugroho;Satoshi Nakaba;Y. Yamagishi;S. Begum;Md Hasnat Rahman;Kayo Kudo;S. N. Marsoem;R. Funada
为了响应重力刺激，被子植物树木通常在倾斜的茎的上侧形成张力木材，以便在垂直方向上重新定向茎。目前还不清楚倾斜角度是否从垂直影响张力木材的形成。研究了不同倾斜角度下马占相思幼苗的负向重力性、张力材形成和生长偏心率。方法采用A. 3个月后，将马占木人工倾斜成30°、45°、60°和90°，并与非倾斜对照进行收获。分析了倾斜角度对树干回复角、抗拉材解剖特征和径向生长的影响。关键结果较小的倾斜角度与较早的股骨柄恢复相关，而股骨柄在较长的延迟后恢复到垂直方向。然而，在负向垂直方向的速度方面，茎受到更大的倾斜更迅速地向垂直方向移动。不同倾斜角度的苗木生长偏心率差异不显著。倾斜30°的苗木形成了最西的抗拉材区，而倾斜45°、60°和90°的苗木之间差异不显著。90°倾斜幼苗形成的凝胶层比30°、45°和60°倾斜幼苗形成的凝胶层厚。结论茎的倾斜角度影响负向重力性、张力木区的宽度和胶质层的厚度。大量的凝胶纤维和较厚的凝胶层可能产生较高的张应力，从而使A.马占木幼苗
Background and Aims In response to a gravitational stimulus, angiosperm trees generally form tension wood on the upper sides of leaning stems in order to reorientate the stems in the vertical direction. It is unclear whether the angle of inclination from the vertical affects tension wood formation. This study was designed to investigate negative gravitropism, tension wood formation and growth eccentricity in Acacia mangium seedlings inclined at different angles. Methods Uniform seedlings of A. mangium were artificially inclined at 30°, 45°, 60° and 90° from the vertical and harvested, with non-inclined controls, 3 months later. We analysed the effects of the angle of inclination on the stem recovery angle, the anatomical features of tension wood and radial growth. Key Results Smaller inclination angles were associated with earlier stem recovery while stems subjected to greater inclination returned to the vertical direction after a longer delay. However, in terms of the speed of negative gravitopism towards the vertical, stems subjected to greater inclination moved more rapidly toward the vertical. There was no significant difference in terms of growth eccentricity among seedlings inclined at different angles. The 30°-inclined seedlings formed the narrowest region of tension wood but there were no significant differences among seedlings inclined at 45°, 60° and 90°. The 90°-inclined seedlings formed thicker gelatinous layers than those in 30°-, 45°- and 60°-inclined seedlings. Conclusion Our results suggest that the angle of inclination of the stem influences negative gravitropism, the width of the tension wood region and the thickness of gelatinous layers. Larger amounts of gelatinous fibres and thicker gelatinous layers might generate the higher tensile stress required for the higher speed of stem-recovery movement in A. mangium seedlings.