Role of xyloglucan in gravitropic bending of azuki bean epicotyl

Authors: Ikushima, Toshimitsu; Soga, Kouichi¹; Hoson, Takayuki¹; Shimmen, Teruo²

Source: Physiologia Plantarum, Volume 132, Number 4, April 2008 , pp. 552-565(14)

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Abstract:

The mechanism of the gravitropic bending was studied in azuki bean epicotyls. The cell wall extensibility of the lower side became higher than that of the upper side in the epicotyl bending upward. The contents of matrix polysaccharides of the cell wall (pectin and xyloglucan in hemicellulose-II) in the lower side became smaller than those in the upper side. The molecular mass of xyloglucans in the lower side decreased. After an epicotyl was fixed to a metal rod to prevent the bending, gravistimulation was applied. Fundamentally the same results were obtained with respect to rheological and chemical characteristics of the cell wall as those of epicotyls showing gravitropic bending. The present results suggested that the initial gravitropic bending was caused by the increase in extensibility of the lower side and the decrease in extensibility of the upper side via the change of the cell wall matrix, especially xyloglucans.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1399-3054.2007.01047.x

Affiliations: 1: Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan 2: Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1, Kouto, Kamigori-cho, Ako-gun, Hyogo, 678-1297, Japan

Publication date: 2008-04-01