Article
Regulation of Sulfur-Responsive Gene Expression by Exogenously Applied Cytokinins in Arabidopsis thaliana

Authors: Ohkama N.¹; Takei K.²; Sakakibara H.²; Hayashi H.¹; Yoneyama T.¹; Fujiwara T.¹

Source: Plant and Cell Physiology, Volume 43, Number 12, 15 December 2002 , pp. 1493-1501(9)

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Abstract:

Effects of plant hormones on a sulfur-deficiency responsive element ( bgr SR) from the promoter region of the bgr subunit gene of bgr -conglycinin, a major seed storage protein of soybean, were investigated using transgenic Arabidopsis thaliana. Among the hormones tested, the cytokinins, trans-zeatin (Z) and trans-zeatin riboside, upregulated gene expression directed by the bgr SR element both in the presence and in the absence of sulfate in the medium. Z also increased transcript accumulation of two endogenous sulfur-responsive genes, the adenosine 5 prime -phosphosulfate reductase (APR1) and the Sultr2;2, a sulfate transporter. Concentrations of cytokinins were unaltered during early stages of sulfur starvation when expression of these genes was upregulated. Z did not alter concentrations of O-acetyl-L-serine, a positive regulator of gene expression in sulfur starvation response. Concentrations of sucrose, which is known to upregulate expression of APR1, were increased in rosette leaves by Z. Sucrose application to the medium also increased expression directed by the bgr SR element, although sucrose concentrations in tissues were not significantly altered by sulfur availability. These results suggest that exogenously applied cytokinins positively regulate expression of these sulfur responsive genes through a pathway independent of that from sulfur starvation, possibly through increasing sucrose concentrations in tissues.

Document Type: Original article

Affiliations: 1: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657 Japan 2: RIKEN (The Institute of Physical and Chemical Research) Plant Science Center, Suehiro, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan

Publication date: 2002-12-15

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Plant and Cell Physiology is an international journal devoted to the publication of original papers pertaining to physiology, biochemistry, biophysics, chemistry, genetics, molecular biology, gene engineering and cell engineering of plants and microorganisms.