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First published online July 7, 2006; 10.1104/pp.106.081109 Plant Physiology 142:45-53 (2006) © 2006 American Society of Plant Biologists Disruption and Overexpression of Arabidopsis Phytosulfokine Receptor Gene Affects Cellular Longevity and Potential for Growth1Graduate School of Bio-Agricultural Sciences, Nagoya University, Chikusa, Nagoya 4648601, Japan
Phytosulfokine (PSK), a 5-amino acid sulfated peptide that has been identified in conditioned medium of plant cell cultures, promotes cellular growth in vitro via binding to the membrane-localized PSK receptor. Here, we report that loss-of-function and gain-of-function mutations of the Arabidopsis (Arabidopsis thaliana) PSK receptor gene (AtPSKR1) alter cellular longevity and potential for growth without interfering with basic morphogenesis of plants. Although mutant pskr1-1 plants exhibit morphologically normal growth until 3 weeks after germination, individual pskr1-1 cells gradually lose their potential to form calluses as tissues mature. Shortly after a pskr1-1 callus forms, it loses potential for growth, resulting in formation of a smaller callus than the wild type. Leaves of pskr1-1 plants exhibit premature senescence after bolting. Leaves of AtPSKR1ox plants exhibit greater longevity and significantly greater potential for callus formation than leaves of wild-type plants, irrespective of their age. Calluses derived from AtPSKR1ox plants maintain their potential for growth longer than wild-type calluses. Combined with our finding that PSK precursor genes are more strongly expressed in mature plant parts than in immature plant parts, the available evidence indicates that PSK signaling affects cellular longevity and potential for growth and thereby exerts a pleiotropic effect on cultured tissue in response to environmental hormonal conditions.
1 This work was supported by the 21st Century Center of Excellence Program (grant no. 14COEA02), by a Grant-in-Aid for Scientific Research for Priority Areas (grant no. 14036214), and by a Grant-in-Aid for Young Scientists (A) (grant no. 18687003). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Yoshikatsu Matsubayashi (matsu{at}agr.nagoya-u.ac.jp). www.plantphysiol.org/cgi/doi/10.1104/pp.106.081109 * Corresponding author; e-mail matsu{at}agr.nagoya-u.ac.jp; fax 81527894118. Received March 29, 2006; accepted July 4, 2006; published July 7, 2006. Related articles in Plant Physiol.:
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