www.elsevier.de/jplph Engineered sorbitol accumulation induces dwarfism in Japanese persimmon Michihito Deguchi a , Yoshiko Koshita b , Mei Gao c , Ryutaro Tao c , Takuya Tetsumura d , Shohei Yamaki e , Yoshinori Kanayama a, * a Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan b Department of Grape and Persimmon Research, National Institute of Fruit Tree Science, Hiroshima 729-2494, Japan c Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan d Faculty of Agriculture, Miyazaki University, Miyazaki 889-2192, Japan e Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan Received 18 February 2004; accepted 27 April 2004 Summary A cDNA encoding sorbitol-6-phosphate dehydrogenase (S6PDH), which is a key enzyme in sorbitol biosynthesis in Rosaceae, was introduced into the Japanese persimmon (Diospyros kaki) to increase the environmental stress tolerance. Resultant transfor- mants exhibited salt-tolerance with dwarfing phenotypes. Therefore, we studied two transgenic lines to understand the physiological mechanism of this dwarfism: lines PS1 and PS6 accumulated high and moderate levels of sorbitol, respectively. The average length of shoots was significantly shorter as compared with the wild-type in line PS1, while no such decrease was observed in line PS6. The myo-inositol and glucose 6- phosphate (G6P) contents were measured in the transgenic lines because previous work with tobacco transformed with S6PDH had suggested that growth inhibition was due to depletion of these metabolites. Although the myo-inositol content was decreased in PS1 plants, the decrease was much smaller than that observed in transgenic tobacco that accumulates sorbitol. The G6P contents were the same in PS1 plants and phenotypically normal PS6 plants. The level of indole-3-acetic acid (IAA), which affects stem elongation, in line PS1 was similar to the levels in the other lines. A decrease in gibberellin (GA) content generally induces dwarfism in plants. However, GA was not decreased in PS1 plants compared with wild-type or control plants. Therefore, we focused on sorbitol accumulation as the most remarkable feature of ARTICLE IN PRESS KEYWORDS Dwarfism; Japanese persimmon; Sorbitol; Sorbitol-6-phosphate dehydrogenase Abbreviations: ABA, abscisic acid; F6P, fructose 6-phosphate; GA, gibberellin; G6P, Glucose 6-phosphate; IAA, indole-3-acetic acid; S6PDH, sorbitol-6-phosphate dehydrogenase *Corresponding author. Tel.: þ81-22-717-8642; fax: þ81-22-717-8878. E-mail address: kanayama@bios.tohoku.ac.jp (Y. Kanayama). 0176-1617/$ - see front matter & 2004 Elsevier GmbH. All rights reserved. doi:10.1016/j.jplph.2004.04.009 Journal of Plant Physiology 161 (2004) 1177–1184