Journal Article

Possible Involvement of Phosphoinositide-Ca<sup>2+</sup> Signaling in the Regulation of <i>α</i>-Amylase Expression and Germination of Rice Seed (<i>Oryza sativa</i> L.)

Mohammad A. Kashem, Kimiko Itoh, Satoru Iwabuchi, Hidetaka Hori and Toshiaki Mitsui

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 41, issue 4, pages 399-407
Published in print April 2000 | ISSN: 0032-0781
Published online April 2000 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/41.4.399
Possible Involvement of Phosphoinositide-Ca2+ Signaling in the Regulation of α-Amylase Expression and Germination of Rice Seed (Oryza sativa L.)

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We have studied the effects of neomycin, a potent inhibitor of inositol phospholipid-specific phospholipase C (PLC), on the germination of rice seed and the gibberellin-induced expression of a-amylase in the aleurone layer and the scutellar tissues. It was shown that, in the absence of exogenous Ca2+, neomycin markedly reduced the germination speed and seedling growth of rice seeds and inhibited the gibberellin-induced expression of a-amylase in both secretory tissues. In addition, neomycin decreased the formation of inositol 1,4,5-trisphosphate (IP3) in the gibberellin-treated aleurone layer and the scutellar tissues. However, the inhibitory effects on the germination speed and the expression of a-amylase activity were overcome by supplementation of Ca2+. In addition, gibberellin elevated the level of IP3, and ABA prevented the gibberellin-induced formation of IP3, although ABA alone did not alter the IP3 level. The expression of a membrane-bound PLC molecule in rice aleurone layer was shown to be induced by gibberellin, and the gibberellin-induced expression of PLC was markedly delayed by treatment with ABA. These results strongly suggest that the phosphoinositide-Ca2+ signal transduction pathway may play an important role in the gibberellin-induced expression of a-amylase molecules closely related to the germination processes of rice seed.

Keywords: α-Amylase isoform I-1; Ca2+; Gibberellin; Inositol 1,4,5-trisphosphate; Neomycin; Rice seed

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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