title: Growth of Pollen Tubes of Papaver rhoeas Is Regulated by a Slow-Moving Calcium Wave Propagated by Inositol 1,4,5-Trisphosphate.
abstract: A signaling role for cytosolic free Ca2+ ([Ca2+]i) in regulating Papaver rhoeas pollen tube growth during the self-incompatibility response has been demonstrated previously. In this article, we investigate the involvement of the phosphoinositide signal transduction pathway in Ca2+-mediated pollen tube inhibition. We demonstrate that P. rhoeas pollen tubes have a Ca2+-dependent polyphosphoinositide-specific phospholipase C activity that is inhibited by neomycin. [Ca2+]i imaging after photolysis of caged inositol (1,4,5)-trisphosphate (Ins[1,4,5]P3) in pollen tubes demonstrated that Ins(1,4,5)P3 could induce Ca2+ release, which was inhibited by heparin and neomycin. Mastoparan, which stimulated Ins(1,4,5)P3 production, also induced a rapid increase in Ca2+, which was inhibited by neomycin. These data provide direct evidence for the involvement of a functional phosphoinositide signal-transducing system in the regulation of pollen tube growth. We suggest that the observed Ca2+ increases are mediated, at least in part, by Ins(1,4,5)P3-induced Ca2+ release. Furthermore, we provide data suggesting that Ca2+ waves, which have not previously been reported in plant cells, can be induced in pollen tubes.
authors.affiliation: Wolfson Laboratory for Plant Molecular Biology, School of Biological Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: V. E.
authors.initials: VE
authors.lastname: Franklin-Tong
authors.forename: B. K.
authors.initials: BK
authors.lastname: Drobak
authors.forename: A. C.
authors.initials: AC
authors.lastname: Allan
authors.forename: PAC.
authors.initials: P
authors.lastname: Watkins
authors.forename: A. J.
authors.initials: AJ
authors.lastname: Trewavas