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Proc Natl Acad Sci U S A. 2001 Aug 28;98(18):10481-6. Epub 2001 Aug 21.

cAMP acts as a second messenger in pollen tube growth and reorientation.

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1
Department of Plant Biology, Faculdade de Ciências de Lisboa, University of Lisbon, Block C2, Lisboa, 1749-016 Lisbon, Portugal.

Abstract

Pollen tube growth and reorientation is a prerequisite for fertilization and seed formation. Here we report imaging of cAMP distribution in living pollen tubes microinjected with the protein kinase A-derived fluorosensor. Growing tubes revealed a uniform distribution of cAMP with a resting concentration of approximately 100-150 nM. Modulators of adenylyl cyclase (AC), forskolin, and dideoxyadenosine could alter these values. Transient elevations in the apical region could be correlated with changes in the tube-growth axis, suggesting a role for cAMP in polarized growth. Changes in cAMP arise through the activity of a putative AC identified in pollen. This signaling protein shows homology to functional motifs in fungal AC. Expression of the cDNA in Escherichia coli resulted in cAMP increase and complemented a catabolic defect in the fermentation of carbohydrates caused by the absence of cAMP in a cyaA mutant. Antisense assays performed with oligodeoxynucleotide probes directed against conserved motifs perturbed tip growth, suggesting that modulation of cAMP concentration is vital for tip growth.

PMID:
11517303
PMCID:
PMC56986
DOI:
10.1073/pnas.171104598
[Indexed for MEDLINE]
Free PMC Article
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