This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (21) Citing Articles via Google Scholar Google Scholar Articles by Shayk, M. Articles by Davis, R. Search for Related Content PubMed PubMed Citation Articles by Shayk, M. Articles by Davis, R. Agricola Articles by Shayk, M. Articles by Davis, R.

Articles

Production of a Novel Extracellular Cutinase by the Pollen and the Chemical Composition and Ultrastructure of the Stigma Cuticle of Nasturtium (Tropaeolum majus) ¹

Ron Davis^b

^a Department of Agricultural Chemistry and Program in Biochemistry and Biophysics, Washington State University, Pullman, Washington 99164, Electron Microscope Center, University of Idaho, Moscow, Idaho 83843

Germinating nasturtium pollen (Tropaeolum majus) is shown to excrete an enzyme(s) which hydrolyzes all types of monomers from biosynthetically labeled cutin and p-nitrophenyl esters, which are model substrates for fungal cutinases. The pollen cutinase showed an optimum pH near 6.5 and was inhibited by thiol-directed reagents such as p-hydroxymercuribenzoate and N-ethyl maleimide but not by diisopropyl-fluorophosphate, an "active serine"-directed reagent indicating that the pollen enzyme is an "-SH cutinase" unlike the fungal enzyme which is a serine cutinase. Excretion of the pollen cutinase into the extracellular fluid was complete within 4 to 6 hours at 30 C. Since actinomycin D and cycloheximide showed little effect on the level of cutinase excreted, it appears that cutinase is an enzyme synthesized prior to germination. Release of cutinase into the medium did not require germination. Electron microscopy revealed the presence of a continuous cutin layer on mature stigma with extensive folds, which are proposed to play a role similar to that played by the cellular papillae found in the stigma of other plants. Chemical analysis of stigma cutin by depolymerization and combined gas-liquid chromatography and mass spectrometry showed that this cutin consists of mainly the C₁₆ family of acids. The major (70%) components were dihydroxy C₁₆ acids which consisted of 10,16- (64%), 9,16- (16%), 8,16- (12%), and 7,16- (8%) dihydroxy plamitic acid. Deuterium-labeling studies showed the presence of 16-oxo-9-hydroxy C₁₆ acid and 16-oxo-10-hydroxy C₁₆ acid in this cutin. The biochemical and ultrastructural studies indicate that the pollen tube may gain entry into stigma using cutinase excreted by the pollen.

¹ Scientific Paper No. 4870, Project 2001, College of Agriculture Research Center, Washington State University, Pullman, Washington 99164. This work was supported in part by Grant PCM 74-09351 A03 from the National Science Foundation and a grant from the Washington Tree Fruit Commission.

This article has been cited by other articles:

				T. L. Sage, K. Hristova-Sarkovski, V. Koehl, J. Lyew, V. Pontieri, P. Bernhardt, P. Weston, S. Bagha, and G. Chiu Transmitting tissue architecture in basal-relictual angiosperms: Implications for transmitting tissue origins Am. J. Botany, January 1, 2009; 96(1): 183 - 206. [Abstract] [Full Text] [PDF]

				A. F. Edlund, R. Swanson, and D. Preuss Pollen and Stigma Structure and Function: The Role of Diversity in Pollination PLANT CELL, June 1, 2004; 16(suppl_1): S84 - S97. [Full Text] [PDF]

				P. E. Kolattukudy Biopolyester Membranes of Plants: Cutin and Suberin Science, May 30, 1980; 208(4447): 990 - 1000. [Abstract] [PDF]