Changes in the Pollen Grain Wall of Linum grandiflorum following Compatible and Incompatible Intraspecific Pollinations |
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Authors: | DICKINSON H G; LEWIS D |
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Institution: | Department of Botany and Microbiology, University College, Cower Street, London, WCl6BT |
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Abstract: | The exine surrounding the colpal furrows in the pollen grainsof Linum grandiflorum is rapidly degraded following the twocompatible pollinations between pin and thrumtypes of flower and also following the incompatible pollinationbetween thrum and thrum. In allthese pollinations the pollen germinates normally. Exine isnot degraded in the incompatible pollination between pinand pin. In this pollination the pollen does notswell or germinate. The exine degradation is restricted to thecolpal regions. Hydration of the pollen grain by buffer solutionwithout contact with the stigma also stimulates the degradationof the exine. The erosion of the exine reveals a fibrous, PAS-positivematrix which follows the original contours of the exine. Vesicles are discharged into the intinc following pollination;these appear to contribute their contents to the intine-likewall which eventually invests the pollen tube. The observations are interpreted by assuming: - 1. an enzyme situatedwithin the pollen and localized underthe colpi; this enzymeis active after hydration;
- 2. the degradation is a means bywhich colpal furrows are enlargedto permit the emergence ofthe pollen tube;
- 3. the degradation process both by bufferand on the stigmais purely the consequence of hydration andis only secondarilyrelated to incompatibility through the pinbypin pollination not permitting hydration ofthepollen.
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