Pollination drop in Juniperus communis: response to deposited material
Serena Mugnaini1, Massimo Nepi, Massimo Guarnieri
1Department of Environmental Sciences "G. Sarfatti", University of Siena, Via P.A. Mattioli 4, 53100 Siena, Italy.
Annals of Botany
|October 19, 2007
Summary
The pollination drop in Juniperus communis retracts upon pollen contact, primarily due to fructose. This interaction, along with particle deposition, influences pollination efficiency.
Area of Science:
- Plant reproductive biology
- Gymnosperm pollination mechanisms
- Pollen-ovule interactions
Background:
- Pollination drops are ovule secretions essential for pollen capture in many gymnosperms.
- Pollen rehydrates and enters the ovule as the pollination drop retracts.
Purpose of the Study:
- Investigate pollination drop formation in Juniperus communis.
- Analyze carbohydrate composition of the pollination drop.
- Determine the response to conspecific pollen, foreign pollen, and particulate matter to understand retraction mechanisms.
Main Methods:
- Collected branches with female cones during pollination drop secretion.
- Used collected pollen or silica gel particles to deposit onto pollination drops.
- Measured volume changes using a stereomicroscope with a micrometer eyepiece.
- Analyzed sugar composition via high-performance liquid chromatography.
Main Results:
- Pollination drops persisted for ~12 days without pollination and reformed after removal.
- Viable conspecific pollen triggered rapid drop retraction; other materials caused partial withdrawal.
- Fructose was the dominant sugar, with glucose present at lower levels.
Conclusions:
- Confirms fructose dominance in gymnosperm pollination drops.
- Complete retraction is likely a biochemical response to pollen-drop interaction.
- Non-specific, particle-size-dependent mechanisms induce partial retraction, potentially reducing pollination efficiency.
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