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Insights into a hydration regulating system in Cupressus pollen grains
R Danti1, G Della Rocca, R Calamassi
1Istituto per la Protezione delle Piante - Consiglio Nazionale delle Ricerche. Via Madonna del Piano n. 10, I-50019, Sesto Fiorentino (FI), Italy. r.danti@ipp.cnr.it
Annals of Botany
|June 21, 2011
Summary
A temporary hemispheric structure on Cupressus pollen grains regulates water entry during initial hydration. This finding clarifies the function of this unique outgrowth in taxoid-type pollen hydration processes.
Area of Science:
- Plant reproductive biology
- Palynology
Background:
- Taxoid-type pollen grains exhibit hydration, rupture, and exine opening due to intine expansion.
- A hemispheric outgrowth on Cupressus and Juniperus pollen grains has been observed, but its existence and role in hydration are debated.
Purpose of the Study:
- To investigate the presence, structure, composition, and function of a peculiar outgrowth on Cupressus pollen grains.
- To confirm the existence and elucidate the role of this structure in pollen hydration.
Main Methods:
- Observation of Cupressus pollen grains using light, fluorescence, phase-contrast, confocal, scanning electron, and environmental scanning electron microscopy.
- Comparative observations on other species with taxoid-type pollen grains.
Main Results:
- A temporary, hemispheric, layered structure was identified above the pore of Cupressus and other taxoid-type pollen grains.
- This structure is composed of polysaccharides and proteins, with proteins localized internally.
- The structure appears to regulate water entry during the initial stages of pollen hydration.
Conclusions:
- The presence of a temporary structure over the pore of taxoid-type pollen grains is confirmed.
- The structure's composition and role in the initial phases of pollen hydration have been elucidated through various observational techniques.
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