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- Title
THE COEXISTENCE OF BICELLULAR AND TRICELLULAR POLLEN IN ANNONA CHERIMOLA (ANNONACEAE): IMPLICATIONS FOR POLLEN EVOLUTION.
- Authors
Lora, Jorge; Herrero, María; Hormaza, José I.
- Abstract
Most angiosperms release bicellular pollen. However, in about one-third of extant angiosperms, the second pollen mitosis occurs before anthesis such that pollen is tricellular upon release. The shift from bicellular to tricellular development has occurred several times independently, but its causes are largely unknown. In this work, we observed the coexistence of both kinds of pollen at anther dehiscence in Annona cheriniola, a species that belongs to the basal angiosperm family Annonaceae. Examination of pollen cell number during anther development showed that this coexistence was due to a late mitosis starting shortly before pollen shedding. Both types of pollen germinated equally well over the course of development. Because variable proportions of bicellular and tricellular pollen were observed at different sampling times, we tested the role of temperature by performingfleld and growth chamber experiments, which showed that higher temperatures near anthesis advanced the time of pollen mitosis II. The results show that selection could favor the production of tricellular pollen under certain environmental circumstancesthat prime rapid pollen germination and provide evidence of a system in which developmental variation persists, but that can be modified by external factors such as temperature.
- Subjects
ANGIOSPERMS; CHERIMOYA; ANNONACEAE; PALYNOLOGY; POLLEN extract; ANTHER; PLANT cells &; tissues; MITOSIS; GERMINATION
- Publication
American Journal of Botany, 2009, Vol 96, Issue 4, p802
- ISSN
0002-9122
- Publication type
Article
- DOI
10.3732/ajb.0800167