Email updates

Keep up to date with the latest news and content from BMC Plant Biology and BioMed Central.

Open Access Highly Accessed Research article

Pollen development in Annona cherimola Mill. (Annonaceae). Implications for the evolution of aggregated pollen

Jorge Lora1, Pilar S Testillano2, Maria C Risueño2, Jose I Hormaza1* and Maria Herrero3

Author Affiliations

1 Estación Experimental "La Mayora", CSIC, 29760 Algarrobo-Costa, Málaga, Spain

2 Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, 28040, Madrid, Spain

3 Dep. Pomología, Estación Experimental "Aula Dei", CSIC, Apdo. 202/50080 Zaragoza, Spain

For all author emails, please log on.

BMC Plant Biology 2009, 9:129  doi:10.1186/1471-2229-9-129

Published: 29 October 2009



In most flowering plants, pollen is dispersed as monads. However, aggregated pollen shedding in groups of four or more pollen grains has arisen independently several times during angiosperm evolution. The reasons behind this phenomenon are largely unknown. In this study, we followed pollen development in Annona cherimola, a basal angiosperm species that releases pollen in groups of four, to investigate how pollen ontogeny may explain the rise and establishment of this character. We followed pollen development using immunolocalization and cytochemical characterization of changes occurring from anther differentiation to pollen dehiscence.


Our results show that, following tetrad formation, a delay in the dissolution of the pollen mother cell wall and tapetal chamber is a key event that holds the four microspores together in a confined tapetal chamber, allowing them to rotate and then bind through the aperture sites through small pectin bridges, followed by joint sporopollenin deposition.


Pollen grouping could be the result of relatively minor ontogenetic changes beneficial for pollen transfer or/and protection from desiccation. Comparison of these events with those recorded in the recent pollen developmental mutants in Arabidopsis indicates that several failures during tetrad dissolution may convert to a common recurring phenotype that has evolved independently several times, whenever this grouping conferred advantages for pollen transfer.