Occurrence of unique three-celled megagametophyte and single fertilization in an aquatic angiosperm-Dalzellia zeylanica (Podostemaceae-Tristichoideae)
| Autor: | Hussain Ara, Anita Sehgal, Jitendra P. Khurana, Minakshi Sethi |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Gametogenesis
Plant Aquatic Organisms Podostemaceae Egg cell biology Polar nucleus Flowers Pollen Tube Cell Biology Plant Science biology.organism_classification Double fertilization Magnoliopsida medicine.anatomical_structure Human fertilization Fertilization Botany medicine Gamete Pollen tube Single fertilization |
| Zdroj: | Sexual Plant Reproduction. 24:199-210 |
| ISSN: | 1432-2145 0934-0882 |
| DOI: | 10.1007/s00497-010-0159-3 |
| Popis: | Angiosperms are characterized by the occurrence of double fertilization. However, Podostemaceae is considered an exception with the presence of only single fertilization (syngamy) though two male gametes are formed conventionally. To determine the cause for the failure of double fertilization in Dalzellia zeylanica (Gardn.) Wight, we closely tracked the movement of the male gametes from the time of pollen tube initiation to the time of entry into the megagametophyte to affect fertilization. We report for the first time, the presence of a novel type of three-nucleate/three-celled mature megagametophyte consisting of two synergids and an egg cell in D. zeylanica. Therefore, of the two male gametes formed in this plant, one fuses with the egg cell resulting in syngamy, whereas the other male gamete eventually degenerates due to the absence of its partner i.e. single polar nucleus of the central cell that degenerates prior to the entry of the pollen tube into the synergid. The present work not only highlights the highly reduced nature of megagametophyte but also the occurrence of single fertilization resulting in sperm selection in D. zeylanica. |
| Databáze: | OpenAIRE |
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