Prolonged embryogenesis in Austrobaileya scandens (Austrobaileyaceae) : its ecological and evolutionary significance
© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
| Publié dans: | The New phytologist. - 1979. - 215(2017), 2 vom: 07. Juli, Seite 851-864 |
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| Auteur principal: | |
| Autres auteurs: | , |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2017
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| Accès à la collection: | The New phytologist |
| Sujets: | Journal Article Austrobaileya ancient angiosperms embryo endosperm ovule development perisperm seed development seed germination |
| Résumé: | © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust. The embryology of basal angiosperm lineages (Amborella, Nymphaeales and Austrobaileyales) is central to reconstructing the early evolution of flowering plants. Previous studies have shown that mature seeds in Austrobaileyales are albuminous, with a small embryo surrounded by a substantial diploid endosperm. However, little is known of seed ontogeny and seedling germination in Austrobaileya scandens, sister to all other extant Austrobaileyales. Standard histochemical techniques were used to study ovule/seed development and germination of Austrobaileya. Early development of the endosperm in Austrobaileya is ab initio cellular with pronounced cell proliferation. The nucellus transiently accumulates some starch, but is obliterated by expansion of a massive endosperm, where all embryo-nourishing reserves are ultimately stored. Twelve months elapse from fertilization to fruit abscission. Seeds are dispersed with a minute embryo, requiring 12 additional months for seedling establishment. The 2 yr required for seedling establishment is an apomorphic feature of Austrobaileya, probably related to germination in extremely dark understory conditions. Remarkably, although Austrobaileya seeds are nearly 50 times larger (by length) than the smallest seeds of extinct and extant members of early divergent angiosperm lineages, the embryo to seed ratio (E : S) falls squarely within the narrow range that characterizes the albuminous seeds of ancient flowering plant lineages |
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| Description: | Date Completed 11.04.2018 Date Revised 30.09.2020 published: Print Citation Status MEDLINE |
| ISSN: | 1469-8137 |
| DOI: | 10.1111/nph.14621 |