Journal Article

The morphophysiological dormancy in Amborella trichopoda seeds is a pleisiomorphic trait in angiosperms

Department of Biology ; Northern Arizona University [Flagstaff], Reproduction et développement des plantes (RDP) ; École normale supérieure de Lyon (ENS de Lyon) ; Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Fabre, Isabelle, Institut Agronomique Néo-Calédonien (IAC), Fogliani, Bruno, Gateble, Gildas, Klein, Nicolas, Villegente, Matthieu, Laboratoire Insulaire du Vivant et de l'Environnement (LIVE) ; Université de la Nouvelle-Calédonie (UNC), Anger, Nicolas, Baskin, Carol C, Fondation Ars-Cuttoli-Paul Appell under the aegis of the Fondation de France; Province Sud de Nouvelle-Caledonie, Scutt, C.P, Department of Plant andSoil Science ; University of Kentucky (UK)

2017

Overview

Background and Aims Recent parsimony-based reconstructions suggest that seeds of early angiosperms had either morphophysiological or physiological dormancy, with the former considered as more probable. The aim of this study was to determine the class of seed dormancy present in Amborella trichopoda, the sole living representative of the most basal angiosperm lineage Amborellales, with a view to resolving fully the class of dormancy present at the base of the angiosperm clade. Methods Drupes of A. trichopoda without fleshy parts were germinated and dissected to observe their structure and embryo growth. Pre-treatments including acid scarification, gibberellin treatment and seed excision were tested to determine their influence on dormancy breakage and germination. Character-state mapping by maximum parsimony, incorporating data from the present work and published sources, was then used to determine the likely class of dormancy present in early angiosperms. Key Results Germination in A. trichopoda requires a warm stratification period of at least approx. 90 d, which is followed by endosperm swelling, causing the water-permeable pericarp-mesocarp envelope to split open. The embryo then grows rapidly within the seed, to radicle emergence some 17 d later and cotyledon emergence after an additional 24 d. Gibberellin treatment, acid scarification and excision of seeds from the surrounding drupe tissues all promoted germination by shortening the initial phase of dormancy, prior to embryo growth. Conclusions Seeds of A. trichopoda have non-deep simple morphophysiological dormancy, in which mechanical resistance of the pericarp-mesocarp envelope plays a key role in the initial physiological phase. Maximum parsimony analyses, including data obtained in the present work, indicate that morphophysiological dormancy is likely to be a pleisiomorphic trait in flowering plants. The significance of this conclusion for studies of early angiosperm evolution is discussed.

• Publisher: Oxford University Press (OUP),CCSD,Oxford University Press
• Subject: Amborella trichopoda / Biological Evolution / Botanics / cotyledons / Development Biology / Editor's Choice / endosperm / evolution / germination / Germination - physiology / gibberellins / Life Sciences / Magnoliopsida - anatomy & histology / Magnoliopsida - physiology / Magnoliopsida - ultrastructure / mechanical properties / Microscopy, Electron, Scanning / Original / ORIGINAL ARTICLES / Plant Dormancy - physiology / seed dormancy / Seeds - anatomy & histology / Seeds - physiology / Seeds - ultrastructure / stone fruits / tissues / Vegetal Biology
• ISBN: 9780003984521, 0003984524