Embryology in <i>Trithuria submersa</i> (Hydatellaceae) and relationships between embryo, endosperm, and perisperm in early‐diverging flowering plants

Friedman, William E.; Bachelier, Julien; Hormaza, J. I.

doi:10.3732/ajb.1200066

Cited by 33 publications

(49 citation statements)

References 77 publications

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“…In contrast, seeds of Trithuria (three species studied), the only genus of Hydatellaceae, have MPD (Tuckett et al, 2010). Interestingly, MPD in Trithuria contains an extreme morphological component as embryos in mature Trithuria seeds show very limited differentiation and consist of only about 18-23 cells, depending on the species (Tuckett et al, 2010;Friedman et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

The morphophysiological dormancy inAmborella trichopodaseeds is a pleisiomorphic trait in angiosperms

Fogliani¹,

Gâteblé²,

Villegente³

et al. 2017

Ann Bot

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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.

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Section: Introductionmentioning

confidence: 99%

The morphophysiological dormancy inAmborella trichopodaseeds is a pleisiomorphic trait in angiosperms

Fogliani¹,

Gâteblé²,

Villegente³

et al. 2017

Ann Bot

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“…A symplastic connection is always absent between spo rophyte and gametophyte tissues (Ligrone et al 1993), so specialized structures are invariably required in order to trans fer nutrients. In most extant gymnosperms (except Gnetum and Welwitchia; see below), as well as in earlydivergent extant angiosperms, the cotyledon tips act as haustoria through which nutrients enter the young sporophyte at seed germination (e.g., Tillich 1990, Ye et al 1993, Friedman et al 2012, Dörken 2014. Admittedly, seed structure is highly diverse across angiosperms, and in some taxa the cotyledons accumulate nutrients rather than act as haustorial structures.…”

Section: с O T Y L E D O N S O F S E E D P L a N T S A S H A U S T O mentioning

confidence: 99%

Functional Aspects of the Origin and Subsequent Evolution of Cotyledons in Seed Plants

Sokoloff¹,

Rudall²,

Bateman³

et al. 2015

Bot Pac

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In most seed plants, cotyledons formed within the seed act as haustorial organs, as well as playing a key role in releasing the shoot apex from the seed coat on germination. Emergence of the shoot apex often results from asymmetric intercalary growth of the cotyledon bases. This process avoids the principal spatial constraint on germination in seed plants, wherein the plumule is surrounded by cotyledons whose tips should be in contact with nutritive tissues. Cotyledons are commonly viewed as a synapomorphy of the seed-plant lineage and as the modified first leaves of a seedling. However, intercalary growth, which is crucial for the cotyledon's role in releasing the plumule, had not yet been acquired by foliage leaves of the earliest seed plants. We explore the possibility that the program of intercalary growth in leaves first evolved in cotyledons and was subsequently recruited for foliage leaves in the seed-plant lineage. We also discuss whether early seed plants already possessed haustorial cotyledons. Семядоли большинства семенных растений выполняют гаустори-альные функции, а также играют важную роль в высвобождении апекса побега из семени при его прорастании. Высвобождение апекса побега часто идет за счет асимметричного интеркалярного роста оснований семядолей. Этот про-цесс позволяет обойти ключевое пространственное ограничение при прорас-тании семенных растений, связанное с тем, что почечка окружена семядоля-ми, верхушки которых связаны с питательными тканями семени. Семядоли обычно считают синапоморфией семенных растений и видоизмененными первыми листьями проростка. Однако интеркалярный рост, столь важный для роли семядолей в высвобождении почечки, еще не был приобретен листья-ми древнейших семенных растений. Из-за отсутствия прямых свидетельств мы обсуждаем четыре гипотетически возможных сценария происхождения семя-долей. Мы рассматриваем возможность того, что интеркалярный рост впервые появился у семядолей, а затем эта программа развития распространилась и на обычные листья семенных растений. С другой стороны, возможно, что древ-нейшие семенные растения еще не имели гаусториальных семядолей.Ключевые слова: гаусторий, голосеменные растения, интеркалярный рост, ме-гафилл, прорастание семени, пространственное ограничение, развитие зародыша

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“…After the evolution of triploid endosperms there were practically no reversals to diploid endosperms or to a strategy of embryo nourishment directly through the female gametophyte [one possible exception are the Nymphaeales, where the diploid endosperm is reduced and the nourishment of the embryo is provided by a perisperm derived from the maternal sporophytic nucellus (30,31)]. An endosperm with an asymmetric contribution of parental genomes became an integral part of the embryogenesis process of flowering plants.…”

Section: The Resurgence Of Moms: Ovule Development and Endosperm Genementioning

confidence: 99%

Seed evolution: parental conflicts in a multi-generational household

Pires

2014

BioMolecular Concepts

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Seeds are multi-generational structures containing a small embryonic plant enclosed in layers of diverse parental origins. The evolution of seeds was a pinnacle in an evolutionary trend towards a progressive retention of embryos and gametes within parental tissue. This strategy, which dates back to the first land plants, allowed an increased protection and nourishing of the developing embryo. Flowering plants took parental control one step further with the evolution of a biparental endosperm that derives from a second parallel fertilization event. The endosperm directly nourishes the developing embryo and allows not only the maternal genes, but also paternal genes, to play an active role during seed development. The appearance of an endosperm set the conditions for the manifestation of conflicts of interest between maternal and paternal genomes over the allocation of resources to the developing embryos. As a consequence, a dynamic balance was established between maternal and paternal gene dosage in the endosperm, and maintaining a correct balance became essential to ensure a correct seed development. This balance was achieved in part by changes in the genetic constitution of the endosperm and through epigenetic mechanisms that allow a differential expression of alleles depending on their parental origin. This review discusses the evolutionary steps that resulted in the appearance of seeds and endosperm, and the epigenetic and genetic mechanisms that allow a harmonious coinhabitance of multiple generations within a single seed.

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Embryology in Trithuria submersa (Hydatellaceae) and relationships between embryo, endosperm, and perisperm in early‐diverging flowering plants

Cited by 33 publications

References 77 publications

The morphophysiological dormancy inAmborella trichopodaseeds is a pleisiomorphic trait in angiosperms

The morphophysiological dormancy inAmborella trichopodaseeds is a pleisiomorphic trait in angiosperms

Functional Aspects of the Origin and Subsequent Evolution of Cotyledons in Seed Plants

Seed evolution: parental conflicts in a multi-generational household

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