A model for the role of surfactants in the assembly of exine sculpture

Hemsley, Alan R.; Griffiths, Peter Charles; Mathias, Robert; Moore, Susannah

doi:10.1080/00173130310008562

Cited by 33 publications

(13 citation statements)

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“…During the transition from premeiosis to young microspore stage, the expression of these genes was mainly limited to the tapetal cells and microspores in a pattern similar to that of a GA biosynthesis gene, GA3 oxidase (SmGA3ox; Fig. 2c-e), where the sporopollenin material is produced for the outer wall development [9][10][11][21][22][23] . Considering that GAMYBs, CYP703As and GA biosynthesis genes in flowering plants are also co-expressed in the tapetal cells and microspores 1,8,12,[24][25][26] , these observations indicate that SmGAMYB activity in these tissues of Selaginella is required to mediate GA signalling during the outer wall formation of microspores.…”

Section: Molecular Characterization Of Smgamyb and Ppgamybsmentioning

confidence: 99%

“…In rice, CYP703A3 is an essential enzyme in sporopollenin biosynthesis, and its expression is positively regulated by a transcription factor, GAMYB, which is controlled by the GA signalling pathway 1,7,8 . Previous anatomical and in silico studies suggest that, similar to flowering plants, present-day bryophytes, including mosses, and lycophytes (lycopods) contain sporopollenin-containing outer walls on the surface of their spores and microspores [9][10][11] , and genes encoding CYP703 homologues have been detected in these genomes 12 . Curiously, however, one of the basal vascular plants, Selaginella, contains a functional GA perception system that is mediated by a GA receptor, GIBBERELLIN-INSENSITIVE DWARF1 (GID1), and suppressor proteins (DELLAs), whereas one of the basal land plants, Physcomitrella patens, does not contain this system [13][14][15][16] .…”

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The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

et al. 2011

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Gibberellin (GA) controls pollen development in flowering plants via the GAMYB transcription factor. Here we show that GAMYB is conserved in Selaginella moellendorffii (lycophyte) and Physcomitrella patens (moss), although the former contains the GA signalling pathway, the latter does not. In the lycophyte, GA treatment promotes the outer wall development on microspores, whereas treatment with GA biosynthesis inhibitors disturbs its development. Contrary, in the moss, GAMYB homologue knockouts also produce abnormal spores that resemble Selaginella microspores treated with GA biosynthesis inhibitors and pollen grains of rice gamyb mutant. Moreover, the knockouts fail to develop male organs, instead ectopically forming female organs. Thus, before the establishment of the GA signalling pathway, basal land plants, including mosses, contained a GAMYB-based system for spore and sexual organ development. Subsequently, during the evolution from mosses to basal vascular plants including lycophytes, GA signalling might have merged to regulate this pre-existing GAMYB-based system.Peer reviewe

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Section: Molecular Characterization Of Smgamyb and Ppgamybsmentioning

confidence: 99%

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confidence: 99%

The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

et al. 2011

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“…However, the best proof of this hypothesis would be experimental modelling of spore and microspore sporoderm-like patterns in vitro. The first series of such experiments was undertaken by Hemsley and co-authors (Hemsley et al, 1996(Hemsley et al, , 2003Griffiths & Hemsley, 2001;Moore et al, 2009). These authors used special techniques for their experiments and selected a number of components, including polystyrene in place of SP .…”

Section: Modelling Of Exine 243mentioning

confidence: 99%

Experimental modelling of exine-like structures

Gabarayeva

Grigorjeva

2013

Grana

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“…The consistency of the pattern within species suggests a high degree of genetic regulation for which there is no obvious explanation. This issue raised an intensive debate whether the establishment of the pollen wall pattern is a consequence of a self-assembly process due to the physical and chemical behavior of the components and their interactions, or if it depends only on a complex cooperation of cellular components (Sheldon and Dickinson, 1983; Fitzgerald and Knox, 1995;Southworth and Jernstedt, 1995;Paxson-Sowders et al, 1997;Hemsley et al, 2003).Pollen wall formation begins soon after meiosis is complete ( Fig. 2 A,B) and it continues during tetrad and vacuolated stages of microspores to almost completion on the first pollen mitosis with a major contribution from the tapetum (Fig.…”

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The making of gametes in higher plants

Boavida¹,

Becker²,

Feijó³

2005

Int. J. Dev. Biol.

102

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Higher plants have evolved to be one of the predominant life forms on this planet. A great deal of this evolutionary success relies in a very short gametophytic phase which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower. In most species the processes of gametogenesis, pollination, syngamy and embryogenesis are sequentially coordinated to give rise to a functional seed in a matter of few weeks. Any of these processes is so intricately complex and precisely regulated that it becomes no wonder that each involves more specific genes and cellular processes than any other function in the plant life cycle. While variability generation -the evolutionary output of the sexual cycle -is the same as in any other Kingdom, plants do it using a completely original set of mechanisms, many of which are not yet comprehended. In this paper, we cover the fundamental features of male and female gametogenesis. While the physiological and cellular bases of these processes have been continuously described since the early nineteen century, recent usage of Arabidopsis and other species as central models has brought about a great deal of specific information regarding their genetic regulation. Transcriptomics has recently enlarged the repertoire and pollen became the first gametophyte to have a fully described transcriptome in plants. We thus place special emphasis on the way this newly accumulated genetic and transcriptional information impacts our current understanding of the mechanisms of gametogenesis. KEY WORDS: pollen, embryo sac, gametogenesis, microsporogenesis, macrosporogenesis The uniqueness of a life formOne of the most remarkable features of life on earth is diversity, a great deal of which is based on the evolutionary output of sexual reproduction. Unlike animals, in which the primordial germ line develops early during embryogenesis, higher plants alternate the growth of the diploid sporophyte organism with a highly reduced growth form on the plant life cycle, the haploid gametophyte. This is a well-suited strategy for selection because plants spend most of their life on the vegetative phase. The gametophytic stage also presents an opportunity for selection at the haploid level (Ottaviano et al., 1990).Plant cells don't move and positional information instead of lineage is the primary determinant of cell fate in plants. Meiosis triggers the separation between sporophytic and gametophytic generations involving various genes (Caryl et al., 2003). This spatial pleiotropy of the sexual organs has prompted evolution for the appearance of safety mechanisms to prevent the fusion of incompatible genomes while supporting genetic variability. In higher animals genetic mechanisms for sex determination establish striking developmental differences between males and feInt. J. Dev. Biol. 49: 595-614 (2005) doi: 10.1387/ijdb.052019lb males. In contrast, most higher plant species develop both male and female structures within the same flower, allowing selffertilizati...

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A model for the role of surfactants in the assembly of exine sculpture

Cited by 33 publications

References 14 publications

The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

Experimental modelling of exine-like structures

The making of gametes in higher plants

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