Sporoderm development and substructure in<i>Magnolia sieboldii</i>and other Magnoliaceae: an interpretation

Gabarayeva, Nina I.; Grigorjeva, Valentina V.

doi:10.1080/00173134.2012.688863

Cited by 27 publications

(6 citation statements)

References 90 publications

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“…5). These simulations mimic mainly massive, almost structureless ectexines, and the endexine consisting of a few lamellae, as has been observed in an ontogenetic study in some Magnoliaceae species (Gabarayeva and Grigorjeva, 2012). It should be noted that in nature endexine lamellae, in contrast to ectexines, arise directly from laminate micelles, without the involvement of the glycocalyx.…”

Section: Discussionsupporting

confidence: 61%

“…The columella-like pattern is represented by the middle (hexagonal) micellar mesophase, in (Fig. 14E in Gabarayeva and Grigorjeva, 2012). (D′) Simulation resembling the acetolysed pollen wall in Magnolia delavayi.…”

Section: Discussionmentioning

confidence: 99%

“…(Fig. 10B in Gabarayeva and Grigorjeva, 2012). (E′) Simulation of Michelia microspore wall mimicking ectexine ('Ect') and the developing lamellae of the endexine (arrows).…”

Section: Discussionmentioning

confidence: 99%

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Mimicking pollen and spore walls: self-assembly in action

2019

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Background and Aims Decades of research have attempted to elucidate the underlying developmental mechanisms that give rise to the enormous diversity of pollen and spore exines. The organization of the exine starts with the establishment of an elaborate glycocalyx within which the subsequent accumulation of sporopollenin occurs. Ontogenetic studies using transmission electron microscopy of over 30 species from many different groups have shown that the sequence of structures observed during development of the exine corresponds to the sequence of self-assembling micellar mesophases (including liquid crystals) observed at increasing concentrations of surfactants. This suggested that self-assembly plays an important part in exine pattern determination. Some patterns resembling separate layers of spore and pollen grain walls have been obtained experimentally, in vitro, by self-assembly. However, to firmly establish this idea, columellate and granulate exines, the most widespread forms, needed to be simulated experimentally. Methods We used our original method, preparing mixtures of substances analogous to those known to occur in the periplasmic space of developing microspores, then leaving the mixtures undisturbed for specific periods of time to allow the process of self-assembly to occur. We developed our method further by using new substances analogous to those present in the periplasmic space and performing the experiments in a thin layer, more closely resembling the dimensions of the periplasmic space. Key Results The artificial microstructures obtained from our in vitro self-assembly experiments closely resembled the main types of exines, including tectate–columellate, granulate, alveolate and structureless, and permitted comparison with both developing and mature microspore walls. Compared with the previous attempts, we managed to simulate columellate and granulate exines, including lamellate endexine. Conclusions Our results show that simple physico-chemical interactions are able to generate patterns resembling those found in exines, supporting the idea that exine development in nature involves an interplay between the genome and self-assembly.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

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Mimicking pollen and spore walls: self-assembly in action

2019

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“…One of them shows slightly wavy filaments, disposed perpendicularly to the sample surface ( Figure 4D). These are similar to young procolumellae of the middle tetrad stage microspores in Magnolia sieboldii ( Figure 4D ; Gabarayeva & Grigorjeva, 2012, figure 5C). …”

Section: Composite Gels and Their Mixtures With Surfactantsmentioning

confidence: 53%

“…Other kinds of crusts, appearing in a mixture of the aqueous 5% colloid gel of HPMC with the addition of 1% saponin solution ( Figure 5C, D) surprisingly mimic not only the mature ectexine of Magnolia sieboldii with its tectum, thinner foot layer and short columellae between them ( Figure 5C), but also the first granular layer of its intine ( Figure 5C ; Gabarayeva & Grigorjeva, 2012, figure 12C). …”

Section: Composite Gels and Their Mixtures With Surfactantsmentioning

confidence: 99%

Experimental modelling of exine-like structures

Gabarayeva

Grigorjeva

2013

Grana

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Self-assembly as the underlying mechanism for exine development in Larix decidua D. C.

Gabarayeva

Grigorjeva

2017

Planta

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Our findings suggest a new approach to pollen ontogenetic investigations, entailing consideration of physical factors, which enable a better understanding of exine developmental processes. The sporopollenin-containing part of the pollen wall-the exine-is one of the most complex cell walls in plants. By tracing each stage of microspore development in Larix decidua with TEM, we aimed to understand the underlying mechanisms of its exine establishment. Our hypothesis is that self-assembly interferes with exine development. Our specific aim is to generate experimental simulations of the exine developmental pattern. The sequence of events leading to exine development includes the appearance of spherical units in the periplasmic space, their rearrangement into radial columns, and the appearance of white-lined endexine lamellae. The final accumulation of sporopollenin proceeds in the post-tetrad period. The sequence of self-assembling micellar mesophases corresponds with that of the developmental events: spherical micelles; columns of spherical micelles; and laminate micelles separated by strata of water and visible as white-lined lamellae in TEM. Several patterns, simulating structures at different stages of exine development in Larix, were obtained from in vitro experiments. Purely physicochemical processes of self-assembly, which are not under direct genetic control, play an important role in exine development and share control with the genome. These findings suggest that a new approach to ontogenetic investigations, entailing consideration of physical factors (e.g., cell tensegrity), is required for a better understanding of developmental processes.

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Sporoderm development and substructure inMagnolia sieboldiiand other Magnoliaceae: an interpretation

Cited by 27 publications

References 90 publications

Mimicking pollen and spore walls: self-assembly in action

Mimicking pollen and spore walls: self-assembly in action

Experimental modelling of exine-like structures

Self-assembly as the underlying mechanism for exine development in Larix decidua D. C.

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