Simulation of exine patterns by self-assembly

Gabarayeva, Nina I.; Grigorjeva, Valentina V.

doi:10.1007/s00606-016-1322-6

Cited by 24 publications

(16 citation statements)

References 104 publications

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“…In some cases, the sizes of simulations and corresponding exine structures differ, whereas in others they actually coincide. But in all cases the difference is within one order of magnitude, as in previous studies (Gabarayeva & Grigorjeva, ; Gabarayeva et al , ).…”

Section: Discussionsupporting

confidence: 86%

“…These are described in Gabarayeva et al (). In brief, we adapted our original, simple method (Gabarayeva & Grigorjeva, , ), preparing mixtures of substances, mostly surfactants, which either occur naturally in the periplasmic space of the developing microspores or are substitutes analogous to naturally occurring substances. We prepared different combinations of substances and used them at different concentrations.…”

Section: Methodsmentioning

confidence: 99%

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Artificial pollen walls simulated by the tandem processes of phase separation and self‐assemblyin vitro

2019

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Despite numerous attempts to elucidate the developmental mechanisms responsible for the observed diversity of pollen and spore walls, the processes involved remained obscure until the structures observed during exine development were recognized as a sequence of selfassembling micellar mesophases. To confirm this, a series of in vitro experiments was undertaken in which exine-like patterns were generated in colloidal mixtures by self-assembly, without any genomic participation. The intention was to test whether all the main types of exine structure could be simulated experimentally.Mixtures of substances, analogous to those involved in microspore development, were left undisturbed while water evaporated and self-assembly occurred. We varied the substances, their combinations and concentrations, and the physical constraints to make the experiments closer to the situation in nature. The resulting dry films were then examined using transmission electron microscopy.A variety of microstructures, simulating the full range of exine types, was obtained by micellar self-assembly. Moreover, the signs of related physicochemical process (i.e. phase separation) were also observed.Simple, energy-efficient, physical-chemical interactions, phase separation and self-assembly, are capable of generating exine-like patterns, providing evidence that these processes share control of exine formation with the well-documented program of gene expression.

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Section: Discussionsupporting

confidence: 86%

Section: Methodsmentioning

confidence: 99%

Artificial pollen walls simulated by the tandem processes of phase separation and self‐assemblyin vitro

2019

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“…Another possibility is that the striped patterns found in pollen have internal structure in the primexine that energetically disfavors the stripe bending required for the chiral stripe patterns observed in our model, such as a preferred orientation of rigid cellulose fibers along the stripes. Indeed, primexine-related materials may exhibit phases with complex, micellar molecular structure, even in vitro (Gabarayeva and Grigorjeva, 2016). The energy associated with these facets of molecular structure would not be captured by our model, which considers molecular concentration alone.…”

Section: Discussionmentioning

confidence: 98%

“…The geometric diversity of pollen grain surface patterns has intrigued scientists for decades. The developmental processes of these cell walls are nearly identical between taxa, and selfassembly may be a mechanism for pattern formation (Hemsley and Gabarayeva, 2007;Gabarayeva and Grigorjeva, 2016); however, no unifying physical theory has emerged to explain the mechanism underlying the diversity of regular patterns (Figures 1 and 2). The outermost layer of pollen cell walls, or exine, serves as a robust physical and chemical barrier providing protection for genetic material: it is robust to desiccation and rehydration while allowing for pollen tube emergence through apertures, i.e., thin regions of the exine (Katifori et al, 2010), and may also have a mechanical role in stigma-pollen recognition (Zinkl et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Pollen Cell Wall Patterns Form from Modulated Phases

Radja

Horsley

Lavrentovich

et al. 2019

Cell

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“…Following the tetrad stage, a characteristic exine pattern is rapidly formed on the surface of young microspores. It has been proposed that certain properties of sporopollenin precursors enable self‐assembly (Hemsley et al ., ; Gabarayeva and Hemsley, ; Gabarayeva and Grigorjeva, ), but it is not known which elements contribute to these intrinsic properties – nor how they control assembly.…”

Section: Introductionmentioning

confidence: 99%

Rice No Pollen 1 (NP1) is required for anther cuticle formation and pollen exine patterning

et al. 2017

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Angiosperm male reproductive organs (anthers and pollen grains) have complex and interesting morphological features, but mechanisms that underlie their patterning are poorly understood. Here we report the isolation and characterization of a male sterile mutant of No Pollen 1 (NP1) in rice (Oryza sativa). The np1-4 mutant exhibited smaller anthers with a smooth cuticle surface, abnormal Ubisch bodies, and aborted pollen grains covered with irregular exine. Wild-type exine has two continuous layers; but np1-4 exine showed a discontinuous structure with large granules of varying size. Chemical analysis revealed reduction in most of the cutin monomers in np1-4 anthers, and less cuticular wax. Map-based cloning suggested that NP1 encodes a putative glucose-methanol-choline oxidoreductase; and expression analyses found NP1 preferentially expressed in the tapetal layer from stage 8 to stage 10 of anther development. Additionally, the expression of several genes involved in biosynthesis and in the transport of lipid monomers of sporopollenin and cutin was decreased in np1-4 mutant anthers. Taken together, these observations suggest that NP1 is required for anther cuticle formation, and for patterning of Ubisch bodies and the exine. We propose that products of NP1 are likely important metabolites in the development of Ubisch bodies and pollen exine, necessary for polymerization, assembly, or both.

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Simulation of exine patterns by self-assembly

Cited by 24 publications

References 104 publications

Artificial pollen walls simulated by the tandem processes of phase separation and self‐assemblyin vitro

Artificial pollen walls simulated by the tandem processes of phase separation and self‐assemblyin vitro

Pollen Cell Wall Patterns Form from Modulated Phases

Rice No Pollen 1 (NP1) is required for anther cuticle formation and pollen exine patterning

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