Morphological and Ultrastructural Diversity of Orbicules in Gentianaceae

Vinckier, Stefan

doi:10.1093/aob/mcg187

Cited by 23 publications

(15 citation statements)

References 31 publications

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“…Comparable with the palynological trend observed in Apocynaceae s.l. and Rubiaceae (Vinckier et al 2000, Vinckier & Smets 2002b, a similar trend is observed in Gentianaceae from genera which have monads possessing orbicules, to species which have more derived pollen dispersal units (tetrads or polyads) which lack orbicules (Table I, Vinckier & Smets 2003). However, no comparable trend in orbicule typology, as recorded in Apocynaceae s.l.…”

Section: Orbicules In Gentianalessupporting

confidence: 53%

“…& Schult. f. and Swertia perennis L. are characterised by amoeboid tapeta (Maheswari Devi 1962, Sankara Rao & Chinnappa 1983, and produce very small orbicules distributed in very low distribution densities on the locule wall surfaces (Vinckier & Smets 2003). Therefore, we suggest that presence of very small orbicules (mean: 0.2 mm), along with a very low distribution density (mean: 2 orbicules/ 25 mm 2 ), may indicate the presence of an amoeboid tapetum in a species, as sporopollenin granules have already been reported in taxa with an amoeboid tapetum by Tiwari & Gunning (1986).…”

Section: Orbicules In Gentianalesmentioning

confidence: 99%

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The manifold characters of orbicules: structural diversity, systematic significance, and vectors for allergens

Vinckier

Cadot

Smets

2005

Grana

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E. 2005. The manifold characters of orbicules: structural diversity, systematic significance, and vectors for allergens. -Grana 44: 300-307. ISSN 0017-3134.In the anthers of flowering plants, gymnosperms, and seed ferns, tiny (¡1 mm) granules might occur on the radial and innermost tangential wall of secretory tapetum cells. These sporopollenin granules develop simultaneously with the pollen exine and are called orbicules or Ubisch bodies. The present paper focuses on two quite different topics associated with orbicules.The morphological and ultrastructural diversity of orbicules in the order Gentianales is summarized, and it is demonstrated that orbicules are a plesiomorphic feature in the order. Furthermore, orbicule characters seemed to be correlated with evolutionary trends in pollen dispersal unit and tapetum type features.In the second part, we report on our investigation of Corylus avellana L. (Hazel) pollen, using immunogold electron microscopy to gain an insight into the possible role that orbicules may play as a vector of pollen allergens. During the pollen season orbicules are dispersed into the atmosphere along with Hazel pollen grains. The localisation of homologues of the new birch pollen allergen Bet v 7 was studied at the subcellular level in Hazel anthers. The results of this study indicate that orbicules and pollen of Hazel might act as very effective vectors for homologues of Bet v 7 and that debris of Hazel anthers represent vectors of allergens after the pollen season.

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Section: Orbicules In Gentianalessupporting

confidence: 53%

Section: Orbicules In Gentianalesmentioning

confidence: 99%

The manifold characters of orbicules: structural diversity, systematic significance, and vectors for allergens

Vinckier

Cadot

Smets

2005

Grana

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“…Some of these characters have been systematically analysed in several other taxa of Gentianales such as Apocynaceae s.l. (Vinckier & Smets, 2002c), Gentianaceae (Vinckier & Smets, 2003) and Loganiaceae s.l. (Vinckier & Smets, 2002a).…”

Section: Introductionmentioning

confidence: 99%

Phylogenetic signal of orbicules at family level: Rubiaceae as case study

Verstraete

Groeninckx

Smets

et al. 2011

TAXON

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Orbicules are tiny a-cellular sporopollenin structures that occur in the anthers of many angiosperms together with the pollen grains. Although their occurrence is common, little is known about their function and systematic usefulness. With regard to orbicules, Rubiaceae (Gentianales) are the most intensively studied plant family and therefore an ideal case to present the evolution and phylogenetic signal of orbicule characters at family level. The occurrence and morphology of orbicules was investigated in 64 species of Rubiaceae using scanning electron microscopy. Five relevant orbicule features (presence/absence, abundance, size, shape, ornamentation) were optimized onto a custom-made phylogeny of the family. By optimizing the five orbicule characters some evolutionary trends can be observed. The previously suggested trend in angiosperms towards orbicule absence in more derived taxa is confirmed for Rubiaceae. Orbicules appear to have been independently lost at least nine times within the family, with two subsequent reversals. Small orbicules represent the plesiomorphic character state for the family. A trend from spherical towards irregular orbicules is observed, while ornamented orbicules occur only in derived lineages. Orbicule characters are constant at generic level and in most cases at tribal level, and therefore have potential for systematics. The presence of orbicules is correlated with the occurrence of a non-amoeboid tapetum.

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“…Thus, the tapetum in dicots and monocots might have different mechanisms for sporopollenin translocation. Analogies are often found between the ornamentation of the pollen exine and that of the Ubisch body wall (Hesse, 1986; Vinckier and Smets, 2002, 2003). Ubisch bodies are considered have great potential as model system to study sporopollenin deposition, since they are acellular structures, independent of cytoplasmic control (Clément and Audran, 1993; Verstraete et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Transcriptome Analysis of Hamelia patens (Rubiaceae) Anthers Reveals Candidate Genes for Tapetum and Pollen Wall Development

et al. 2017

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Studies of the anther transcriptome on non-model plants without a known genome are surprisingly scarce. RNA-Seq and digital gene expression (DGE) profiling provides a comprehensive approach to identify candidate genes contributing to developmental processes in non-model species. Here we built a transcriptome library of developing anthers of Hamelia patens and analyzed DGE profiles from each stage to identify genes that regulate tapetum and pollen development. In total 7,720 putative differentially expressed genes across four anther stages were identified. The number of putative stage-specific genes was: 776 at microspore mother cell stage, 807 at tetrad stage, 322 at uninucleate microspore stage, and the highest number (1,864) at bicellular pollen stage. GO enrichment analysis revealed 243 differentially expressed and 108 stage-specific genes that are potentially related to tapetum development, sporopollenin synthesis, and pollen wall. The number of expressed genes, their function and expression profiles were all significantly correlated with anther developmental processes. Overall comparisons of anther and pollen transcriptomes with those of rice and Arabidopsis together with the expression profiles of homologs of known anther-expressed genes, revealed conserved patterns and also divergence. The divergence may reflect taxon-specific differences in gene expression, the use RNA-seq as a more sensitive methodology, variation in tissue composition and sampling strategies. Given the lack of genomic sequence, this study succeeded in assigning putative identity to a significant proportion of anther-expressed genes and genes relevant to tapetum and pollen development in H. patens. The anther transcriptome revealed a molecular distinction between developmental stages, serving as a resource to unravel the functions of genes involved in anther development in H. patens and informing the analysis of other members of the Rubiaceae.

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Morphological and Ultrastructural Diversity of Orbicules in Gentianaceae

Cited by 23 publications

References 31 publications

The manifold characters of orbicules: structural diversity, systematic significance, and vectors for allergens

The manifold characters of orbicules: structural diversity, systematic significance, and vectors for allergens

Phylogenetic signal of orbicules at family level: Rubiaceae as case study

Transcriptome Analysis of Hamelia patens (Rubiaceae) Anthers Reveals Candidate Genes for Tapetum and Pollen Wall Development

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