Morphological, histological and ultrastructural changes in the olive pistil during flowering

Suárez, Cynthia; Castro, Antonio Jesús; Rapoport, Hava F.; Rodríguez-García, Marìa Isabel

doi:10.1007/s00497-012-0186-3

Cited by 29 publications

(25 citation statements)

References 51 publications

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“…17,19 Interestingly, the olive stigma exudate shows a manifest vesicular aspect at anthesis, and contains numerous vesicle-like particles in the size range (40-100 nm) expected for exosomes. 1,9 Therefore, a similar mechanism of secretion may also exist in the plant stigma in addition to the canonical ER-Golgi exocytic pathway, although this possibility needs to be further investigated.…”

Section: The Plant Stigma Exudatementioning

confidence: 99%

The plant stigma exudate

Rejón

Delalande

Schaeffer-Reiss

et al. 2014

Plant Signaling & Behavior

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D uring sexual reproduction, pollenperformance is greatly influenced by the female tissues. The stigma exudate, i.e., the extracellular secretion that covers the stigma outermost surface, has been usually regarded as a reservoir of water, secondary metabolites, cell wall precursors and compounds that serve as energy supply for rapid pollen tube growth. In an attempt to identify the proteins present in the stigma secretome, we performed a large-scale analysis in two species (Lilium longiflorum and Olea europaea) following a proteomicbased approach. The resulting data strongly suggest that the stigma exudate is not a mere storage site but also a biochemically active environment with a markedly catabolic nature. Thus, this secretion may modulate early pollen tube growth and contribute to the senescence of stigma after pollination. In addition, a putative cross-talk between genetic programs that regulate stress/defense and pollination responses in the stigma is also suggested. The stigma exudate might also functionally diverge between species on the basis on their ecology and the biochemical, morphological and anatomical features of their stigmas. Unexpectedly, we identified in both exudates some intracellular proteins, suggesting that a mechanism other than the canonical ER-Golgi exocytic pathway may exist in the stigma and contribute to exudate secretion.During sexual reproduction, pollen performance is greatly influenced by the biochemical, morphological and anatomical features of the female counterpart (i.e., the pistil). In some plants, the stigma outermost surface is coated by a secretion that is released by specialized cells called papillae. This extracellular fluid, the so-called stigma exudate, mostly contains water, sugars, lipids and proteins, 1 but other compounds such as phenols, amino acids, ROS/ RNS and Ca 2+ ions are also present in measurable amounts. [2][3][4][5] The picture of the stigma secretome remains fragmentary and only a few proteins have been identified and characterized so far. [6][7][8] In a recent publication, we performed a largescale protein profiling study of the stigma exudate in two plant species, namely Eastern lily (Lilium longiflorum) and olive (Olea europaea), that substantially differ in their taxonomical position, pistil morphology and anatomy, ecology and cultivation purposes. 9 Following a proteomic-based strategy, we identified 51 and 57 unique proteins in lily and olive, respectively, most of which are first described in this secretion. The resulting data shows that the complexity of the stigma exudate, in terms of protein diversity, is higher than initially expected. 10 Under a functional perspective, this secretion has often been regarded as a mere source of water for pollen hydration, and storage compounds for sustaining

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Section: The Plant Stigma Exudatementioning

confidence: 99%

The plant stigma exudate

Rejón

Delalande

Schaeffer-Reiss

et al. 2014

Plant Signaling & Behavior

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“…The ultrastructural characteristics of pistil cells influence stigma receptivity and pollen-stigma interactions [23]. Considering only one pistil and numerous pollen grains are developed simultaneously in one flower, stigma receptivity may have a prominent role during successful artificial hybridizations.…”

Section: Introductionmentioning

confidence: 99%

Identification of pre-fertilization reproductive barriers and the underlying cytological mechanism in crosses among three petal-types of Jasminum sambac and their relevance to phylogenetic relationships

Deng

Sun

et al. 2017

PLoS ONE

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Crosses among single-, double- and multi-petal jasmine cultivars (Jasminum sambac Aiton) are unable to easily generate hybrids. To identify the reproductive barriers restricting hybrid set, dynamic changes in jasmine pollen viability and pistil receptivity were compared at different flowering stages. Pollen-pistil interactions in six reciprocal crosses were also investigated to characterize pollen-stigma compatibility. Additionally, paraffin sections of pollinated embryo sacs were prepared for subsequent analyses of developmental status. Furthermore, pistil cell ultrastructural characteristics were observed to reveal cytological mechanism regulating pistil receptivity and the pollen-pistil interactions. We observed that pollen viability and stigma receptivity varied depending on petal phenotype and flowering stage and were easily lost during flowering. Different reciprocal crosses exhibited varied pollen-stigma compatibilities according to the pollen germination rates. Although some pollen grains germinated normally on maternal stigmas, the pollen tubes were arrested in the pistils and were unable to reach the ovaries. Additionally, the embryo sacs remained unfertilized until degenerating. Therefore, jasmine crosses are affected by pre-fertilization reproductive barriers. Low pollen fertility and poor stigma receptivity are detrimental to pollen germination and pollen-pistil compatibility, indicating they are two factors affecting hybrid set. Ultrastructural observation of the pistil cells revealed that cell death occurred during flowering. Thus, the early and rapid senescence of pistils is likely responsible for the decreased pistil receptivity and inhibited pollen tube growth. These findings may be relevant for future jasmine hybridizations. They provide new insights for the development of methods to overcome reproductive barriers and may also be useful for clarifying the phylogenetic relationships among jasmine cultivars with differing petal phenotypes.

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“…On wet stigmas, pollen grains land on an extracellular secretion called the stigmatic exudate [84,97]. In some species such as the olive tree, this secretion facilitates pollen hydration without direct contact with the papillary cells [97].…”

Section: Molecular and Biological Functions Of The Pollen Coat-assmentioning

confidence: 99%

“…In some species such as the olive tree, this secretion facilitates pollen hydration without direct contact with the papillary cells [97]. In tobacco, however, the pollen grain sinks through the exudate and establishes direct contact with the papillary cell wall and/or other grains [98].…”

Section: Molecular and Biological Functions Of The Pollen Coat-assmentioning

confidence: 99%

The Pollen Coat Proteome: At the Cutting Edge of Plant Reproduction

et al. 2016

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The tapetum is a single layer of secretory cells which encloses the anther locule and sustains pollen development and maturation. Upon apoptosis, the remnants of the tapetal cells, consisting mostly of lipids and proteins, fill the pits of the sculpted exine to form the bulk of the pollen coat. This extracellular matrix forms an impermeable barrier that protects the male gametophyte from water loss and UV light. It also aids pollen adhesion and hydration and retains small signaling compounds involved in pollen–stigma communication. In this study, we have updated the list of the pollen coat’s protein components and also discussed their functions in the context of sexual reproduction

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Morphological, histological and ultrastructural changes in the olive pistil during flowering

Cited by 29 publications

References 51 publications

The plant stigma exudate

The plant stigma exudate

Identification of pre-fertilization reproductive barriers and the underlying cytological mechanism in crosses among three petal-types of Jasminum sambac and their relevance to phylogenetic relationships

The Pollen Coat Proteome: At the Cutting Edge of Plant Reproduction

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