Pollination drops as dynamic apoplastic secretions

Coulter, Andrea; Poulis, Brett A. D.; Aderkas, Patrick von

doi:10.1016/j.flora.2012.06.004

Cited by 23 publications

(37 citation statements)

References 97 publications

(138 reference statements)

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“…AGPs have been found in the stigma of several early divergent angiosperms ( Prychid et al, 2011 ; Costa et al, 2013 ; Losada et al, 2014 ), and recent work shows that they also mark stigmatic receptivity in Magnolia ( Losada et al, 2014 ), strongly suggesting that the secretion of AGPs could well be a conserved process in flowering plants marking stigmatic receptivity. Interestingly, AGPs were also reported in the pollination drop of the gymnosperm Taxus x media ( Coulter et al, 2012 ). Low-esterified homogalacturonans are also involved in the adhesion of the pollen to the stigma of angiosperms ( Mollet et al, 2000 ) and seem to be play a role also in pollen grain adhesion in the gymnosperm Larix decidua ( Rafińska et al, 2014 ).…”

Section: Changing the Meeting Placementioning

confidence: 93%

“…In gymnosperms, the pollination drop is a viscous liquid secretion produced by the ovule, usually by the nucellar tissue ( Gelbart and von Aderkas, 2002 ; Coulter et al, 2012 ), with the probable contribution of other tissues such as the megagametophyte and the integument ( Owens et al, 1998 ). The pollination drop is composed of carbohydrates, amino acids, and a miscellany of other compounds ( Gelbart and von Aderkas, 2002 ; Nepi et al, 2009 ; von Aderkas et al, 2015 ).…”

Section: Changing the Meeting Placementioning

confidence: 99%

“…In fact, in angiosperms pollen landing occurs in a highly specialized structure: the stigma. While several molecules such as surface esterases, arabinogalactan proteins (AGPs), low-esterified homogalaturonans, or glycoside hydrolases can be found in both stigma and pollination drops ( Coulter et al, 2012 ) and could be analogous ( Villar et al, 1984 ), the stigma represents a major evolutionary transition that provides adhesion, hydration, and germination media for the pollen grains ( Sanzol et al, 2003 ; Hiscock, 2008 ). A number of factors, such as reactive oxygen species (ROS; McInnis et al, 2006 ; Allen et al, 2011 ; Traverso et al, 2013 ; Serrano et al, 2015 ) commonly proposed to mediate cell–cell communication ( Gilroy et al, 2014 ), or surface esterases ( Hiscock et al, 2002 ) contribute to this receptivity.…”

Section: Changing the Meeting Placementioning

confidence: 99%

“…Low-esterified homogalacturonans are also involved in the adhesion of the pollen to the stigma of angiosperms ( Mollet et al, 2000 ) and seem to be play a role also in pollen grain adhesion in the gymnosperm Larix decidua ( Rafińska et al, 2014 ). Glycoside hydrolases that are required for cell wall elongation and, consequently, for pollen tube growth, are found in both the angiosperm stigmas and the gymnosperm pollination drop, but expansins that are also involved in cell wall elongation are only found in the stigma of angiosperms ( Coulter et al, 2012 ).…”

Section: Changing the Meeting Placementioning

confidence: 99%

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The Diversity of the Pollen Tube Pathway in Plants: Toward an Increasing Control by the Sporophyte

2016

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Plants, unlike animals, alternate multicellular diploid, and haploid generations in their life cycle. While this is widespread all along the plant kingdom, the size and autonomy of the diploid sporophyte and the haploid gametophyte generations vary along evolution. Vascular plants show an evolutionary trend toward a reduction of the gametophyte, reflected both in size and lifespan, together with an increasing dependence from the sporophyte. This has resulted in an overlooking of the importance of the gametophytic phase in the evolution of higher plants. This reliance on the sporophyte is most notorious along the pollen tube journey, where the male gametophytes have to travel a long way inside the sporophyte to reach the female gametophyte. Along evolution, there is a change in the scenery of the pollen tube pathway that favors pollen competition and selection. This trend, toward apparently making complicated what could be simple, appears to be related to an increasing control of the sporophyte over the gametophyte with implications for understanding plant evolution.

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Section: Changing the Meeting Placementioning

confidence: 93%

Section: Changing the Meeting Placementioning

confidence: 99%

Section: Changing the Meeting Placementioning

confidence: 99%

Section: Changing the Meeting Placementioning

confidence: 99%

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The Diversity of the Pollen Tube Pathway in Plants: Toward an Increasing Control by the Sporophyte

2016

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“…12 With the application of proteomics technologies, functional proteins have been detected in the PDs of several gymnosperms. [13][14][15] The proteins detected in PDs can be divided into five categories: (1) those involved in the modification of sugars, e.g., xylosidase and galactosidase, 13 (2) those serving a defense-like function, e.g., glucan-β-1,3-glucosidase, chitinase, and thaumatin-like protein, [14][15][16] (3) those associated with the freeze-proofing function, 17 (4) those associated with plant cell metabolism, e.g., peroxidase, 18 and (5) those capable of accelerating pollen tube growth, e.g., aspartyl protease and serine carboxypeptidase. 13 However, most studies investigating the proteins present in PDs have focused on conifers, whereas detailed analyses on non-conifer PDs in gymnosperms are lacking.…”

Section: Introductionmentioning

confidence: 99%

Constituent analysis and proteomic evaluation of ovular secretions inGinkgo biloba: not just a pollination medium

Cheng

Zhao

Jiang

et al. 2018

Plant Signaling & Behavior

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Pollination drop (PD) is a characteristic feature of major wind-pollinated gymnosperms and plays a vital role during the course of pollination, however, the composition and proteomic profile of PDs in Ginkgo biloba remain unclear. Through inductively coupled plasma mass spectrometry, we detected mineral elements in PDs, including calcium (Ca), sulfur (S), magnesium, boron, and potassium (K), among which S, Ca, and K were found at high levels. The total sugar concentration was approximately 5.908 mg/mL, which accounted for approximately 5.9% (mass ratio) of the PD. The sugars primarily consisted of fructose, glucose, and sucrose, of which the glucose level was highest, accounting for 57.6%, followed by fructose (37.1%) and sucrose (5.3%). We also used FTIR to validate the presence of sugars and proteins in PDs. Further proteomic analysis revealed that the PD contained calmodulin, α-L-arabinofuranosidase, β-D-xylosidase, superoxide dismutase, α-L-arabinosidase, glutathione S-transferase, histones, glycine-rich family protein, methionine synthase, and arabinogalactan, suggesting that proteins present in PDs of G. biloba play a critical role in the defense against external bacteria and facilitate germination and growth of the pollen tube. Our results suggest that PDs are not merely a medium to receive and transport pollen but may also play a more complex biological role in pollination and fertilization.

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True nectar or stigmatic secretion? Structural evidence elucidates an old controversy regarding nectaries in Anthurium

Paiva

Ballego-Campos

Gibernau

2021

American J of Botany

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Floral rewards are essential in understanding floral function and evolution of the relationships between flowers and pollinators. Whether sugars are present in stigmatic exudates in Anthurium and whether it has floral nectaries have remained controversial because of the scarcity of structural studies. To solve these questions, we investigated the floral anatomy of A. andraeanum to elucidate whether (1) tepals are secretory organs, (2) tepals possess a structurally recognizable nectary, and (3) tepalar secretion differs from stigmatic secretion. METHODS: Floral structure was assessed through light and electron microscopy of samples of immature, pistillate, and staminate flowers. The dynamics of the starch reserve was investigated using histochemical tests, and the sugar content in the floral exudates was assessed using thin-layer chromatography. RESULTS: Sugar analysis did not detect sucrose, glucose, or fructose in stigmatic secretions, but confirmed their presence in tepalar secretions. Stigmatic secretion was produced by secretory stigmatic papillae; tepalar exudates were produced by nonvascularized nectaries in the apex of tepals. These nectaries were characterized by modified stomata and cells with cytoplasm rich in organelles, and a high content of calcium oxalate crystals. CONCLUSIONS: Our results showed for the first time nectaries on tepals and true nectar secretion for A. andraeanum. Stigmatic secretion appears to be a distinct substance, and its often-reported sugar content seems to be a result of sample contamination. Nectar and stigmatic secretions have been often mistaken in other Anthurium species and deserve a revision for this genus.

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Pollination drops as dynamic apoplastic secretions

Cited by 23 publications

References 97 publications

The Diversity of the Pollen Tube Pathway in Plants: Toward an Increasing Control by the Sporophyte

The Diversity of the Pollen Tube Pathway in Plants: Toward an Increasing Control by the Sporophyte

Constituent analysis and proteomic evaluation of ovular secretions inGinkgo biloba: not just a pollination medium

True nectar or stigmatic secretion? Structural evidence elucidates an old controversy regarding nectaries in Anthurium

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