Driouich, Azeddine

Kiefer-Meyer, Marie-Christine

Lehner, Arnaud

Lerouge, Patrice

Leroux, Christelle

Mollet, Jean-Claude

Pelloux, Jérôme

English

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HAL Id: hal-02082495
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A new model depicting the role of PME during
dehydration and germination of pollen grain
Christelle Leroux, Arnaud Lehner, Marie-Christine Kiefer-Meyer, Jérôme
Pelloux, Azeddine Driouich, Patrice Lerouge, Jean-Claude Mollet
To cite this version:
Christelle Leroux, Arnaud Lehner, Marie-Christine Kiefer-Meyer, Jérôme Pelloux, Azeddine Driouich,
et al.. A new model depicting the role of PME during dehydration and germination of pollen grain.
Colloque Grands Réseaux de Recherche, Nov 2012, Rouen, France. ￿hal-02082495￿
A new model depicting the role of PME during 
dehydration and germination of pollen grain.  
Leroux C¹, Lehner A¹, Kiefer-Meyer MC¹, Pelloux J ², Driouich A¹, Lerouge P¹ & Mollet JC¹ 
What are the roles of PMEs during pollen dehydration, imbibition and germination? 
Figure 2. RT-PCR amplification of 
PPME1 and PME48 transcripts in wild 
type pollen grains, imbibed pollen 
grains and pollen tubes. ACT12 and 
TUB4 have been used as positive 
controls. 
I. During sexual plant reproduction, pollen germination and pollen 
tube elongation in the pistil are essential for delivering sperm cells to 
the ovule (Fig. 1, a-e). 
Figure 1. Scanning Electron Micrographs of 
unpollinated pistil (a), stamen (b) and pollinated 
pistil (c) of the model plant Arabidopsis thaliana. d, 
Aniline blue staining of pollen tubes growing 
through the female tissue. Pollen tubes that have 
reached the ovule are marked with an *. e, Scanning 
Electron Micrograph of a germinated pollen grain on 
the stigma. f, Schematic representation of a 
transversal section of a pollen grain. Pg, pollen grain, 
pt, pollen tube, sp cell, sperm cell, veg n, vegetative 
nucleus. 
100 µm 100 µm 
100 µm 100 µm 
a b 
c d e 
Stigma 
Style 
Ovary 
Anther 
Filament 
Pollen 
grains 
pg 
pt 
pg 
Pollen 
tubes 
ovule ovule 
ovule 
* * 
* 
veg n 
sp cell 
sp cell 
Plasma membrane 
Intine 
Exine 
Aperture 
f 
, PME may be secreted in the intine during the 
dehydration and start demethylesterifying HG, 
randomly (a) or upon block wise actions (b). In 
dry grain, intine is weakly methylesterified.  
 
, imbibition of pollen grain is enhanced by the 
hydrophilic weakly methylesterified HG.  
 
, Calcium influx in the pollen grain may originate 
from the expulsion of Ca2+ from the pectate gel (b) 
thus weakening the mechanical properties of the 
intine that may break under turgor pressure (b).  
 
Alternatively, the randomly demethylesterified HG 
of intine may be degraded by polygalacturonases 
(a) leading to the degradation of the intine wall 
(a).  
 
, Pollen tube germination.  
III. Mutants for PME48 and PPME1 germinated very slowly, 
13h to reach 50% of germination (T50) compared to 2h for 
the wild type. Mutants presented phenotypes with two 
tubes emerging from the grain. 
 
IV. Immunodetection of highly methylesterified HG showed 
that intine was more methylesterified in the mutants than in 
the wild type. 
II. Two PME, PPME1 and PME48 are strongly expressed in 
dry pollen grain (PG) and slightly expressed in imbibed PG 
and pollen tube (Fig.2) 
line T50
(h)
phenotype Immunodetection of highly
methylesterified HGs
Wild type 2
pme48 -/-
KO for 
PME48
13
ppme1-/-
KO for 
PPME1
13
*
*
*
*
*
*
*
*
20 µm
20 µm
20 µm
Pollen grain contains two sperm cells and a vegetative cell limited by 
the exine, the intine and the plasma membrane (Fig.1, f). The intine is 
composed of complex polysaccharides including homogalacturonans 
(HGs) which are secreted in the cell wall in a highly methylesterified 
form. Demethylesterification of HGs is catalyzed in the cell wall by 
pectin methylesterases (PMEs). 
HG, homogalacturonans, pm, plasma membrane, Sp cells, sperm cells, Veg n, vegetative nucleus  
 ¹ Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, UPRES-EA 4358, IRIB, Université de Rouen, 76821 Mont Saint-Aignan Cedex, France.  
 ² Biologie des Plantes Innovation, UPRES-EA 3900,  Université de Picardie-Jules Verne, 80039 Amiens, France. 


A new model depicting the role of PME during dehydration and germination of pollen grain

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A new model depicting the role of PME during dehydration and germination of pollen grain

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