Homepage

 

Role of pectin in pollen tube cell adhesion and growth

 

Principal Investigator: Jean Claude Mollet


Participants: Arnaud Lehner

PhD students: Ferdousse Laggoun, Jeremy Dehors

Project:

During pollination of Arabidopsis, following the initial adhesion of the pollen grains on the stigma, pollen grains germinate; pollen tubes grow within the specialized extracellular matrix (ECM) of the pistil transmitting tract (TT) guiding their progressions to theovary. During their long journey, adhesion of pollen tube cell wall with the ECM of the TT in the female tissues was observed (Lennon et al., 1998, Palanivelu et al., 2003) but the significance of this event in pollen tube growth and guidance is not known. Pollen tube is a unique model of fast tip-localized expanding single semi-autonomous cell that can be studied in vivo and in vitro conditions. Our objective is to study the biosynthesis and remodelling of the pollen tube cell wall and the implication of cell wall glycomolecules in pollen tube growth and adhesion. As a first step, we have recently characterized the cell wall structure of Arabidopsis pollen tube cell wall (Dardelle et al., 2010, Lehner et al., 2010) and developed an in vitro pollen tube adhesion assay using a pectic matrix similar to that established for lily (Mollet et al., 2000). Our next step is to screen, via chemical genetic approach, a chemical library (CERMN, Caen) and select the compounds able to disturb pollen tube growth, pollen tube morphology and adhesion. Selected compounds will be tested at various concentrations for reduction or increase of the phenotypes. The effect of the compound on the pollen tubes will be investigated at the cellular and sub-cellular levels for modification of cell wall polymer localization compared to untreated samples with the ultimate goal being the identification of the target(s) of the compound.

(A) Mature Arabidopsis flower,
(B) Pollinated stigma of Arabidopsis (stained with decolorized aniline blue for callose),
(C) 3h-old in vitro liquid grown Arabidopsis pollen tube,
(D) 16h-old in vitro liquid grown Arabidopsis pollen tubes stained with calcofluor white showing periodic callose plug deposition within the tubes to maintain the vegetative cell at the tip region.