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The knock-out of ARP3a gene affects F-actin cytoskeleton organization altering cellular tip growth, morphology and development in moss <i>Physcomitrella patens</i>
Auteur(s)
Finka, Andrija
Saidi, Younousse
Goloubinoff, Pierre
Zrÿd, Jean-Pierre
Schaefer, Didier G.
Date de parution
2008
In
Cell Motility and the Cytoskeleton, Wiley, 2008/65/10/769-784
Résumé
The seven subunit Arp2/3 complex is a highly conserved nucleation factor of actin microfilaments. We have isolated the genomic sequence encoding a putative Arp3a protein of the moss <i>Physcomitrella patens</i>. The disruption of this ARP3A gene by allele replacement has generated loss-of-function mutants displaying a complex developmental phenotype. The loss-of function of ARP3A gene results in shortened, almost cubic chloronemal cells displaying affected tip growth and lacking differentiation to caulonemal cells. In moss <i>arp3a</i> mutants, buds differentiate directly from chloronemata to form stunted leafy shoots having differentiated leaves similar to wild type. Yet, rhizoids never differentiate from stem epidermal cells. To characterize the F-actin organization in the <i>arp3a</i>-mutated cells, we disrupted ARP3A gene in the previously described HGT1 strain expressing conditionally the GFP-talin marker. In vivo observation of the F-actin cytoskeleton during <i>P. patens</i> development demonstrated that loss-of-function of Arp3a is associated with the disappearance of specific F-actin cortical structures associated with the establishment of localized cellular growth domains. Finally, we show that constitutive expression of the <i>P. patens</i> Arp3a and its <i>Arabidopsis thaliana</i> orthologs efficiently complement the mutated phenotype indicating a high degree of evolutionary conservation of the Arp3 function in land plants.
Identifiants
Type de publication
journal article
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