Pectins are the most abundant components in plant primary cell wall and the most heterogenous cell wall polysaccharides. The most common domain of pectins is homogalacturonan, built on a GalA backbone which can be methylesterfied and acetylated. The structure of homogalacturonan can be modified during plant development due to action of homogalacturonan modifying enzymes. As such, these enzymes play a key role in the maturation and degradation of homogalacturonans and therefore in the control of cell wall rheology. Pectin methylesterases (PMEs) can hydrolyze methyl groups from GalA residues, generating negatively charged groups and creating substrates for other HG-modifying enzymes that can hydrolyze pectins. As PMEs are encoded by a large multigenic family of 66 genes in Arabidopsis, this represents a major challenge for reverse genetic approaches. As an alternative; we chose the exogenous application of recombinant enzyme to study their effects during plant development. During this thesis, five plant (PME-32, PME-2, TT-PME, PME-41 and PME-20) and one fungal (VdPME) PMEs were studied. All proteins were heterogeneously produced in Pichia pastoris as active enzymes and their biochemical properties were compared. For three of them (PME-32, PME-20 and VdPME), their mode of action and their roles in planta were assessed at acidic and alkaline pH. Mode of action was determined using size exclusion chromatography coupled to mass spectrometry, while their roles in planta were assessed through exogenous application of the enzymes and analysis of the phenotypical consequences on dark-grown Arabidopsis thaliana seedlings. This overall showed that the mode of action between PME isoforms differ but appears difficult to predict on the basis of sequences. On the other hand, new approach based on electrostatic potential measurements gives promising results that could greatly facilitate understanding the variability within the PME family.