Knockout mutants of Arabidopsis thaliana beta-galactosidase. Modifications in the cell wall saccharides and enzymatic activities

This work studied the six beta-galactosidases (BGALs) of the subfamily a1 of Arabidopsis, that have been proposed to play important roles in the cell wall remodelling during plant development, although their precise functions are still unknown. Knockout mutants bgal1, bgal2, bgal3, bgal4, bgal5, and bgal12 of Arabidopsis and their wild type (WT) plants were analysed to determine their morphology and composition of their cell walls. The gas chromatography and the Fourier transform infrared spectroscopy revealed differences between the mutants and their WT such as in the proportions of glucose, galactose, or xylose in bgal2 and bgal4 and in cell walls polysaccharides in bgal1, bgal3, and bgal5. However, these slight changes did not result in morphological variations during plant development. None of the mutant seedlings displayed a clear reduction in beta(1,4)-galactan content, analysed by immunolocalization. The absence of significant phenotypic changes in the beta-galactosidase subfamily a1 mutants could indicate possible beta-galactosidases functional redundancy. Future studies will focus on the construction of multiple mutants that help to establish the precise function of each member of the beta-galactosidase subfamily a1.