The cell wall-localized atypical {beta}-1,3 glucanase ZERZAUST controls tissue morphogenesis in Arabidopsis thaliana [RESEARCH ARTICLE]

Prasad Vaddepalli, Lynette Fulton, Jennifer Wieland, Katrin Wassmer, Milena Schaeffer, Stefanie Ranf, and Kay Schneitz

Orchestration of cellular behavior in plant organogenesis requires integration of intercellular communication and cell wall dynamics. The underlying signaling mechanisms are poorly understood. Tissue morphogenesis in Arabidopsis depends on the receptor-like kinase STRUBBELIG. Mutations in ZERZAUST were previously shown to result in a strubbelig-like mutant phenotype. Here we report on the molecular identification and functional characterization of ZERZAUST. We show that ZERZAUST encodes a putative GPI-anchored β-1,3 glucanase suggested to degrade the cell wall polymer callose. However, a combination of in vitro, cell biological and genetic experiments indicate that ZERZAUST is not involved in the regulation of callose accumulation. Nonetheless, Fourier-transformed infrared-spectroscopy revealed that zerzaust mutants show defects in cell wall composition. Furthermore, the results indicate that ZERZAUST represents a mobile apoplastic protein, and that its carbohydrate binding module family 43 domain is required for proper subcellular localization and function whereas its GPI anchor is dispensable. Our collective data reveal that the atypical β-1,3 glucanase ZERZAUST acts in a non-cell autonomous manner and is required for cell wall organization during tissue morphogenesis.

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