Functional dissection of the PEROXIN11 gene family in Arabidopsis

Peroxisomes are metabolic organelles in eukaryotes, whose proliferation is regulated by the PEROXIN 11 (PEX11) protein family. Arabidopsis (Arabidopsis thaliana) contains five PEX11 genes that show phylogenetic divergence and distinct expression patterns, but their individual functions remain unclear. Here, we generated a series of higher-order null mutants of the Arabidopsis PEX11 genes. The combined mutation of all PEX11 members within each lineage caused no obvious growth or metabolic defects, pointing to functional redundancy throughout the entire family. However, the pex11abcd quadruple mutant showed impaired fatty acid β-oxidation and photorespiration, along with significantly reduced peroxisome abundance. The pex11abcde quintuple mutant failed to germinate unless its seed coats were manually removed and showed seedling mortality after germination. The results demonstrate that the functions of certain PEX11 proteins in Arabidopsis depend primarily on gene dosage rather than paralog specificity, providing insight into the roles of specific members of this family in maintaining peroxisome abundance and plant viability.