Kinase MPK17 and the Peroxisome Division Factor PMD1 Influence Salt-induced Peroxisome Proliferation

Abstract

Peroxisomes are small organelles that house many oxidative reactions. Peroxisome proliferation is induced under multiple stress conditions, including salt stress; however, factors regulating this process are not well defined. We have identified a role for Arabidopsis () MAP KINASE17 (MPK17) in affecting peroxisome division in a manner that requires the known peroxisome division factor PEROXISOME AND MITOCHONDRIAL DIVISION FACTOR1 (PMD1). MPK17 and PMD1 are involved in peroxisome proliferation in response to NaCl stress. Additionally, we found that PMD1 is an actin-binding protein and that a functioning actin cytoskeleton is required for NaCl-induced peroxisome division. Our data suggest roles for MPK17 and PMD1 in influencing the numbers and cellular distribution of peroxisomes through the cytoskeleton-peroxisome connection. These findings expand our understanding of peroxisome division and potentially identify factors connecting the actin cytoskeleton and peroxisome proliferation.

A PEX5 missense allele preferentially disrupts PTS1 cargo import into Arabidopsis peroxisomes

“…Thus, in seedlings with functioning peroxisomes, IBA treatment confers high‐auxin phenotypes including reduced root and hypocotyl elongation (Strader et al., ; Zolman et al., ), and IBA‐resistance screens have uncovered genes needed for peroxisome biogenesis and function (reviewed in Bartel et al., ). As salt increases Arabidopsis peroxisome abundance (Fahy et al., ; Frick & Strader, ; Mitsuya et al., ), we reasoned that screening for IBA resistance in the presence of salt might uncover factors impacting salinity‐induced peroxisome proliferation. We therefore identified seedlings with elongated roots on normally inhibitory concentrations of IBA and NaCl.…”

Peroxisomes: versatile organelles with diverse roles in plants

“…The transcription of Arabidopsis PEX11b is induced by the HY5 HOMOLOG (HYH) transcription factor in response to light stimulation through phytochrome A (phyA), and repressed by another nuclear protein, Forkhead-Associated Domain Protein 3 (FHA3; Fig. 2) (Frick & Strader, 2017). Arabidopsis PEX11e is up-regulated by salt stress, and both PEX11e overexpression and salt stress can increase peroxisome number, but PEX11e overexpression does not improve salt tolerance (Mitsuya et al, 2010).…”

Peroxisome Function, Biogenesis, and Dynamics in Plants

“…Interestingly, salt-induced proliferation also requires MAP Kinase 17 (Frick and Strader, 2017), implying a role for phosphorylation in peroxisome proliferation.…”

“…pmd1 mutants display elongated mitochondria and larger and fewer peroxisomes than wild type (Aung and Hu, 2011). Like PEX11 (Mitsuya et al, 2010), PMD1 promotes peroxisome proliferation in response to salt (Frick and Strader, 2017), although this proliferation does not seem to impact Figure 2. Peroxisome dynamics.…”