OsCUL3a-Associated Molecular Switches Have Functions in Cell Metabolism, Cell Death, and Disease Resistance

This study applies parallel reaction
monitoring (PRM) proteomics
and CRISPR-Cas9 mutagenesis to identify relationships between cell
metabolism, cell death, and disease resistance. In oscul3a (oscullin3a) mutants, OsCUL3a-associated molecular
switches are responsible for disrupted cell metabolism that leads
to increased total lipid content in rice grain, a late accumulation
of H2O2 in leaves, enhanced Xanthomonas
oryzae pv. oryzae disease
resistance, and suppressed panicle and first internode growth. In oscul3a mutants, PRM-confirmed upregulated molecular switch
proteins include lipoxygenases (CM-LOX1 and CM-LOX2), suggesting a
novel connection between ferroptosis and rice lesion mimic formation.
Rice immunity-associated proteins OsNPR1 and OsNPR3 were shown to
interact with each other and have opposing regulatory effects based
on the cell death phenotype of osnpr1/oscul3a and osnpr3/oscul3a double mutants.
Together, these results describe a network that regulates plant growth,
disease resistance, and grain quality that includes the E3 ligase
OsCUL3a, cell metabolism-associated molecular switches, and immunity
switches OsNPR1 and OsNPR3.