OsCUL3a-Associated Molecular Switches Have Functions in Cell Metabolism, Cell Death, and Disease Resistance
Zhiqiang Gao, Qunen Liu, Yingxin Zhang, Daibo Chen, Xiaodeng Zhan, Chenwei Deng, Shihua Cheng, Liyong Cao
Abstract
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.