LIR1 Controls Light-regulated LFNR Complex Attachment With Plant Thlakoid

Genes orthologous to LIR1 (Light induced Rice gene) are found in many higher plant species. LIR1 was originally named based on its light-induced transcriptional activity. However, its physiological role and molecular mechanism remain unknown. Previously, unpublished data in our lab showed that light could trigger the degradation of OsLIRl protein and that the degradation rate is correlated with light intensity in rice. We further found that OsLIRl and OsLFNR (Leaf-type Ferredoxin-NADP+ oxidoreductase) interacted with each other and co-localized in various compartments inside the chloroplast, including the thylakoid membrane, stroma, and inner envelope membrane.In this thesis, I constructed rice Oslirl mutant by CRISPR-Cas system and characterized Arabidopsis Atlirl T-DNA insertional mutant. By separating different chloroplast subfraction and performing both SDS-PAGE and blue native PAGE, compared with wild type, I detected that much less LFNR complex was associated with the thylakoids in both Oslirl and Atlirl mutant, suggesting that LIR1 might play a role in attachment of the complex to the thylakoid membranes. The difference between these two species is that Oslirl mutant exhibited decreased electron transfer rate, photosynthesis rate and growth whereas Atlirl mutant didn't show obvious growth phenotype.Together with previous unpublished data in our lab, we concluded that LIR1 is a novel LFNR interacting partner and mainly affect LFNR complex attachment with thylakoids. Meanwhile, the LIR1 degradation system represents a novel mechanism on light-controlled LFNR allocation. Moreover, we found that decreased LFNR complex attachment with thylakoids would impair photosynthesis and growth in rice whereas not obvious in Arabidopsis.