Arabidopsis thaliana FIBRILLIN6 is involved in acclimation to moderate light stress and cadmium tolerance

By mining public co-expression databases, we have identified FBN6 as a photosynthesis-associated gene. FBN6 is located in thylakoids and plastoglobules, and its knock-out results in stunted plants characterized by slightly reduced chlorophyll contents, shorter roots and late flowering under long-day conditions. The delayed growth phenotype of fbn6-1 cannot be attributed to altered basic photosynthesis parameters or a reduced CO2 assimilation rate. FBN6 is also co-expressed with redox/ROS-associated genes, and we show that under moderate light stress, the primary leaves of fbn6 plants begin to bleach and contain enlarged plastoglobules. Furthermore, anthocyanin accumulation is reduced in fbn6 mutants. RNA-Seq and metabolomics analyses point to an altered sulfate assimilation leading to accumulation of reduced glutathione which in turn confers cadmium tolerance of fbn6 seedlings. Examination of differential gene expression in the Arabdidopsis thaliana fbn6-1 mutant compared to wild type in three replicates