Reduced growth temperature suppresses ribosome-related leaf abnormalities in Arabidopsis thaliana

Arabidopsis thaliana normally produces flat leaves, whereas impairment of ribosome biogenesis induces ribosomal stress and results in leaf abaxialization. When the as2-1 mutation is combined with ribosome biogenesis-related mutations, this phenotype is further enhanced, such that some leaves lose adaxial identity and develop into needle-like structures composed almost entirely of abaxial tissue. In ribosome biogenesis-related mutants, ribosomal stress is thought to arise, at least in part, because the amount of functional ribosomes becomes insufficient to support normal growth. In this study, I show that growth suppression under lower growth temperature conditions alleviates ribosomal stress. Ribosome biogenesis-related mutants carrying the as2-1 mutation, which produce needle-like leaves at high frequencies under normal conditions, showed a marked reduction in the frequency of needle-like leaves when grown at lower growth temperature. These results suggest that reduced growth under such temperature conditions lowers the cellular requirement for ribosomes relative to their limited supply and thereby may partially alleviate ribosomal stress in ribosome biogenesis-related mutants.