Hydrogen peroxide facilitates Arabidopsis seedling establishment by interacting with light signalling pathway in the...

Light is essential for the plant establishment. Arabidopsis seedlings germinated in the dark cannot grow leaf and only have closed cotyledons. However, exogenous application of H₂ O₂ can induce leaves (establishment) in the dark. Comparative transcriptomic analysis revealed that light-responsive genes were activated by H₂ O₂ treatment. These genes are functionally correlated with photosynthesis, photorespiration, and components of photosystem, such as antenna proteins and light-harvesting chlorophyll proteins. We further found that application of H₂ O₂ facilitates cell cycle by accelerating G₂ -M checkpoint transition in shoot apical meristem. Phytochrome-mediated light signalling pathway was also involved in the H₂ O₂ -facilitated establishment process. The constitutive photomorphogenesis 1 and phytochrome interacting factor 3 proteins were shown to be down-regulated by H₂ O₂ treatment and accordingly removed their inhibitory effects on photomorphogenesis in the dark. The crosstalk between oxidation and light signal pathways explains the mechanism that H₂ O₂ regulates plant dark establishment. The endogenous photorespiratory H₂ O₂ production was mimicked by overexpression of glycolate oxidase genes and supplement of substrate glycolate. As expected, seedling establishment was also induced by the endogenously produced H₂ O₂ under dark condition. These findings also suggest that photorespiratory H₂ O₂ production is at least partially involved in postgermination establishment.