PP2A mediates lateral root development under NaCl-induced osmotic stress throughout auxin redistribution in Arabidopsis thaliana

Aim Auxin plays an important role in modulating root system architecture. The effect of salinity on root development has been extensively studied; however, evidence on how salinity affects lateral root development and its underlying molecular mechanism is scarce. Here, we analyzed the role of protein phosphatase PP2A activity in auxin redistribution during Arabidopsis root system adaptation under NaCl-induced osmotic stress. Method Arabidopsis Col-0 and DR5::UidA seedlings were grown in MS media containing NaCl alone or in combination with the auxin transport inhibitor naphthylphthalamic acid, the synthetic auxin alpha-Naphthaleneacetic acid or the phosphatase inhibitor Okadaic acid. After 8 days, primary root length and lateral root number in seedlings were quantified and the auxin distribution was analyzed. Results Promotion of primary root shortening and lateral root development induced by osmotic stress correlated with an increase in active auxin content and a >50 % reduction in protein phosphatase type 2A (PP2A) activity. Moreover, the observed effects on seedlings under osmotic stress are more pronounced with the PP2A inhibitor Okadaic acid. Conclusion Our data suggest PP2A is a positive regulator of osmotic stress-induced root system architecture modulation, involving auxin redistribution in Arabidopsis thaliana.