The ultraviolet- B response of Arabidopsis thaliana hypocotyls is regulated by nitric oxide via the UVR8 signaling pathway

LATORRE, LUCAS; FERNÁNDEZ, MARÍA BELÉN; CASSIA, RAUL

Congreso; SAIB 2022; 2022

The photomorphogenic response is triggered by sensing light and involves adaptative changes that prepare the plant to optimize photosynthesis under environmental changes. Ultraviolet- B (UV-B) radiation has dual effects on these organisms: while high doses induce stress, low doses act as a regulatory signal. The UV-B receptor UVR8 is a master regulator of several of these responses. It was reported that both UVR8 and the gasotransmitter Nitric oxide (NO) are involved in the hypocotyl shortening. This work aimed to find if the NO participates in the UVR8-regulated photomorphogenesis. Results obtained showed that UV-B induced the accumulation of NO in A. thaliana wild type (wt) hypocotyls, but not in the lines lacking UVR8 (uvr8-1). The use of the NO donor S-nitrosoglutathione (GSNO), restored the inhibition of hypocotyl elongation caused by UV-B irradiation in uvr8-1 mutants. In this sense, the AtNOA1 mutant line with reduced levels of NO, partially inhibit hypocotyl elongation when grown with UV-B. In accordance, RT- qPCR analysis showed that GSNO treatment overlaps the effect of UV-B irradiation, downregulating cell elongation-related (PRE5, PRE1, HBI1) and gibberellic acid-related genes (GA3oxi1, GA2oxi1). Furthermore, the irradiation of GSNO-pretreated seedlings failed to induce the expression of cyclobutane pyrimidine dimers (CPDs) photolyase (PHR1) which correlated with increased levels of CPDs, the major type of UV-B induced DNA damage. Moreover, the accumulation of anthocyanins and chlorophyll induced by GSNO in wt hypocotyls was impaired in uvr8-1. Altogether, these results suggest a key role of NO in the complex regulatory network of UV-B-induced photomorphogenesis.