Nitric oxide and auxin regulate root meristem during gravitropism in Arabidopsis thaliana

VAZQUEZ M. MAGDALENA, ; GOLDY CAMILA, ; CASALONGUE, CA; PARIS, R,; RODRÍGUEZ RAMIRO,

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress,; 2019

SAIB

ST-C02 NITRIC OXIDE AND AUXIN REGULATE ROOT MERISTEM DURING GRAVITROPISM IN ARABIDOPSIS THALIANA Vazquez MM1, Goldy C2, Rodríguez R2,3, Casalongué C1, París R1. 1 IIB-CONICET-UNMdP, Funes 3250, 4to nivel, Mar del Plata, Argentina, 2 Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), 3 Centro de Estudios Interdisciplinarios (UNR). E-mail: vazquezmaguie@gmail.com Nitric oxide (NO) is a gaseous redox-active molecule with a role in different physiological auxin-mediated processes including gravitropism. Roots bend in response to gravity by the formation of an asymmetric distribution auxin pattern between the upper and the lower sides of elongation and meristematic zones of the root. However, the mechanisms by which auxin and NO interplay during the gravitropic response are not still fully understood. In this work, we focus on deciphering the spatio-temporal pattern of auxin and the functional contribution of NO in the meristematic cells during early events of gravitropism in Arabidopsis roots. In Arabidopsis thaliana, the meristematic root zone comprises all the cells that undergo mitotic divisions and stretches longitudinally up to 350 μm from the quiescent center (QC). By using the auxin sensor DII-VENUS we demonstrated that within the first 30 min of a 90º gravity stimulus, the hormone was distributed asymmetrically between the upper and lower sides in lateral root cap, epidermal and cortical cells extending up to 120 μm from the QC in the meristematic region of the root. In addition, we demonstrated that NO is accumulated asymmetrically between the lower and upper sides of the root meristem. Next, we measured the length of individual epidermal cells along the meristematic zone. Scavenging of endogenous NO affects the characteristic epidermal cell length observed during the gravitropic response. Therefore, we hypothesize that the disturbance of the interaction between auxin and NO signals could affect the meristematic cell size pattern which leads to an agravitropic response in Arabidopsis roots. Since cyclins play a vital role in controlling cell cycle progress, one of our current challenges is to