AtAzg1 is a high affinity purine cell importer of A. thaliana with a role in cytokinin mediated root development

HARTER, KLAUS; STRNAD MIROSLAV; MOURINO, VERÓNICA G.; FLÜGGE ULF-INGO; SCHUMACHER, BENJAMIN; TESSI, TOMÁS M.; DESIMONE, MARCELO; GREFEN, CHRISTOPHER; GRUBE, ESTHER

Capital Federal

Congreso; Reunión Conjunta De Sociedades De Biociencias; 2017

SAIB

To coordinate developmental processes plants have established a complex signalling system involving different hormones, including auxins and cytokinins (CK). Auxin research shows the importance of hormone transport to successfully drive morphogenetic processes. However, little is known about the transport of CKs. For many year our group has been studying the AtAZG transporter family. In vitro essays showed that AZGs are able to transport not only purines, but also a set of structurally similar compounds including CKs with high affinities. To further investigate the potential role of AZGs in CK transport, experiments in Arabidosis thaliana were performed. Plant overexpressing AZG1, took up significative more radiolabeled CKs from the media than wildtype (Wt) and knock-out (KO) plants. To investigate the expression of Azg1, a promoter fusion with GUS was constructed. Promoter activity was found in distinct plant organs, but was particularly intense in roots. Interestingly, Azg1 has a different expression pattern whether expressed in the main root meristem or in lateral root meristems. To address the subcellular localization, different reporters fusions (e.g. pU10::AZG1-GFP) showed that AZG1 is localized to the plasma membrane. If AZG1 is a physiologically important transporter, its lack should lead to a morphologic disorder. In this direction, two independent KOs, and two overexpressor (OE) lines are being described. First approaches, pointed out that KOs are partially insensitive to exogenous CKs and OEs are more sensitive (p>0,0001). To know how AZG1 expression could affect root architecture, different experiments were performed, and they suggest that Azg1 is an important gene in root development regulation. These results together support the hypothesis that AZG1 is a CKs transporter playing a role in hormonal regulation of root development.