Jeudi 11 avril 2019
Salle 106 (Cœur d’Ecole) à 14h00
Control of Arabidopsis root hair growth by auxin and the receptor-like kinase ERULUS
( IMPRES, Biology Department, University of Antwerp, 2020 Antwerpen, Belgiumb Plant Biochemistry & Biotechnology Lab, Department of Agriculture, Technological Educational Institute of Crete, Stavromenos PC 71410, Heraklion, Crete, Greece)
Root Hair (RH) growth is an auxin-controlled process which depends on modification of the apical cell wall (CW). We identified ERULUS, a plasma membrane receptor-like kinase whose expression is regulated by the AUXIN RESPONSE FACTORs 7&19 (ARF7&19). Eru RHs are slow growing, short and bulged. ERU regulates CW pectin dynamics, likely by changing apoplastic pH through FERONIA/H+-ATPase2.
Next, we investigated how auxin controls RH morphogenesis upstream of ERU. ERU is a putative target of the core RH transcription factors RSL4/RSL2. ChIP-qPCR and transcriptome analysis of WT and arf7arf19 auxin-treated roots revealed that RSL4 is also a direct target of ARF7/19. In addition, when auxin signalling is blocked or when RSL4/RSL2 expression is absent, RH formation is abolished. Using promERU::GFP as a proxy (a target of RSL4) we confirmed that genes that function downstream of RSL4/RSL2 are only expressed when both RSL2/RSL4 and active ARFs are present. This strongly suggests that RSLs and ARFs need to interact to regulate downstream gene expressions.
We conclude that auxin (1) regulates all stages of RH development, (2) needs RSL4/RSL2 to express RH growth genes, and (3) controls ERULUS to fine-tune RH growth by CW integrity sensing and changing CW pectin dynamics.
Contact : Nadine Paris