Analysis of participation of nitric oxide in cell wall changes related to root hair formation in Arabidopsis thaliana

Author(s)

Camila Fernandes Moro

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2016-01-22

Examining board members

Marcia Regina Braga; Rosy Mary dos Santos Isaias; Luciano Freschi; Carlos Takeshi Hotta; Marcos Silveira Buckeridge

• Advisor: Marcia Regina Braga; Ione Salgado

Abstract

During the root hair formation (RHF), major changes occur in the cell wall resulting in expansion of cell in apical region. This polarized growth is hormonal- and genetically regulated, and recent studies suggest the involvement of nitric oxide (?NO) in this process. To better understand the ?NO participation in cell wall changes during RHF, root hairless (rhd6) and hairy root (ttg) mutants of Arabidopsis thaliana were grown in culture medium containing S-nitrosoglutathione (GSNO a ?NO donor) or auxin (indole acetic acid) or auxin together with cPTIO (scavenger ?NO) or cPTIO. The control group was grown in culture medium containing only nutrients. After 4 or 5 days of germination, morphological analysis, in situ ?NO emission, immunolocalization assays, glycomic profile and RNA seq were performed. Roots of ttg produced more ?NO than rhd6, however, when the rhd6 was treated with auxin, RHF was observed followed by an increase of ?NO emission, similar to that visualized in ttg. In rhd6 treated with auxin, ?NO emission followed an alternating arrangement pattern with intense emission in trichoblasts rows while atrichoblasts remained weakly labeled, similar to WS-2 wild type. This suggests that ?NO is related to the RHF since hairy roots emited more ?NO than root hairless and auxin was able to induce RHF with an increase in ?NO emission in the rhd6 mutant. GSNO induced RHF mimicking the auxin effect. When auxin was provided simultaneously to cPTIO an opposite effect was observed. Yet, cPTIO reduced the number and lenght of root hairs in ttg indicating the importance of ?NO for cell elongation. These data indicate that ?NO induced chemical changes in cell wall during RHF in rhd6 due to recovery of gene expression related to biosynthesis and/or remodeling of its components through the auxin-mediated signaling pathway, in which ?NO appears to play a key role (AU)

• FAPESP's process: 11/13220-3 - Analysis of the involvment of nitric oxide in the cell wall changes related to root hair formation in Arabidopsis thaliana
• Grantee: Camila Fernandes Moro
• Support Opportunities: Scholarships in Brazil - Doctorate