Arabidopsis thaliana Mutant with T-DNA Insertion in the Flot1 (At5g25250) Gene Promotor Possesses Increased Resistance to NaCl

Abstract

Flotillin membrane proteins are involved in many cellular processes and physiological functions. However, these proteins’ participation in plant response to stresses remains poorly understood. In the present report, the possible involvement of flotillin Flot1 in Na+ and K+ homeostasis in cells under sodium chloride salinization of the medium was studied in Arabidopsis thaliana (L.) Heynh. For this purpose, the Flot1 gene transcription was analyzed in the roots and leaves of wild-type (WT) and flot1 mutant plants with a T-DNA insertion in the promoter using the quantitative Real Time-RT PCR (qRT-PCR). Along with this, a mutant phenotype was studied (growth characteristics, content of Na+ and K+ ions in organs, and ultrastructure of root cells) under normal conditions and in the presence of 100 mM NaCl in the culture medium. The mutation led to the activation of AtFlot1 expression, which was more noticeable in the roots during salinization. Under these conditions, the mutants had larger organ mass, lower Na+ content, and higher K+ content in organs than that of WT. The study of the ultrastructure of A. thaliana root cells in mutant plants showed more intensive formation of post-Golgi vesicles and multivesicular bodies (MVB) in the cytoplasm. In both mutant and WT plants, the presence of sodium chloride in the nutrient solution stimulated the formation of MVB and microvacuoles in the cytoplasm and fusion of the latters into larger structures. It is assumed that changes in the ultrastructure of root cells that are caused by mutation and salinization reflect the stimulation, respectively, of vesicular trafficking and biogenesis of vacuoles—processes involved in maintaining Na+ and K+ cell homeostasis.