ANALYSIS OF PHYSIOLOGICAL CHARACTERISTICS OF ABSCISIC ACID SENSITIVITY AND SALT RESISTANCE IN ARABIDOPSIS ANAC MUTANTS (ANAC019, ANAC072 AND ANAC055)

This study was carried out to investigate the sensitivity to abscisic acid (ABA) and the resistance to salt of homologous ANAC (Arabidopsis thaliana NAM/ATAF/CUC protein) mutants of Arabidopsis, namely anac019, anac072 and anac055. Three Arabidopsis mutants were identified by a genome and gene expression approach before carrying out any physiological experiments. Multiple sequence alignment of the amino acids of NAG genes showed that the ANAC proteins share the highest degree of homology with other proteins of the ATAF subfamily. The three physical signs of seed germination rate, cotyledon greening and root growth of anac019 were lower compared to the WT (wild type) under different concentrations of ABA. However, for anac055 these signs were higher, indicating insensitivity to ABA. In tests of root length and cotyledon greening, anac072 was sensitive to ABA, however the germination rates were reversed. In the survival rate and the chlorophyll content experiments, ANAC mutants showed lower resistance to salt stress than WT under high salt treatment. In conclusion, the three homologous genes of Arabidopsis (ANAC019, ANAC072 and ANAC055) may play synergistic or antagonistic roles in ABA signaling and ionic osmotic stress.