Abstract
We have applied an approach based on activation tagging in de-differentiated cells to Arabidopsis for identification of genes governing salt response, being designated "salt tolerant callus (stc)" genes (JSPP meeting, 2007; 2009). We identified 18 potential mutants exhibiting tolerance to 150 to 200 mM NaCl, among which to stc5 attention has been paid. Three insertion loci of T-DNA for activation have been found in stc5 by TAIL-PCR. In these loci, gene for an ABC transporter assigned to AtWBC27 expressed approx. 2 times higher without salt stress or 4 times higher with the stress in stc5 calli in comparison with those in the wild-type as revealed by real-time PCR. Knock-out (KO) lines of AtWBC27 (hereafter WBC27) were more sensitive to NaCl, as well as to KCl, KNO3 and LiCl. The KO lines were also sensitive to different levels of ABA, indicating that salt stress regulation by WBC27 may be linked to ABA signal. We have been developing over-expression lines to clarify the participation of WBC27 in salt tolerance. It is an intriguing question how WBC27 plays a role in a signal transduction network in salt stress and ABA response in Arabidopsis.
