Characterization of many osmotic stress-induced genes has greatly cont
ributed to the understanding of the physiological responses of plant c
ells to osmotic stress at the molecular level. In this study we constr
ucted a subtraction library and generated 15 salt stress-inducible EST
s from this library to use as molecular markers that reflect the cellu
lar responses to salt stress responses in Arabidopsis. The sequence an
alysis showed that 5 salt stress-inducible ESTs were identical to prev
iously identified genes in Arabidopsis, 6 cDNAs were homologous to kno
wn genes found in plants as well as yeast, and 4 cDNAs were new genes.
To confirm that expression of these clones are induced by salt stress
, we carried out Northern blot analysis. When we examined for 15 cDNA
clones, they were indeed induced by NaCl treatment. The induction leve
l was variable among these genes ranging from approximately 2-fold to
more than 50-fold. Also, Northern blot analysis revealed that these ge
nes can be divided into three different induction patterns: early indu
ction, late induction, and continuous induction.