Alteration of Arabidopsis SLAC1 promoter and its association with natural variation in drought tolerance

Surveying in the locus, we extrapolated that the SLAC1 gene, which is associated with stomatal closure, was likely responsible for the difference of drought tolerance. Comparison of their nucleotide and amino acid sequences revealed that there were few differences in regions encoding SLAC1 protein but was a large deletion in SLAC1 promoter of Ws-2. Histochemical GUS staining showed that the SLAC1 expressed dominantly in guard cells of Col-0, but did less in guard cells of Ws-2.

Quantitative PCR analysis also showed that transcript level of SLAC1 in guard cells was higher in Col-0 than in Ws-2. The SLAC1 transcription analyses indicate low accumulation of SLAC1 in guard cells of Ws-2. When taken together, our results suggest that the low drought tolerance of Ws-2 was associated with the deletion of the promoter region of Ws-2 SLAC1 .