Alteration ofArabidopsis SLAC1promoterand its association with natural variationin drought tolerance

摘要

Natural variation for drought tolerance is a major issue in adaptation and geographic distribution of terrestrial plants.Despite the importance, little is known about the genes and molecular mechanisms that determine its naturallyoccurring diversity.We analyzed the intraspecific drought tolerance variation between 2 accessions ofArabidopsisthaliana, Columbia (Col)-0 and Wassilewskija (Ws)-2. Measurement of weight loss in detached seedlings demonstrated aclear difference between drought-tolerant Col-0 and drought-sensitive Ws-2. They also differed in their stomatalresponse under drought condition. Using a quantitative genetic approach, we found a significant quantitative locus onchromosome 1. Surveying in the locus, we extrapolated that theSLAC1gene, which is associated with stomatal closure,was likely responsible for the difference of drought tolerance. Comparison of their nucleotide and amino acidsequences revealed that there were few differences in regions encodingSLAC1protein but was a large deletion inSLAC1promoter of Ws-2. Histochemical GUS staining showed that theSLAC1expressed dominantly in guard cells ofCol-0, but did less in guard cells of Ws-2. Quantitative PCR analysis also showed that transcript level ofSLAC1in guardcells was higher in Col-0 than in Ws-2. TheSLAC1transcription analyses indicate low accumulation ofSLAC1in guardcells of Ws-2. When taken together, our results suggest that the low drought tolerance of Ws-2 was associated with thedeletion of the promoter region of Ws-2SLAC1.