Microarray analysis of transcriptional responses to alkali stress in two rice genotypes

To investigate possible genetic basis of alkali tolerance in rice, we generated an introgressed rice line (K83) with significantly enhanced tolerance to alkali stress than its recipient parental cultivar (Jijing88). By using microarray analysis, we examined global gene expression profiles in K83 and Jijing88, found more than 1,200 genes were constitutively differentially expressed in K83 compared with Jijing88, with 572 up- and 654 down-regulated. Upon alkali treatment, a total of 347 genes in K83 were found up- and 156 down-regulated in K83, compared with 591 and 187 respectively in Jijing88. Seven-day-old uniform-sized seedlings grown in hydroponic medium were transferred to fresh hydroponic medium alone or containing 50 mM alkali salts. Shoots were harvested 24 h after transfer and 10 shoots were pooled for microarray analysis.