Abstract

The aim of this study was to quantify the expression of the SalT, LTP-Plant, CDPK and PP1 genes, described as responsive to salinity in rice genotypes, describe the promoter region of these genes and identify possible cis-elements that may be involved in the induction of gene expression under salinity. The cultivars BRS Bojuru (tolerant) and BRS Agrisul (sensitive) were subjected to 0, 12, 24, 36 and 48 h of exposure to salt. For the analysis of qRT-PCR, two detoxification/defense genes and two cell signal transduction genes were selected. In the identification of cis-elements, a region spanning 1.000 bp in the promoter region of genes was analyzed. The Os01g0348900-SalT gene presented an increase in quantification of the relative expression (QR) of 2.081 times in the sensitive and 63.7 times in the tolerant cultivar. The Os03g0251000-LTP gene showed a contrasting increase of the expression between the cultivars BRS Agrisul (QR = 11.0) and BRS Bojuru (QR = 1.54). The genes Os03g0688300-CDPK and Os02g0820000-PP1 apparently do not show response to salinity, since in most treatments, the QR values were lower than the control. Thirty-eight cis-elements distributed in the four analyzed genes were identified. Of these, six were found only in the Os01g0348900-SalT gene promoter, suggesting a possible involvement of these cis-elements in the induction of expression of this gene under salinity. Based on these results, it can be concluded that these genes do not maintain a direct relation with salinity tolerance, but with mechanisms that allow acclimation to this condition.

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