Drought and Salinity Alter Adaptive Molecular Response in Two Genetically unlike Egyptian Rice Cultivars

Egypt, the largest rice producer in the near east and North Africa, reached the point where the insufficient irrigation water (drought) and its low quality (saline) imposed serious limitations on rice production. Understanding molecular adaptive mechanisms through studying the expression profile of wide range of different stress-marker genes can consolidate breeding programs aimed to develop certain rice varieties capable of fitting in challenging agro-ecosystems. Rice is notoriously sensitive to drought and salinity but there is variation within examined rice varieties represented in two genetically unlike Egyptian rice commercial cultivars: Sakha 106 (Japonica) and Giza 179 (Indica/Japonica). The two Egyptian rice genotypes were submitted to osmotically equivalent doses of drought (mimicked by mannitol) and/or salinity (triggered by NaCl). The observed significant alternations in the transcriptional response among 14 stress-related genes displayed a genotype dependent and stress specific pattern. The expected knowledge might enhance the background about how rice plants differ in sensing and restoring its adaptive mechanisms in response to drought and salinity, two kind of stresses that frequently co-occur in the Egyptian agricultural environment. KEYWORDS: Rice, drought, salinity, japonica, indica, stress-marker genes, quantitative PCR