The Study of Functional Groups and Changes in Genes Expression Pattern of Rice (C3) and Maize (C4) under Drought Stress using Microarray Data Analysis

Drought is one of the major environmental stresses that greatly affects growth and development of plants. The plants reaction against this stress is associated with showing massive changes in complex gene networks. In the present study, the changes of gene expression patterns in two sensitive and tolerant genotypes of rice (as C3 plant) and maize (as C4 plant) were investigated using maize genome arrays containing 17,734 probe sets and the rice genome containing 57/381 probe set. The microarray data were taken from the GEO/NCBI database on both stress and control conditions to identify the genes involved in responses to the stress. The results indicated that 1861 (10.49%) and 1753 (8.9%) genes in the sensitive and tolerant maize, respectively, and 9252 (16%) and 7971 (13.8%) genes in the sensitive and tolerant rice, respectively, changed significantly after drought stress at the level of one percent. From of these genes, 1012 and 175 genes in the sensitive and tolerant genotype leaf of rice and maize, were significantly up-regulated, respectively. The Venn diagram showed that 663 genes of rice and 158 genes of maize, have significantly down-regulated. Rice plant, as a C3 plant, showed five times wider reaction to drought stress in compared with maize plant, as a C4 plant. The functional grouping of the up-regulated genes in two species revealed that functional group of ribosomal proteins and phosphatases in maize plant have the most abundant categories, whereas the functional groups of metal-binding, stress response, response to biological stimuli and signals in rice plant contained the highest percentage of the genes.