Comparative Transcriptional Profiling of Two Rice Genotypes, FR13A and Goda Heenati, Under Submergence Stress

Most rice (Oryza sativa L.) cultivars die within several days of complete submergence, but some indica cultivars, such as FR13A, can survive up to 2 weeks of complete submergence. In FR13A, a major quantitative trait locus (QTL), named Sub1, provides mature plants with submergence tolerance. However, the Sub1 locus can not confer flooding tolerance during germination to FR13A. Another indica cultivar, Goda Heenati, shows both tolerance to flooding during germination and submergence in mature plants. It was once reported that submergence tolerance in FR13A and Goda Heenati cultivars was controlled by their respective genetic locus. These evidences indicate that tolerance to submergence in these two cultivars may involve differential mechanisms. To gain insight into their putatively differential responses to submergence stress, the Agilent rice genome 4×44 K oligonucleotide microarray was used to explore the transcriptome of FR13A and Goda Heenati under control and submergence-stressed conditions. Two-way ANOVA analysis with Benjamini-Hochberg false discovery rate demonstrated that at an overall P＜0.01 level, 2810, 8207, and 4 probes were significantly regulated for genotype, treatment, and genotype×treatment interaction, respectively. To identify statistically significant differentially expressed genes, a combined criterion of 2-fold or more change and unpaired t-test P value < 0.01 was uesd for both FR13A and Goda Heenati. A total of 504 probes were up-regulated and 592 probes were down-regulated in FR13A under submergence stress. In Goda Heenati, 998 probes were induced and 1186 probes were suppressed by submergence treatment. Gene expression levels in the leaves of rice seedlings submerged for 3 d and the corresponding non-submerged controls were measured using Agilent rice genome 4×44 K oligonucleotide microarray. Three biological replicates were performed for each genotype and treatment. A total of 12 samples were hybridized to 12 arrays.