ASIAN CULTIVATED RICE DOMESTICATION SUPPRESSES THE EXPRESSION OF ABIOTIC STRESS- AND REACTIVE OXYGEN SPECIES SCAVENGING-RELATED GENES IN ROOTS

Asian cultivated rice (Oryza sativa L), the important cereal crop, has low resistance to numerous biotic and abiotic stresses compared to its ancestral wild rice (Oryza rufipogon). Although genetic studies have shown that the susceptibility of cultivated rice towards various environmental stresses is due to its narrow genetic diversity caused by domestication, whereas wild rice possesses tremendous gene pools; yet very little is known about the domestication-induced transcriptional changes in abiotic stress-related genes and/or pathways in cultivated rice. Thus, to investigate these changes, we retrieved the root transcriptome data sets of cultivated and wild rice from the GenBank of National Center for Biotechnology information. Next, we performed MapMan-based analysis of the root transcriptome data sets of cultivated and wild rice. Cellular response overview from MapMan analysis showed that key genes related to abiotic stress categories; heat stress and drought/salt stress were significantly suppressed in cultivated rice relative to wild rice. In addition, the expression level of ascorbate- and dismutase-related transcripts, which also function in abiotic stress tolerance through involvement in the detoxification of reactive oxygen species (ROS), were also down-regulated in cultivated rice compared with wild rice. In conclusion, transcriptomic-based survey of cultivated rice and wild rice reflects that domestication has significantly changed (reduced) the transcriptional level of abiotic stress and ROS-scavenging related transcripts in cultivated rice. These findings further explain the susceptibility of cultivated rice towards abiotic stresses. Thus, re-introduction of the identified desirable genes of wild rice through conventional breeding and genetic engineering may improve the abiotic stress resistance mechanisms of modern rice cultivars.