Transcriptomic Profiling of Malaysia Rice Cultivars (Oryza sativa) under the Effect of Osmotic Stress Induced by PEG 6000

Drought is one of the abiotic stresses on plants, causing significant detrimental impacts, especially to lowland rice (Oryza sativa L.) ecosystems. In order to obtain new insights on osmotic stress in rice, a comparative study using a Next-Generation Sequencing platform was conducted to elucidate osmotic-responsive genes from two local Malaysian rice cultivars, namely the commercially available drought-tolerant MR220 and the drought-sensitive MR211. In the study, 21-day-old seedlings of MR220 and MR211 were exposed to 6% PEG 6000 for 24 h, which produced osmotic stress that mimicked the drought condition. The samples were collected and total RNA extracted. Two transcriptomic libraries were constructed from both rice cultivars using the Illumina HiSeq 2000 platform. A total of 77,964,138 and 92,699,454 raw sequence reads were generated from these libraries. Based on the gene annotation of O. sativa, a total of 106 genes were identified as differentially and significantly expressed in drought-tolerant and drought-susceptible cultivars, and a total of 29 genes were categorized as unknown genes. From the 106 differentially expressed genes (DEGs), 14 genes were up-regulated, while another 92 were down-regulated in RM220. Gene Ontology (GO) and KEGG analysis were conducted to obtain the functional and biological role of the differentially expressed genes. Overall, this study gave further insight on rice defense mechanisms system in low water potentials at early stages of stress. (C) 2019 Friends Science Publishers