Study on the influence of clinorotation on growth and yield and gene expression profiling of rice variety MR 219

Rice {Oryza saliva L.) is the staple food in many Asian countries and the demand for this commodity is continuously increasing. However, the current irce production practice is and will unable to meet the continuouslygrowing demand due to rising of the population. Research on plants growth in space are rare, costly and limited by the access in terms of flight opportunities. Nevertheless, similar experiments can be conducted on the ground through microgravitysimulationusing a 2-D clinostat. Therefore, this research was conducted to determine effects ofsimulated microgravity of the following parameters: growth, yield, gene expression profiles and the content of starch and protein for irce seeds 219) by using a 2-D clinostat and to optimize the simulated microgravity conditions to enhance the parameters the irce yield. The clinorotated and control irce seeds were planted in a glasshouse (as a preliminary study) and an open area. In the preliminary study, the clinorotation of irce seeds MR 219 were performed at two different rotation speeds (2 and 10 ipm) at 1.5 cm distance firom the centre of clinostat for 10 days. The chlorophyll content and total grain weight per plant were significantly affected by both rotation speeds Le. 2 and 10 rpm while the number of tiller, stem width and weight of grains and panicles were influenced only by 10 ipm as compared to those of the control. The most significant parameters WCTe mostly found firom the sanqiles at 10 rpm rotation clinorotated irce seeds. For the control and clinorotated irce seeds which were cultivated in an open area, height of tiller firom soil, leaves length, leaves width, stem width and chlorophyll content number ofpanicles, filled grains per panicle, number of fiUed grains per plant, total grain weight per plant and lOOO-grain weight were significantly affected by chnorotation. The optimum conditions of the simulated gravity conditions were found to be as follows: rotation of the irce seeds, 10 rpm; the rotation period, 10 days; and the distance firom the centre of clinostat, 1.5 cm. Rice seeds that were treated under the optimum conditions were then used for gene expression profiling and, starch and protein contents analyses. Semi-quantitative reverse transcription-polymerasechain reaction (RT-PCR) analysis on treated and control irce seeds show^ liiat irbosomal protein SI was significantly e:?qjressed gene in the first generation meanwhile in the second generation, PSI PsaE, ribosomal protein SI, chlorophyll synthase and GPX showed significant level of e;q)ressions between treated and control. The data obtained firom semi-quantitative RT-PCR supported the growth and yield results. In addition, significantly higher starch content but similar protein compositionwere found in the treated irce seeds as compared to those of the control. Therefore, the results of this study showed that better irce production can be achieved by using treated irce seeds under optimum simulated microgravity condition.