Investigating The Complex Effect Of Free Air CO₂ Enrichment And TiO₂ Nanoparticles On Different Rice Genotypes With RNA-seq Technology

With the development of human industrial activity, the concentration of CO2 in the atmosphere has been increasing gradually. It will affect the physiological features and growth of rice, not only by benefiting the rice with the fertilizing effect, but also by causing precocity and presenility of the rice. TiO2 nanoparticle (NP) is very stable, thus making it a proper model to investigate the ecotoxicology of the nanoparticles. Rice is an important kind of food crop in China, making it of great urgency for the good of food security and ecosystem safety to investigate the behavior of the rice facing the stress of TiO2 NP at an elevated level of CO2 in the atmosphere. It has been focused on 3 different genotypes of rice in this experiment, being Ⅱyou, Wuyunjing and Yongyou. With the help of the RNA-seq technology, bioinformatics database is fully studied to uncover the behavior and mechanics of the rice affected by the FACE and TiO2 NP. The main contents and conclusions are as follows:1. Precocity and presenility of 3 different genotypes of rice were observed at elevated level of CO2. The introduction of TiO2 was found of no effect on this change on the circadian. The 3 genotypes showed different patterns. Ⅱyou was not affected. However, the elevated level of CO2 brought Wuyunjing and Yongyou into an earlier heading stage. On the transcripts level. Pathways involving monoterpenoid, sesquiterpenoid and triterpenoid biosynthesis were differentially regulated. It could be the consequences instead of causes of this procedure.2. All 3 genotypes benefited from the fertilizing effect of the elevated level of CO2 by increasing biomass and panicle weight. However, once the TiO2 NP was introduced,3 genotypes behaved in different ways. For Wuyunjing, the benefit of elevated level of CO2 was greatly reduced. Ilyou hardly suffered from TiO2 NP. And Yongyou was in between. It seemed Ⅱyou could adapt the complex effect of the scenario in a best way, for it not only gained extra biomass and panicle weight, but also avoided precocity and presenility which happened on Yongyou and Wuyunjing.3. Enriched KEGG pathway with the help of RNA-seq showed correlation between the photosystem, being key part of photosynthesis and the 2 conclusions mentioned. In Ⅱyou case, the pathways of Lhca2 and Lhcbl regulation which were part of LHC in the PSI and PSII antenna protein ontology was expressed. In the Yongyou case, several pathways concerning PSII were also enriched. Wuyunjing was found lacking correlations to photosystem pathways. It meant Ⅱyou and Youngyou adjusted their own photosystems on transcripts level, while Wuyunjing didn’t behave as well responding to the stress.