Modeling of plant responses to environmental stress based on gene expression information

本研究的目的是建立一个利用基因表达信息和植物生理信息来评估植物对环境胁迫响应的生长模型，我们开发了一个生长箱，能够在受控环境条件下测量冠层光合速率、蒸腾速率和臭氧气体吸收速率。我们还发展了基因表达分析技术，利用实时荧光定量RT-PCR方法分析了水稻在不同臭氧浓度下抗氧化酶（SOD、CAT和APX）基因和光诱导基因的mRNA水平。治疗为每天7小时41 ppb，每天12小时74 ppb。抗氧化基因的mRNA水平在41 ppb时增加，但在74 ppb时下降。长期试验表明，水稻在基因表达方面存在着适应低浓度臭氧的适应机制，随后将水稻暴露于93、185和317 ppb的高浓度臭氧中6 h。抗氧化基因的mRNA水平在6小时暴露结束时增加到93 ppb，并在暴露后保持较高水平，但mRNA水平在185和317 ppb时下降。从结果来看，臭氧浓度对水稻生长的限制在100 ~ 200 ppb之间。最后，我们建立了一个基于叶片生长模型的水稻生长模型来预测环境胁迫条件下水稻的生长变化。

The objective of this study was to develop a plant growth model to evaluate the responses to environmental stress using gene expression information and plant physiological information.We have developed a growth chamber, capable of measurement of canopy photosynthetic rate, transpiration rate and ozone gas absorption rate under controlled environment conditions. We also developed the technique of gene expression analysis using the real-time RT-PCR method in order to analyze mRNA levels of genes encoding antioxidant enzymes such SOD,CAT and APX and light induced genes of the rice plant under various ozone gas concentrations.Rice plants were exposed to low ozone gas concentrations for long periods. The treatments were 41 ppb for 7 hours a day and 74 ppb for 12 hours a day. The mRNA levels of antioxidant genes increased at 41 ppb, but decreased at 74 ppb. The long-term experiment showed that rice plant has an adaptation system in gene expression to get acclimatized to low ozone concentrations.Next, rice plants were exposed to higher ozone gas concentrations at 93,185 and 317 ppb for 6 hours. The mRNA levels of antioxidant genes increased at 93 ppb at the end of 6-h exposure and maintained higher levels after the exposure, but mRNA levels decreased at 185 and 317 ppb. From the result, limitation of ozone gas concentration for rice plants was considered between 100 and 200 ppb.Finally we developed a rice growth model based on a leaf growth model to predict changes of growth under environmental stress conditions.