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

本研究旨在利用基因表达信息和植物生理信息建立植物生长模型，以评价植物对环境胁迫的响应。我们开发了一个生长室，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率。我们还开发了实时RT-PCR基因表达分析技术，以分析不同臭氧气体浓度下水稻植株SOD、CAT、APX等抗氧化酶编码基因和光诱导基因的mRNA水平。水稻长期暴露在低臭氧浓度的环境中。每天7小时41 ppb，每天12小时74 ppb。抗氧化基因mRNA水平在41 ppb时升高，在74 ppb时降低。长期试验表明，水稻具有适应低臭氧浓度的基因表达系统。接下来，水稻植株暴露在更高浓度的臭氧气体中，分别为93,185和317 ppb，持续6小时。暴露6 h后，抗氧化基因mRNA水平在暴露93 ppb时升高，并在暴露后保持较高水平，但在暴露185和317 ppb时mRNA水平下降。从结果来看，臭氧气体对水稻的浓度限制在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.