Project description:High light stress in subtropical and tropical regions strongly limits agricultural production due to photo-oxidative damage, decreased growth and yield. Here, we investigated whether beneficial microbes can protect plants under high light stress. We show that Enterobacter sp. SA187 (SA187) assists Arabidopsis in maintaining growth under high light stress, reducing the accumulation of reactive oxygen species (ROS) and maintaining photosynthesis. Under high light stress, SA187 induces dynamic transcriptional changes related to a fortified iron metabolism and redox system in Arabidopsis. A genetic analysis shows that SA187-induced plant high light stress tolerance is mediated by ethylene signaling via the transcription factor EIN3 to enhance iron metabolism. In summary, we show that Arabidopsis interaction with SA187 results in sustained photosynthesis under high light stress suggesting that beneficial microbes could be effective and cheap means for enhancing high light stress tolerance in crops.
Project description:Today, nanoparticles are used in various commercial products. One of the most common nanoparticles is titanium dioxide (TiO2). It has a catalytic activity and UV absorption (λ<400 nm), and it generates reactive oxygen species (ROS). The catalytic activity of TiO2 nanoparticle is capable of killing a wide range of microorganisms. In the environment, nanoparticles form structures consisting of primary particles, and their aggregates and agglomerates. These compounds are defined NOAA (nano-objects, and their aggregates and agglomerates greater than 100 nm). The unique properties of TiO2 nanoparticles can be maintained in the environment, thus, the growing use of TiO2 nanoparticles is raising concerns about the environmental risks. The assessment of biological and ecological effects of TiO2-NOAA is necessary. In our previous study, we assessed the effect of TiO2-NOAA on microbes by using Saccharomyces cerevisiae and Escherichia coli. It was shown that TiO2-NOAA decomposed methylene blue under UV irradiation. It suggested that TiO2-NOAA generated ROS under UV irradiation. However, TiO2-NOAA did not show growth inhibition in minimal agar medium under UV irradiation. By adding TiO2-NOAA in medium, colony formation was observed with UV intensity that inactivates microbes. Moreover, TiO2-NOAA adsorbed microbes. These results suggested that the amount of ROS generated by TiO2-NOAA was not enough to inactivate microbes, and TiO2-NOAA might protect microbes from UV. In this study, we assessed the effect of TiO2-NOAA in more detail by using S. cerevisiae. We used DNA microarray analysis for qualitative assessment. Further, we carried out quantitative assessment by using Real Time RT-PCR method for characteristic genes in DNA microarray analysis. To compare yeast cells in various conditions, six kinds of treatment conditions were prepared (Condition 1. adsorbed fraction to TiO2-NOAA under UV, 2. non-adsorbed fraction to TiO2-NOAA under UV, 3. adsorbed fraction to TiO2-NOAA without UV, 4. non-adsorbed fraction to TiO2-NOAA without UV, 5. irradiated UV and 6. negative control). From the result of DNA microarray analysis, the most number of genes was altered in Condition 1, followed by Condition 3 and 5. The genes related to oxidative stress, and the genes related to synthesis of trehalose and glycogen were significantly up-regulated of yeast cells in Condition 1 and 5, and Condition 1 and 3, respectively. These results suggest that yeast cells suffer oxidative stress by TiO2-NOAA under UV, and they also suffer membrane damage by TiO2-NOAA itself, as a result, they reserve energy sources. From the result of Real Time RT-PCR, genes related to oxidative stress (GRE2, SOD2) were up-regulated in Condition 1 and 3, however, these expression levels in each condition were not significant. And genes related to synthesis of trehalose and glycogen (GSY1, TPS2) were up-regulated in Condition 1 and 3. These results suggest that oxidative stress is caused not by TiO2-NOAA but by UV. It is also suggested that yeast cells were damaged at their membranes by TiO2-NOAA, as a result, genes related to synthesis of trehalose and glycogen were up-regulated. Thus, we suggest that the effect of TiO2-NOAA on yeast cells under UV irradiation is greater due to TiO2-NOAA itself than due to ROS generated by TiO2-NOAA.
Project description:Integration of genome wide association studies (GWAS), metabolomics and transcriptomics reveals phenolic acids and flavonoids associated genes and their regulatory elements under drought stress in rapeseed flowers
Project description:Seed of 4 lines of S. tuberosum var andigena were sown and, after transplanting, grown in 3 gal nursery containers in a greenhouse with natural daylight. The seeds were sown in July and the drought stress experiment began in September. Drought stress was administered by withholding water and monitored by measuring the rate of photosynthesis (PS; LiCor 6400). We found that loss of photosynthetic capability (ie a PS rate of 0-2 mM CO2/m2/sec) correlated with a severe drought stress. Control plants were watered normally and maintained a PS rate of 18-20 mM CO2/m2/sec. After drought stress, the treated plants were re-watered and PS measurements taken again. After the first cycles of stress, control and treated plants were harvested and roots, tubers and shoots were stored at –80°C for RNA extractions. The drought experiment was then repeated for the remaining plants such that they were exposed to a second cycle of stress. For each line of S. andigena, there were 2 control and 2 treated plants per cycle of stress. RNA was extracted following the acid phenol protocol of TIGR. Keywords: Direct comparison, loop design
2007-09-01 | GSE8207 | GEO
Project description:Transcriptome sequencing in yeast under acetic acid stress condition