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:Super study for large-scale analysis of novel cellular microbes
Project description:Understanding ecological linkages between above- and below-ground biota is critical for deepening our knowledge on the maintenance and stability of ecosystem processes. Nevertheless, direct comparisons of plant-microbe diversity at the community level remain scarce due to the knowledge gap between microbial ecology and plant ecology. We compared the ?- and ?- diversities of plant and soil bacterial communities in two temperate forests that represented early and late successional stages. We documented different patterns of aboveground-belowground diversity relationships in these forests. We observed no linkage between plant and bacterial ?-diversity in the early successional forest, and even a negative correlation in the late successional forest, indicating that high bacterial ?-diversity is not always linked to high plant ?-diversity. Beta-diversity coupling was only found at the late successional stage, while in the early successional forest, the bacterial ?-diversity was closely correlated with soil property distances. Additionally, we showed that the dominant competitive tree species in the late successional forest may play key roles in driving forest succession by shaping the soil bacterial community in the early successional stage. This study sheds new light on the potential aboveground-belowground linkage in natural ecosystems, which may help us understand the mechanisms that drive ecosystem succession.
Project description:Grasslands are integral to maintaining biodiversity and key ecosystem services and are under threat from climate change. Plant and soil microbial diversity, and their interactions, support the provision of multiple ecosystem functions (multifunctionality). However, it remains virtually unknown whether plant and soil microbial diversity explain a unique portion of total variation or shared contributions to supporting multifunctionality across global grasslands. Here, we combine results from a global survey of 101 grasslands with a novel microcosm study, controlling for both plant and soil microbial diversity to identify their individual and interactive contribution to support multifunctionality under aridity and experimental drought. We found that plant and soil microbial diversity independently predict a unique portion of total variation in above- and belowground functioning, suggesting that both types of biodiversity complement each other. Interactions between plant and soil microbial diversity positively impacted multifunctionality including primary production and nutrient storage. Our findings were also climate context dependent, since soil fungal diversity was positively associated with multifunctionality in less arid regions, while plant diversity was strongly and positively linked to multifunctionality in more arid regions. Our results highlight the need to conserve both above- and belowground diversity to sustain grassland multifunctionality in a drier world and indicate climate change may shift the relative contribution of plant and soil biodiversity to multifunctionality across global grasslands.