Aims
Root exudates are known to shape microbial activities in the rhizosphere and to be of fundamental importance for plant-soil-microbe-carbon–nitrogen interactions. However, it remains unclear how and to what extent the amount and composition of root exudation affects rhizosphere denitrification.
Methods
In this study root exudation patterns and rhizosphere denitrification enzyme activity of three different grass species grown on two agricultural soils under two different soil water contents were investigated under controlled conditions.
Results
We found that root exudation of primary metabolites largely depends on plant species, soil type, soil moisture and root exudation medium. In dependence of soil properties and soil moisture levels, plants largely controlled amount and quality of root exudation. Exudates affected denitrification activity and plant–microbe competition for nitrate. Specifically, exudation of organic acids stimulated denitrifying activity while the sugar lyxose exhibited an inhibitory effect.
Conclusion
We show that interactive effects of physicochemical soil properties and species-specific effects of plant metabolism on root exudation act as a dominant control of rhizosphere denitrification, thereby explaining more than half of its variance.
Background and Aims
The processes connected with prey capture and the early consumption of prey by carnivorous Dionaea muscipula require high amounts of energy. The aim of the present study was to identify processes involved in flytrap energy provision and ATP homeostasis under these conditions.
Methods
We determined photosynthetic CO2 uptake and chlorophyll fluorescence as well as the dynamics of ATP contents in the snap traps upon closure with and without prey.
Key Results
The results indicate that upon prey capture, a transient switch from linear to cyclic electron transport mediates a support of ATP homeostasis. Beyond 4 h after prey capture, prey resources contribute to the traps’ ATP pool and, 24 h after prey capture, export of prey-derived resources to other plant organs may become preferential and causes a decline in ATP contents.
Conclusions
Apparently, the energy demand of the flytrap for prey digestion and nutrient mining builds on both internal and prey-derived resources.
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