Project description:A cultivation facility that can assist users in controlling the soil water condition is needed for accurately phenotyping plants under drought stress in an artificial environment. Here we report the Internet of Things (IoT)-based pot system controlling optional treatment of soil water condition (iPOTs), an automatic irrigation system that mimics the drought condition in a growth chamber. The Wi-Fi-enabled iPOTs system allows water supply from the bottom of the pot, based on the soil water level set by the user, and automatically controls the soil water level at a desired depth. The iPOTs also allows users to monitor environmental parameters, such as soil temperature, air temperature, humidity, and light intensity, in each pot. To verify whether the iPOTs mimics the drought condition, we conducted a drought stress test on rice varieties and near-isogenic lines, with diverse root system architecture, using the iPOTs system installed in a growth chamber. Similar to the results of a previous drought stress field trial, the growth of shallow-rooted rice accessions was severely affected by drought stress compared with that of deep-rooted accessions. The microclimate data obtained using the iPOTs system increased the accuracy of plant growth evaluation. Transcriptome analysis revealed that pot positions in the growth chamber had little impact on plant growth. Together, these results suggest that the iPOTs system represents a reliable platform for phenotyping plants under drought stress.
Project description:Surviving the nutrient-poor aquatic environment for extended periods of time is important for transmission of various water-borne pathogen to the host, including Legionella pneumophila (Lp). Lp is a leading cause of community-acquired and nosocomial pneumonia called Legionnaires’ disease. The remarkable ability of the bacterium to survive in water for periods ranging from several months to years under starvation conditions alludes to regulatory pathways that mediate adaptation to the water environment. In the present study, we investigated a potential role for the LetA/LetS signal transduction system in the successful survival of Lp in water. During infection of host cells, the LetA/LetS two-component system controls the transition from the replicative phase to the transmissive phase in response to nutrient deprivation. In accordance with previous work, the letS mutant used in the present study is defective for pigment production and contributed to cell size reduction in the post-exponential phase. LetS also contributed to cell size reduction when Lp was exposed to water. Importantly, absence of the sensor kinase resulted in a significantly lower survival rate in water at various temperatures, as well as an increase sensitivity to heat shock. Transcriptomic analysis indicated that a general transcriptomic downshift of major pathways is orchestrated by LetA/LetS upon water exposure leading to better survival, suggesting a potential link with the stringent response. However, the expression of the LetA/S regulated small regulatory RNAs RsmY and RsmZ was not changed in a relAspoT mutant, which indicates that the stringent response and the LetA/S response are two distinct regulatory systems important for the survival of Lp in water.
