The importance of fine-root diameter for ecosystem functioning is increasingly recognized; yet, much remains to be learned about the variation in fine-root diameter at large scale. We conducted an analysis of fine-root diameter for 1,163 plant species to detect root diameter patterns in relation to resource availability (e.g. carbon, nitrogen and water), stress intensity (e.g. plant/soil biodiversity, soil bulk density) and temperature. First- to fourth-order root diameter showed non-linear relationships with latitude and/or mean annual temperature (except for first-order root diameter). The diameter of five root orders decreased with increasing mean annual precipitation, but increased with net primary production (NPP), which was the strongest determinant of fine-root diameter. Increasing soil biodiversity was associated with decreasing root diameter of fourth- to fifth-order roots while increased plant biodiversity was associated with decreasing diameter of first- to third-order roots. Total soil nitrogen had a positive effect on first-order root diameter, but a negative effect on fourth- and fifth-order root diameter. The patterns reversed for total soil phosphorus. First- to third-order and fifth-order root diameters increased with increasing soil bulk density. Second- to fourth-order root diameter increased with soil pH. Overall, the variables related to climate, biology and soil explained 44% to 63% of the total variance in the diameter of the different root orders. The unique patterns of plasticity observed in fine-root diameter across root orders in response to varying environmental conditions contributes to a diversification of strategies for nutrient/water acquisition and transport under climate change.

Synthetic biology has promoted the development of biosensors as tools for detecting trace substances. In the past, biosensors based on synthetic biology have been designed on living cells, but the development of cell biosensors has been greatly limited by defects such as the obstruction of cell membrane. However, the advent of cell-free synthetic biology addresses these limitations. Biosensors based on the cell-free protein synthesis system have the advantages of higher safety, higher sensitivity, and faster response time over cell biosensors, which makes cell-free biosensors have a broader application prospect. This review summarizes the workflow of various cell-free biosensors, including the identification of analytes and signal output. The detection range of cell-free biosensors is greatly enlarged by different recognition mechanisms and output methods. In addition, the review also discusses the applications of cell-free biosensors in environmental monitoring and health diagnosis, as well as existing deficiencies and aspects that should be improved. In the future, through continuous improvement and optimization, the potential of cell-free biosensors will be stimulated, and their application fields will be expanded.