Salicylic acid (SA) is a phytohormone regulating immune responses against pathogens. SA and its derivatives can be found in perse food products, medicines, cosmetics and preservatives. While salicylates have potential disease-preventative activity, they can also cause health problems to people who are hypersensitive. The current SA detection methods are costly, labor-intensive and require bulky instruments. In this study, a structures-switching aptamer-based nanopore thin film sensor was developed for cost-effective, rapid, sensitive and simple detection of SA in both buffer and plant extracts. SA is a challenging target for aptamer selection using conventional systemic evolution of ligands by exponential enrichment (SELEX) due to its small size and scarcity of reactive groups for immobilization. By immobilizing the SELEX library instead of SA and screening the library using a structure-switching SELEX approach, a high affinity SA aptamer was identified. The nanopore thin film sensor platform can detect as low as 0.1 μM SA. This is much better than the sensitivity of antibody-based detection method. This nanosensor also exhibited good selectivity among SA and its common metabolites and can detect SA inArabidopsisand rice using only about 1 μl plant extracts within less than 30 min. The integration of SA aptamer and nanopore thin film sensor provides a promising solution for low-cost, rapid, sensitive on-site detection of SA.

The plant circadian clock evolved to increase fitness by synchronizing physiological processes with environmental oscillations. Crop fitness was artificially selected through domestication and breeding, and the circadian clock was identified by both natural and artificial selections as a key to improved fitness. Despite progress inArabidopsis, our understanding of the crop circadian clock is still limited, impeding its rational improvement for enhanced fitness. To unveil the interactions between the crop circadian clock and various environmental cues, we comprehensively mapped abiotic stress inputs to the soybean circadian clock using a 2-module discovery pipeline. Using the “molecular timetable” method, we computationally surveyed publicly available abiotic stress-related soybean transcriptomes to identify stresses that have strong impacts on the global rhythm. These findings were then experimentally confirmed using a multiplexed RNA sequencing technology. Specific clock components modulated by each stress were further identified. This comprehensive mapping uncovered inputs to the plant circadian clock such as alkaline stress. Moreover, short-term iron deficiency targeted different clock components in soybean andArabidopsisand thus had opposite effects on the clocks of these 2 species. These unique responses in soybean demonstrate the need to directly study crop circadian clocks. Our discovery pipeline may serve as a broadly applicable tool to facilitate these explorations.

Ying Li, Yuhua Deng, Yue Li, Shuyu Wang, Yabo Shi, Yuchen Tu, Yanfei Hu, Xiaoyuan Chen, Zhaoqi Wang, Li Yao, Yue Chen