Development of a widely targeted volatilomics method for profiling volatilomes in plants

Volatile organic compounds play essential roles in plant environment interactions as well as determining the fragrance of plants.Although gas chromatography-mass spectrometry-based untargeted metabolo-mics is commonly used to assess plant volatiles,it suffers from high spectral convolution,low detection sensitivity,a limited number of annotated metabolites,and relatively poor reproducibility.Here,we report a widely targeted volatilomics(WTV)method that involves using a“targeted spectra extraction”algorithm to address spectral convolution,constructing a high-coverage MS2 spectral tag library to expand volatile annotation,adapting a multiple reaction monitoring mode to improve sensitivity,and using regression models to adjust for signal drift.The newly developed method was used to profile the volatilome of rice grains.Compared with the untargeted method,the newly developed WTV method shows higher sensitivity(for example,the signal-to-noise ratio of guaicol increased from 4.1 to 18.8),high annotation coverage(the number of annotated volatiles increased from 43 to 132),and better reproducibility(the number of volatiles in quality control samples with relative standard deviation value below 30.0%increased from 14 to 92 after normalization).Using the WTV method,we studied the metabolic responses of tomato to environmental stimuli and profiled the volatilomes of different rice accessions.The results identified benzothiazole as a potential airborne signal priming tomato plants for enhanced defense and 2-nonanone and 2-heptanone as novel aromatic compounds contributing to rice fragrance.These case studies suggest that the widely targeted volatilomics method is more efficient than those currently used and may considerably promote plant volatilomics studies.

Recent Development in Symmetries and Integrability of Difference Equations

Difference equations or discrete systems are mathematical models of various fields such as physics, chemistry, biology, and economics and have been subjects of extensive study of both pure mathematicians and applied mathematicians. Through its interaction with modern integrable systems, the theory of difference equations is enriched greatly and has been undergoing a rapid development. SIDE-10, the tenth of a series of biennial conferences devoted to Symmetries and Integrability of Difference Equations and related topics, was held during 10-16 June, 2012 at Ningbo, China. It was sponsored and supported by the National Natural Science Foundation of China, Ningbo Association of Science and Technology, Ningbo University, Academy of Mathematics and Systems Science of Chinese Academy of Sciences, China University of Mining and Technology （Beijing）, Tsinghua University, and Shanghai University. The conference attracted over 100 participants from more than a dozen of countries. During the conference, 44 contributed talks were arranged and the topics covered by the meeting include