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Abstract Aldoximes are amino acid derivatives that serve as intermediates for numerous specialized metabolites including cyanogenic glycosides, glucosinolates, and auxins. Aldoxime formation is mainly catalyzed by cytochrome P450 monooxygenases of the 79 family (CYP79s) that can have broad or narrow substrate specificity. Except for SbCYP79A1, aldoxime biosynthetic enzymes in the cereal sorghum (Sorghum bicolor) have not been characterized. This study identified nine CYP79-encoding genes in the genome of sorghum. A phylogenetic analysis of CYP79 showed that SbCYP79A61 formed a subclade with maize ZmCYP79A61, previously characterized to be involved in aldoxime biosynthesis. Functional characterization of this sorghum enzyme using transient expression in Nicotiana benthamiana and stable overexpression in Arabidopsis thaliana revealed that SbCYP79A61 catalyzes the production of phenylacetaldoxime (PAOx) from phenylalanine but, unlike the maize enzyme, displays no detectable activity against tryptophan. Additionally, targeted metabolite analysis after stable isotope feeding assays revealed that PAOx can serve as a precursor of phenylacetic acid (PAA) in sorghum and identified benzyl cyanide as an intermediate of PAOx-derived PAA biosynthesis in both sorghum and maize. Taken together, our results demonstrate that SbCYP79A61 produces PAOx in sorghum and may serve in the biosynthesis of other nitrogen-containing phenylalanine-derived metabolites involved in mediating biotic and abiotic stresses. 

Abstract We introduce “The Integrator,” a novel technique to quantify transport and reaction metrics commonly used to characterize flow systems. This development consists of two products: (1)The Integratorsampling device and (2) its supporting mathematical framework, which is compatible with semi‐continuous sensor data. The use ofThe Integratordevice simplifies the logistics of sample collection and greatly reduces the number of samples needed, making it ideal to characterize systems that are: (1) difficult to access, (2) large and thus intractable or highly heterogeneous, and (3) highly instrumented otherwise but where a more holistic, mechanistic understanding may be gained by monitoring one or more currently untracked elements. We tested and validatedThe Integratortechnique using experimental data collected from a heart rate monitor (high‐quality, high‐frequency data in response to known excitation events) and solute tracer experiments conducted in two contrasting (fourth and seventh order) rivers. In theSupporting Information, we provide details concerning the design ofThe Integratordevice used in our field case studies and provide insight into potential improvements. Despite our case studies focus on the analysis of conservative and reactive transport of solutes in rivers, the principles behindThe Integratortechnique can be used to monitor water quality in hyporheic zones, aquifers, wetlands, swamps, karsts, oceans, wastewater treatment plants, pipe networks, and air quality. Furthermore, special arrangements ofIntegratordevices can be used to gather data at spatial and temporal resolutions that are currently unattainable due to high transportation and/or personnel costs.