Using a portable hydrogen cyanide gas meter to uncover a dynamic phytochemical landscape

Abstract

Premise Over 3000 species of plants and animals release toxic hydrogen cyanide (HCN) gas when their tissues are crushed. To investigate the role of cyanogenesis in Passiflora–herbivore interactions, we developed an inexpensive, rapid, sensitive method for measuring HCN emissions from crushed tissues. Methods The method includes crushed tissue confinement in a closed chamber, where cyanogenesis reactions occur, followed by evacuation of gas to a portable HCN meter. Parts per million readings are repeated at 5‐min intervals until HCN is depleted. Three versions of the closed reaction chamber apparatus were tested: plastic cup, airtight combination mortar‐pestle, and glass desiccator jar. Results We calibrated the method by comparing with a closed chamber measurement apparatus. The procedure's repeatability was demonstrated with a standard curve using known quantities of cyanogenic glycoside standard. Data collected with this method were also compared with the conventional colorimetric procedure. We processed over 2000 samples using this technique, revealing diverse elements of cyanogenic variation. Conclusions These methods produced well‐defined data with minimal error. Results illustrated a one to four order‐of‐magnitude variation at organizational levels ranging from individual leaves to the entire Passiflora community. We now have a promising tool for uncovering the HCN phytochemical landscape in unprecedented detail.

Growth‐chemical defence‐metabolomic expression trade‐off is relaxed as soil nutrient availability increases for a tropical passion vine

“…on a variety of soil types, from central Mexico to the Colombian Amazon, and is associated with edge habitats and treefall gaps with available sunlight in lowland wet forests undergoing secondary succession (C. R. Morrison & L. E. Gilbert, unpublished data ). It is a perennial, early successional species that expresses significant variation in cyanogenic glucoside concentration within a region (Smiley & Morrison, 2020).…”

“…We sampled the cyanide, the toxic byproduct of cyanogenic glucoside metabolites in P. biflora leaves from 2 August 2021 to 14 August 2021 between 08:00 and 11:00 h. Cyanogenic glucosides are constitutively present in specialized vacuoles in Passiflora leaf cells; when herbivores chew the leaves, the cells ruptures causing the cyanogenic glucosides to come into contact with β‐glucosidase enzymes in the cytoplasm that cleave the glycosidic linkage releasing hydrogen cyanide gas as the biproduct (Smiley & Morrison, 2020). The second and third leaves from the shoot tip of vines were sampled because these leaves tend to have the highest cyanide concentrations among passion vine species (Smiley & Morrison, 2020), and they are most commonly consumed by their insect herbivores (Smiley, 1982; Thomas, 1987). We used a gas detection method to calculate the total cyanide content of leaf tissues, in which cyanide released from grinding leaves in a mortar and pestle is captured in the airtight head space of a handheld meter apparatus and recorded (Smiley & Morrison, 2020; Appendix S1, Method S1.1).…”

The role of host plant usage and the accumulation of toxic secondary chemical compounds across the life cycle of a passion vine specialist butterfly

“…Some insect clades have even evolved the ability to defend themselves against natural enemies by incorporating cyanogenic glucosides into their tissues via sequestration and biosynthesis (de Castro et al, 2019; Zagrobelny et al, 2007). Passion vines ( Passiflora L., Passifloraceae) contain cyanogenic glucosides, with concentrations that vary considerably within and among species (Smiley & Morrison, 2020). The zebra longwing butterfly, Heliconius charithonia Linnaeus 1767 (Lepidoptera: Nymphalidae; Figure 1), incorporates cyanogenic glucosides from their Passiflora host plants as larvae and retains these compounds through their adulthood (Engler & Gilbert, 2007).…”

Hydrogen sensor based on surface plasmon polaritons in palladium layer structure

“…Hydrogen atoms have the smallest atomic weight. Hydrogen (H 2 ) is considered one of the cleanest energy sources [1][2][3][4][5][6][7][8][9][10][11][12][13]. The combustion of hydrogen only produces water, which makes a huge contribution to controlling carbon emissions.…”