Production of the Green Leaf Volatile (Z)-3-Hexenal by a Zea mays Hydroperoxide Lyase

Abstract

Plant-produced volatile compounds play important roles in plant signaling and in the communication of plants with other organisms. Many plants emit green leaf volatiles (GLVs) in response to damage or attack, which serve to warn neighboring plants or attract predatory or parasitic insects to help defend against insect pests. GLVs include aldehydes, esters, and alcohols of 6-carbon compounds that are released rapidly following wounding. One GLV produced by maize (Zea mays) is the volatile (Z)-3-hexenal; this volatile is produced from the cleavage of (9Z,11E,15Z)-octadecatrienoic acid by hydroperoxide lyases (HPLs) of the cytochrome P450 CYP74B family. The specific HPL in maize involved in (Z)-3-hexenal production had not been determined. In this study, we used phylogenetics with known HPLs from other species to identify a candidate HPL from maize (ZmHPL). To test the ability of the putative HPL to produce (Z)-3-hexenal, we constitutively expressed the gene in Arabidopsis thaliana ecotype Columbia-0 that contains a natural loss-of-function mutant in AtHPL and examined the transgenic plants for restored (Z)-3-hexenal production. Volatile analysis of leaves from these transgenic plants showed that they did produce (Z)-3-hexenal, confirming that ZmHPL can produce (Z)-3-hexenal in vivo. Furthermore, we used gene expression analysis to show that expression of ZmHPL is induced in maize in response to both wounding and the insect pests Spodoptera frugiperda and Spodoptera exigua. Our study demonstrates that ZmHPL can produce GLVs and highlights its likely role in (Z)-3-hexenal production in response to mechanical damage and herbivory in maize.

A persistent major mutation in canonical jasmonate signaling is embedded in an herbivory-elicited gene network

“…It is likely that natural populations of other plant species harbor such major mutations in other canonical signaling cascades, despite large fitness effects of these mutations. Indeed, two commonly used models in plant biology are consistent with this inference: The laboratory strain of N. benthamiana , a workhorse for plant biotechnology and synthetic biology, is a natural RdR1 mutant, highly deficient in the RNAi mechanisms required for viral resistance ( 91 – 93 ); the reference strain of A. thaliana , Col-0, is a natural hydroperoxide lyase mutant ( 94 , 95 ) deficient in green leaf volatile production. The coarse-grained perturbation analysis presented here of an herbivory-induced gene network stabilizing a natural mutation in canonical JA-signaling reveals how much more remains to be discovered in the complex signaling systems that plants use to optimize their fitness in heterogeneous natural environments.…”

Epoxyalcohol Synthase Branch of Lipoxygenase Cascade

“…These activities yield different products involved in plant communication. Thus, GLVs (HPL products) are compounds of communication between plants and other organisms (plants, insects, herbivores) [67,70,71,144,148], whereas epoxyalcohols (EAS products) possess antimicrobial and fungicide properties [45,149]. The last group of enzymes, DESs, is apparently the last of the described evolutional acquisitions of plants.…”

“…Additionally, unusual oxylipins, such as graminoxins [47], and complex oxylipins, such as linolipins [48], have been identified. The physiological properties of plant oxylipins have been studied, with unjustifiably great attention being paid to jasmonates [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63], traumatin, and green leaf volatiles (GLVs) [46,[64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]. Much less attention has been paid to other branches of the lipoxygenase cascade, including the formation of epoxy hydroxy derivatives (epoxyalcohols) and trihydroxy derivatives (trihydroxy acids), despite the fact that these compounds are found in organisms belonging to different taxa [79][80][81][82][83][84][85][86][87][88][89][90][91]…”

Volatile‐mediated signalling in barley induces metabolic reprogramming and resistance against the biotrophic fungus Blumeria hordei

“…2013; Yactayo‐Chang et al . 2022). Next, the aldehyde is reduced to its corresponding alcohol by alcohol dehydrogenases.…”

“…In the lipoxygenase pathway, membranebound hydroperoxide lyases catalyse the release of two structurally different aldehydes from unsaturated fatty acid hydroperoxides into the cytosol, namely hexanal and (Z)-3hexenal. An isomerase factor is responsible for the spontaneous conversion of (Z)-3-hexenal to its isomer, (E)-2-hexenal (Scala et al 2013;Yactayo-Chang et al 2022). Next, the aldehyde is reduced to its corresponding alcohol by alcohol dehydrogenases.…”