Stomatal closure prevents xylem transport of green leaf volatiles and impairs their systemic function in plants

Abstract

Plants perceive environmental stresses as whole organisms via distant signals conveying danger messages through their vasculature. In parallel to vascular transport, airborne plant volatile compounds, including green leaf volatiles (GLVs), can bypass the lack of vascular connection. However, some small volatile compounds move through the vasculature; such vascular transport is little known about GLVs. Here we illustrate GLV alcohols as solutes move within xylem vessels in Zea mays. We describe GLV alcohols, including Z-3-hexenol and its isomer E-3-hexenol, which is not synthesized in maize, is mobilized through the transpiration stream via xylem vessels. Since transpiration is mediated by stomatal aperture, closing stomata by two independent methods diminishes the transport of GLV alcohol and its isomer. In addition, lower transport of GLV alcohols impairs their function in inducing terpenoid biosynthesis suggesting xylem transport of GLV alcohols plays a significant role in their systemic function. Our study not only shows that GLV alcohols can be transported in the xylem but points to stomatal regulation as a mechanism that climatic factors such as drought, heat, flooding, and high CO levels affect systemic signaling functions of GLVs.

Stomata: Gatekeepers of Uptake and Defense Priming by Green Leaf Volatiles in plants

“…Also Seidl-Adams and colleagues in (2014) reported plants accumulate E-B-farnesene if stomata were closed by darkness or ABA after challenging plants with a fatty acid conjugate elicitor. In our experiments, reopening stomata after the GLV-exposure period was not followed by terpenoid induction or emission from potent storage in the tissue (Figure 6A, and B), consistent with our previous study (Maleki et al, 2024). While we found that plants perceive GLV alcohol as an imminent danger signal and increase terpenoids biosynthesis at neighboring tissue, this perception is not activated in the dark (Figure 6, and Supplementary Table S2) or in the plants treated with ABA (Aguirre et al, 2023).…”

“…GLVs diffuse through air or tissue and prepare neighboring plant cells for upcoming environmental stresses. Like other airborne signals, the delivery of GLVs depends on the stomatal aperture (Maleki, 2021;Aguirre et al, 2023;Aratani et al, 2023). Fast stomatal closure is one of the early physical responses of plants to environmental stresses, like water stress and wounding.…”

“…An interesting aspect of some noctuid armyworms (especially fall army worm) is their nocturnal feeding. As recent evidence suggests, stomatal closure can dampen signaling function of GLVs at intra (Maleki et al, 2024) and inter-plant (Aguirre et al, 2023) levels in maize, and the consequence of such regulation on the noctuid larvae begs more investigation.…”