Immunity-associated volatile emissions of β-ionone and nonanal propagate defence responses in neighbouring barley plants

Abstract

Plants activate biochemical responses to combat stress. (Hemi-)biotrophic pathogens are fended off by systemic acquired resistance (SAR), a primed state allowing plants to respond faster and stronger upon subsequent infection. Here, we show that SAR-like defences in barley (Hordeum vulgare) are propagated between neighboring plants, which respond with enhanced resistance to the volatile cues from infected senders. The emissions of the sender plants contained 15 volatile organic compounds (VOCs) associated with infection. Two of these, β-ionone and nonanal, elicited resistance upon plant exposure. Whole genome transcriptomics analysis confirmed that inter-plant propagation of defence in barley is established as a form of priming. Although gene expression changes were more pronounced after challenge infection of the receiver plants with Blumeria graminis f. sp. hordei, differential gene expression in response to the volatile cues of the sender plants included an induction of HISTONE DEACETYLASE 2 (HvHDA2) and priming of TETRATRICOPEPTIDE REPEAT-LIKE superfamily protein (HvTPL). Because HvHDA2 and HvTPL transcript accumulation was also enhanced by exposure of barley to β-ionone and nonanal, our data identify both genes as possible defence/priming markers in barley. Our results further suggest that VOCs and plant-plant interactions are relevant for possible crop protection strategies priming defence responses in barley.

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

“…The GLVs are involved in a range of interactions and possess antibacterial or antifungal activity (Nakamura & Hatanaka 2002;Kishimoto et al 2008). It has been demonstrated that GLV-priming of plants modulates phytohormonal levels and stress-related gene expression (Engelberth et al 2004;Frost et al 2008;Ameye et al 2015;Najdabbasi et al 2021;Brambilla et al 2022). These responses, and our observations, suggest an important role of GLVs in inducing resistance in barley.…”

“…2021; Brambilla et al . 2022). These responses, and our observations, suggest an important role of GLVs in inducing resistance in barley.…”

“…(Brambilla et al . 2022) described that nonanal and β‐ionone, emitted by Pseudomonas syringae pv. japonica ‐infected barley, show a high potential to induce resistance to Bh infection in plants exposed to these VOCs.…”

“…From earlier studies, it appears likely that a reduced number of microcolonies can be explained by reduced success in initial cell wall penetration and haustoria formation, which is the pivotal step in early powdery mildew pathogenesis and is crucial for further pathogen development and reproductive success (Eichmann & H€ uckelhoven 2008). Most recently, Brambilla et al (Brambilla et al 2022) described that nonanal and b-ionone, emitted by Pseudomonas syringae pv. japonica-infected barley, show a high potential to induce resistance to Bh infection in plants exposed to these VOCs.…”

Herbivore-Dependent Induced Volatiles in Pear Plants Cause Differentialattractive Response by Chrysoperla Externa (Neuroptera: Chrysopidae)

“…Plants damaged by C. bidens emitted blends enriched in aliphatic aldehydes, a result in line with previous studies negatively with plant nonanal emissions(Du et al 2022). An increase in aldehyde emissions in psylla-damaged plants may also in uence plant-plant communication and prime the activation of pathogen defenses in neighboring plants(Brambilla et al 2022;Yi et al 2009;Yi et al 2010). Taking into account that Cacopsylla species are important phytoplasma vectors, it is conceivable that psylla-induced volatiles such as aliphatic aldehydes may both attract natural enemies and elicit a defensive response in nearby plants(Görg et al 2021;Gross et al 2019;Rid et al 2016).…”