VOCs Are Relevant Biomarkers of Elicitor-Induced Defences in Grapevine

Abstract

Grapevine is susceptible to fungal diseases generally controlled by numerous chemical fungicides. Elicitors of plant defence are a way of reducing the use of these chemicals, but still provide inconsistent efficiency. Easy-to-analyse markers of grapevine responses to elicitors are needed to determine the best conditions for their efficiency and position them in protection strategies. We previously reported that the elicitor sulphated laminarin induced the emission of volatile organic compounds (VOCs) by grapevine leaves. The present study was conducted to characterise and compare VOC emissions in response to other elicitors. Bastid® was first used to test the conditions of VOC collection and analysis. Using SBSE-GC-MS, we detected several VOCs, including the sesquiterpene α-farnesene, in a time-dependent manner. This was correlated with the induction of farnesene synthase gene expression, in parallel with stilbene synthesis (another defence response), and associated to resistance against downy mildew. The other elicitors (Redeli®, Romeo®, Bion®, chitosan, and an oligogalacturonide) induced VOC emission, but with qualitative and quantitative differences. VOC emission thus constitutes a response of grapevine to elicitors of various chemical structures. Therefore, VOC analysis is relevant for studying the impact of environmental factors on grapevine defence responses and optimising the performance of elicitors in vineyards.

Recent applications of metabolomics in plant breeding

“… Yu et al (2020) elucidated metabolic profiles of 136 accessions of tea trees as part of a study on characterizing tea genetic resources in China. In a study on marker discovery, Lemaitre-Guillier et al (2021) demonstrated that the profiles of volatile organic compounds (VOCs) can be used as diagnostic markers for stress in grapevines.…”

Elicitor-Induced VOC Emission by Grapevine Leaves: Characterisation in the Vineyard

“…Among them are the well-studied stilbene phytoalexins associated with resistance to downy mildew and grey mould [17][18][19]. They are induced by various elicitors [6,8,12,15,20,21]. However, their analysis requires destructive sampling and is time-consuming because of several extraction and analysis steps.…”

“…Previous works have shown that elicitors can trigger VOC emission in plants [21,27,[31][32][33]. In greenhouse conditions, application of the elicitors, sulphated laminarin, chitosan (a chito-oligosaccharide (COS)) and Bastid ® , on grapevine plants increased the emission of mono-and sesquiterpenes [21,34].…”

“…Previous works have shown that elicitors can trigger VOC emission in plants [21,27,[31][32][33]. In greenhouse conditions, application of the elicitors, sulphated laminarin, chitosan (a chito-oligosaccharide (COS)) and Bastid ® , on grapevine plants increased the emission of mono-and sesquiterpenes [21,34]. The elicitor Bastid ® is composed of a mixture of oligochitosan and oligogalacturonic acid (COS-OGA) complexed by cations, which act synergistically in Arabidopsis [35].…”

“…The elicitor Bastid ® is composed of a mixture of oligochitosan and oligogalacturonic acid (COS-OGA) complexed by cations, which act synergistically in Arabidopsis [35]. It induces the emission of mono-and sesquiterpenes in tomatoes [31], rice [32] and grapevines [21], and also has a potential antimicrobial action [36]. We also used copper sulphate (CuSO 4 ) as an abiotic elicitor.…”