Volatilome profiles of soybean cultivars: from floral emissions to plant–pathogen interaction

Abstract

Background and aims Fusarium tucumaniae is a soil-borne pathogen that infects soybean plants (Glycine max) through the roots and causes sudden death syndrome (SDS) in susceptible cultivars. Roles of volatile organic compounds (VOCs) during the belowground interaction of F. tucumaniae with roots from two soybean genotypes with contrasting levels of resistance to SDS can help understanding soybean innate immunity to prevent SDS infection. In addition, VOC emission from soybean flowers was characterized for understanding constitutive VOC diversity across different genotypes. Methods Volatilomes of F. tucumaniae, soybean flowers and roots, F. tucumaniae inoculated soybean roots and rhizosphere were characterized using headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS). Then, the potential antifungal properties of some identified VOCs were also evaluated. Results 1-Octen-3-ol was the most abundant compound released by F. tucumaniae. Aldehydes and alcohols were predominant in VOC profiles from soybean flowers. These compounds were also released from roots of the uninoculated susceptible cultivar. F. tucumaniae inoculation significantly decreased aldehyde levels but increased ketone levels. Interestingly, VOCs emitted by roots of the uninoculated partially resistant cultivar were poorly affected by fungal inoculation and some of these molecules could also be detected in the rhizosphere of this cultivar and were found to inhibit F. tucumaniae growth. Conclusion Soybean VOC emissions are influenced by the plant organ, genotype and response to pathogen inoculation. In particular, some of these VOCs can be considered as promising candidates for SDS prevention and control.