Biocontrol Ability and Production of Volatile Organic Compounds as a Potential Mechanism of Action of Olive Endophytes against Colletotrichum acutatum

Abstract

Olive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth and anthracnose symptoms, and to assess A. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences on anthracnose development. Among the endophytes tested, only A. pullulans significantly reduced the incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose in detached fruits, as well as the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and germination (up to 3.5-fold) of C. acutatum in dual culture assays. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans + C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or Tween) led to the identification of 37 VOCs, with alcohols being the most diversified and abundant class. The volatile profile of A. pullulans + C. acutatum revealed qualitative and quantitative differences from the controls and varied over the time course of microbial interactions. The most significant differences among treatments were observed at a maximal reduction in anthracnose development. At this stage, a set of VOCs, particularly Z-3-hexen-1-ol, benzyl alcohol and nonanal, were highly positively correlated with the A. pullulans + C. acutatum treatment, suggesting they play a critical role in anthracnose reduction. 6-Methyl-5-hepten-2-one and 2-nonanone were positively associated with the C. acutatum treatment and thus likely have a role in pathogen infection.

Identification and characterization of TMV-induced volatile signals in Nicotiana benthamiana: evidence for JA/ET defense pathway priming in congeneric neighbors via airborne (E)-2-octenal

“…(E)-2-Octenal is widely present as a flavoring substance in a variety of plants (Cheng et al 2020 ; Ebert et al 2022 ; Raffo et al 2018 ), and previous results have shown that plant-produced (E)-2-octenal causes severe perturbation of the lipid fraction of bacterial plasma membranes and inhibits the activity of microorganisms such as rhizospheric fungi and Candida (Battinelli et al 2006 ; Trombetta et al 2002 ). A recent publication (Sdiri et al 2022 ) found a significant increase in 6-methyl-5-hepten-2-one levels in olive plants after inoculation with S epia acuminata , and the authors speculated that 6-methyl-5-hepten-2-one may play a role in pathogen infection. Page et al (Page et al 2014 ) found that flowers of Silene latifolia and Silene dioica hybrids released 6-methyl-5-hepten-2-one and influenced pollinator preference.…”

Novel Approaches for Sustainable Horticultural Crop Production: Advances and Prospects

“…Endophytic PGPMS, along with growth promoting [126][127][128][129][130][131][132][133] also plays a pivotal role in maintaining plant resilience to diseases [95,123,126,127,129,132,[134][135][136][137][138][139][140][141][142][143][144][145][146][147] and abiotic stressors [22,24,66,90,121,139,143,148]. Some endophytes also have the potential to control insects [147,149,150] and nematodes [62], as well as combined biotic and abiotic stresses [62,[151][152][153].…”

Sustainable Management of Diseases in Horticulture: Conventional and New Options

“…Generally, these microbes live within plant tissues and provide useful metabolites for plant growth and tolerance to stress, including plant pathogens [13,173]. Volatile organic compounds could also be used to control plant diseases [174]. The genus Trichoderma also includes endophytic species that can be exploited as mycoparasites, as in the case of coffee leaf rust caused by Hemileia vastatrix [175].…”