Downy mildew symptoms on grapevines can be reduced by volatile organic compounds of resistant genotypes

Abstract

Volatile organic compounds (VOCs) play a crucial role in the communication of plants with other organisms and are possible mediators of plant defence against phytopathogens. Although the role of non-volatile secondary metabolites has been largely characterised in resistant genotypes, the contribution of VOCs to grapevine defence mechanisms against downy mildew (caused by Plasmopara viticola) has not yet been investigated. In this study, more than 50 VOCs from grapevine leaves were annotated/identified by headspace-solid-phase microextraction gas chromatography-mass spectrometry analysis. Following P. viticola inoculation, the abundance of most of these VOCs was higher in resistant (BC4, Kober 5BB, SO4 and Solaris) than in susceptible (Pinot noir) genotypes. The post-inoculation mechanism included the accumulation of 2-ethylfuran, 2-phenylethanol, β-caryophyllene, β-cyclocitral, β-selinene and trans-2-pentenal, which all demonstrated inhibitory activities against downy mildew infections in water suspensions. Moreover, the development of downy mildew symptoms was reduced on leaf disks of susceptible grapevines exposed to air treated with 2-ethylfuran, 2-phenylethanol, β-cyclocitral or trans-2-pentenal, indicating the efficacy of these VOCs against P. viticola in receiver plant tissues. Our data suggest that VOCs contribute to the defence mechanisms of resistant grapevines and that they may inhibit the development of downy mildew symptoms on both emitting and receiving tissues.

Ants suppressing plant pathogens: a review

“…Lastly, volatile antibiotics may also be in play. Atta and Acromyrmex ants are known to produce volatile chemicals with antibiotic properties in their mandibular glands, and volatile molecules, including some produced by ants, have been shown to inhibit the development of downy mildew Plasmapara viticola on grapewine (Lazazzara et al 2018). In conclusion, mechanical mechanisms seem highly plausible, and pathways by which antibiotics may travel from ants to plants are multiple.…”

Óleos essenciais no controle de Botrytis cinerea: influência na qualidade pós-colheita de uvas ‘Rubi’

“…Além desses efeitos proporcionados pelo OEP, ressalta-se que esse óleo essencial apresenta volatilização lenta, o que permite a formação de envelopes de proteção sobre o tecido vegetal (Lazazzara et al, 2018), fato que, possivelmente, protegeu os frutos de uvas 'Rubi'.…”

“…Resultados referentes aos voláteis eliminados pelo OEP podem-se relacionar com a capacidade de seus compostos em causar alterações degenerativas nas hifas, acarretando aumento nos vacúolos, elevado número de peroxissomos e de mitocôndrias nas células fúngicas, e perda da integridade da membrana plasmática (Pârvu et al, 2013;Shao et al, 2013 naturalmente emitem compostos voláteis ricos em monoterpenos e sesquiterpenos. Videiras resistentes ao Plasmopara viticola liberam, principalmente muroleno, cariofileno e germacreno B, como forma de proteção (Lazazzara et al, 2018). Esses compostos são encontrados no OEP e em OEG, os quais, possivelmente, foram os responsáveis pela redução do mofo cinzento nas bagas de uva 'Rubi'.…”

Biological Characteristics and Assessment of Virulence Diversity in Pathosystems of Economically Important Biotrophic Oomycetes

“…At the molecular level, resistant hosts react in many different ways after infection has started. Localized callose deposition (Kortekamp et al, 1997;Gindro et al, 2003), volatile organic compounds (Lazazzara et al, 2018), accumulation of secondary metabolites (Figueiredo et al, 2008;Chang et al, 2011), and hypersensitive reaction (HR) (Kortekamp et al, 1997;Gindro et al, 2003;Casagrande et al, 2011) have been reported as important mechanisms to avoid downy mildew infection. Strong expression of defense-related genes has been reported as well from resistant hosts (Polesani et al, 2010;Figueiredo et al, 2012) early after their contact with the oomycete.…”