Responses to Drought Stress Modulate the Susceptibility to Plasmopara viticola in Vitis vinifera Self-Rooted Cuttings

Abstract

Climate change will increase the occurrence of plants being simultaneously subjected to drought and pathogen stress. Drought can alter the way in which plants respond to pathogens. This research addresses how grapevine responds to the concurrent challenge of drought stress and Plasmopara viticola, the causal agent of downy mildew, and how one stress affects the other. Self-rooted cuttings of the drought-tolerant grapevine cultivar Xynisteri and the drought-sensitive cultivar Chardonnay were exposed to full or deficit irrigation (40% of full irrigation) and artificially inoculated with P. viticola in vitro or in planta. Leaves were sampled at an early infection stage to determine the influence of the single and combined stresses on oxidative parameters, chlorophyll, and phytohormones. Under full irrigation, Xynisteri was more susceptible to P. viticola than the drought-sensitive cultivar Chardonnay. Drought stress increased the susceptibility of grapevine leaves inoculated in vitro, but both cultivars showed resistance against P. viticola when inoculated in planta. Abscisic acid, rather than jasmonic acid and salicylic acid, seemed to play a prominent role in this resistance. The irrigation-dependent susceptibility observed in this study indicates that the practices used to mitigate the effects of climate change may have a profound impact on plant pathogens.

The Durability of Quantitative Host Resistance and Variability in Pathogen Virulence in the Interaction Between European Grapevine Cultivars and Plasmopara viticola

“…For each replicate, two leaves of the same plant were pooled, immediately frozen in liquid N 2 , and kept at −80 • C until analysis. The procedure for the quantification of phytohormones is described in detail by Haeck et al (2018) and Heyman et al (2021).…”

Leaf Polyphenolic Profile as a Determinant of Croatian Native Grapevine Varieties’ Susceptibility to Plasmopara viticola

“…Such a pyramided resistance provides a higher level of resistance generally expressed as a more stable and durable feature ( Merdinoglu et al, 2018 ). However, it was found that its response to P. viticola infection is isolate-specific and highly variable ( Heyman et al, 2021 ). Due to its genetic background based on V. vinifera [Merzling × (Zarya Severa × Muscat Ottonel)] ( Pezet et al, 2004 ), it reacted more similarly to V. vinifera varieties, when compared to V. riparia upon P. viticola inoculation.…”

Organic Cultivation and Deficit Irrigation Practices to Improve Chemical and Biological Activity of Mentha spicata Plants

“…Plants were cultivated for four months, and were harvested in two harvesting periods, right before flowering stage. Soil water content measured every five days by a portable field-scout TDR300 apparatus, equipped with 20 cm rods (Spectrum Technologies Inc, Aurora, IL, USA), based on preliminary measures and previous experimentation [5,[36][37][38]. Plants were irrigated approximately every 5-7 days.…”