Histochemical and histopathological analyses of cv. Solaris infected with Plasmopara viticola and expression of pathogenesis-related genes in two temperatures

• Grant number: 19/11590-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Effective date (Start): August 01, 2019
• Effective date (End): October 31, 2019
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Lilian Amorim
• Grantee: Antonio Fernandes Nogueira Júnior
• Supervisor: Ulrich Schaffrath
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Research place: RWTH Aachen University, Germany
• Associated to the scholarship: 17/02432-6 - Simulation modeling of damage caused by downy mildew and grapevine rust in Vitis spp. under different training systems, BP.PD

Abstract

Downy mildew caused by Plasmopara viticola is the most destructive disease of Vitis vinifera worldwide. Grapevine breeding programs have introgressed P. viticola-resistant traits into cultivated V. vinifera genotypes and launched interspecific hybrids with resistance against downy mildew. Defense mechanisms of grapevine to P. viticola comprise pre-existing chemical defenses and induce structural and biochemical defenses, such as accumulation of stilbenes and pathogenesis-related proteins, the generation of reactive oxygen species, and cell death-like hypersensitive reactions. In several pathosystems, temperature affects host plant resistance responses. Previously, results obtained during the BEPE internship (2018/00952-5) showed that the downy mildew resistant cultivar Solaris responds differently to the downy mildew infection at temperatures of 20 or 25 oC. Resistant grapevine Solaris inoculated with P. viticola showed larger leaf necrosis at 25 oC compared with leaves kept at 20 oC. The objectives of this work are to characterize the effect of temperatures at 20 or 25 oC on (i) the colonization of the resistant grapevine cv. Solaris and susceptible cv. Riesling infected with Plasmopara viticola by microscopic analyses using with different staining techniques and bright field/epi-fluorescence microscopy; (ii) determine expression of pathogenesis-related genes by qPCR at early stages of P. viticola infection in resistant and susceptible cultivars after inoculation with P. viticola and kept at 20 or 25 oC. Information on how diseases affect leaf physiology in their hosts is key for understanding yield losses caused by pathogens and for improving crop modelling, which is one of the objectives of postdoctoral project FAPESP (2017-02432-6). This proposal will be held under the supervision of Prof. Ulrich Schaffrath, at the Department of Plant Physiology at RWTH Aachen University, Germany, with the collaboration of University of Göttingen.