Effect of air temperature on the interaction of Neophysopella tropicalis and cv. Niagara Rosada and cv. Cabernet Sauvignon vines

Author(s)

Júlia Boscariol Rasera

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2021-02-24

Examining board members

Beatriz Appezzato da Gloria; João Paulo Rodrigues Marques; Isabela Vescove Primiano; Rafael Vasconcelos Ribeiro

• Advisor: Beatriz Appezzato da Gloria; Lilian Amorim

Abstract

Brazil is the fourteenth largest grape producer in the world, and produced approximately 1.5 million tons in 2020. Rio Grande do Sul is the largest producer in the country and has 20% of its area planted with vines with Vitis vinifera cv. Cabernet Sauvignon, and the State of São Paulo remains as the third largest producer, with its planted area predominated by the V. labrusca cv. Niagara Rosada. A major obstacle that growers in the region face is the Grapevine rust, caused by Neophysopella tropicalis. Climate change has indicated an increase in both global temperature and the concentration of greenhouse gases in the atmosphere and has triggered a new alert in agriculture. In this context, there is a need to understand the implications of these changes in the N. tropicalis-grapevine pathosystem. Thus, the objectives of this work were: a) to characterize the photosynthetic activity of grapevines cv. Niagara Rosada and cv. Cabernet Sauvignon healthy non inoculated and inoculated with N. tropicalis at different temperatures and b) to characterize the monocycle of N. tropicalis in cv. Niagara Rosada and cv. Cabernet Sauvignon under different temperatures. Therefore, in vitro and in vivo experiments were carried out in a temperature range of 15 to 35°C, for analysis of the pathogen\'s pre-penetration process, and in vivo experiments at 20, 25 and 30°C to characterize the monocycle of this rust, the gas exchanges and responses of the host, with the variations of temperature. The experiments were carried out in cv. Niagara Rosada and cv. Cabernet Sauvignon. Germination rates of N. tropicalis urediniospores in vitro were much lower than those observed in vivo, regardless of temperature, and there was no germination at 35°C. Epidemiological and histopathological analyzes showed that the optimal temperature range for the development of the pathogen is between 20 and 30°C, with the final severity at 30°C being as high as at other temperatures, even if the host has defense mechanisms against the pathogen at this temperature. The presence of the pathogen reduced the assimilation of CO2 at 25 and 30°C and this reduction followed a negative exponential model due to the severity of the disease. At a temperature of 30°C there was a sharp drop in the efficiency of water use, especially in cv. Niagara Rosada. Thus, even though the temperature of 30°C is not ideal for the development of the pathogen, the combination of abiotic and biotic stresses proved to be as harmful as the occurrence of isolated stress. (AU)

• FAPESP's process: 19/15191-2 - Can the stress caused by temperature affect the grapevine rust pathosystem? Epidemiologic, physiological and histopathological analyses in Vitis labrusca 'Niagara Rosada' and V. vinifera 'Cabernet'
• Grantee: Júlia Boscariol Rasera
• Support Opportunities: Scholarships in Brazil - Master