Agradecimentos: The authors gratefully acknowledge the financial support from FAPESP (2013/24003-9; 2019/13191-5; 2019/15191-2). L.A., B.A.G. and R.V.R. are fellows from the National Council for Scientific and Technological Development (304881/2017-1; 311721/2018-4, 302460/2018-7). The authors also acknowledge the technical support provided by Professor Elliot W. Kitajima from the Laboratory of Electron Microscopy (ESALQ/USP), and all support provided by Renan Fernandes Alves and Dr Marcel B. Sposito (ESALQ/USP) Ver menos

Abstract: Asian grapevine leaf rust (AGLR), caused by Neophysopella tropicalis, is a problem for viticulture, especially in latitudes lower than 25° S, which include the most significant production regions in Brazil. Climate change has raised new concerns in agriculture as temperature can affect the resistance of plants to pathogens. With the aim of understanding how air temperature rise affects the AGLR pathosystem, measurements of leaf gas exchange and epidemiological and histopathological analyses were carried out on control and inoculated leaves of Vitis labrusca ‘Niagara Rosada’ grown at 25°C and 30°C. The lesion density and rust severity were higher at 25°C than 30°C, and the ratio between adaxial surface necrosis and the abaxial surface area occupied by pustules was >1 only at 30°C, presenting a necrosis not associated to the pathogen lesion. In fact, leaf necrosis was identified on control plants kept at 30°C and associated with gerontoplasts, representing accelerated leaf senescence. The AGLR pathogen reduced gas exchange and photosystem II activities at 25°C, with no difference between control and inoculated plants at 30°C. Our results indicate that AGLR is sensitive to increasing air temperature. However, the accelerated leaf senescence caused by the combination of N. tropicalis infection and temperature on Niagara Rosada can lead to high leaf damage. Inoculated plants kept at 30°C presented cell alterations that blocked colonization, reducing lesion density and severity. However, accelerated leaf senescence due to temperature raise may increase leaf damage and reduce yield Ver menos