Avaliação in vitro da resistência de diferentes genótipos de videira à ferrugem

Abstract

Grapevine leaf rust - GLR (Phakopsora euvitis ONO) was firstly indentified in Brazil in the North of Paraná in 2001. After that, the pathogen was also detected in Mato Grosso do Sul, São Paulo, Rio Grande do Sul, Mato Grosso and, more recently, in Santa Catarina. Due GLR does not cause major losses at traditional wine growing regions of the world, there are only few investigations involving the disease. The assessment of genotypes resistant to P. euvitis is extremely relevant and necessary for grapevine breeding programs. The present investigation aimed the evaluation of the level of resistance to P. euvitis from different grapevine genotypes. The investigation was performed at the Laboratory of Microbiology and Phytopathology of the Unipampa/Campus Itaqui. Twenty four different genotypes, belonging to different grapevine species, were evaluated. Leaves were cut into discs, placed on moist filter paper with the under (abaxial) surface facing upwards and sealed individually in Petri dishes. Leaf discs were inoculated on the under surface with a spore suspension containing 2x10³ spores.mL-¹. The Petri dishes were stored in BOD, under temperature of 24 oC ± 2 and photoperiod of 16 hours light. The parameters evaluated were: determination from the latent period; quantification of the number of pustules per disc; quantification of the sporulation and determination of a resistance scale based on the number of pustules. None of the 24 grapevine genotypes evaluated was symptomless to GLV, i.e. none of the grapevine genotypes evaluated possesses major resistance genes to the disease. The genotypes V. candicans, V. longii, V. caribea, V. amurensis, Gropel and IAC-572 revealed a moderate resistance to the disease, while the genotypes Baco 10, V. thumbergii, V. slavinii and V. vulpine are the most susceptible. These findings are very important for the grapevine breeding, because they can be used for the development of strategies to avoid or to reduce the damages caused by the GLR. However, further investigations are required in order to find genotypes more resistant to the disease.