Evaluating coffee genotypes for resistance to coffee leaf rust in Brazil

This study integrates data from Brazilian coffee cultivars with different resistant genetic sources to coffee leaf rust (CLR), a foliar disease caused by the fungus Hemileia vastatrix Berk. & Broome. The aim was to characterize the performance of some of the main Brazilian cultivars regarding resistance to CLR. Seedlings of 29 genotypes, including 25 established cultivars and four coffee progenies in the final selection phase, were maintained in a greenhouse, and inoculated with spores of H. vastatrix. Evaluation of CLR disease was based on incidence (leaf with or without spores) and severity (sporulating leaf area) parameters, assessed using diagrammatic scale and digital image analysis. Twenty-one coffee genotypes, representing 72% of those studied, showed no disease symptoms despite their diverse genetic backgrounds. Eighteen cultivars and three progenies were classified as highly resistant (HR). However, cultivars Guar & aacute;, Rouxinol, IPR 102, and Catuca & iacute; Amarelo 2SL displayed intermediate disease incidence and severity levels, categorized as moderately resistant (MR). The Catua & iacute; Vermelho IAC 99 cultivar and H29-1-8-5 progeny were susceptible to CLR exhibiting 100% incidence and severity levels of 5 (10.1-25.0%) and 6 (> 25% of area infected by rust), respectively, while others such as Catuca & iacute; Amarelo and Azul & atilde;o cultivars were slightly susceptible. The information obtained here is crucial for plant breeders to strategically incorporate diverse sources of resistance (complete and partial) into crop varieties to enhance their resilience against a wide array of pathogen races. Additionally, identifying genotypes whose resistance remains unaffected by H. vastatrix pathotypes from the southern region of Minas Gerais, as observed in this study, can provide a solid basis for recommending coffee cultivars for planting and defining disease management, ultimately contributing to the sustainability of coffee production.