Resistance of mango cultivar Ubá to Ceratocystis fimbriata depends on the pathogen's physiological variability

Abstract

Mango sudden decline (MSD) caused by Ceratocystis fimbriata is one of the major diseases affecting mango crop in Brazil, Oman, and Pakistan. In Brazil, the main strategy for MSD management has been the use of resistant plants as rootstock for grafting. In this study, we tested the resistance of mango cultivar Ubá to C. fimbriata isolates from different populations. Firstly, we inoculated 2173 seedlings from 129 accessions of mango cv. Ubá using three representative fungal isolates from Brazil. Following the inoculation, the potential resistant plants were challenged against ten C. fimbriata isolates from Brazil and three from Oman. Finally, to confirm its resistance, clonal replicates of the resistant accessions were re-inoculated with the same fungal isolates. In the first selection, 13 accessions were pre-selected as resistant. In subsequent selections, they proved to be resistant to C. fimbriata isolates from populations from Oman/Pakistan and Southeastern Brazil. However, all 13 accessions were susceptible to fungal isolates from populations from Northeastern Brazil and Rio de Janeiro (also in Brazil). Our results reveal that mango cv. Ubá resistance to MSD is isolate specific and depends on the pathogen population. We obtained 13 mango cv. Ubá clones resistant to C. fimbriata, which may be useful as rootstock to MSD management in Oman and specific regions from Brazil.