ABSTRACT
Bacterial wilt, induced by the soil pathogen ralstonia solanacearum, is a serious tomato disease in tropical countries in areas subject to high temperatures and high humidity. Disease control is very difficult and requires a set of management measures, among them grafting, which has become more popular after the release of a set of commercial tomato resistant rootstocks. Although protection conferred by these rootstocks has been effective in many locations, it is not enough under situations very conducive to bacterial wilt, such as high populations of the pathogen in the soil, high temperature, high soil humidity and presence of an aggressive strain of the pathogen. The objective of this work was to assess the potential of accessions of two solanum species known as "jurubeba" in brasil, as rootstocks to protect tomato plants against bacterial wilt through grafting. In experiments carried out under greenhouse conditions in brasilia, 26 accessions of each solanum scuticum and s. Stramonifolium were tested. In a first phase, the set of accessions were challenged with one isolate of r. Solanacearum previously known by its high virulence to solanaceous crops. In a second phase, three representative resistant accessions were challenged with three isolates of the pathogen also previously chosen for their high virulence to tomato and sweet pepper and distinct biovar/phylotype. Accessions of s. Scuticum reacted differently to the pathogen's isolates, but 15 out of 26 accessions presented an immune-like resistance to all bacterial isolates. No correlation was observed between resistance and origin of the accessions. S. Stramonifolium accessions, differently from s. Scuticum, were all resistant to the bacterial isolates. The two species of "jurubeba", therefore, contain accessions that are higly resistant to a range of virulent isolates of r. Solanacearum. Their use as rootstocks to protect tomato against bacterial wilt is viable, but further research is needed to solve eventual problems related to the rootstock-scion compatibility.
Keywords:
Ralstonia solanacearum; Solanum scuticum; Solanum stramonifolium; Solanum lycopersicum; grafting.
