Reaction of Luffa spp. to Macrophomina pseudophaseolina inoculation

Abstract

The genus Macrophomina is responsible for causing diseases in various species of the Cucurbitaceae family. This study aimed to evaluate the reaction of Luffa species when associated with M. pseudophaseolina. Initially, a prospection study was carried out to identify fungi associated with Luffa roots. Three isolates belonging to the M. pseudophaseolina species were identified and confirmed by DNA extraction and PCR amplification, using specific primers. One isolate was selected to test pathogenicity on Luffa. Twelve Luffa spp. accessions from the cucurbitaceous germplasm collection of Universidade Federal Rural do Semi-Árido were used, along with two positive controls: melon and watermelon plants. Inoculation was performed using the infested toothpick method. The plants were maintained under greenhouse conditions in a completely randomized design with four replications. The trial was repeated. The following variables were assessed: disease incidence and severity, reaction class, shoot length (SL), root length (RL), fresh shoot weight (FSW), dry shoot weight (DSW), fresh root weight (FRW), and dry root weight (DRW). Accession AB39 proved to be immune to the pathogen, as well as exhibiting the highest values of SL (163.9 cm), RL (43.4 cm), FSW (24.9 g), FRW (9.8 g), DSW (3.4 g), and DRW (0.5 g). These results indicate that the immune resistance of AB39 makes this accession promising, both in terms of disease resistance and vegetative growth, standing out as the best option among the accessions evaluated. Additionally, this is the first report of Luffa spp. acting as an alternative host of M. pseudophaseolina.