Diversidade de espécies de Lasiodiplodia associadas às podridões apical e estilar da goiaba

Abstract

Stem-end rot and stylar-end rot are among the main postharvest diseases of guava (Psidium guajava), severely compromising fruit quality and reducing shelf life, resulting in significant economic losses. These rots have been associated with fungi of the Botryosphaeriaceae family, including the genus Lasiodiplodia, which stands out for its wide ecological diversity, high genetic variability, and recognized taxonomic complexity. Despite its phytopathological importance, studies using molecular tools to identify Lasiodiplodia species associated with stemend and stylar-end rots in guava are still scarce worldwide, highlighting a significant knowledge gap. In this context, the present study aimed to characterize the diversity of Lasiodiplodia species associated with stem-end and stylar-end rots of guava fruits in Northeast Brazil, based on phylogenetic analyses inferred from sequences of the internal spacer transcript (ITS) region and the elongation factor 1-alpha (EF1-α) and β-tubulin (TUB2) genes. To this end, 53 Lasiodiplodia isolates were obtained from fruits collected in 13 municipalities in the states of Ceará, Pernambuco, and Rio Grande do Norte. Genomic DNA from the isolates was extracted, followed by amplification of the ITS region and the EF1-α and TUB2 genes by polymerase chain reaction (PCR). The amplicons were purified, sequenced, and compared with reference sequences of Lasiodiplodia species available in GenBank. Phylogenetic relationships were inferred using the Maximum Likelihood method. Phylogenetic analysis identified six species: L. brasiliensis, L. euphorbiaceicola, L. hormozganensis, L. iraniensis, L. pseudotheobromae, and L. theobromae. One isolate did not group into any of the clades corresponding to recognized species of the genus. Lasiodiplodia brasiliensis was the most frequent species, representing 43.4% of the isolates, followed by L. theobromae (17%), L. pseudotheobromae (15%), and L. hormozganensis (13.2%). The identification of these species constitutes the first record of their association with guava in Brazil. Additionally, this study reports, for the first time worldwide, the association of L. brasiliensis and L. euphorbiaceicola with rots in guava fruits. The results significantly expand our knowledge of the diversity of Lasiodiplodia species associated with guava fruits and indicate that this pathosystem is more complex than previously recognized.