Species of Fusarium fujikuroi complex causing seed and seedling rot of Baru (Dipteryx alata Vogel) in Brazil

Abstract

Abstract Baru (Dipteryx alata Vogel) is a plant native to the Brazilian Cerrado and has numerous uses. In October 2022, Baru seedlings were received at the NPF plant disease diagnosis clinic, Universidade Federal de Goiás. These plants showed symptoms of stem lesions and apical death, in addition to rotten seeds. To investigate the cause of the disease, isolation was initially carried out on potato dextrose agar medium, and 30 conidia were measured. Then, the pathogenicity test was conducted on Baru seedlings and seeds. Molecular characterization was performed by partial sequencing of act, its, rpb2 and tef1-α markers and concatenated phylogenetic analysis by Bayesian inference. Based on the isolations, it was observed that the mycelium presented a cotton-like appearance in culture, from pink to purple. The microconidia were ellipsoid, unicellular, and ranged from 5.224 to 12.773 µm x 2.250 to 4.532 µm. In the pathogenicity test, apical death of seedlings, lesions and seed rot were observed. In the laboratory test, the appearance of depressed lesions on the seed coat, cotyledons, stem, and roots was observed, from which it was also possible to recover the fungi, fulfilling Koch's postulates. The molecular identification revealed that the isolates belong to the species Fusarium sacchari and F. musae. To our knowledge, this is the first report of them associated with rot of Baru seeds and seedlings in Brazil.