Diversity and pathogenicity of Botryosphaeriaceae species associated with black root rot and stem cutting dry rot in Manihot esculenta in Brazil

Abstract

Cassava is a starch-rich, high-calorie tuberous root used as human and animal food, as well as an input material in various industries. Black root rot (BRR) and stem cutting dry rot (SCDR) are cassava diseases that compromise product quality and can greatly reduce crop yields. Consequently, the aim of this study was to identify Botryosphaeriaceae species associated with both diseases in areas of the northeast of Brazil and in areas of the Minas Gerais State in the southeast of the country and infer a correlation between them. Fungal species were identified by morphology combined with phylogenetic analyses of partial sequences of translation elongation factor 1 alpha (tef1-α), internal transcribed spacer (ITS) and RNA polymerase subunit II (rpb2). Five species were identified as being associated with both BRR and SCDR (Lasiodiplodia euphorbicola, L. hormozganensis, L. parva, L. theobromae, and Neoscytalidium dimidiatum), while five others were associated only with SCDR (L. brasiliense, L. caatinguensis, L. iraniensis, L. laeliocattleyae, and L. pseudotheobromae). All species identified in this survey were able to induce disease in cassava roots and seedlings. In decreasing order, the most frequently isolated species were L. theobromae, N. dimidiatum, and L. euphorbicola. This is the first report of L. brasiliense, L. caatinguensis, L. hormozganensis, L. iraniensis, L. laeliocattleyae, and L. parva associated with cassava diseases worldwide.