Capillaureum caryovora gen. sp. nov. (Cryphonectriaceae) pathogenic to pequi (Caryocar brasiliense) in Brazil

Abstract

Caryocar brasiliense Camb. (Ca. brasiliense) is a typical tree of the Brazilian Cerrado commonly known as pequi. The pequi fruits have a high potential for use in cosmetic and food industries. Due to its economic importance, during the fruiting period, numerous families living in the Cerrado biome benefit from direct fruit harvesting, which is often their only income source. There are no commercial plantations, and the only source of the pequi fruits is the natural Brazilian Cerrado. During a disease survey, an unknown fungus was observed on stem cankers of dying trees. The fungus has similar characteristics to the well-known family of canker pathogens, the Cryphonectriaceae. Thus, the aims of this study were to isolate and identify the fungus from those canker symptoms and assess its pathogenicity. Identification of the fungus was based on morphological characteristics as well as DNA sequence data. DNA from the internal transcribed spacer (ITS) regions, two fragments of the b-tubulin gene (BT1 and BT2), and large subunit of rDNA (LSU) was sequenced and compared with published sequences for 20 genera in the Cryphonectriaceae family. Pathogenicity tests were conducted on Ca. brasiliense seedlings. Morphological characterizations revealed that the fungus isolated from Ca. brasiliense differed from those typically found in the Cryphonectriaceae, especially for the presence of ostiolar septate single or branched hyphae. Phylogenetic analyses showed that this novel fungus from Ca. brasiliense grouped separately from other genera in the Cryphonectriaceae. Pathogenicity tests on Ca. brasiliense showed that the fungus is able to cause stem cankers. Taking all findings together, we propose that the pathogenic fungus isolated from Ca. brasiliense is a novel genus and a novel species in the Cryphonectriaceae, and thus, we named it as Capillaureum caryovora.