Molecular phylogeny and morphology reveal two new graminicolous species, Bipolaris adikaramae sp. nov and B. petchii sp. nov., with new records of fungi from cultivated rice and weedy grass hosts

Authors: FERNANDEZ, HIMASHI - University Of Sri Jayewardenepura; MANAMGODA, DIMUTHU - University Of Sri Jayewardenepura; UDAYANGA, DHANUSHKA - University Of Sri Jayewardenepura; DESHAPPRIYAA, NELUM - University Of Sri Jayewardenepura; MUNASINGHEA, MAYURI - University Of Sri Jayewardenepura; Castlebury, Lisa

Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2022
Publication Date: 5/27/2022
Citation: Fernandez, H.S., Manamgoda, D.S., Udayanga, D., Deshappriyaa, N., Munasinghea, M.S., Castlebury, L.A. 2022. Molecular phylogeny and morphology reveal two new graminicolous species, Bipolaris adikaramae sp. nov and B. petchii sp. nov., with new records of fungi from cultivated rice and weedy grass hosts. Mycological Progress. 21:59. https://doi.org/10.1007/s11557-022-01809-w.
DOI: https://doi.org/10.1007/s11557-022-01809-w

Interpretive Summary: The fungal genus Bipolaris represents many destructive fungal plant pathogens with a worldwide distribution. Pathogenic species in this genus affect many grasses, including corn and rice. Given the importance of Bipolaris species as plant pathogens, a survey was undertaken in Sri Lanka where few reports have been recorded. Using DNA and microscopic characteristics, two species new to science were found on weedy grass hosts. This research will be useful for mycologists and plant pathologists to develop quick and efficient assays for its targeted detection, to understand pathogenicity and to develop strategies to control the spread and prevent the economic and societal losses associated with Bipolaris diseases.

Technical Abstract: Phytopathogenic fungi in the genus Bipolaris are usually associated with poaceous hosts including major cereal crops. Morphological identification alone is often insufficient for species discrimination due to overlapping microscopic characters. Thus, molecular phylogenetic analyses are utilized for accurate species identification within the genus. Although there are 134 species of Bipolaris listed in Index Fungorum, only 43 species have been identified and accurately placed within the genus using molecular data, with only four Bipolaris species reported from Sri Lanka. During this study, diseased and dead leaf specimens of weeds and cultivated rice were collected from several locations in Sri Lanka and associated fungal species isolated. The morphological characters together with phylogenetic inference from the analyses of three loci, internal transcribed spacers 1 and 2 with 5.8S region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and translation elongation factor 1-a (TEF1), supported the introduction of two novel species namely Bipolaris adikaramae from Panicum maximum and B. petchii from Ischaemum sp. Morphological descriptions and illustrations are provided for the newly described taxa. In addition, B. shoemakeri from Echinochloa sp. and Oryza sativa and B. sivanesaniana from O. sativa were identified as novel records from Sri Lanka. This study reinforces the need for extensive surveys of crops and associated weedy hosts in order to accurately assess the diversity of emerging species of phytopathogenic graminicolous fungi.