Root associated Fusarium solani Species Complex (FSSC) in epiphytic and terrestrial orchids

Abstract

Abstract. Sukarno N, Mursidawati S, Listiyowati S, Nugraha NH, Fadillah WN, Waite M. 2023. Root associated Fusarium solani Species Complex (FSSC) in epiphytic and terrestrial orchids. Biodiversitas 24: 2577-2586. Members of the Fusarium solani Species Complex (FSSC) are ecologically diverse, covering human and plant pathogens, saprobes, and endophytic fungi of economically important plants. The role of FSSC on tropical orchids, however, has received little attention. This research aimed to isolate and identify the FSSC found as endophytes in roots of the epiphytic orchids Cymbidium finlaysonianum Lindl. and Vanda tricolor Lindl., and the terrestrial orchids Calanthe triplicata (Willemet) Ames and Phaius tankervilleae (Banks) Blume. Fungal isolation was obtained from peloton structures within the root. Fungal identification was done using combined morphological and molecular characteristics using ITS rDNA sequences. Four isolates of Fusarium were identified based on morphological characteristics. The BLAST analysis showed that all the isolates were in the Fusarium solani Species Complex (FSSC). Further phylogenetic relationship analysis indicated that all the FSSC isolates belonged to FSSC5 lineage or Fusarium solani sensu stricto, which is nested in FSSC clade 3 as a subgroup. The fungi F. solani sensu stricto V2 and CF34 were isolated from the epiphytic orchids, and F. solani sensu stricto C5 and P44 were isolated from the terrestrial orchids. It is interesting that the FSSC5 isolated from the epiphytic orchids form different groups than those of the terrestrial orchids. This is the first report showing the tropical orchids are the host of the FSSC5 as endophytes and this broadens the known host range and ecological behavior of the FSSC5.