Fusarium amaranthi sp. nov. from Amaranth Is an Emergent Species Closely Related to F. circinatum .

Amaranth ( Amaranthus spp. L) is not native to South Korea but is cultivated in small scales for ornamental purposes as well as leafy vegetables and pseudo cereals. In this study, a new species within the genus Fusarium was isolated from amaranth, showing stem rot symptoms from a farmer field in Hwaseong, South Korea. The disease is characterized by dark-brown spots with black borders, leading to withering. Phylogenetic analysis-based concatenated sequences of translation elongation factor 1-alpha ( TEF1 ), beta-tubulin ( tub 2), calmodulin ( cmd A), RNA polymerase largest subunit ( RPB 1), and RNA polymerase II second largest subunit ( RPB 2) genes revealed that the obtained isolates formed a distinct clad within the Fusarium fujikuroi species complex and is closely related to F . circinatum . Cultural and morphological characteristics and pathogenicity on healthy amaranth plants (stem and leaves) were examined. The isolates readily differentiated from F. circinatum based on one- to five-septate macroconidia and the absence of sterile hyphae. Based on molecular and morphological characteristics, this fungus is demonstrated to be a new species and is described here as F. amaranthi , the causal agent of stem rot of amaranth in South Korea.