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Title: New species from the Fusarium solani species complex derived from perithecia and soil in the Old World tropics

Author
item NALIM, F.A. - New Mexico State University
item Samuels, Gary
item WIJESUNDERA, R.L. - University Of Colombo
item GEISER, D.M. - Pennsylvania State University

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2011
Publication Date: 12/12/2011
Citation: Nalim, F., Samuels, G.J., Wijesundera, R., Geiser, D. 2011. New species from the Fusarium solani species complex derived from perithecia and soil in the Old World tropics. Mycologia. 103(6):1302-1330.

Interpretive Summary: Members of a complex group of fungi in the genus Fusarium are responsible for many soil borne diseases and fruit rots, including the Soybean Sudden Death Syndrome. Some members of the complex cause eye infections in humans. This is a very large fungal complex with possibly 28 species recognized on the basis of their DNA sequences. Only a few of these have been formally described and given scientific names. One complication is that these fungi often produce both a sexual state that may be given one name while they also reproduce asexually and thus are given another name for that state. These scientific names must be linked so that they refer to just one species. In this research the species in this complex are defined based on DNA sequences. In addition many species are described and illustrated some of which are based on fungal isolates from the original place from which they were first described in Sri Lanka in the mid 19th century. As a result of this research plant and forest pathologists, plant disease diagnosticians, and plant quarantine officials will be able to accurately identify these fungal species and thus control the diseases of plants caused by these fungi.

Technical Abstract: The Fusarium solani species complex (FSSC) is a highly diverse, cosmopolitan group of fungi that occur in soil and on living and dead plant tissue and can cause both human and plant infections. This monophyletic group was previously divided into three clades with some biogeographic structure, termed Clades 1, 2 and 3. The sexual stage associated with the FSSC, commonly known as Nectria haematococca, was originally described based on material collected on wood in Sri Lanka. To identify new species in the FSSC and to better understand its biogeography, we investigated the phylogenetics of F. solani isolates obtained from soil and perithecia found on bark from primary tropical forests in Sri Lanka and Queensland, Australia. Portions of the translation elongation factor 1-alpha (tef) gene, the nuclear large subunit (NLSU), and internal transcribed spacer regions (ITS) of the nuclear ribosomal RNA genes, were sequenced in 52 isolates from soil and perithecia. All soil isolates from Sri Lanka were found to be members of Clade 3, with most grouping with the cosmopolitan soil-associated species F. falciforme. All but one isolate derived from perithecia were associated with a set of five divergent phylogenetic lineages that were associated with the previously described Clade 2 of the FSSC. Isolates from perithecia and those cultured from soil were always members of different species lineages, even when derived from proximal locations. The previous biogeographic assignment of Clade 2 to South America is now expanded to the worldwide tropics. The results of our study indicate that Sri Lanka appears to be an important center of diversity for the FSSC and suggest that there is a great deal of unsampled diversity. Nectria haematococca is epitypified with a collection from the type locality in Sri Lanka; its anamorph is described as a new species, Fusarium haematococcum. On phylogenetic grounds Neocosmospora E.F. Smith is adopted as the correct genus for Nectria haematococca and the new combination Neocosmospora haematococca is proposed. The following new species are described: Neo. pseudoensiformis/Fusarium pseudoensiforme, Neo. kurunegalensis/F. kurunegalense, Neo. rectiphora/F. rectiphorus, Neo. mahasenii/F. mahasenii, Neo. keleraja/F. kelerajum.