Submitted to: Mycological Progress
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/16/2010
Publication Date: 9/20/2010
Citation: Pei, Y., Geng, Y., Oneill, N.R., Zhang, X. 2010. Three novel species of Stemphylium from Sinkiang, China: their morphological and molecular characterization. Mycological Progress. 10:163-173. Interpretive Summary: Fungus diseases caused by species of Stemphylium severely reduce yields and quality in important forage and food crops, including forage legumes, fruit tree, and vegetable crops. The fungi cause leaf, stem, and pod necrosis in humid climates throughout the world. It is important to know specifically which fungi are causing certain diseases so that control measures can be developed and quarantine procedures implemented when needed. Many of these fungi are difficult to distinguish from one another based on their morphology alone, as seen microscopically. We compared several species and strains causing diseases in vegetable crops, alfalfa, pear, and apple, using molecular DNA sequencing and morphology. The research resulted in the identification and characterization of three new pathogen species. The research will enable scientists, breeders, and industry to identify the specific causes of Stemphylium diseases and lead to implementation of appropriate disease control strategies.
Technical Abstract: Three new species of Stemphylium were isolated from diseased leaves of Luffa cylindrica, Lycium chinense and Cucumis melo growing in the Sinkiang province of Northwest China. Stemphylium luffae, S. lycii and S. cucumis are described by morphological and molecular phylogenetic analyses. The principal morphological characteristics of these three species are congruent with those of Stemphylium. They are distinguished from morphologically similar Stemphylium species based on characteristics of their conidia and conidiophores. In order to establish the molecular phylogenetic status of these species, DNA loci including the internal transcribed spacer (ITS) nuclear rDNA region and the glyceraldehyde-3-phosphate dehydrogenase (gpd) genes were amplified and sequenced. Phylogenetic analyses using Maximum-Parsimony (MP) and Neighbor-Joining (NJ) were performed on the combined DNA sequences of ITS and gpd gene regions. Both morphological observations and molecular analyses support S. luffae, S. lycii and S. cucumis as three new taxa.