Seimatosporium chinense, a Novel Pestalotioid Fungus Associated with Yellow Rose Branch Canker Disease

Abstract

Yellow rose (Rosa xanthina) is a common ornamental shrub species widely cultivated in China. However, canker disease symptoms were discovered during our investigations in Beijing and Xinjiang, China. The fungal isolates were obtained from diseased barks and identified using combined methods of morphology and phylogeny based on a partial region of ITS, LSU, rpb2, tef1, and tub2 sequences. As a result, a new species of Seimatosporium named S. chinense was proposed and described herein. The new species is distinguished from its phylogenetic sister species, S. gracile and S. nonappendiculatum, by conidial characters. The present study improves the species concept in Seimatosporium and provides fundamental data for the yellow rose canker disease control in the future.

Keywords: Sporocadaceae; morphology; new species; phylogeny; plant disease.

Figure 1

Symptoms of yellow rose canker disease: arrows show diseased branches.

Figure 2

Phylogram of Seimatosporium resulting from a maximum likelihood analysis based on a combined matrix of ITS, LSU, rpb2, tef1, and tub2 loci. Numbers above the branches indicate ML bootstrap values (left, ML BS ≥ 50%) and Bayesian posterior probabilities (right, BPP ≥ 0.9). Isolates from the present study are marked in blue.

Figure 3

Seimatosporium chinense. (A) Disease symptoms. (B) Appearance of conidiomata on host substrate. (C–F) Conidiogenous cells with attached conidia. (G) Conidia.—Scale bars: (B) = 200 μm; (C–G) = 10 μm.

Figure 4

Colonies of Seimatosporium chinense grown on PDA (A), OA (B), and SNA (C) after 20 days.