Ophiostomatoid fungi associated with pines infected by Bursaphelenchus xylophilus and Monochamus alternatus in China, including three new species

Huimin Wang,Xingyao Zhang,Yingying Lun,Huixiang Liu,Quan Lu,Cony Decock

doi:10.3897/mycokeys.38.27014

Abstract

The activity of the pine wood nematodeBursaphelenchusxylophilusleads to extremely serious economic, ecological and social losses in East Asia. The nematode causes pine wilt disease, which is currently regarded as the most important forest disease in China. The pathogenic nematode feeds on dendrocola fungi to complete its cycle of infection. As the vector of the nematode, the Japanese pine sawyer (Monochamusalternatus) also carries dendrocola fungi. Pine woods, infected byB.xylophilusand tunnelled byM.alternatus, are also inhabited by ophiostomatoid fungi. These fungi are well known for their association with many bark and ambrosia beetles. They can cause sapstain and other serious tree diseases. The aims of our study were to investigate and identify the ophiostomatoid communities associated with the epidemic pine wood nematode and the pine sawyer inPinusmassonianaandP.thunbergiiforests, which are the main hosts of the pine wood nematode in China. Two hundred and forty strains of ophiostomatoid fungi were isolated from nematode and sawyer–infected trees in the coastal Shandong and Zhejiang Provinces, representing newly and historically infected areas, respectively. Six ophiostomatoid species were identified on the basis of morphological, physiological and molecular data. For the latter, DNA sequences of the internal transcribed spacer (ITS1–5.8S–ITS2) region and partial b-tubulin gene were examined. The ophiostomatoid species included one known species,Ophiostomaips, three novel species, viz.Ophiostomaalbumsp. nov.,Ophiostomamassonianasp. nov.andSporothrixzhejiangensissp. nov.and two species whose identities are still uncertain, Ophiostomacf.deltoideosporum and Graphilbumcf.rectangulosporium, due to the paucity of the materials obtained. The ophiostomatoid community was dominated byO.ips. This study revealed that a relatively high species diversity of ophiostomatoid fungi are associated with pine infected byB.xylophilusandM.alternatusin China.

Highlights

The pathogenic pine wood nematode (PWN) Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle (Aphelenchida, Parasitaphelenchidae), presumably native to North America (Steiner and Buhrer 1934, Robbins 1982, Ryss et al 2005, Zhao et al 2014), is a mild threat to pine trees in its native area
This study revealed that a relatively high species diversity of ophiostomatoid fungi are associated with pine infected by B. xylophilus and M. alternatus in China
240 strains belonging to Ophiostomatales were obtained from PWN-infected galleries and pupal chambers of M. alternatus

Summary

Introduction

The pathogenic pine wood nematode (PWN) Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle (Aphelenchida, Parasitaphelenchidae), presumably native to North America (Steiner and Buhrer 1934, Robbins 1982, Ryss et al 2005, Zhao et al 2014), is a mild threat to pine trees in its native area This species and the concomitant systematic wilt symptom are responsible for pine tree deaths affecting many trees in eastern Asia, notably in Japan and China (Evans et al 1996, Mota and Vieira 2008, Mamiya and Shoji 2009, Jung 2010, Futai 2013). It feeds on the dendrocola fungi to maintain its population and propagate (Suh et al 2013, Zhao et al 2013, 2014)

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