Differential patterns of ophiostomatoid fungal communities associated with three sympatric Tomicus species infesting pines in south-western China, with a description of four new species

Abstract

Bark beetles and their associated fungi, which cause forest decline and sometimes high mortality in large areas around the world, are of increasing concern in terms of forest health. ThreeTomicusspp. (T.brevipilosus,T.minorandT.yunnanensis) infect branches and trunks ofPinusyunnanensisandP.kesiyain Yunnan Province, in south-western China.Tomicusspp. are well known as vectors of ophiostomatoid fungi and their co-occurrence could result in serious ecological and economic impact on local forest ecosystems. Nonetheless, knowledge about their diversity, ecology, including pathogenicity and potential economic importance is still quite rudimentary. Therefore, an extensive survey of ophiostomatoid fungi associated with theseTomicusspecies infestingP.yunnanensisandP.kesiyawas carried out in Yunnan. Seven hundred and seventy-two strains of ophiostomatoid fungi were isolated from the adult beetles and their galleries. The strains were identified based on comparisons of multiple DNA sequences, including the nuclear ribosomal large subunit (LSU) region, the internal transcribed spacer regions 1 and 2, together with the intervening 5.8S gene (ITS) and the partial genes of β-tubulin (TUB2), elongation factor 1α (TEF1-α) and calmodulin (CAL). Phylogenetic analyses were performed using maximum parsimony (MP) as well as maximum likelihood (ML). Combinations of culture features, morphological characters and temperature-dependent growth rates were also employed for species identification. Eleven species belonging to five genera were identified. These included six known species,Esteyavermicola,Leptographiumyunnanense,Ophiostomabrevipilosi,O.canum,O.minusandO.tingensand four novel taxa, described asGraphilbumanningense,O.aggregatum,SporothrixpseudoabietinaandS.macroconidia. A residual strain was left unidentified asOphiostomasp. 1. The overall ophiostomatoid community was by far dominated by three species, representing 87.3% of the total isolates; in decreasing order, these wereO.canum,O.brevipilosiandO.minus. Furthermore, the ophiostomatoid community of each beetle, although harbouring a diversity of ophiostomatoid species, was differentially dominated by a single fungal species;Ophiostomacanumwas preferentially associated with and dominated the ophiostomatoid community ofT.minor, whereasO.brevipilosiandO.minuswere exclusively associated with and dominated the ophiostomatoid communities ofT.brevipilosusandT.yunnanensis, respectively. Eight additional species, representing the remaining 12.7% of the total isolates, were marginal or sporadic. These results suggested that sympatricTomicuspopulations are dominated by distinct species showing some level of specificity or even exclusivity.

Ophiostomatoid fungi associated with pine bark beetles and infested pines in south-eastern Australia, including Graphilbum ipis-grandicollis sp. nov.

“…abietina or Sporothrix sp., which included isolates from the USA, Mexico, South Africa, Poland and China (Zhou et al 2004a ; Min et al 2009 ; Romón et al 2014 ; Jankowiak et al 2018 ). In 2019, this taxon was formally described as S. pseudoabietina, with the type specimen originating in China (Wang et al 2019 ). Our results confirm that S. pseudoabietina is a commonly isolated fungus from Australian-grown pine which was first detected in 2019 (Carnegie et al 2019 ).…”

“…This is particularly true for pine (Pinus) plantations globally (Seifert et al 2013;de Errasti et al 2018;Jankowiak et al 2021). Systematic surveys of bark beetles and ophiostomatoid fungi associated with pine have been completed in North and Central America (Zhou et al 2004a;Kim et al 2011;Klepzig and Hofstetter 2011;Taerum et al 2013;Marincowitz et al 2020), Europe (Linnakoski et al 2012;Romón et al 2014;Jankowiak et al 2012Jankowiak et al , 2020, Asia (Zhou et al 2013;Masuya et al 2013;Kirisits et al 2013), with a significant number of surveys conducted recently in China (Chang et al 2017(Chang et al , 2019Wang et al 2018Wang et al , 2019Wang et al , 2020, South America (Zhou et al 2004b;de Errasti et al 2018) and New Zealand (Thwaites et al 2005(Thwaites et al , 2013. The diversity of ophiostomatoid fungi present in exotic pine plantations in Australia, however, remains largely undetermined.…”

Six new species of Sporothrix from hardwood trees in Poland

“…The second largest number of isolates (81 in total) included in this study represented two species in the S. gossypina-complex, bringing the total number of species in that complex to 15 Wang et al 2019). Sporothrix cracoviensis was represented by 45 isolates from the ambrosia beetles Trypodendron domesticum and T. signatum collected on Fagus sylvatica (Jankowiak et al 2019a).…”

“…As currently recognized, Sporothrix includes 56 species Ngubane et al 2018;Wang et al 2019;Musvuugwa et al 2020), which are characterized by their dark brown to black, globose ascomata with elongated necks up to 1600 μm, occasionally terminating in an ostiole, often surrounded by ostiolar hyphae. Ascospores are usually curved and lunate to reniform, without a sheath (De Beer and Wingfield 2013).…”

Two new species of Leptographium associated with Tomicus spp. infesting Pinus spp. in Southwestern China

“…A total of 34 ophiostomatoid fungi have been reported in Southwestern China, suggesting the diversity of fungi associated with bark beetles was extremely abundant there (Table S1, available in the online version of this article). Fourteen of them were obtained from the beetle bodies and the galleries of Tomicus spp., residing in the genera of Ophiostoma , Graphilbum , Sporothrix and Leptographium [8, 10–16].…”