Neonectria Wollenw., Annls mycol. 15(1/2):52 (1917)

Neonectria is a cosmopolitan genus, and their asexual morphs are common in tropical and temperate regions (Chaverri et al. 2011). Neonectria species can be found on the bark of recently dead woody plants and sometimes on decaying herbaceous material (Samuels et al. 1990; Samuels and Brayford 1990, 1993, 1994; Rossman et al. 1999; Castlebury et al. 2006; Chaverri et al. 2011). Some species of Neonectria are plant pathogens causing cankers and other diseases on hardwood and coniferous trees (Castlebury et al. 2006; Rossman et al. 2008; Crane et al. 2009; Chaverri et al. 2011; Schmitz et al. 2017; Wenneker et al. 2017). Neonectria neomacrospora has been added to the European and Mediterranean Plant Protection Organization (EPPO) alert list (EPPO, 2019).

Classification Sordariomycetes, Hypocreomycetidae, Hypocreales, Nectriaceae

Type speciesNeonectria ramulariae Wollenw., Annls mycol. 15(1/2):52 (1917)

Distribution – Worldwide

Disease symptoms – Canker

Dead shoots can be observed in the lower branches or all over the affected tree. Affected branches or trunks show canker and some may have abundant resin flow. When the canker girdles the affected area, part of the tree above the canker dies. Under humid conditions characteristic small, red fruiting bodies will be formed. Badly affected trees will eventually die (Castlebury et al. 2006).

Beech (Fagus) bark disease is caused by N. coccinea, N. ditissima, N. fuckeliana and N. faginata. Cankers of fruit trees are caused by N. rugulosa and N. ditissima. Shoot dieback of Abies species is caused by N. neomacrospora (Castlebury et al. 2006; Rossman et al. 2008; Crane et al. 2009; Chaverri et al. 2011; Schmitz et al. 2017; Wenneker et al. 2017).

Hosts – Wide host range including plant genera in Amaryllidaceae, Aracaceae, Araliaceae, Betulaceae, Ericaceae, Fagaceae, Lauraceae, Myrtaceae, Pinaceae, Proteaceae, Rosaceae, Sapindaceae and Vitaceae (Farr and Rossman 2019).


Morphological based identification and diversity

The genus Neonectria was established by Wollenweber (1917). The generic concept of Neonectria has been revised by different authors (Booth 1959; Samuels and Brayford 1994; Rossman et al. 1999). Rossman et al. (1999) accepted only three species (N. coccinia, N. galligena, and N. ramulariae) in Neonectria. Subsequently, species were added to the genus based on morphology and/or phylogeny (Hirooka and Kobayashi 2005; Castlebury et al. 2006; Luo and Zhuang 2010a, b; Peng et al. 2011; Lombard et al. 2014, 2015). However, some unrelated species were transferred to other genera based on molecular analyses and morphological data (Lombard et al. 2014, 2015). There are 31 species recognized in the genus, while 23 species have sequence data in GenBank (4/7/2019). Morphological characters (perithecial morphology, ascospore size, macroconidial morphology, presence or absence of microconidia and chlamydospores) along with DNA sequence analysis are appropriate for identification of Neonectria species (Brayford et al. 2004).


Molecular based identification and diversity

Since 2001, DNA sequence analysis has been used to clarify the taxonomy of Neonectria (Mantiri et al. 2001; Brayford et al. 2004; Halleen et al. 2004; Hirooka et al. 2005; Chaverri et al. 2011). Mantiri et al. (2001) and Brayford et al. (2004) used mt SSU rDNA sequence data to infer intrageneric relationships of some Neonectria and Cylindrocarpon species. Later, Halleen et al. (2004) used mt LSU rDNA, TUB2 and nrDNA ITS regions to separate some Cylindrocarpon species included in the N. mammoidea group. Chaverri et al. (2011) approached a comprehensive treatment of Cylindrocarpon and Neonectria based on combined loci analyses and morphological data. Chaverri et al. (2011) defined Neonectria sensu stricto within Nectriaceae with Cylindrocarpon sensu stricto based on multi-gene phylogeny of ITS, LSU, tef1, TUB2, ACT, and RPB1. The ITS, tef1 and TUB2 loci possess highly variable regions (Chaverri et al. 2011) and are important in species delimitation of Neonectria. Rossman et al. (2013) proposed to protect the generic name Neonectria over Cylindrocarpon. Maharachchikumbura et al. (2015) considered Cylindrodendrum not to be congeneric with Neonectria and accepted Neonectria over Cylindrocarpon.

This study reconstructs the phylogeny of Neonectria based on analyses of a combined ITS, LSU, tef1 and TUB2 sequence data (Table 11, Fig. 17). The phylogenetic tree is updated with recently introduced Neonectria species and corresponds to previous studies (Chaverri et al. 2011; Lombard et al. 2014; Mantiri et al. 2001).


Recommended genetic markers (genus level) – LSU, ITS, tef1 and TUB2

Recommended genetic markers (species level) – ITS, tef1 and TUB2

The accepted number of species: 28 species

References: Rossman et al. 1999 (morphology), Brayford et al. 2004; Hirooka and Kobayashi 2007; Chaverri et al. 2011; Lombard et al. 2014 (morphology, phylogeny).


Table. Details of the Neonectria isolates used in the phylogenetic analyses. Ex-type (ex-epitype) strains are in bold and marked with an asterisk* and voucher strains are in bold

Species Isolate/Voucher no ITS LSU TUB tef1
Neonectria austroradicicola  PDD 46334/ G.J.S. 83-154 EF607077
N. candida  CBS 151.29/ IMI

113894/ MUCL 28083

AY677291 AY677333 DQ789863 DQ789723
N. coccinea  CBS 119158/ GJS 98-114 JF268759 KC660620 KC660727 JF268734
N. confusa  CBS 127485/ HMAS 99197* FJ560437 KM515934 FJ860054
N. confusa  CBS 127484/ HMAS 99198 KM515889 KM515933 KM515886
N. ditissima CBS 100318 KM515890 KM515935 DQ789858 KM515944
N. ditissima CBS 100317 KM515891 KM515936 KM515887 KM515945
N. ditissimopsis HMAS 98329* JF268764 JF268729 JF268745
N. faginata CBS 217.67/ IMI 105738/ ATCC 16547* HQ840385 HQ840382 JF268730 JF268746
N. faginata CBS 119160/ GJS 04-159 HQ840384 HQ840383 DQ789883 DQ789740
N. fuckeliana CBS 239.29/ IMI 039700 HQ840386 HQ840377 DQ789871 JF268748
N. hederae IMI 058770a/ ATCC 16543* KC660617 DQ789895 DQ789752
N. hederae CBS 714.97/ PD 97/1932 KC660616 DQ789878 KC660461
N. lugdunensis CBS 125485/ DAOM 235831/ TG 2008-07 KM231762 KM231625 KM232019 KM231887
N. major CBS 240.29/ IMI 113909* JF735308 KM515942 DQ789872 JF735782
N. microconidia HMAS 98294 KC660530 KC660587
N. neomacrospora CBS 198.62/ BBA 9628/ IMI 113890 AJ009255 HM364316 HM352865 HM364351
N. neomacrospora CBS 324.61/ DSM 62489/ IMB 9628 JF735312 HM364318 DQ789875
N. obtusispora CBS 183.36/ IMI 113895 AM419061 KM515943 AM419085 JF735796
N. punicea CBS 242.29 KC660522 KC660565 DQ789873 DQ789730
N. shennongjiana HMAS 183185 FJ560440 FJ860057
N. tsugae CBS 788.69* KM231763 HQ232146 KM232020
Thelonectria gongylodes CBS 12511/ GJS 90-48 JQ403330 JQ403369 HM352870 HM364357

Fig.  Phylogenetic tree generated by maximum likelihood analysis of combined ITS, LSU, tef1 and TUB sequence data of Neonectria species. Related sequences were obtained from GenBank. Twenty-three strains are included in the analyses, which comprise 2336 characters including gaps. Tree topology of the ML analysis was similar to the one generated from BI (figure not shown). The best scoring RAxML tree with a final likelihood value of -7942.756270 is presented. The matrix had 525 distinct alignment patterns, with 18.13% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.223071, C = 0.285136, G = 0.261197, T = 0.230596; substitution rates AC = 1.213729, AG = 2.500008, AT = 1.727890, CG = 0.720430, CT = 6.191594, GT = 1.000000; gamma distribution shape parameter α = 0.749195. Maximum likelihood bootstrap support (≥55%) and posterior probabilities (BYPP≥0.90) from Bayesian inference analysis are indicated respectively near the nodes. Ex-type strains are in bold. The tree is rooted in Thelonectria gongylodes.

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