Cylindrocladiella

Cylindrocladiella Boesew., Canadian Journal of Botany 60 (11): 2289 (1982)

= Nectricladiella Crous & C.L. Schoch, Studies in Mycology 45: 54 (2000)

Background

Boeswinkel (1982) established Cylindrocladiella to accommodate five Cylindrocladium-like species producing small, cylindrical conidia. Even though the generic status of Cylindrocladiella was initially opposed by Crous and Wingfield (1993), later studies on morphological comparisons by Crous et al. (1994) and molecular data (Victor et al. 1998; Schoch et al. 2000) supported the establishment of Cylindrocladiella as a genus. This genus is commonly confused with the asexual morph of Calonectria but can be distinguished by clear morphological differences, such as aseptate stipe extensions, different branching patterns of the conidiophores and comparatively small, aseptate conidia. Although species are generally not regarded as important plant pathogens, correct identification is essential for disease control and biosecurity implications.

Classification Ascomycota, Sordariomycetes, Hypocreomycetidae, Hypocreales, Nectriaceae

Type species Cylindrocladiella parva (P.J. Anderson) Boesew.

Distribution as a soil-borne fungus, the species in Cylindrocladiella have a cosmopolitan distribution in various geographically and climatically distinct regions around the world (Farr and Rossman 2020).

Disease symptoms black-foot disease, damping-off, leaf spot, root rot and shoot die-back

Many species belonging to Cylindrocladiella are opportunistic plant pathogens but they are not considered as primary pathogens. They can be isolated associated with disease symptoms such as leaf spot, damping off and shoot die-back (Scattolin and Montecchio 2007; Pham et al. 2018). Chocolate brown lesions around the shoots spread primarily to be followed by wilting of the shoot tip, reddish discolouration, dropping of leaves, and finally plant death (Brielmaier-Liebetanz et al. 2013). Characteristic symptoms of the black-foot disease include a reduction in root biomass and root hairs with sunken and necrotic root lesions (Agustí-Brisach and Armengol 2013). Symptoms of Cylindrocladiella root rot are black lesions on the tap and lateral roots, wilting and foliar necrosis, and the outer bark of the seedlings will crack and become loose (Sinclair and Lyon 2005).

Hosts — Species are soil-borne, weak pathogens of forestry, agricultural and horticultural crops. There are 270 records of Cylindrocladiella associated with different plant species (Farr and Rossman 2020). Among them, different Vitis species and Eucalyptus species are common hosts associated with different species of Cylindrocladiella.

Morphological based identification and diversity

Cylindrocladiella can be distinguished from related species by penicillate and/or subverticillate symmetrically branched conidiophores which produce small, cylindrical, 1-septate conidia and aseptate stipe extensions (Lombard et al. 2012). The generic status of Cylindrocladiella was earlier strongly contested (Sharma and Mohanan 1991), however, based on morphological evaluation and comparisons by Crous and Wingfield (1993) and Crous et al. (2017) confirmed its generic status. Victor et al. (1998) and Schoch et al. (2000) provided molecular data to support generic status. Lombard et al. (2011) in his revision of Cylindrocladiella mentioned that only two species have been recognized with their respective Nectricladiella sexual morph. Rossman et al. (2013) proposed that the generic name Cylindrocladiella be used rather than Nectricladiella. Lombard et al. (2015) showed that Cylindrocladiella formed a monophyletic group in Nectriaceae (Wijayawardene et al. 2020).

 

Molecular based identification and diversity

Using RFLPs and AT-DNA data, Victor et al. (1998) recognised seven species in the genus. Schoch et al. (2000) added another species based on ITS and partial tub2. Van Coller et al. (2005) introduced the use of his3 sequence data for this group. A combined multilocus phylogeny of his, tef1, tub2 and ITS was used by Lombard et al. (2011) which resulted in 18 new Cylindrocladiella species and several unresolved species complexes. Lombard et al. (2017) introduced six new species based on a combined ITS, tef1 and tub2 dataset. Pham et al. (2018) introduced five new species based on his, tef1, tub2 and ITS sequence data and Marin-Felix et al. (2019) introduced two new species based on ITS, tef1 and tub2 sequence data. Here we reconstruct the phylogenetic analyses of these species based on ITS, tef1 and tub2 sequence data (Fig. 1).

Recommended genetic markers (genus level) ITS, LSU

Recommended genetic markers (species level) his, tef1, tub2

Accepted number of species – There are 47 species epithets in Index Fungorum (2020). However, only 46 species have DNA sequence data (Table 1).

References –Crous and Wingfield 1993, Lombard et al. 2011 (morphology); Victor et al. 1998, Schoch et al. 2000, Lombard et al. 2015 (morphology, phylogeny).

Table 1 DNA barcodes available for Cylindrocladiella. Ex-type/ex-epitype/ex-neotype/ex-lectotype strains are in bold and marked with an asterisk (*). Voucher strains are also in bold. Species confirmed with pathogenicity studies are marked with #.

Species Isolate No ITS tef1 tub2
Cylindrocladiella addiensis CBS 143794* MH111383 MH111393 MH111388
C. arbusta# CMW 47295* MH017015 MH016977 MH016958
C. australiensis CBS 129567* JN100624 JN099060 JN098747
C. brevistipitata CBS 142786* MF444940 MF444926
C. camelliae IMI 346845 AF220952 JN099087 AY793471
C. clavata CBS 129564* JN099095 JN098974 JN098752
C. cymbiformis CBS 129553* JN099103 JN098988 JN098753
C. elegans CBS 338.92* AY793444 JN099039 AY793474
C. ellipsoidea CBS 129573* JN099094 JN098973 JN098757
C. hahajimaensis MAFF 238172* JN687561 JN687562
C. hawaiiensis CBS 129569* JN100621 JN099057 JN098761
C. horticola CBS 142784* MF444911 MF444938 MF444924
C. humicola CBS 142779* MF444906 MF444933 MF444919
C. infestans CBS 111795* AF220955 JN099037 AF320190
C. kurandica CBS 129577* JN100646 JN099083 JN098765
C. lageniformis CBS 340.92* AF220959 JN099003 AY793481
C. lanceolata CBS 129566* JN099099 JN098978 JN098789
C. lateralis CBS 142788* MF444914 MF444942 MF444928
C. longiphialidica CBS 129557* JN100585 JN098966 JN098790
C. longistipitata CBS 116075* AF220958 JN098993 AY793506
C. malesiana# CMW 48278*

 

MH017019

 

MH016981

 

MH016962

 

C. microcylindrica CBS 111794* AY793452 JN099041 AY793483
C. natalensis CBS 114943* JN100588 JN099016 JN098794
C. nederlandica CBS 152.91* JN100603 JN099033 JN098800
C. novazelandica CBS 486.77* AF220963 JN099050 AY793485
C. nauliensis CBS 143792* MH111387 MH111397 MH111392
C. obpyriformis# CMW 47194*

 

MH017022

 

MH016966
C. parva CBS 114524 AF220964 JN099009 AY793486
C. parvispora# CMW 47197* MH017025 MH016987 MH016968
C. peruvianum IMUR 1843* AF220966 JN098968 AY793500
C. postalofficium CPC 37513*

 

MN562148

 

MN556845
C. pseudocamelliae CBS 129555* JN100577 JN098958 JN098814
C. pseudohawaiiensis CBS 210.94* JN099128 JN099012 JN098819
C. pseudoinfestans CBS 114531* AF220957 JN099004 AY793508
C. pseudoparva CBS129560* JN100620 JN099056 JN098824
C. queenslandica CBS 129574* JN099098 JN098977 JN098826
C. reginae CBS 142782* MF444909 MF444936 MF444922
C. solicola# CMW47198* MH017021 MH016983 MH016964
C. stellenboschensis CBS 110668* JN100615 JN099051 JN098829
C. terrestris CBS 142789* MF444915 MF444943 MF444929
C. thailandica CBS 129571* JN100582 JN098963 JN098834
C. variabilis CBS 129561* JN100643 JN099080 JN098719
C. viticola# CBS 112897* AY793468 JN099064 AY793504
C. vitis# CBS 142517* KY979751 KY979891 KY979918
C. xishuangbannaensis KUMCC 16-0146* MH388337 MH388372

Fig. 1 Phylogram generated from MP analysis based on combined sequences of ITS, tef1 and tub2 sequences of all the accepted species of Cylindrocladiella. Related sequences were obtained from GenBank. Fourty-six taxa are included in the analyses, which comprise 2460 characters including gaps. Single gene analyses were carried out and compared with each species, to compare the topology of the tree and clade stability. The tree was rooted with Gliocladiopsis sagariensis (CBS 19955). The best scoring RAxML tree with a final likelihood value of – 6772.195394 is presented. The matrix had 261 distinct alignment patterns, with 0.96% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.230657, C = 0.279364, G = 0.252128, T = 0.237852; substitution rates AC = 1.388608, AG = 2.845402, AT = 2.389715, CG = 0.838197, CT = 7.220493, GT = 1.000000; gamma distribution shape parameter a = 0.650385. Maximum likelihood and MP bootstrap support value >50% are shown respectively near the nodes. Ex-type strains are in bold.

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