17 Oct Ilyonectria
Ilyonectria P. Chaverri & Salgado, in Chaverri et al., Stud. Mycol. 68:69 (2011)
Species of Ilyonectria (Nectriaceae, Hypocreales) are important soil-borne pathogens of various woody and herbaceous plant hosts. Ilyonectria species are cosmopolitan and are found on a wide range of hosts (Chaverri et al. 2011). They are mostly associated with root diseases and stem cankers (Seifert et al. 2003; Halleen et al. 2004, 2006; Chaverri et al. 2011; Cabral et al. 2012a,b,c; Vitale et al. 2012; Lombard et al. 2013; Aiello et al. 2014). There are 23 species of Ilyonectria, all associated with disease symptoms of their original plant hosts (Chaverri et al. 2011; Cabral et al. 2012a,c; Lombard et al. 2013, 2014; Aiello et al. 2014). Ilyonectria is a well-known genus causing black foot rot of grapevines in various countries (Halleen et al. 2003, 2004, 2006; Chaverri et al. 2011; Cabral et al. 2012a, b, c; Lombard et al. 2014).
Classification – Sordariomycetes, Hypocreomycetidae, Hypocreales, Nectriaceae
Type species – Ilonectria radicicola (Gerlach & L. Nilsson) P. Chaverri & Salgado, in Chaverri et al., Stud. Mycol. 68:71 (2011)
Distribution – Worldwide
Disease symptoms – Black foot disease, black root rot
Characteristic symptoms of black foot disease include a reduction in root biomass and root hairs with sunken and necrotic lesions (Hallen et al. 2006). Severe necrosis of the root system results in stunting, wilting, leaf chlorosis, browning and leaf drop prior to death (Parkinson et al. 2017).
Hosts – Wide host range including plant genera in Amaryllidaceae, Aracaceae, Araliaceae, Cupressaceae, Fagaceae, Liliaceae, Myrtaceae, Pinaceae, Proteaceae, Rosaceae, Strelitziaceae and Vitaceae (Farr and Rossman 2019).
Morphological based identification and diversity
The genus Ilyonectria was introduced based on I. radicicola as the type species, to accommodate Neonectria species belonging to the “N. radicicola” group (Booth 1959). This genus has asexual morphs and belonged to Booth’s Group 3 (chlamydospores and microconidia present, Booth 1966; Chaverri et al. 2011; Lombard et al. 2014). Molecular phylogenetic studies revealed that Ilyonectria, as originally conceived, was paraphyletic (Cabral et al. 2012a, c; Lombard et al. 2013, 2014). There are 31 species epithets of Ilyonectria listed in Index Fungorum (2019). Conidial size, culture characters, and molecular data enabled the separation of Ilyonectria species (Cabral et al. 2012a, c; Lombard et al. 2013, 2014).
Molecular based identification and diversity
The highest resolution between species of Ilyonectria can be achieved with histone (His3) gene region. The topologies of the phylogenetic tree (Fig. 15) is similar to previous studies done on this genus (Cabral et al. 2012a; Lombard et al. 2014).
Recommended genetic markers (genus level) – ITS, LSU, tef1, TUB2
Recommended genetic markers (species level) –tef1, TUB2, His3
The accepted number of species: 23 species
References: Booth 1959, 1966 (morphology), Cabral et al. 2012a,b,c; Lombard et al. 2013, 2014 (morphology, phylogeny).
Table Details of the Ilyonectria isolates used in the phylogenetic analyses. Ex-type (ex-epitype) strains are in bold and marked with an * and voucher strains are in bold
|Campylocarpon fasciculare||CBS 112613||AY677301||JF735691||AY677221||JF735502|
|Ilyonectria capensis||CBS 132815*||JX231151||JX231119||JX231103||JX231135|
|I. coprosmae||CBS 119606*||JF735260||JF735694||JF735373||JF735505|
|I. crassa||CBS 139.30*||JF735275||JF735723||JF735393||JF735534|
|I. cyclaminicola||CBS 302.93*||JF735304||JF735770||JF735432||JF735581|
|I. destructans||CBS 264.65*||AY677273||JF735695||AY677256||JF735506|
|I. europaea||CBS 129078*||JF735294||JF735756||JF735421||JF735567|
|I. gamsii||CBS 940.97||AM419065||JF735766||AM419089||JF735577|
|I. leucospermi||CBS 132809*||JX231161||JX231129||JX231113||JX231145|
|I. liliigena||CBS 189.49*||JF735297||JF735762||JF735425||JF735573|
|I. liriodendri||CBS 110.81*||DQ178163||JF735696||DQ178170||JF735507|
|I. lusitanica||CBS 129080||JF735296||JF735759||JF735423||JF735570|
|I. macroconidialis||CBS 112615||AY677290||JF735836||AY677233||JF735647|
|I. mors-panacis||CBS 306.35*||JF735288||JF735746||JF735414||JF735557|
|I. palmarum||CBS 135754*||HF937431||HF922614||HF922608||HF922620|
|I. panacis||CBS 129079*||AY295316||JF735761||JF735424||JF735572|
|I. protearum||CBS 132811*||JX231157||JX231125||JX231109||JX231141|
|I. pseudodestructans||CBS 129081||AJ875330||JF735752||AM419091||JF735563|
|I. robusta||CBS 308.35*||JF735264||JF735707||JF735377||JF735518|
|I. rufa||CBS 156.47||AY677272||JF735730||AY677252||JF735541|
|I. strelitziae||CBS 142253 *||KY304649||KY304727||KY304755||KY304621|
|I. venezuelensis||CBS 102032 *||AM419059||JF735760||AY677255||JF735571|
|I. vredenhoekensis||CBS 132807*||JX231155||JX231123||JX231107||JX231139|
Fig. Phylogenetic tree generated by maximum likelihood analysis of combined ITS, TEF, TUB, and His3 sequence data of Ilyonectria species. Twenty-three strains are included in the analyses, which comprise 2242 characters including gaps. The tree is rooted in Campylocarpon fasciculare. The 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 -9669.617830 is presented. The matrix had 507 distinct alignment patterns, with 5.11% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.219321, C = 0.325516, G = 0.222910, T = 0.230587; substitution rates AC = 0.215721, AG = 0.328038, AT = 0.225653, CG = 0.615208, CT = 5.798530, GT = 1.000000; gamma distribution shape parameter α = 0.518017. Maximum likelihood bootstrap support values ≥60% and Bayesian posterior probabilities ≥95 (BYPP) are indicated above or near the nodes. Ex-type strains are in bold.