16 Oct Pseudopestalotiopsis
Pseudopestalotiopsis Maharachch., K.D. Hyde & Crous (2014), in Marachchikumbura et al., in Maharachchikumbura et al., Stud. Mycol. 79:180(2014)
The genus was introduced by Maharachchikumbura et al. (2014b) with Pseudopestalotiopsis theae (Sawada) Maharachch., K.D. Hyde & Crous as the type species. Species of Pseudopestalotiopsis are appendage-bearing phenotypically diverse coelomycetes in the family Sporocadaceae and are commonly found in tropical and subtropical ecosystems (Jaklitsch et al. 2016; Maharachchikumbura et al. 2016b). Pseudopestalotiopsis is characterized by brown to dark brown or olivaceous median cells and knobbed or not knobbed apical appendages (Maharachchikumbura et al. 2014b, 2016b). The epitype of Pseudopestalotiopsis theae (Sawada) Steyaert was designated from fresh leaves of Camellia sinensis collected in Thailand (Maharachchikumbura et al. 2013). Pseudopestalotiopsis has been studied for the production of various secondary metabolites with diverse structural features, with antitumor, antifungal, antimicrobial and other activities (Ding et al. 2008; Maharachchikumbura et al. 2011, 2016b).
Pseudopestalotiopsis theae is economically significant as it has been identified as a pathogen in major tea-growing areas in the world (Maharachchikumbura et al. 2016b). Pseudopestalotiopsis theae causes grey blight of tea and reduces yield (Maharachchikumbura et al. 2011, 2013, 2016b). Pseudopestalotiopsis theae was also isolated as an endophyte from different hosts (Camellia nitidissima, C. sinensis, Holarrhena antidysenterica, Podocarpus macrophyllus, Terminalia arjuna) or as a saprobe (seeds of Diospyros crassiflora) (Maharachchikumbura et al. 2011, 2013, 2016b).
Classification – Sordariomycetes, Xylariomycetidae, Amphisphaeriales, Sporocadaceae
Type species – Pseudopestalotiopsis theae (Sawada) Maharachch., in Maharachchikumbura et al., Stud. Mycol. 79:183 (2014)
Distribution – China, India, Indonesia, Malaysia, Thailand (Maharachchikumbura et al. 2016b)
Disease symptoms –Pseudopestalotiopsis theae causes grey blight in major tea growing areas in the world (Horikawa 1986, Maharachchikumbura et al. 2013, 2016b). The pathogen develops circular to irregular leaf spots initially and grey, brown margins when mature, covering up to half of the leaf with acervuli (Maharachchikumbura et al. 2016b). Pseudopestalotiopsis ixorae and P. taiwanensis cause a leaf spot that initially develops small, circular, ash-colored spots which later turn into brown spots (Tsai et al. 2018).
Hosts – Averrhoa carambola, Camellia sp., Cinnamomum sp., Cocos nucifera, Diospyros crassiflora, Fragaria sp., Hibiscus rosa-sinensis, Holarrhena antidysenterica, Ixora sp., Kandelia obovate, Macaranga sp., Pandanus odoratissimus, Podocarpus macrophyllus, Prunus sp., Terminalia arjuna and Thea sinensis
Morphological based identification and diversity
There are 14 species recorded in Index Fungorum (2019). Pseudopestalotiopsis can be distinguished from Neopestalotiopsis and Pestalotiopsis by dark concolorous median cells with indistinct conidiophores (Maharachchikumbura et al. 2014b, 2016b). However, there could be a wide host range for Pseudopestalotiopsis species and the actual number of species could be much higher than presently known (Maharachchikumbura et al. 2011, 2016b).
Conidial morphology is widely used in taxonomy in pestalotioid fungi (Steyaert 1949; Guba 1961; Nag Raj 1993; Maharachchikumbura et al. 2011, 2012, 2014b). Species delimitation based on morphological characters is limited as these characters are plastic and vary between hosts and environments (Maharachchikumbura et al. 2011, 2016a). Therefore, phylogenetic species recognition is an effective method to identify different pestalotioid species (Maharachchikumbura et al. 2016a).
Molecular based identification and diversity
ITS sequence data alone is not sufficient for species delimitation of Pseudopestalotiopsis. Therefore, Maharachchikumbura et al. (2012) suggested a phylogenetic analysis of combined ITS, TUB2 and tef1 genes provide better resolution as compared to single-gene phylogeny (Fig. 22).
Recommended genetic markers (genus level) – LSU (as outlined in Maharachchikumbura et al. 2012)
Recommended genetic markers (species level) – ITS, TUB2 and tef1 (as outlined in Maharachchikumbura et al. 2012)
The accepted number of species: 20 species
References: Maharachchukumbura 2013, 2014b, 2016b (morphology, phylogeny)
Table Details of the Pseudopestalotiopsis 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.
|P. avucenniae||MFLUCC 17-0434*||MK764287||MK764353||MK764331|
|P. cocos||CBS 272.29*||KM199378||KM199467||KM199553|
|P. curvatispora||MFLUCC 17-1722*||MK764288||MK764354||MK764332|
|P. ignota||NN 42909*||KU500020||–||KU500016|
|P. indica||CBS 459.78*||KM199381||KM199470||KM199560|
|P. ixorae||NTUCC 17-001.1*||MG816316||MG816326||MG816336.|
|P. jiangxiensis||LC 4479*||KX895034||KX895343||KX895229|
|P. kubahensis||UMAS KUB-P20*||KT006749||–||–|
|P. myanmarina||NBRC 112264*||LC114025||LC114045||LC114065|
|P. rhizophorae||MFLUCC 17-1560*||MK764291||MK764357||MK764335|
|P. smitheae||MFLUCC 12-0121*||KJ503812||KJ503815||KJ503818|
|P. thailandica||MFLUCC 17-1724*||MK764292||MK764358||MK764336|
|P. taiwanensis||NTUCC 17-002.1*||MG816319||MG816329||MG816339|
|P. theae||MFLUCC 12-0055*||JQ683727||JQ683711||JQ683743|
|P. vietnamensis||NBRC 112252*||LC114034||LC114054||LC114074|
Fig. Phylogram generated from maximum likelihood analysis based on combined ITS, TUB2 and tef1 sequence data of Pseudopestalotiopsis species. Related sequences were obtained from GenBank. Twenty-five strains are included in the combined sequence analyses, which comprise 1404 characters with gaps. Neopestalotiopsis natalensis (CBS 138.41) was used as the outgroup taxa. The best scoring RAxML tree with a final likelihood value of -4028.799660 is presented. The matrix had 274 distinct alignment patterns, with 6.34% of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.235765, C = 0.270775, G = 0.213073, T = 0.280387; substitution rates AC = 1.242401, AG = 3.217138, AT = 1.272343, CG = 0.837226, CT = 4.463116, GT = 1.000000; gamma distribution shape parameter α = 0.229606. The maximum parsimonious dataset consisted of 1122 constant, 79 parsimony-informative and 203 parsimony-uninformative characters. The parsimony analysis of the data matrix resulted in the maximum of four equally most parsimonious trees with a length of 386 steps (CI = 0.832, RI = 0.737, RC = 0.613, HI = 0.168) in the first tree. RAxML and maximum parsimony bootstrap support value ≥ 50% are shown respectively near the nodes. Bayesian posterior probabilities ≥0.95 (BYPP) indicated as thickened black branches. Ex-type strains are in bold.