Phyllosticta

Phyllosticta Pers., Traité champ. (Paris): 55, 147 (1818)

 

Background

Phyllosticta is an important coelomycetous genus of plant pathogens known to cause diseases in a wide range of host plants worldwide. Examples include citrus black spot, black rot of grapevines and banana freckle, which cause severe economic damage to their hosts (Baayen et al. 2002; Pu et al. 2008; Glienke et al. 2011; Wikee et. al 2013 a, b, c). Some species have been reported as endophytes, saprobes or biocontrol agents. Species identification in Phyllosticta has historically been based on morphology, culture characters and host association. In recent decades molecular data have improved the knowledge of species relationships and taxonomic classifications and are expected to reveal novel cryptic species in some of the complex groups of Phyllosticta (Wikee et. al 2013a, b, c).

Phyllosticta was introduced by Persoon (1818) and typified by P. convallariae Pers. Since then numerous species have been added to the genus and 3215 names are listed under Phyllosticta in Index Fungorum (30 Jan 2018). Sexual morphs are in Guignardia with 344 species names listed in Index Fungorum (30 Jan 2018). Following the introduction of the one-fungus one-name rule, Phyllosticta (1818) was adopted as the correct name for this genus because it is older than Guignardia (1892) and names in Guignardia should be made synonyms of Phyllosticta (Sultan et al. 2011; Wikee et al 2011, 2013a,b,c ).

 

Classification Dothideomycetes, incertae sedis, Botryosphaeriales, Phyllostictaceae

Type species Phyllosticta convallariae Pers, Traité champ. (Paris): 148 (1818)

Distribution – Worldwide

Disease Symptoms – Normally Phyllosticta species cause small necrotic leaf lesions that are circular, brown to dark brown or sometimes reddish at the margin. Pycnidia can be found on the lesions and are usually black, globose to subglobose and semi immersed. After infection, the leaf may become dry in the centre of the lesion and the infected tissue falls out leaving a hole (Glienke et al. 2011). When freckle disease occurs on banana species, pycnidia and ascomata formed on fruits give the lesion a sandpaper texture. Leaves of banana turn yellow when infected with this Phyllosticta (Wikee et. al 2013a).

Hosts Phyllosticta species are mostly plant pathogens causing diseases in fruits and leaf spots on a broad range of host plants including economically important crops and ornamentals such as citrus, banana, apple, grapes, cranberry, orchids, Ficus sp., Buxus sp. and maple amongst many others (Baayen et al. 2002; Glienke et al. 2011; Wikee et. al 2013a).

 

Morphological based identification and diversity

This genus has undergone many significant changes since its introduction. Phyllosticta species were considered to be Phoma-like foliar pathogens. On other plant parts, Phyllosticta was regarded as a parasite and Phoma as a saprobe or wound parasite. The first monograph on Phyllosticta sensu stricto was by van der Aa (1973) using material collected in Europe and North America. He described and illustrated 46 species, and listed the sexual morphs for twelve species and the spermatial morphs for 17 species. In 2002 van der Aa & Vanev further revised the species in Phyllosticta and accepted 190 epithets (Wikee et al. 2013).

Schoch et al. (2006) placed Phyllosticta in Botryosphaeriaceae in order Botryosphaeriales and this was accepted by Crous et al. (2006) and Liu et al. (2012). The family Phyllostictaceae (as Phyllostictei) was first proposed by Fries (1849). This family name was re-instated by Wikee et al (2013) who revealed that it is sister to Botryosphaeriaceae.

Species in Phyllosticta are recognised by the production of pycnidia containing aseptate, hyaline, ovoid to ellipsoid or cylindrical conidia with a single apical appendage and covered by a mucous layer (van der Aa 1973; Wikee et al 2013a). However, some Phyllosticta species, such as P. colocasiicola, P. minima, and P. sphaeropsoidea do not have an appendage or mucus layer. Furthermore, these mucoid appendages may vary in size and shape according to the media on which the culture is grown, and sometimes with time, it may disappear. Pycnidia are usually globose to subglobose, unilocular and closely connected on a subepidermal pseudostroma. Ascomata are globose to pyriform, unilocular with a central ostiole and erumpent through the host epidermis. There is a thin peridium with a wall comprising a few layers of angular cells. Asci are 8 spored, bitunicate, clavate to broadly ellipsoid with a wide, obtusely rounded apex and tapering gradually to a small pedicel and with a well-developed ocular chamber. Ascospores are hyaline, aseptate, ellipsoid to limoniform, usually with mucilaginous caps and often surrounded by a mucilaginous sheath, sometimes slightly elongated and often multiguttulate or with a large single central guttule (van der Aa 1973; Wikee et al 2013a). However, species cannot be identified reliably on the basis of morphological characters alone due to plasticity and overlapping of dimensions.

Molecular based identification and diversity

Molecular methods have been used in taxonomic studies of Phyllosticta to reveal phylogenetic relationships between the species and also to resolve species complexes within the genus (Wulandari et al. 2009; Glienke et al. 2011; Wikee et al.2011). Combined DNA phylogenetic analysis based on ITS, intron-dominated loci of genes like TEF1- α, ACT and more conserved gene regions such as LSU and GAPDH are used to reconstruct the phylogenetic relationships between the species. We reconstruct the phylogeny of the genus Phyllosticta (Fig) based on analyses of a combined ITS, TEF1- α, ACT, LSU and GAPDH sequence data. It contains recently introduced species and corresponds to previous studies.

Recommended genetic markers (genus level) – ITS

Recommended genetic markers (species level) – ITS, LSU, TEF, GAPDH and ACT

Accepted number of species: There are 3208 species epithets in Index Fungorum (2018) under this genus, but only 190 are currently accepted.

References: Wulandari et al. 2009 (pathogens), Glienke et al. 2011 (taxonomy), Wikee et al. 2011, 2013a, b (review), Su and Cai 2012 (Phylogeny), Hyde et al. 2013 (taxonomy, phylogeny), Kirk et al. 2013 (genus accepted), Slippers et al. 2013 (phylogeny), Wijayawardene et al. 2014c (Outline, phylogeny), Wu et al. 2014c (species in banana).

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

Species Isolate ITS LSU TEF-I ACT GAPDH
P. abieticola CBS112067* KF170306 EU754193 KF289238
P. alliacea MUCC0014* AB454263
P. ampelicida ATCC200578* KC193586 KC193581 KC193584
P. ardisiicola NBRC102261* AB454274
P. aspidistricola NBRC102244* AB454260
P. beaumarisii CBS 535.87* AY042927 KF306229 KF289170 KF306232 KF289074
P. bifrenariae CBS 128855* JF343565 KF206209 JF343586 JF343649 JF433744
P. capitalensis IMI 260.576* JF261459 KF206222 JF261501 JF343641 JF343748
P. capitalensis CPC 18848* JF261465 KF206255 JF261507 KF289289 JF343776
P. cavendishii BRIP554196* JQ743562 KF009743 KF014080
P. citriasiana CBS 120486* FJ538360 KF206314 FJ538418 FJ538476 JF343686
P. citribraziliensis CBS 100098* FJ538352 KF206221 FJ538410 FJ538468 JF343691
P. citricarpa CBS 127454* JF343583 KF206306 JF343604 JF343667 JF343771
P. citrichinaensis ZJUCC 200956* JN791620 JN791459 JN791533
P. citrimaxima CPC 20276* KF170304 KF206229 KF289222 KF289300 KF289157
P. concentric CBS 937.70* FJ538350 KF206291 FJ538408 KF289257 JF411745
P. cordylinophila CPC 20261* KF170287 KF206242 KF289172 KF289295 KF289076
P. cussonia CPC 14875* JF343579 KF206278 JF343600 JF343663 JF343765
P. dendrobii CGMCC 3.18666* MF180193 MF180210 MF180202 MF180220 MF180229
P. elongate CBS 126.22* FJ538353 FJ538411 FJ538469 KF289164
P. ericarum CBS 132534* KF206170 KF206253 KF289227 KF289291 KF289162
P. fallopiae MUCC0113* AB454307
P. foliorum CBS 447.68* KF170309 KF206287 KF289201 KF289247 KF289132
P. gaultheriae CBS 447.70* JN692543 KF206298 JN692531 KF289248 JN692508
P. gaultheriae CBS 447.70* JN692543 KF206298 JN692531 KF289248 JN692508
P. hostae CGMCC 3.14355* JN692535 JN692524 JN692512 JN692504
P. hubeiensis CGMCC 3.14986* JX025037 JX025042 JX025032 JX025027
P. hymenocallidicola CBS 131309* JQ044423 JQ044443 KF289211 KF289242 KF289142
P. hypoglossi CBS 434.92* FJ538367 KF206299 FJ538425 FJ538483 JF343695
P. ilicis-aquifolii CGMCC 3.14358* JN692538 JN692526 JN692514
P. illicii CGMCC 3.18670* MF180195 MF180212 MF180203 MF180221
P. kerriae MAFF240047* AB454266
P. leucothoicola CBS 136073* AB454370 AB454370 KF289310
P. ligustricola MUCC0024* AB454269 AB704212
P. maculate CPC18347* JP743570 KF009700 KF014016
P. mangifera-indica CPC 20274* KF170305 KF206240 KF289190 KF289296 KF289121
P. minima CBS 585.84* KF206176 KF206286 KF289204 KF289249 KF289135
P. musicola CBS123405* FJ538334 FJ538392 FJ538450
P. neopyrolae CPC 21879* AB454318 AB454241 AB704233
P. owaniana CBS 776.97* KJ538368 KF206293 FJ538426 KF289254 JF343767
P. pachysandricola MUCC 124* AB454317 AB454317 AB704232
P. parthenocissi CBS111645* EU683672 JN692530 JN692518
P. paxistimae CBS 112527* KF206172 KF206320 KF289209 KF289239 KF289140
P. podocarpicola CBS 728.79* KF206173 KF206295 KF289203 KF289252 KF289134
P. rhaphiolepidis MUCC 432* DQ632660 AB704242
P. rubra CBS 111635* KF206171 EU754194 KF289198 KF289233 KF289129
P. schimae CGMCC 3.14354* JN692534 JN692522 JN692510 JN692506
P. schimicola CGMCC 3.17319* KJ847426 KJ847448 KJ847434 KJ854895
P. styracicola CGMCC 3.14985* JX052040 JX025045 JX025036 KF289141
P. telopeae CBS 777.97* KF206205 KF766384 KF289210 KF289255 KF289141
P. vaccinii ATCC 46255* NR147339 KC193582 KC193580

 

 

KC193583
P. vacciniicola CPC18590* KF206257 KF289229 KF289287 KF289165
P. vitis-rotundifoliae CGMCC 3.17322* KJ847428 KJ847450 KJ847436 KJ847442
Diplodia seriata CMW8232 AY972105 DQ280419 AY972111

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. Phylogenetic tree generated by maximum likelihood analysis of combined ITS, TEF1, ACT, LSU and GPDH sequence data of Phyllosticta species. Sequences were obtained from GenBank. Fifty-four strains are included in the analyses, which comprise 2739 characters including gaps. Single gene analyses were carried out to compare the topology of the tree and clade stability. The tree was rooted with Diplodia seriata (CMW8232) Tree topology of the Bayesian analysis was similar to the RAxML. The best scoring RAxML tree with a final likelihood value of = -18593.839155 is presented. The matrix had 1110 distinct alignment patterns, with 37.85%of undetermined characters or gaps. Estimated base frequencies were as follows; A = 0.209468, C = 0.292249, G = 0.275727, T = 0.222557; substitution rates AC = 1.099701, AG = 2.944335, AT = 1.274132, CG = 1.149823, CT = 6.450643, GT = 1.000000; gamma distribution shape parameter α = 0.456374. RAxML and Bayesian posterior probabilities value ≥70% (BT) and 0.9 (PP) are shown respectively near the nodes.

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