Erysiphales

Erysiphales
	Powdery mildew
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Ascomycota
Class:	Leotiomycetes
Order:	Erysiphales; H.Gwynne-Vaughan,1922
Family:	Erysiphaceae; Tul.&C.Tul.,1861
Genera
	Genera (See Text)

Erysiphalesare anorderofascomycete fungi.The order contains one family,Erysiphaceae.Many of them cause plant diseases calledpowdery mildew.

Systematics

The order contains onefamily(Erysiphaceae), 28generaand around 1000species.^[2]Manyimperfect fungi(fungi whose sexual reproduction is unknown) belong here, especially the genusOidium. Recentmoleculardata have revealed the existence of six main evolutionary lineages.Clade1 consists ofErysiphe,Microsphaera,andUncinula,all of which have anOidiumsubgenusPseudoidiummitosporicstate. Clade 2 consists ofErysiphe galeopsidisandErysiphe cumminsiana(anamorphsinOidiumsubgenusStriatoidium). Clade 3 consists ofErysiphespecies with anamorphs inOidiumsubgenusReticuloidium.Clade 4 consists ofLeveillulaandPhyllactinia,which haveOidiopsisandOvulariopsismitosporic states, respectively. Clade 5 consists ofSphaerotheca,Podosphaera,andCystotheca,which haveOidiumsubgeneraFibroidiumandSetoidiummitosporic states. Clade 6 consists ofBlumeria graminis,which has anOidiumsubgenusOidiummitosporic state. Several morphological characters have been analysed and found not to conflict with the molecular data.

Characteristics

Erysiphales have a superficialmyceliumwhich extracts nourishment from the host plant through specializedhyphaethat penetrate theepidermalcells of the host by means of absorbing organs calledhaustoria.
Theteleomorphsare usually more distinctive and diverse than the anamorphs. Whether theasciare bitunicate or unitunicate (i.e. consisting of one or two layers), is as yet a matter of discussion.
Thecleistothecia(orchasmothecia) have the asci arranged in ahymeniallayer, resemblingperithecia.

The cleistothecia are minute, usually not much more than0.1 millimetres (1⁄256in) in diameter. From the outer wall of the cleistothecium specialised hyphae (appendages) grow out. The number of asci perascomavaries, and is important in discriminating between genera.

Life cycle

The infection of the host plant begins with the sexualascospores,or the asexualconidiagerminating on the surface of the plant's leaf or stem, resulting inseptatemycelium ofuninucleatecells. In most powdery mildews only theepidermalcells are attacked. The external mycelium gives rise to short, erectconidiophores,each of which bears a single row of barrel-shapedspores,the youngest being at the base (the affected parts become thus covered with a forest of conidiophores assuming a white powdery appearance). The ripe spores become detached and are readily dispersed by the wind, causing fresh infection. In autumn the sexualcleistotheciaare produced. The cleistothecia represent the resting (hibernating) stage of the pathogen. The ascospores remain dormant all winter to germinate in spring. When the asci expand they rupture the cleistothecia wall, throwing the ascospores into the air.

Ecology

Erysiphales areobligate parasiteson leaves and fruits of higher plants, causing diseases calledpowdery mildews.Most attempts to grow them inculturehave failed.^[3]

Erysiphales have a nearlycosmopolitan distribution,^[4]and have developedfungicide resistancejust as widely.^[5]Total loss of function has resulted in some cases.^[5]Resistance management planning, use of multi-mode of actionfungicides, and altered frequency and quantity of application are needed to slow the progress of resistance.^[5]

Genera

As accepted by Wijayawardene et al. 2020 (with amount of species);^[2]

ArthrocladiellaVassilkov(1)
BlumeriaGolovin ex Speer(1)
BrasiliomycesViegas(6)
BulbomicroidiumMarm., S. Takam. &U. Braun(1)
CaespitothecaS. Takam. & U. Braun(1)
CystothecaBerk. & Curtis(9)
Erysiphe(Oidium)DC.(478)
Golovinomyces(U. Braun) Heluta(66)
Leveillula(Oidiopsis)G. Arnaud(49)
Microidium(To-anun & S. Takam.) To-anun & S. Takam.(3)
Microsphaera(15)
NeoerysipheU. Braun(15)
Oidium(53)
ParauncinulaS. Takam. & U. Braun(4)
Phyllactinia(Ovulariopsis)Lev.(117)
PleochaetaSacc. & Speg.(5)
PodosphaeraKunze(124)
PseudoidiumY.S. Paul & J.N. Kapoor(80)
QueiroziaViegas & Cardoso(1)
SawadaeaMiyabe(10)
Sphaerotheca(4)
TakamatsuellaU. Braun & A. Shi(1)
TyphulochaetaIto & Hara(4)
Uncinula(8)
Uncinuliella(1)

References

^"Erysiphaceae".NCBI taxonomy.Bethesda, MD: National Center for Biotechnology Information.Retrieved29 December2019.
^^a ^bWijayawardene, Nalin; Hyde, Kevin; Al-Ani, Laith Khalil Tawfeeq; Somayeh, Dolatabadi; Stadler, Marc; Haelewaters, Danny; et al. (2020)."Outline of Fungi and fungus-like taxa".Mycosphere.11:1060–1456.doi:10.5943/mycosphere/11/1/8.hdl:10481/61998.
^Linde, M.; Shishkoff, N. (2003). "DISEASE | Powdery Mildew".Encyclopedia of Rose Science.pp. 158–165.doi:10.1016/B0-12-227620-5/00068-9.ISBN 978-0-12-227620-0.
^Kiss, Levente; et al. (2020)."Australia: A Continent Without Native Powdery Mildews? The First Comprehensive Catalog Indicates Recent Introductions and Multiple Host Range Expansion Events, and Leads to the Re-discovery of Salmonomyces as a New Lineage of the Erysiphales".Frontiers in Microbiology.11:1571.doi:10.3389/fmicb.2020.01571.PMC7378747.PMID 32765452.
^^a ^b ^cMcGrath, Margaret Tuttle (2001)."Fungicide Resistance in Cucurbit Powdery Mildew: Experiences and Challenges".Plant Disease.85(3).American Phytopathological Society:236–245.doi:10.1094/pdis.2001.85.3.236.PMID 30832035.