Bipolaris

Shoemaker Canad. J. Bot. 37: 882. 1959.

Synonym: Cochliobolus Drechsler, Phytopathology 24: 973. 1934.
Classification: Dothideomycetes, Pleosporomycetidae, Pleosporales, Pleosporaceae.
Type species: Bipolaris maydis (Y. Nisik. & C. Miyake) Shoemaker. Neotype and ex-neotype culture: ATCC 48332, CBS 137271.
DNA barcodes (genus): LSU, ITS.
DNA barcodes (species): ITS, gapdh, tef1.

Ascomata pseudothecial, mostly globose to ellipsoidal, sometimes flask-shaped or flattened on hard substrata, brown or black, immersed, erumpent, partially embedded or superficial, free, smooth or covered with vegetative hyphae; ostiole central, papillate or with a sub-conical, conical, paraboloid or cylindrical neck; ascomatal wall comprising pseudoparenchymatous cells of equal thickness or slightly thickened at apex of the ascoma. Hamathecium comprising septate, filiform, branched pseudoparaphyses. Asci bitunicate, clavate, cylindrical-clavate or broadly fusoid, straight or slightly curved, thin-walled, fissitunicate, often becoming more or less distended prior to dehiscence, short pedicellate, rounded at apex. Ascospores multiseriate, filiform or flagelliform, hyaline or sometimes pale yellow or pale brown at maturity, septate, helically coiled within ascus, ascospore coiling moderate to strongly, often with a mucilaginous sheath. Conidiophores single, sometimes arranged in small groups, straight to flexuous or geniculate, pale to dark brown, branched, thick-walled, septate. Conidiogenous nodes smooth to slightly verruculose. Conidia canoe-shaped, fusoid or obclavate, mostly curved, hyaline, pale or dark brown, reddish brown or pale to deep olivaceous, thick-walled, smooth-walled, 3–14-distoseptate, germinating by production of one or two germination tubes by polar cells; hila often slightly protruding or truncate, sometimes inconspicuous; septum ontogeny first septum median to sub-median, second septum delimits basal cell and third delimits distal cell (adapted from Manamgoda et al. 2014).

Culture characteristics:

Colonies on PDA white or pale grey when young, brown or dark grey when mature, fluffy, cottony, raised or convex with papillate surface, margin lobate, undulate, entire or sometimes rhizoid.

Optimal media and cultivation conditions: Sterilised Zea mays leaves placed on 1.5 % WA or slide cultures of PDA under near-ultraviolet light (12 h light, 12 h dark) at 25 °C to induce sporulation of the asexual morph, while for the sexual morph Sach's agar with sterilised rice or wheat straw at 25 °C is used.

Distribution:

Worldwide.

Hosts:

Mainly pathogens of grasses, but some also on non-grass hosts, causing devastating diseases on staple crops in the Poaceae, including rice, maize, wheat and sorghum and on various other host plants. Moreover, this genus can occur on at least 60 other genera in Anacardiaceae, Araceae, Euphorbiaceae, Fabaceae, Malvaceae, Rutaceae and Zingiberaceae as either saprobes or pathogens.

Disease symptoms:

Leaf spots, leaf blight, melting out, root rot, and foot rot among others.

Notes:

Species delimitation based on morphology alone is limited since many species have overlapping characters. Moreover, the morphology of the sexual morph is of limited value due to difficulties to induce this morph in culture, or find it in nature. The genus is morphologically similar to Curvularia, and distinguishing these genera can be problematic. Both genera contain species with straight or curved conidia, but in Bipolaris the curvature is continuous throughout the length of the conidium, while the conidia of Curvularia have intermediate cells inordinately enlarged which contributes to their curvature. Moreover, conidia in Bipolaris are usually longer than in Curvularia. Another morphological difference is the presence of stromata in some species of Curvularia, a feature not observed in species of Bipolaris. This genus tends to not be host specific. In order to properly delineate both genera, phylogenetic studies using ITS, gapdh and tef1 sequences were recently performed (Manamgoda et al. 2014, 2015).

References:

Ellis 1971, Sivanesan 1987 (morphology and pathogenicity); Manamgoda et al. 2011, Tan et al. 2016 (morphology, phylogeny and pathogenicity); Manamgoda et al. 2014 (morphology, phylogeny, pathogenicity and key of all Bipolaris spp.).
Ellis MB (1971). Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, UK.
Manamgoda DS, Cai L, Bahkali AH, et al. (2011). Cochliobolus: an overview and current status of species. Fungal Diversity 51: 3–42.
Manamgoda DS, Rossman AY, Castlebury LA, et al. (2014). The genus Bipolaris. Studies in Mycology 79: 221–288.
Manamgoda DS, Rossman AY, Castlebury LA, et al. (2015). A taxonomic and phylogenetic re-appraisal of the genus Curvularia (Pleosporaceae): human and plant pathogens. Phytotaxa 212: 175–198.
Sivanesan A (1987). Graminicolous species of Bipolaris, Curvularia, Drechslera, Exserohilum and their teleomorphs. Mycological Papers 158: 1–261.
Tan YP, Crous PW, Shivas RG (2016). Eight novel Bipolaris species identified from John L. Alcorn’s collections at the Queensland Plant Pathology Herbarium (BRIP). Mycological Progress 15: 1203–1214.

DNA barcodes of accepted Bipolaris spp.

Species	Isolates¹		GenBank accession numbers²			References
		ITS		*gapdh*	*tef1*
Bi. austrostipae	BRIP 12490^T	KX452442		KX452408	KX452459	Tan et al. (2016)
Bi. axonopicola	BRIP 11740^T	KX452443		KX452409	KX452460	Tan et al. (2016)
Bi. bamagaensis	BRIP 13577^T	KX452445		KX452411	KX452462	Tan et al. (2016)
Bi. bicolor	CBS 690.96	KJ909762		KM042893	KM093776	Manamgoda et al. (2014)
Bi. chloridis	BRIP 10965^T	KJ415523		KJ415423	KJ415472	Tan et al. (2014)
Bi. clavata	BRIP 12530^T	KJ415524		KJ415422	KJ415471	Tan et al. (2014)
Bi. coffeana	BRIP 14845^IsoT	KJ415525		KJ415421	KJ415470	Tan et al. (2014)
Bi. cookei	AR 5185	KJ922391		KM034833	KM093777	Manamgoda et al. (2014)
Bi. crotonis	BRIP 14838	KJ415526		KJ415420	KJ415479	Tan et al. (2014)
Bi. cynodontis	CBS 109894	KJ909767		KM034838	KM093782	Manamgoda et al. (2014)
Bi. drechsleri	CBS 136207^T	KF500530		KF500533	KM093760	Crous et al. (2013), Manamgoda et al. (2014)
Bi. gossypina	BRIP 14840^T	KJ415528		KJ415418	KJ415467	Tan et al. (2014)
Bi. heliconiae	BRIP 17186^T	KJ415530		KJ415417	KJ415465	Tan et al. (2014)
Bi. heveae	CBS 241.92	KJ909763		KM034843	KM093791	Manamgoda et al. (2014)
Bi. luttrellii	BRIP 14643^IsoT	AF071350		AF081402	-	Berbee et al. (1999)
Bi. maydis	CBS 137271^N^T	AF071325		KM034846	KM093794	Berbee et al. (1999), Manamgoda et al. (2014)
Bi. microlaenae	CBS 280.91^T	JN601032		JN600974	JN601017	Manamgoda et al. (2011)
Bi. microstegii	CBS 132550^T	JX089579		JX089575	KM093756	Crous et al. (2012), Manamgoda et al. (2014)
Bi. oryzae	MFLUCC 10-0715^NT	JX256416		JX276430	JX266585	Manamgoda et al. (2012)
Bi. panici-miliacei	CBS 199.29^LT	KJ909773		KM042896	KM093788	Manamgoda et al. (2014)
Bi. peregianensis	BRIP 12790^T	JN601034		JN600977	JN601022	Manamgoda et al. (2011)
Bi. pluriseptata	BRIP 14839^IsoT	KJ415532		KJ415414	KJ415461	Tan et al. (2014)
Bi. sacchari	ICMP 6227	KJ922386		KM034842	KM093785	Manamgoda et al. (2014)
Bi. salkadehensis	Bi 1^T	AB675490		-	-	Ahmadpour et al. (2012)
Bi. salviniae	BRIP 16571^LT	KJ415535		KJ415411	KJ415457	Tan et al. (2014)
Bi. saccharicola	CBS 155.26^T	KY905674		KY905686	KY905694	Marin-Felix et al. (2017)
Bi. secalis	BRIP 14453^IsoLT	KJ415537		KJ415409	KJ415455	Tan et al. (2014)
Bi. setariae	CBS 141.31	EF452444		EF513206	-	Andrie et al. (2008)
Bi. shoemakeri	BRIP 15929^T	KX452453		KX452419	KX452470	Tan et al. (2016)
Bi. simmondsii	BRIP 12030^T	KX452454		KX452420	KX452471	Tan et al. (2016)
Bi. sivanesaniana	BRIP 15847^T	KX452455		KX452421	KX452472	Tan et al. (2016)
Bi. sorokiniana	CBS 110.14	KJ922381		KM034822	KM093763	Manamgoda et al. (2014)
Bi. subramanianii	BRIP 16226^T	KX452457		KX452423	KX452474	Tan et al. (2016)
Bi. urochloae	ATCC 58317	KJ922389		KM230396	KM093770	Manamgoda et al. (2014)
Bi. variabilis	CBS 127716^T	KY905676		KY905688	KY905696	Marin-Felix et al. (2017)
Bi. victoriae	CBS 327.64^T	KJ909778		KM034811	KM093748	Manamgoda et al. (2014)
Bi. yamadae	CBS 202.29^ET	KJ909779		KM034830	KM093773	Manamgoda et al. (2014)
Bi. woodii	BRIP 12239^T	KX452458		KX452424	KX4524725	Tan et al. (2016)
Bi. zeae	BRIP 11512^IsoPT	KJ415538		KJ415408	KJ415454	Tan et al. (2014)
Bi. zeicola	FIP 532^ET	KM230398		KM034815	KM093752	Manamgoda et al. (2014)

¹AR, FIP: Isolates housed in Systematic Mycology and Microbiology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, USA; Bi: Isolates housed in the Department of Plant Protection, Faculty of Agricultural Sciences and Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran (TUPP); ATCC: American Type Culture Collection, Virginia, USA; BRIP: Queensland Plant Pathology Herbarium, Brisbane, Australia; CBS: Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands; ICMP: International Collection of Micro-organisms from Plants, Landcare Research, Private Bag 92170, Auckland, New Zealand; MFLUCC: Mae Fah Luang University Culture Collection, Chiang Ria, Thailand. ^{T, ET, IsoT, IsoLT, IsoPT, LT}and ^NT indicate ex-type, ex-epitype, ex-isotype, ex-isolectotype, ex-isoparatype, ex-lectotype and ex-neotype strains, respectively.

²ITS: internal transcribed spacers and intervening 5.8S nrDNA; gapdh: partial glyceraldehyde-3-phosphate dehydrogenase gene; tef1: partial translation elongation factor 1-alpha gene.

Ahmadpour A, Heidarian Z, Donyadoost-Chelan M, et al. (2012). A new species of Bipolaris from Iran. Mycotaxon 120: 301–307.
Andrie RM, Schoch CL, Hedges R, et al. (2008). Homologs of ToxB, a host-selective toxin gene from Pyrenophora tritici-repentis, are present in the genome of sister-species Pyrenophora bromi and other members of the Ascomycota. Fungal Genetics and Biology 45: 363–377.
Berbee ML, Pirseyedi M, Hubbard S (1999). Cochliobolus phylogenetics and the origin of known, highly virulent pathogens, inferred from ITS and glyceraldehyde-3-phosphate dehydrogenase gene sequences. Mycologia 91: 964–977.
Crous PW, Shivas RG, Wingfield MJ, et al. (2012). Fungal Planet description sheets: 128–153. Persoonia 29: 146–201.
Crous PW, Wingfield MJ, Guarro J, et al. (2013). Fungal Planet description sheets: 154–213. Persoonia 31: 188–296.
Manamgoda DS, Cai L, Bahkali AH, et al. (2011). Cochliobolus: an overview and current status of species. Fungal Diversity 51: 3–42.
Manamgoda DS, Cai L, McKenzie EHC, et al. (2012). A phylogenetic and taxonomic re-evaluation of the Bipolaris – Cochliobolus – Curvularia complex. Fungal Diversity 56: 131–144.
Manamgoda DS, Rossman AY, Castlebury LA, et al. (2014). The genus Bipolaris. Studies in Mycology 79: 221–288.
Marin-Felix Y, Groenewald JZ, Cai, L, et al. (2017). Genera of phytopathogenic fungi: GOPHY 1. Studies in Mycology xxxx.
Tan YP, Crous PW, Shivas RG (2016). Eight novel Bipolaris species identified from John L. Alcorn’s collections at the Queensland Plant Pathology Herbarium (BRIP). Mycological Progress 15: 1203–1214.
Tan YP, Madrid H, Crous PW, et al. (2014). Johnalcornia gen. et. comb. nov., and nine new combinations in Curvularia based on molecular phylogenetic analysis. Australasian Plant Pathology 43: 589–603.