Robert W. Barreto

Sizing up Septoria

Septoria represents a genus of plant pathogenic fungi with a wide geographic distribution, commonly associated with leaf spots and stem cankers of a broad range of plant hosts. A major aim of this study was to resolve the phylogenetic generic limits of Septoria, Stagonospora, and other related genera such as Sphaerulina, Phaeosphaeria and Phaeoseptoria using sequences of the the partial 28S nuclear ribosomal RNA and RPB2 genes of a large set of isolates. Based on these results Septoria is shown to be a distinct genus in the Mycosphaerellaceae, which has mycosphaerella-like sexual morphs. Several septoria-like species are now accommodated in Sphaerulina, a genus previously linked to this complex. Phaeosphaeria (based on P. oryzae) is shown to be congeneric with Phaeoseptoria (based on P. papayae), which is reduced to synonymy under the former. Depazea nodorum (causal agent of nodorum blotch of cereals) and Septoria avenae (causal agent of avenae blotch of barley and rye) are placed in a new genus, Parastagonospora, which is shown to be distinct from Stagonospora (based on S. paludosa) and Phaeosphaeria. Partial nucleotide sequence data for five gene loci, ITS, LSU, EF-1α, RPB2 and Btub were generated for all of these isolates. A total of 47 clades or genera were resolved, leading to the introduction of 14 new genera, 36 new species, and 19 new combinations. Taxonomic novelties: New genera - Acicuseptoria Quaedvlieg, Verkley & Crous, Cylindroseptoria Quaedvlieg, Verkley & Crous, Kirstenboschia Quaedvlieg, Verkley & Crous, Neoseptoria Quaedvlieg, Verkley & Crous, Neostagonospora Quaedvlieg, Verkley & Crous, Parastagonospora Quaedvlieg, Verkley & Crous, Polyphialoseptoria Quaedvlieg, R.W. Barreto, Verkley & Crous, Ruptoseptoria Quaedvlieg, Verkley & Crous, Septorioides Quaedvlieg, Verkley & Crous, Setoseptoria Quaedvlieg, Verkley & Crous, Stromatoseptoria Quaedvlieg, Verkley & Crous, Vrystaatia Quaedvlieg, W.J. Swart, Verkley & Crous, Xenobotryosphaeria Quaedvlieg, Verkley & Crous, Xenoseptoria Quaedvlieg, H.D. Shin, Verkley & Crous. New species - Acicuseptoria rumicis Quaedvlieg, Verkley & Crous, Caryophylloseptoria pseudolychnidis Quaedvlieg, H.D. Shin, Verkley & Crous, Coniothyrium sidae Quaedvlieg, Verkley, R.W. Barreto & Crous, Corynespora leucadendri Quaedvlieg, Verkley & Crous, Cylindroseptoria ceratoniae Quaedvlieg, Verkley & Crous, Cylindroseptoria pistaciae Quaedvlieg, Verkley & Crous, Kirstenboschia diospyri Quaedvlieg, Verkley & Crous, Neoseptoria caricis Quaedvlieg, Verkley & Crous, Neostagonospora caricis Quaedvlieg, Verkley & Crous, Neostagonospora elegiae Quaedvlieg, Verkley & Crous, Paraphoma dioscoreae Quaedvlieg, H.D. Shin, Verkley & Crous, Parastagonospora caricis Quaedvlieg, Verkley & Crous, Parastagonospora poae Quaedvlieg, Verkley & Crous, Phlyctema vincetoxici Quaedvlieg, Verkley & Crous, Polyphialoseptoria tabebuiae-serratifoliae Quaedvlieg, Alfenas & Crous, Polyphialoseptoria terminaliae Quaedvlieg, R.W. Barreto, Verkley & Crous, Pseudoseptoria collariana Quaedvlieg, Verkley & Crous, Pseudoseptoria obscura Quaedvlieg, Verkley & Crous, Sclerostagonospora phragmiticola Quaedvlieg, Verkley & Crous, Septoria cretae Quaedvlieg, Verkley & Crous, Septoria glycinicola Quaedvlieg, H.D. Shin, Verkley & Crous, Septoria oenanthicola Quaedvlieg, H.D. Shin, Verkley & Crous, Septoria pseudonapelli Quaedvlieg, H.D. Shin, Verkley & Crous, Setophoma chromolaenae Quaedvlieg, Verkley, R.W. Barreto & Crous, Setoseptoria phragmitis Quaedvlieg, Verkley & Crous, Sphaerulina amelanchier Quaedvlieg, Verkley & Crous, Sphaerulina pseudovirgaureae Quaedvlieg, Verkley & Crous, Sphaerulina viciae Quaedvlieg, H.D. Shin, Verkley & Crous, Stagonospora duoseptata Quaedvlieg, Verkley & Crous, Stagonospora perfecta Quaedvlieg, Verkley & Crous, Stagonospora pseudocaricis Quaedvlieg, Verkley, Gardiennet & Crous, Stagonospora pseudovitensis Quaedvlieg, Verkley & Crous, Stagonospora uniseptata Quaedvlieg, Verkley & Crous, Vrystaatia aloeicola Quaedvlieg, Verkley, W.J. Swart & Crous, Xenobotryosphaeria calamagrostidis Quaedvlieg, Verkley & Crous, Xenoseptoria neosaccardoi Quaedvlieg, H.D. Shin, Verkley & Crous. New combinations - Parastagonospora avenae (A.B. Frank) Quaedvlieg, Verkley & Crous, Parastagonospora nodorum (Berk.) Quaedvlieg, Verkley & Crous, Phaeosphaeria papayae (Speg.) Quaedvlieg, Verkley & Crous, Pseudocercospora domingensis (Petr. & Cif.) Quaedvlieg, Verkley & Crous, Ruptoseptoria unedonis (Roberge ex Desm.) Quaedvlieg, Verkley & Crous, Septorioides pini-thunbergii (S. Kaneko) Quaedvlieg, Verkley & Crous, Sphaerulina abeliceae (Hiray.) Quaedvlieg, Verkley & Crous, Sphaerulina azaleae (Voglino) Quaedvlieg, Verkley & Crous, Sphaerulina berberidis (Niessl) Quaedvlieg, Verkley & Crous, Sphaerulina betulae (Pass.) Quaedvlieg, Verkley & Crous, Sphaerulina cercidis (Fr.) Quaedvlieg, Verkley & Crous, Sphaerulina menispermi (Thüm.) Quaedvlieg, Verkley & Crous, Sphaerulina musiva (Peck) Quaedvlieg, Verkley & Crous, Sphaerulina oxyacanthae (Kunze & J.C. Schmidt) Quaedvlieg, Verkley & Crous, Sphaerulina patriniae (Miura) Quaedvlieg, Verkley & Crous, Sphaerulina populicola (Peck) Quaedvlieg, Verkley & Crous, Sphaerulina quercicola (Desm.) Quaedvlieg, Verkley & Crous, Sphaerulina rhabdoclinis (Butin) Quaedvlieg, Verkley & Crous, Stromatoseptoria castaneicola (Desm.) Quaedvlieg, Verkley & Crous. Typifications: Epitypifications - Phaeosphaeria oryzae I. Miyake, Phaeoseptoria papayae Speg.; Neotypification - Hendersonia paludosa Sacc. & Speg.

The mycobiota of the weed Mikania micrantha in southern Brazil with particular reference to fungal pathogens for biological control

A survey of the fungi associated with the tropical weed Mikania micrantha was conducted during 1988 and 1989 in part of its native range in southern Brazil. Sampling was concentrated mainly in the state of Rio de Janeiro, covering 70 sites in different climatic or ecological zones. Nine species were identified, including the recently described downy mildew species Basidiophora montana and the previously undescribed Mycosphaerella mikania-micranthae sp. nov. with its anamorph Septoria mikania-micranthae. Asperisporium mikaniae comb. nov., Asperisporium mikaniigena comb. nov., Pseudocercospora plunketii comb. nov., and Cercospora mikaniacola are new records for Brazil. Field observations indicate that Basidiophora montana has potential as a classical biological control agent of the weed in Old World subtropical or montane climates, whilst Mycosphaerella mikania-micranthae and the microcyclic rust Puccinia spegazzinii appear to be equally damaging to the host but to have a wider climatic range and thus are highly promising agents for introduction throughout the Palaeotropics.

Biological control of neotropical aquatic weeds with fungi

Many of the world’s worst tropical aquatic weeds are native to the Neotropics. Besides, the majority of the most aggressive aquatic weeds in that vast region of the world are endemic and therefore there is a need for exploration for biological control agents in that area. Entomologists had an early lead on this search. Only in the late 1970s did plant pathologists started sporadic collections of fungal pathogens of aquatic weeds in the Neotropics for evaluation and use as classical biocontrol agents or as mycoherbicides. Although intensive search of the mycobiota of water hyacinth and other plant species are recent, they have already yielded a range of new potential biocontrol agents. A discussion on the status of studies of the mycobiota of the following selected Neotropical species is presented: Alternanthera philoxeroides, Azolla xliculoides, Echinochloa polystachya, Eichhornia azurea, Eichhornia crassipes, Egeria densa, Myriophyllum aquaticum, Paspalum repens, Pistia stratiotes, Polygonum spectabile, Salvinia auriculata, Salvinia molesta and Typha domingensis. ( 2000 Elsevier Science Ltd. All rights reserved.

The mycobiota of the weed Lantana camara in Brazil, with particular reference to biological control.

A survey of the fungi associated with the tropical weed Lantana camara was conducted during 1988 and 1989 in part of its native range in southern Brazil. The sampling activity was concentrated mainly in the state of Rio de Janeiro, covering 70 sites located in different climatic or ecological zones. The survey continued and was extended to the Amazon and northeast regions. Nine fungal species were identified as members of the mycobiota, including the previously undescribed fungi: Ceratobasidium lantanae-camarae sp. nov., Dendryphiella aspera sp. nov. and Micropustulomyces mucilaginosus gen. et sp. nov. Perisporiopsis lantanae , which has not been recorded previously in Brazil, has its anamorph described for the first time. The rusts Aecidium lantanae were also recorded. Field observations suggest that several fungal pathogens have potential as classical biocontrol agents of the weed in the Old World tropics: Ceratobasidium lantanae-camarae and Puccinia lantanae in lowland humid climates; Mycovellosiella lantanae, Prospodium tuberculatum and Micropustulomyces mucilaginosus in more elevated or subtropical areas. In addition, databases and herbaria were consulted in order to compile a world list of fungal pathogens associated with L. camara .

The Colletotrichum orbiculare species complex: important pathogens of field crops and weeds.

Colletotrichum orbiculare causes anthracnose of Cucurbitaceae and is phylogenetically closely related to pathogens of several other herbaceous hosts belonging to the Asteraceae, Fabaceae and Malvaceae. Most of them are known for their hemibiotrophic infection strategy and as destructive pathogens either of field crops or weeds. In order to study the phylogenetic relationships of these fungi, a multilocus analysis (ITS, GAPDH, CHS-1, HIS3, ACT, TUB2, GS) of 42 strains of C. orbiculare and related species was conducted. The analysis resulted in nine clades that confirmed the four species previously known as belonging to this species complex, C. lindemuthianum, C. malvarum, C. orbiculare and C. trifolii, and recognised four new species from weeds, namely C. bidentis, C. sidae, C. spinosum and C. tebeestii. The name C. orbiculare itself is widely used in plant pathology and science, but is invalid according to current nomenclatural rules. Therefore we described a new species with the same epithet and a type specimen that agrees with our current understanding of this species, and is linked to a living culture. Following the recent epitypification of C. lindemuthianum, we chose appropriate specimens with associated strains to serve as epitypes of C. malvarum and C. trifolii, and selected an authentic specimen of C. trifolii as lectotype.

Prospects for the Management of Invasive Alien Weeds Using Co-Evolved Fungal Pathogens: A Latin American Perspective

Invasive alien weeds pose a serious threat to the biodiversity of natural ecosystems and a significant constraint to agricultural production worldwide. The use of co-evolved natural enemies, a strategy referred to as classical biological control (CBC), has proven to be a potentially efficacious, cost-effective, and safe option for the management of alien weeds. An analysis of CBC of invasive weeds in Latin America is presented, which shows that only 5% of the worldwide releases of agents, overwhelmingly arthropod, have been in this region. Fungal pathogens are increasingly being considered in CBC programmes, and there are now 11 examples of Latin American fungi having been released as biocontrol agents in other regions of the world. In contrast, only three weed pathogens have been deliberately released in the region. Possible reasons for the paucity of CBC programmes in Latin America are presented, despite the presence of a significant number of alien weed species (60 are listed). An analysis of these weeds reveals that many of them could be amenable to control using natural enemies, including nine weed species for which CBC programmes have been successfully implemented elsewhere in the world. In addition, for many of these 60 species, a co-evolved and damaging mycobiota has already been recorded. The prospects for management of invasive alien weeds in Latin America, using co-evolved fungal pathogens, are assessed with particular reference to selected species from the genera Ambrosia, Broussonetia, Calotropis, Commelina, Cyperus, Dichrostachys, Echinochloa, Pittosporum, Rottboellia, Rubus, Sonchus and Ulex.

Cryptosexuality and the Genetic Diversity Paradox in Coffee Rust, Hemileia vastatrix

Background Despite the fact that coffee rust was first investigated scientifically more than a century ago, and that the disease is one of the major constraints to coffee production - constantly changing the socio-economic and historical landscape of the crop - critical aspects of the life cycle of the pathogen, Hemileia vastatrix, remain unclear. The asexual urediniospores are regarded as the only functional propagule: theoretically, making H. vastatrix a clonal species. However, the well-documented emergence of new rust pathotypes and the breakdown in genetic resistance of coffee cultivars, present a paradox. Methods and Results Here, using computer-assisted DNA image cytometry, following a modified nuclear stoichiometric staining technique with Feulgen, we show that meiosis occurs within the urediniospores. Stages of spore development were categorised based on morphology, from the spore-mother cell through to the germinating spore, and the relative nuclear DNA content was quantified statistically at each stage. Conclusions Hidden sexual reproduction disguised within the asexual spore (cryptosexuality) could explain why new physiological races have arisen so often and so quickly in Hemileia vastatrix. This could have considerable implications for coffee breeding strategies and may be a common event in rust fungi, especially in related genera occupying the same basal phylogenetic lineages.

Evaluation of Colletotrichum gloeosporioides for Biological Control of Miconia calvescens in Hawaii

Miconia calvescens (Melastomataceae), from the Neotropics, is a noxious forest weed in Hawaii. We evaluated an isolate of Colletotrichum gloeosporioides that causes leaf spots on Miconia spp. in Brazil for its potential in biological control. Hawaii has no native Melastomataceae genera but does have members of 12 introduced genera. Following Wapsheres centrifugal phylogenetic method (2), eight species of Melastomataceae genera in Hawaii were inoculated in addition to Miconia spp. Naturalized and native Hawaiian members of the order Myrtales also were inoculated to determine host specificity, including Terminalia catappa (Combretaceae); Cuphea hysopifolia and C. ignea (Lythraceae); Arthrostema ciliatum, Clidemia hirta, Dissotis rotundifolia, Heterocentron subtriplinervium, Medinilla scortechenii, Melastoma candidum, Pterolepsis glomerata, and Tibouchina herbaceae (Melastomataceae); Eucalyptus grandis, Eucalyptus microcorys, Eugenia reinwardtiana, Eugenia uniflora, Leptospermum laevigatum, Melaleuca quinquenervia, Metrosideros polymorpha, Psidium guajava, and Syzgium malaccanse (Myrtaceae); Fuchsia magellanica and Oenothera stricta (Onagraceae); and Wikstroemia oahuensis and W. uva-ursi (Thymelaeaceae). All M. calvescens plants were grown from seed collected in Hawaii. Other test plants were grown from seeds or cuttings in artificial potting medium in a greenhouse. Plants had 6 to 8 mature leaves when inoculated. C. gloeosporioides was cultured on 10% potato dextrose agar supplemented with plain agar (35 g/liter) and incubated under constant fluorescent illumination at 20°C. Conidia were harvested by flooding 10-to 14-day-old cultures with sterile tap water, followed by light scraping with a scalpel. Conidial suspensions were adjusted to 106 conidia per ml and applied to both leaf surfaces with a hand-held sprayer. Inoculated plants were kept at 100% relative humidity and 16 to 25°C for 48 h. Four replicate plants and one plant of M. calvescens per species were inoculated. Plants were observed for symptom development for up to 6 weeks. The entire test was repeated once. Lesions were visible after 7 to 10 days. Young lesions had chlorotic halos and expanded in a roughly circular pattern to diameters of 5 to 10 mm. Mature lesions developed necrotic centers, coalesced, and became dry and brittle with age, resulting in extensive leaf necrosis. Defoliation of moderately to severely infected leaves occurred ≈ 30 days after inoculation. With the exception of M. calvescens, C. gloeosporioides did not produce visible symptoms on test plants. The failure of Clidemia hirta, the taxonomic species most closely related to M. calvescens, to become symptomatic was particularly significant relative to the centrifugal phylogenetic concept. The results demonstrate that our pathogen (VIC 19306) is distinct from C. gloeosporioides f. sp. clidemiae (1), which did not infect M. calvescens. We designate our pathogen C. gloeosporioides f. sp. miconiae. Voucher specimens (VIC 19306, Sana, RJ, 24.II.1998, and R. W. Barreto) and cultures are maintained at the Departamento de Fitopatologia, Universidade Federal de Viçosa MG, Brazil. References: (1) E. E. Trujillo et al. Plant Dis. 70:974, 1986. (2) A. J. Wapshere. Ann. Appl. Biol. 77:201, 1974.

Fungal pathogens of Euphorbia heterophylla and E. hirta in Brazil and their potential as weed biocontrol agents.

A two-year survey of the fungi associated with two important congeneric pantropical weeds, Euphorbia heterophylla and E. hirta, was conducted in part of their native range in southern Brazil. Sampling was concentrated mainly in Rio de Janeiro State and ten species were identified as pathogens of these weeds. Two taxa, Botrytis ricini and Uromyces euphorbiae, were common to both weed hosts. Alternaria euphorbiicola, Bipolaris euphorbiae, Melampsora sp., Oidium sp. and Sphaceloma poinsettiae were recorded only from E. heterophylla, whereas Colletotrichum gloeosporioides, Sphaceloma sp. and Sphaerotheca fuliginea were restricted to E. hirta. Botrytis ricini and Colletotrichum gloeosporioides are new records for E. hirta, and Alternaria euphorbiicola and Sphaerotheca fuliginea are new host records for Brazil. Bipolaris euphorbiae, previously identified as Helminthosporium sp., is considered to be the correct name for the causal agent of a major disease of E. heterophyllum in Brazil. The potential of these pathogens as biocontrol agents is discussed and the mycobiota associated with both these weeds worldwide is reviewed.

Fungal Planet description sheets: 128-153

Novel species of microfungi described in the present study include the following from Australia: Catenulostroma corymbiae from Corymbia, Devriesia stirlingiae from Stirlingia, Penidiella carpentariae from Carpentaria, Phaeococcomyces eucalypti from Eucalyptus, Phialophora livistonae from Livistona, Phyllosticta aristolochiicola from Aristolochia, Clitopilus austroprunulus on sclerophyll forest litter of Eucalyptus regnans and Toxicocladosporium posoqueriae from Posoqueria. Several species are also described from South Africa, namely: Ceramothyrium podocarpi from Podocarpus, Cercospora chrysanthemoides from Chrysanthemoides, Devriesia shakazului from Aloe, Penidiella drakensbergensis from Protea, Strelitziana cliviae from Clivia and Zasmidium syzygii from Syzygium. Other species include Bipolaris microstegii from Microstegium and Synchaetomella acerina from Acer (USA), Brunneiapiospora austropalmicola from Rhopalostylis (New Zealand), Calonectria pentaseptata from Eucalyptus and Macadamia (Vietnam), Ceramothyrium melastoma from Melastoma (Indonesia), Collembolispora aristata from stream foam (Czech Republic), Devriesia imbrexigena from glazed decorative tiles (Portugal), Microcyclospora rhoicola from Rhus (Canada), Seiridium phylicae from Phylica (Tristan de Cunha, Inaccessible Island), Passalora lobeliae-fistulosis from Lobelia (Brazil) and Zymoseptoria verkleyi from Poa (The Netherlands). Valsalnicola represents a new ascomycete genus from Alnus (Austria) and Parapenidiella a new hyphomycete genus from Eucalyptus (Australia). Morphological and culture characteristics along with ITS DNA barcodes are also provided.