Rosalie Daniel

Fungal Planet description sheets: 371-399

Novel species of fungi described in the present study include the following from Australia: Neoseptorioides eucalypti gen. & sp. nov. from Eucalyptus radiata leaves, Phytophthora gondwanensis from soil, Diaporthe tulliensis from rotted stem ends of Theobroma cacao fruit, Diaporthe vawdreyi from fruit rot of Psidium guajava, Magnaporthiopsis agrostidis from rotted roots of Agrostis stolonifera and Semifissispora natalis from Eucalyptus leaf litter. Furthermore, Neopestalotiopsis egyptiaca is described from Mangifera indica leaves (Egypt), Roussoella mexicana from Coffea arabica leaves (Mexico), Calonectria monticola from soil (Thailand), Hygrocybe jackmanii from littoral sand dunes (Canada), Lindgomyces madisonensis from submerged decorticated wood (USA), Neofabraea brasiliensis from Malus domestica (Brazil), Geastrum diosiae from litter (Argentina), Ganoderma wiiroense on angiosperms (Ghana), Arthrinium gutiae from the gut of a grasshopper (India), Pyrenochaeta telephoni from the screen of a mobile phone (India) and Xenoleptographium phialoconidium gen. & sp. nov. on exposed xylem tissues of Gmelina arborea (Indonesia). Several novelties are introduced from Spain, namely Psathyrella complutensis on loamy soil, Chlorophyllum lusitanicum on nitrified grasslands (incl. Chlorophyllum arizonicum comb. nov.), Aspergillus citocrescens from cave sediment and Lotinia verna gen. & sp. nov. from muddy soil. Novel foliicolous taxa from South Africa include Phyllosticta carissicola from Carissa macrocarpa, Pseudopyricularia hagahagae from Cyperaceae and Zeloasperisporium searsiae from Searsia chirindensis. Furthermore, Neophaeococcomyces is introduced as a novel genus, with two new combinations, N. aloes and N. catenatus. Several foliicolous novelties are recorded from La Réunion, France, namely Ochroconis pandanicola from Pandanus utilis, Neosulcatispora agaves gen. & sp. nov. from Agave vera-cruz, Pilidium eucalyptorum from Eucalyptus robusta, Strelitziana syzygii from Syzygium jambos (incl. Strelitzianaceae fam. nov.) and Pseudobeltrania ocoteae from Ocotea obtusata (Beltraniaceae emend.). Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

Potassium phosphonate alters the defence response of Xanthorrhoea australis following infection by Phytophthora cinnamomi

Potassium phosphonate (phosphite) is widely used in the management of Phytophthora diseases in agriculture, horticulture and natural environments. The Austral grass tree, Xanthorrhoea australis, a keystone species in the dry sclerophyll forests of southern Australia, is susceptible to Phytophthora cinnamomi, but is protected by applications of phosphite. We examined the effect of phosphite application on the infection of X. australis seedlings and cell suspension cultures by zoospores of P. cinnamomi. Phosphite induced more intense cellular responses to pathogen challenge and suppressed pathogen ingress in both seedlings and cell cultures. In untreated X. australis seedlings, hyphal growth was initially intercellular, became intracellular 24h after inoculation, and by 48h had progressed into the vascular tissue. In phosphite-treated seedlings, growth of P. cinnamomi remained intercellular and was limited to the cortex, even at 72 h after inoculation. The cell membrane retracted from the cell wall and phenolic compounds and electron dense substances were deposited around the wall of infected and neighbouring cells. Suspension cells were infected within 6 h of inoculation. Within 24 h of inoculation, untreated cells were fully colonised, had collapsed cytoplasm and died. The protoplast of phosphite-treated suspension cells collapsed within 12 h of inoculation, and phenolic material accumulated in adjacent, uninfected cells. No anatomical response to phosphite treatment was observed before infection of plant tissues, suggesting that the phosphite-associated host defence response is induced following pathogen challenge. Anatomical changes provide evidence that phosphite stimulates the host defence system to respond more effectively to pathogen invasion.

Phosphonate alters the defence responses of Lambertia species challenged by Phytophthora cinnamomi

Phytophthora cinnamomi is a destructive pathogen that causes dieback and death in many plant species in Australian native ecosystems. Susceptibility varies widely between related taxa, although the reasons for this variability are poorly understood. In glasshouse studies we confirmed field observations that Lambertia formosa, a New South Wales shrub, is less susceptible to P. cinnamomi than the related Western Australian species, L. inermis. Following inoculation, L. inermis roots are heavily colonised by the pathogen, leading to dieback and high mortality rates. Pathogen restriction in L. formosa correlates with more rapid and intense release of superoxide at the penetration site, and the activation of the phenylpropanoid pathway, than in L. inermis root tissues. Potassium phosphonate reduces symptom severity in inoculated L. formosa, and reduces both mortality and symptom severity in L. inermis. Phosphonate-induced protection in both species is associated with increased superoxide release 8 h after inoculation, and increased phenylalanine ammonia lyase activity 24 h after inoculation.

Distribution and occurrence of Phytophthora cinnamomi at Middle Head and North Head, Sydney Harbour

Dieback due to Phytophthora cinnamomi has significant impacts on susceptible native Australian vegetation communities and dependent fauna. Here we report the occurrence and distribution of P. cinnamomi at North Head and Middle Head, Sydney Harbour.

Sciarid and shore flies as aerial vectors of Fusarium oxysporum f. sp. cucumerinum in greenhouse cucumbers

The options for managing Fusarium wilt in greenhouse cucumbers are limited by our poor understanding of the modes of survival and dissemination of the pathogen. This study uses a specific quantitative real‐time PCR assay for Fusarium oxysporum f. sp. cucumerinum to investigate the significance of flying insects as aerial vectors of the pathogen in a commercial cucumber greenhouse. Shore flies were more frequently detected (35.5%) carrying F. oxysporum f. sp. cucumerinum than sciarids (25%), with both species carrying between 1 × 102 and 1 × 106 pathogen genome copies/individual. Sciarid and shore flies acquired F. oxysporum f. sp. cucumerinum following exposures to agar cultures of the pathogen of up to 94 h. Light microscopy revealed that spores were carried externally on the bodies of the adult flies. The ability of adult sciarid flies to vector the pathogen from peat‐grown diseased cucumber plants and infect healthy cucumber plants was demonstrated in a caged glasshouse trial. An inoculum density trial showed that vascular wilt disease was initiated after inoculation of peat‐grown seedlings with as few as 1000 conidia. We conclude that sciarid and shore flies play significant roles as vectors of F. oxysporum f. sp. cucumerinum in greenhouse cucumbers and need to be recognized in developing integrated crop management strategies.

Colletotrichum species in Australia

Forty-four species of Colletotrichum are confirmed as present in Australia based on DNA sequencing analyses. Many of these species were identified directly as a result of two workshops organised by the Subcommittee on Plant Health Diagnostics in Australia in 2015 that covered morphological and molecular approaches to identification of Colletotrichum. There are several other species of Colletotrichum reported from Australia that remain to be substantiated by DNA sequence-based methods. This body of work aims to provide a basis from which to critically examine a number of isolates of Colletotrichum deposited in Australian culture collections.

Elevated soil nitrogen increases the severity of dieback due to Phytophthora cinnamomi

A survey of a dieback-affected urban bushland reserve on the foreshore of Sydney Harbour found that deaths of native trees and increased weed density were associated with high levels of nutrients, particularly nitrogen, and Phytophthora cinnamomi. To test the interaction between P. cinnamomi and elevated soil nitrogen, a glasshouse trial was established to determine the susceptibility of the most common native trees of the Sydney Harbour foreshore; Angophora costata, Corymbia gummifera, Eucalyptus botryoides and Eucalyptus piperita to P. cinnamomi. Under low nitrogen conditions, inoculation with P. cinnamomi reduced the health of A. costata and C. gummifera, and reduced the root biomass of E. botryoides. Angophora costata and C. gummifera displayed signs of phytotoxicity with elevated levels of inorganic nitrogen. The presence of the pathogen, in combination with elevated nitrogen reduced the health of all species, but the symptoms were more severe in A. costata and E. piperita. The results suggest that the effect of elevated nitrogen application and susceptibility to P. cinnamomi is species specific. Mitigating soil nutrient loading in urban bushland areas by redirecting stormwater flow and surface runoff away from vulnerable bushland may assist in the management of dieback caused by P. cinnamomi.

Airborne inoculum of Fusarium oxysporum f. sp. cucumerinum

Fusarium oxysporum f. sp. cucumerinum is the fungal pathogen responsible for Fusarium vascular wilt of cucumber. In Australia, disease management in soilless greenhouse cucumbers is limited by the understanding of the disease cycle, in particular the risk associated with infection of pruning wounds by airborne propagules. Aerial dissemination of the pathogen in response to temperature and relative humidity was investigated using a specific and sensitive quantitative real-time PCR assay. Both macroconidia and microconidia were identified as airborne propagules and a potential relationship between fluctuation in relative humidity and spore release was found, however, it appears that crop disturbance may also influence conidia liberation. Experimental inoculation of stem wounds with conidia however, failed to establish infections. These results suggest that aerial inoculum propagates and disseminates the pathogen, however airborne spores are deposited on the substrate surface and infection occurs primarily through the root. We conclude that while airborne conidia are a risk to infection of cucumber plants in soilless greenhouse crops, resistant rootstocks are likely to provide good protection against this pathogen.

Technology Adoption: Classroom in the Cocoa Block

The adoption of technology aimed at improving the sustainability of food, fibre and fuel production is one of the greatest impediments to improving the quality of life, particularly for smallholder farmers in developing countries. Cocoa is Papua New Guinea’s third most important agricultural export crop, after coffee and palm oil, contributing up to 17% of the national agricultural revenue. This chapter describes and discusses a participatory research approach undertaken with smallholder cocoa farmers in Papua New Guinea aimed at providing different levels of farm management tailored to be implemented by farmers according to their particular circumstances.

Botryosphaeriales associated with stem blight and dieback of blueberry (Vaccinium spp.) in New South Wales and Western Australia

Stem blight and dieback caused by species of the Botryosphaeriales are important diseases of blueberry worldwide. In recent years, stem blight and dieback symptoms have been increasingly observed affecting blueberry production in Australia. Thirty samples were collected from symptomatic plants in an orchard at Corindi NSW, a major blueberry growing region. In addition, samples from symptomatic blueberry plants were submitted by growers to the Plant Health Diagnostic Service, NSW Department of Primary Industries from eight orchards in New South Wales (NSW), and a single orchard in Western Australia (WA). Culture isolations, DNA sequencing and pathogenicity testing were undertaken to determine the species causing the disease. Fifty-two isolates were recovered in total, forty-eight from NSW, and four from WA. A multi-locus sequencing approach was used to assist species identification including the internal transcribed spacer region of rDNA including 5.8S (ITS), partial translation elongation factor 1-alpha (tef1-α), and DNA-directed RNA polymerase II second largest subunit (rpb2). Eight species from three genera were identified; the most common was Neofusicoccum parvum (n = 34), followed by N. kwambonambiense (n = 7), N. occulatum (n = 5), L. theobromae (n = 2), Botryosphaeria dothidea (n = 1), N. australe (n = 1), N. macroclavatum (n = 1) and Lasiodiplodia pseudotheobromae (n = 1). The pathogenicity testing showed all isolates produced lesions on blueberry stems. This study provides the first survey of Botryosphaeriales causing blueberry stem blight and dieback in Australia, and is a valuable resource for plant pathologists and growers trying to manage the disease.