Potential gains through selecting for resistance in spotted gum to Quambalaria pitereka

Abstract Quambalaria shoot blight, caused by the fungus Quambalaria pitereka, is a serious disease affecting the expanding eucalypt plantation estate in subtropical and tropical eastern Australia. Trees that are severely infected are often multi-stemmed and stunted and infection of young trees may give rise to poor form in mature trees. A spotted gum clonal trial provided the opportunity to investigate the impact of the disease on tree growth and factors influencing tree architecture (tree form), which affects wood quality. We measured the effect that Q. pitereka infection during plantation establishment (up to 6 months old) has on growth and tree architecture and productivity to age 3 years. Our results show that the pathogen has a significant impact on trees at plantation establishment, which results in a negative impact on wood quality, potentially reducing merchantable value at final harvest. Tree growth and form was significantly improved where germplasm with low susceptibility to Q. pitereka infection was used.

Fungal Biopesticide for cattle tick and buffalo fly control

Cattle ticks and buffalo flies impose significant economic burdens on the Northern Australian cattle and dairy industries. With the increased temperatures expected under climate change the range of parasites such as these is likely to extend. Current control options for these ectoparasites are limited by problems associated with chemical resistance and residues. Fungal biopesticides offer a sustainable and promising alternative method of control. Laboratory and animal studies have established the potential for the fungus Metarhizium in tick control and provided data that suggests a secondary effect of buffalo fly control is possible. Small field trials are required to obtain a proof of concept for the control of ticks and buffalo flies on animals.

Bacterial and fungal community composition over time in chicken litter with high or low moisture content

1. Changes in bacterial and fungal communities in chicken litter with high and low moisture content over a five week period during a single chicken grow out cycle in a poultry shed in subtropical Australia were investigated to study the association between specific microbes and odour production. 2. Microbial biomass, as indicated by DNA yields, was higher and community composition was more dynamic over time in moist compared with dry chicken litter. 3. Bacillus, Atopostipes and Aspergillus species increased in relative abundance in moist chicken litter samples over time reflecting the relatively high fitness and hence activity of these specific bacteria and this specific fungus in this environment.

First report of shoot blight of persimmon caused by Diaporthe neotheicola in Australia

Shoot blight symptom was found on persimmon (Diospyros kaki) in southern Western Australia in December 2010. The pathogen was isolated and identified as Diaporthe neotheicola on the basis of morphology, sequence analysis of the internal transcribed spacer (ITS) and the translation elongation factor 1-α (TEF). A pathogenicity test was conducted and Koch's postulates were fulfilled by re-isolation of the fungus from diseased tissues. This is the first report of D. neotheicola causing shoot blight on persimmon in Australia and worldwide. © 2012 Australasian Plant Pathology Society Inc.

Genera of fungivorous Phlaeothripinae (Thysanoptera) from dead branches and leaf-litter in Australia

An illustrated key is provided for the identification of 39 genera of Thysanoptera-Phlaeothripinae with species that live in association with dead branches and leaf-litter in Australia and are considered to be fungus-feeding. Seven of these gen-era are not previously recorded from this continent, including un-named species of Deplorothrips, Malacothrips, Mystro-thrips, Preeriella and Tylothrips, together with Azaleothrips lepidus Okajima and Terthrothrips ananthakrishnani Kudo. A brief generic diagnosis is provided for each genus, together with comments on systematic problems and numbers of species. Copyright © 2013 Magnolia Press.

Screening bacterial metabolites for inhibitory effects against Batrachochytrium dendrobatidis using a spectrophotometric assay

Certain bacteria present on frog skin can prevent infection by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), conferring disease resistance. Previous studies have used agar-based in vitro challenge assays to screen bacteria for Bd-inhibitory activity and to identify candidates for bacterial supplementation trials. However, agar-based assays can be difficult to set up and to replicate reliably. To overcome these difficulties, we developed a semi-quantitative spectrophotometric challenge assay technique. Cell-free supernatants were prepared from filtered bacterial cultures and added to 96-well plates in replicated wells containing Bd zoospores suspended in tryptone-gelatin hydrolysate-lactose (TGhL) broth medium. Plates were then read daily on a spectrophotometer until positive controls reached maximum growth in order to determine growth curves for Bd. We tested the technique by screening skin bacteria from the Australian green-eyed tree frog Litoria serrata. Of bacteria tested, 31% showed some degree of Bd inhibition, while some may have promoted Bd growth, a previously unknown effect. Our cell-free supernatant challenge assay technique is an effective in vitro method for screening bacterial isolates for strong Bd-inhibitory activity. It contributes to the expanding field of bioaugmentation research, which could play a significant role in mitigating the effects of chytridiomycosis on amphibians around the world.

Responses of tribolium castaneum to olfactory cues from cotton seeds, the fungi associated with cotton seeds, and cereals

We tested, in an olfactometer, whether or not Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) responds preferentially to the volatiles that emanate from the fungi associated with cotton [Gossypium hirsutum L. (Malvaceae)] seed over those that emanate from cereals, because cereals are usually portrayed as the primary resources of these beetles. Pairwise comparisons were conducted between cotton seed, wheat (Triticum aestivum L.), and sorghum [Sorghum bicolor (L.) Moench] (both Poaceae); volatiles were tested from intact seeds and from both water and ethanol extracts. The results demonstrate that T. castaneum is attracted more strongly to cotton seeds with its lint contaminated with fungi, than to the conventional resources of this species (i.e., wheat and sorghum). Further tests prove that it is the fungus on the lint that produces the active volatiles, because the beetles did not respond to sterilized cotton lint (i.e., without the fungi typically associated with it when cotton seed is stored). Tests with five fungal cultures (each representing an unidentified species that was isolated from the field-collected cotton lint) were variable across the cultures, with only one of them being significantly attractive to the beetles. The others were not attractive and one may even have repulsed the beetles. The results are consistent with the beetles having a strong ecological association with fungi and suggest it would be worth investigating the ecology of T. castaneum from this perspective. © 2012 The Netherlands Entomological Society.

Morphological and molecular diversity of Colletotrichum spp. causing pepper spot and anthracnose of lychee (Litchi chinensis) in Australia

Since the 1980s a new disease has been affecting Australian lychee. Pepper spot appears as small, black superficial lesions on fruit, leaves, petioles and pedicels and is caused by Colletotrichum gloeosporioides, the same fungus that causes postharvest anthracnose of lychee fruit. The aim of this study was to determine if a new genotype of C.gloeosporioides is responsible for the pepper spot symptom. Morphological assessments, arbitrarily-primed PCR (ap-PCR) and DNA sequencing studies did not differentiate isolates of C.gloeosporioides from anthracnose and pepper spot lesions. The ap-PCR identified 21 different genotypes of C.gloeosporioides, three of which were predominant. A specific genotype identified using ap-PCR was associated with the production of the teleomorph in culture. Analysis of sequence data of ITS and -tubulin regions of representative isolates did not group the lychee isolates into a monophyletic clade; however, given the majority of the isolates were from one of three genotypes found using ap-PCR, the possibility of a lychee specific group of C.gloeosporioides is discussed.

Symptom development proceeds at different rates in susceptible and partially resistant cereal seedlings infected with Fusarium pseudograminearum

Variation in the reaction of cereal cultivars to crown rot caused by Fusarium spp., in particular Fusarium pseudograminearum, was identified over 50 yrs ago, however the parameters and pathways of infection by F. pseudograminearum remain poorly understood. Seedlings of wheat, barley and oat genotypes that differ in susceptibility to crown rot were inoculated with a mixture of F. pseudograminearum isolates. Seedlings were harvested from 7 to 42 days after inoculation and expanded plant parts were rated for severity of visible disease symptoms. Individual leaf sheaths were placed onto nutrient media and fungal colonies emerging from the leaf sheathes were counted to estimate the degree of fungal spread within the host tissue. Significant differences in both the timing and the severity of disease symptoms were observed in the leaf sheath tissues of different host genotypes. Across all genotypes and plant parts examined, the development of visible symptoms closely correlated with the spread of the fungus into that tissue. The degree of infection of the coleoptile and sub-crown internode varied between genotypes, but was unrelated to the putative resistance of the host. In contrast leaf sheath tissues of the susceptible barley cv. Tallon and bread wheat cv. Puseas scored higher disease ratings and consistently showed faster, earlier spread of the fungus into younger tissues than infections of the oat cv. Cleanleaf or the wheat lines 2-49 and CPI 133814. While initial infections usually spread upwards from near the base of the first leaf sheath, the pathogen did not appear to invade younger leaf sheaths only from the base, but rather spread laterally across from older leaf sheaths into younger, subtended leaf sheaths, particularly as disease progressed. Early in the infection of each leaf sheath, disease symptoms in the partially resistant genotypes were less severe than in susceptible genotypes, however as infected leaf sheaths aged, differences between genotypes lessened as disease symptoms approached maximum values. Hence, while visual scoring of disease symptoms on leaf sheaths is a reliable comparative measure of the degree of fungal infection, differences between genotypes in the development of disease symptoms are more reliably assessed using the most recently expanded leaf sheaths.

First report of Vialaea minutella in Australia, its association with mango branch dieback and systematic placement of Vialaea in the Xylariales

Vialaea minutella was consistently isolated from infected mango trees showing branch dieback symptoms in northern Queensland. The fungus was identified by morphology and confirmed with molecular sequence data. This is the first report of V. minutella in Australia. The systematic position of Vialaea was confirmed to be in the Xylariales based on reconstructed LSU sequence data.

Puccinia psidii in Queensland, Australia: disease symptoms, distribution and impact

Puccinia psidii has long been considered a significant threat to Australian plant industries and ecosystems. In April 2010, P. psidii was detected for the first time in Australia on the central coast of New South Wales (NSW). The fungus spread rapidly along the east coast and in December 2010 was found in Queensland (Qld) followed by Victoria a year later. Puccinia psidii was initially restricted to the southeastern part of Qld but spread as far north as Mossman. In Qld, 48 species of Myrtaceae are considered highly or extremely susceptible to the disease. The impact of P. psidii on individual trees and shrubs has ranged from minor leaf spots, foliage, stem and branch dieback to reduced fecundity. Tree death, as a result of repeated infection, has been recorded for Rhodomyrtus psidioides. Rust infection has also been recorded on flower buds, flowers and fruits of 28 host species. Morphological and molecular characteristics were used to confirm the identification of P. psidii from a range of Myrtaceae in Qld and compared with isolates from NSW and overseas. A reconstructed phylogeny based on the LSU and SSU regions of rDNA did not resolve the familial placement of P. psidii, but indicated that it does not belong to the Pucciniaceae. Uredo rangelii was found to be con-specific with all isolates of P. psidii in morphology, ITS and LSU sequence data, and host range.

Leichhardt's vanishing thrips: A remarkable new genus and species of Insecta, Thysanoptera, Phlaeothripinae

Leichhardtithrips evanidus gen. et sp. nov., a wingless, fungus-feeding species of Phlaeothripidae, is described from a single female taken in D'Aguilar National Park, Brisbane. This species has exceptionally reduced sclerotisation rendering systematic comparisons of the new genus difficult. The cylindrical form of the eighth antennal segment is unique in the family, and the compound eyes are not developed on the ventral surface of the head. © The State of Queensland, Queensland Museum 2013.

First report of Masseeëlla capparis in Australia

The rust fungus Masseeëlla capparis is reported for the first time in Australia on Flueggea virosa (Phyllanthaceae). This is the first species of Masseeëlla found in Australia. The rust is described and illustrated from Australian specimens. A discussion on species of Masseeëlla is provided. A reconstructed phylogeny with the Large Subunit region of ribosomal DNA indicated that Masseeëlla has an affinity with the Phakopsoraceae.

The Myrtle Rust pathogen has arrived - and South African Myrtales are at risk : green news - plant disease alert

For many years Australian forest pathologists and other scientists have dreaded the arrival of the rust fungus, Puccinia psidii, commonly known as Myrtle Rust, in Australia. This pathogen eventually did arrive in that country and was first detected in New South Wales in 2010 on Willow Myrtle (Agonis flexuosa). It is generally accepted that it entered the country on an ornamental Myrtales* host brought in by a private nursery. Despite efforts to eradicate the invasive rust, it has already spread widely, now occurring along the east coast of Australia, from temperate areas in Victoria and southern North South Wales to tropical areas in north Queensland.

Eco-Taxonomic Insights into Actinomycete Symbionts of Termites for Discovery of Novel Bioactive Compounds

Termites play a major role in foraging and degradation of plant biomass as well as cultivating bioactive microorganisms for their defense. Current advances in “omics” sciences are revealing insights into function-related presence of these symbionts, and their related biosynthetic activities and genes identified in gut symbiotic bacteria might offer a significant potential for biotechnology and biodiscovery. Actinomycetes have been the major producers of bioactive compounds with an extraordinary range of biological activities. These metabolites have been in use as anticancer agents, immune suppressants, and most notably, as antibiotics. Insect-associated actinomycetes have also been reported to produce a range of antibiotics such as dentigerumycin and mycangimycin. Advances in genomics targeting a single species of the unculturable microbial members are currently aiding an improved understanding of the symbiotic interrelationships among the gut microorganisms as well as revealing the taxonomical identity and functions of the complex multilayered symbiotic actinofloral layers. If combined with target-directed approaches, these molecular advances can provide guidance towards the design of highly selective culturing methods to generate further information related to the physiology and growth requirements of these bioactive actinomycetes associated with the termite guts. This chapter provides an overview on the termite gut symbiotic actinoflora in the light of current advances in the “omics” science, with examples of their detection and selective isolation from the guts of the Sunshine Coast regional termite Coptotermes lacteus in Queensland, Australia