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Life-history characteristics of Theodore’s threadfin bream, Nemipterus theodorei (Ogilby, 1916), and the yellow-lip butterfly bream, Nemipterus aurifilum (Ogilby, 1910), from southern Queensland, Australia
Get PDFTheodore’s threadfin bream (Nemipterus theodorei) and the yellow-lip butterfly bream (Nemipterus aurifilum) are two of the most common nemipterids in eastern Queensland. These two species are caught incidentally and at times retained for sale as ‘permitted’ species in Australia’s largest trawl fishery, the Queensland East Coast Otter Trawl Fishery (QECOTF). Despite their prevalence, little biological information is available for these species. This paper reports key life-history characteristics of these nemipterids. Growth and length-at-maturity parameters were estimated from samples collected in southern Queensland. Growth parameters were estimated using back-calculation of fork length (FL) from otolith increment data and modelled within a Bayesian framework to overcome bias resulting from the small number of larger, older animals in the retained bycatch. The von Bertalanffy growth function (VBGF) was identified as the most appropriate growth model with significant differences in sex-specific growth rates evident for both species. Maximum ages were six and four years for N. theodorei and N. aurifilum respectively, with individuals maturing within their first year of life. The length-at-maturity for females was 91 mm FL and 77 mm FL for N. theodorei and N. aurifilum respectively. Increased reproductive activity was observed in the austral spring and summer months. The results from this study can be used to assess the ecological risk posed to these species by the QECOTF. © 2022, Queensland Museum. All rights reserved
Isolation of Glucose Fermenting Nitrogen Fixing Gene (nifH) Containing Endophytic Bacteria from Seed and Roots of Wheat (Triticum aestivation l.)
Get PDFThe present study was conducted to study the nifH gene containing endophytic bacterial frequency in wheat seed and roots obtained from the soil of Chitwan and Kaski. One hundred and four isolates were studied for the presence of the nifH gene. There was a diversity in isolate characters obtained from root sample Root (R), direct seed sample (ds), and plant sample (P). None of the isolates from any sources showed indole-producing ability. About 18 isolates (15% of the total) contained the nifH gene through amplification of the gene by universal primers PolF and PolR. About 6 isolates from seed sample ds and 12 isolates from root sample R contained nifH gene. None of the isolates from root sample P manifested the presence of the nifH gene. Among 18 nifH- containing isolates, only 6 isolates manifested presence of cel3 gene of 400 bp, whereas, 11 isolates showed cel3 gene of 200 bp. All nifH gene containing isolates were confirmed to be bacteria by PCR amplification of 16s rRNA gene by universal primer 27F and 1492R and visualization of agarose gel matrix with bp range of approximately 530 under UV ray. Further research scope exists to use these microbes as a bio fertilizer in plant growth promotion studies by inoculation
Community structure and antifungal activity of actinobacteria in a fungus‐growing termite
No full textFungus‐growing termites cultivate the fungal mutualist Termitomyces as their main food source; however, how fungus‐growing termites protect Termitomyces from threats is still unclear. In this study, we investigated the actinobacterial communities in Odontotermes formosanus individuals and their fungal combs.
Moreover, the antifungal activities of the isolated actinobacteria were tested. 16 S rRNA gene sequencing results indicated that the actinobacteria in O. formosanus and its fungal combs belong to 5 classes, 17 orders, 40 families, and 84 genera.
The relative abundance of Coriobacteriia in the nymphs, young workers, old workers, and soldiers was higher than that in the queens and fungal combs, and the relative abundance of class Actinobacteria in the queens and the fungal combs was higher than that in the nymphs, young workers, old workers, and soldiers.
Based on antifungal bioassays, 3 strains of Amycolatopsis and 2 strains of Streptomyces isolated from old workers had strong inhibitory activity against Xylaria angulosa but weak inhibitory activity against Termitomyces sp.
These results indicated that the actinobacteria of O. formosanus may contribute to protecting termite fungal food via their asymmetric antifungal activities
Bruising of Avocado (Persea americana M.) Fruit
No full textAvocado is prized as a fruit of high economic, nutritional, and medicinal value. Its worldwide production and trade are continuously rising. However, a major concern of avocado consumers is inconsistent value for money spent on purchase of the fruit. Despite decades of research, development, extension effort, and considerable financial investment, this perception persists. Flesh bruising and fruit rot are predominant among the quality issues that concern consumers. Flesh bruising is typically associated with physical impact and compression events. Skin abrasion bruising may result from vibration. Understanding the bruising of avocado fruit during handling through supply chains is important so that preventative measures can be implemented. This chapter reviews the causative factors of avocado fruit bruising, the occurrence and severity of bruising associated with supply chain handling practices, and technology options towards avoiding fruit bruising. Based on the present understanding, best practice recommendations for the avocado industry are presented
Phylogenetic analyses reveal multiple new stem-boring Tetramesa taxa (Hymenoptera: Eurytomidae): implications for the biological control of invasive African grasses
Get PDFMany native South African grass species have become invasive elsewhere in the world. The application of biological control to invasive grasses has been approached with trepidation in the past, primarily due to concerns of a perceived lack of host specific herbivores. This has changed in recent times, and grasses are now considered suitable candidates. The Tetramesa Walker genus (Hymenoptera: Eurytomidae) has been found to contain species that are largely host specific to a particular grass species, or complex of closely related congeners. Very little taxonomic work exists for Tetramesa in the southern hemisphere, and the lack of morphological variability between many Tetramesa species has made identification difficult. This limits the ability to assess the genus for potential biological control agents. Species delimitation analyses indicated 16 putative novel southern African Tetramesa taxa. Ten of these were putative Tetramesa associated with Eragrostis curvula (Schrad.) Nees and Sporobolus pyramidalis Beauv. and S. natalensis Steud., which are alien invasive weeds in Australia. Of these ten Tetramesa taxa, eight were only found on a single host plant, while two taxa were associated with multiple species in a single grass genus. The Tetramesa spp. on S. pyramidalis and S. africanus were deemed suitably host-specific to be used as biological control agents. Field host range data for the Tetramesa species on E. curvula revealed that the wasp may not be suitably host specific for use as a biological control agent. However, further host specificity testing on non-target native Australian species is required
Transmission modes and efficiency of iflavirus and cripavirus in Queensland fruit fly, Bactrocera tryoni
No full textInfections of insects with insect-specific RNA viruses are common and can affect host fitness and health. Previously, persistent RNA virus infections were detected in tephritid fruit flies, including the Queensland fruit fly (Bactrocera tryoni), Australia’s most significant horticultural pest. Their transmission modes and efficiency are unclear yet may influence virus epidemiology in field and laboratory populations. Using standard RT-PCR and RT-qPCR we detected iflavirus, cripavirus and sigmavirus in five laboratory populations recently established with field-collected B.tryoni. Virus absence in some individuals suggested that virus transmission is incomplete. Random virus segregation in an isofemale experiment resulted in the establishment of isofemale lines with and without iflavirus and cripavirus. In infected lines, viral loads normalised against host gene transcripts were variable, but did not differ between pupae and adults. Iflavirus and cripavirus were transmitted horizontally, with viruses detected (including at low viral loads) in many previously uninfected individuals after four days, and in most after 12 days cohabitation with infected flies. Iflavirus, but not cripavirus, was transmitted vertically, and surface-sterilised embryos contained high loads. Furthermore, high iflavirus loads in individual females resulted in high loads in their offspring. We demonstrated that viruses are highly prevalent in laboratory populations and that it is possible to establish and maintain uninfected fly lines for the assessment of virus transmission and host effects. This is important for pest management strategies such as the sterile insect technique which requires the mass-rearing of flies, as their fitness and performance may be affected by covert virus infections
The in planta gene expression of Austropuccinia psidii in resistant and susceptible Eucalyptus grandis
No full textAustropuccinia psidii, commonly known as myrtle rust, is an obligate, biotrophic rust pathogen that causes rust disease on a broad host range of Myrtaceae species. Eucalyptus grandis, a widely cultivated hardwood Myrtaceae species, is susceptible to A. psidii infection, with this pathogen threatening both their natural range and various forest plantations across the world. This study aimed to investigate the A. psidii transcriptomic responses in resistant and susceptible E. grandis at four time points. RNA-seq reads were mapped to the A. psidii reference genome to quantify expressed genes at 12-hours post inoculation (hpi), 1-, 2- and 5-days post inoculation (dpi). A total of eight hundred and ninety expressed genes were found, of which forty-three were candidate effector proteins. These included a rust transferred protein (RTP1) gene, expressed in susceptible hosts at 5-dpi and a hydrolase protein gene expressed in both resistant and susceptible hosts over time. Functional categorisation of expressed genes revealed processes enriched in susceptible hosts, including malate metabolic and malate dehydrogenase activity, implicating oxalic acid in disease susceptibility. These results highlight putative virulence or pathogenicity mechanisms employed by A. psidii to cause disease and provides the first insight into the molecular responses of A. psidii in E. grandis over time
Peronosclerospora neglecta sp. nov.—a widespread and overlooked threat to corn (maize) production in the tropics
Get PDFDowny mildew is a serious threat to corn (maize) production in the tropics and subtropics. Corn is native to Central America, and was introduced into South-East Asia by the Spanish colonisers in the 1700s. Corn is evolutionarily naïve to downy mildews of the genus Peronosclerospora. Consequently, corn monocultures are particularly susceptible to a variety of Peronosclerospora species, which spread to the crop from local grasses. Globally, corn is one of the most important crops for both humans and livestock. Several downy mildews of corn have been identified as potential threats to global food security, and trade with corn seeds is strictly regulated to avoid spreading the pathogens. Despite their importance, little is known about the biodiversity of graminicolous downy mildews, because their identification has often relied on variable morphological features, such as conidial dimensions. DNA barcodes for most species have become available only recently. During surveys for downy mildews on corn in Indonesia, a previously unrecognised species of Peronosclerospora was found and investigated using a combination of morphological characters and molecular phylogenetic analyses. The new species, introduced here as Peronosclerospora neglecta, is widely distributed in South-East Asia from Thailand to eastern Indonesia. The impact of this downy mildew can be severe, with complete crop losses in heavily affected fields. Given the aggressiveness of the species, close surveillance is warranted to restrict its further spread
Fusarium Yellows of Ginger (Zingiber officinale Roscoe) Caused by Fusarium oxysporum f. sp. zingiberi Is Associated with Cultivar-Specific Expression of Defense-Responsive Genes
Get PDFGinger (Zingiber officinale Roscoe) is an important horticultural crop, valued for its culinary and medicinal properties. Fusarium yellows of ginger, caused by Fusarium oxysporum f. sp. zingiberi (Foz), is a devastating disease that has significantly reduced the quality and crop yield of ginger worldwide. The compatible interaction between ginger and Foz leading to susceptibility is dissected here. The pathogenicity of two Foz isolates on ginger was confirmed by their ability to colonise ginger and in turn induce both internal and external plant symptoms typical of Fusarium yellows. To shed light on Foz susceptibility at the molecular level, a set of defense-responsive genes was analysed for expression in the roots of ginger cultivars challenged with Foz. These include nucleotide-binding site (NBS) type of resistant (R) genes with a functional role in pathogen recognition, transcription factors associated with systemic acquired resistance, and enzymes involved in terpenoid biosynthesis and cell wall modifications. Among three R genes, the transcripts of ZoNBS1 and ZoNBS3 were rapidly induced by Foz at the onset of infection, and the expression magnitude was cultivar-dependent. These expression characteristics extend to the other genes. This study is the first step in understanding the mechanisms of compatible host–pathogen interactions in ginger