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Introduction: The development of bacterial strains that are resistant to multiple antibiotics has made the discovery of new antibiotics a priority for medical research. Examination of plants for new antimicrobial agents is an attractive prospect and numerous recent studies have screened plants for antibacterial activity. Despite this, Australian native plants have been relatively neglected. Heritiera actinophyllum (F.M.Bailey) Kosterm. is a rainforest tree that is native to eastern coastal regions of Australia. Material from this species has not yet been examined for antibacterial properties against human pathogens. Materials and Methods: The ability of H. actinophyllum leaf extracts to inhibit the growth of a panel of bacterial pathogens was investigated by disc diffusion assay. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: H. actinophyllum methanolic and aqueous extracts were ineffective at inhibiting the growth of gram-positive and gram-negative panels of bacteria. The extracts were non-toxic or of low toxicity following 24 h exposure. Conclusion: The H. actinophyllum leaf extracts lacked growth inhibitory bioactivity against a panel of pathogenic bacteria and were nontoxic in the Artemia nauplii assay. However, these extracts may have other therapeutic properties and testing against protozoa, fungi, and virus and tumour cells is required. [ABSTRACT FROM AUTHOR]

Introduction: Brachychiton acerifolius (A.Cunn. ex G.Don) Macarthur and C. moore is a large tree that is native to subtropical regions of the east of Australia. Decoctions and infusions produced from the leaves of the related species Brachychiton diversifolius were used by the first Australians to treat a variety of bacterial diseases. Despite this, B. acerifolius leaf and flower extracts have not been rigorously examined for antibacterial properties against many pathogens. Methods: The antimicrobial activity of B. acerifolius leaf and flower extracts was investigated by disc diffusion and growth time course assays against a panel of pathogenic bacteria. The growth inhibitory activity was quantified by MIC determination. Toxicity was determined using the Artemia franciscana nauplii bioassay. Results: Methanolic B. acerifolius leaf and flower extracts inhibited the growth of a wide range of bacterial species. Growth of both gram positive and gramnegative bacteria was inhibited by the B. acerifolius leaf and flower extracts, although the gram negative bacteria were substantially more susceptible to the extracts than the gram positive bacteria were. The leaf extracts were more potent growth inhibitors than the flower extracts against all bacteria tested. The B. acerifolius leaf extract was a strong inhibitor of A. faecalis, K. pneumonia, P. fluorescens, S. newport, S. sonnei, B. cereus, S. aureus and S. pyogenes growth, with MIC values substantially <1000µg/mL. The antibacterial activity of the methanolic B. acerifolius leaf extract was further investigated by growth time course assays which showed significant growth inhibition in cultures of P. fluorsecens and B. cereus within 1hr of exposure. Both extracts were determined to be nontoxic in the Artemia franciscana nauplii bioassay, indicating their safety for internal use as well as for topical uses. Conclusion: The lack of toxicity of the B. acerifolius leaf and flower extracts and their growth inhibitory bioactivity against a panel of pathogenic bacteria partially validate the traditional usage of this species to treat bacterial diseases and indicates their potential in the development of antiseptic agents. [ABSTRACT FROM AUTHOR]

Background and Aims: Polyploidy is an important process that often generates genomic diversity within lineages, but it can also cause changes that result in loss of genomic material. Island lineages, while often polyploid, typically show chromosomal stasis but have not been investigated in detail regarding smaller-scale gene loss. Our aim was to investigate post-polyploidization genome dynamics in a chromosomally stable lineage of Malvaceae endemic to New Zealand., Methods: We determined chromosome numbers and used fluorescence in situ hybridization to localize 18S and 5S rDNA. Gene sequencing of 18S rDNA, the internal transcribed spacers (ITS) with intervening 5.8S rDNA, and a low-copy nuclear gene, GBSSI-1, was undertaken to determine if gene loss occurred in the New Zealand lineage following polyploidy., Key Results: The chromosome number for all species investigated was 2n = 42, with the first published report for the monotypic Australian genus Asterotrichion. The five species investigated all had two 5S rDNA signals localized interstitially on the long arm of one of the largest chromosome pairs. All species, except Plagianthus regius, had two 18S rDNA signals localized proximally on the short arm of one of the smallest chromosome pairs. Plagianthus regius had two additional 18S rDNA signals on a separate chromosome, giving a total of four. Sequencing of nuclear ribosomal 18S rDNA and the ITS cistron indicated loss of historical ribosomal repeats. Phylogenetic analysis of a low-copy nuclear gene, GBSSI-1, indicated that some lineages maintained three copies of the locus, while others have lost one or two copies., Conclusions: Although island endemic lineages show chromosomal stasis, with no additional changes in chromosome number, they may undergo smaller-scale processes of gene loss and concerted evolution ultimately leading to further genome restructuring and downsizing., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Annals of Botany Company.)

A literature review was conducted to collate best practice techniques for soil compaction management within cotton-farming systems in Australia. Universally negative effects of traffic-induced soil compaction on the whole-farm system and the wider environment include: (i) increased gap between attainable and potential yields, (ii) increased costs of energy and labour, (iii) reduced fertiliser-use efficiency, (iv) reduced water use efficiency (irrigation and rainfall), (v) increased tillage intensity. Knowledge gaps that merit research priority, and research strategies, are suggested. These include: (i) identifying wider impacts on farm economics to guide decision-making and development of decision support systems that capture the effects of compaction on fertiliser, water, and energy use efficiency; (ii) predicting risks at the field or subfield scale and implementing precision management of traffic compaction; (iii) canopy management at terminal stages of the crop cycle to manipulate soil-moisture deficits before crop harvest, thereby optimising trafficability for harvesting equipment; (iv) the role of controlled traffic farming (CTF) in mitigating greenhouse gas emissions and loss of soil organic carbon, and in enhancing fertiliser and water-use efficiencies; (v) recent developments in tyre technology, such as low ground-pressure tyres, require investigation to assess their cost-effectiveness compared with other available options; and (vi) catchment-scale modelling incorporating changes in arable land-use, such as increased area under CTF coupled with no-or minimum-tillage, and variable rate technology is suggested. Such modelling should assess the potential of CTF and allied technologies to reduce sediment and nutrient losses, and improve water quality in intensively managed arable catchments. Resources must be efficiently managed within increasingly sophisticated farming systems to enable long-term economic viability of cotton production. Agronomic and environmental performance of cotton farming systems could be improved with a few changes, and possibly, at a reasonable cost. Key to managing soil compaction appears to be encouraging increased adoption of CTF. This process may benefit from financial support to growers, such as agri-environmental stewardships, and it would be assisted by product customisation from machinery manufacturers. [ABSTRACT FROM AUTHOR]

Cultivars of Bollgard II cotton [ Gossypium hirsutum L. (Malvaceae)] express the cry1Ac and cry2Ab genes from Bacillus thuringiensis Berliner (Bt) and are valuable for managing Helicoverpa spp. in Australia. However, substantial densities of Helicoverpa larvae can survive and feed on flowering Bollgard II plants. Monitoring demonstrates that this larval survival is not because of physiological resistance. One hypothesis for this occurrence is that larvae have adapted their behaviour to reduce exposure to toxic compounds. The survival and distribution among cotton structures of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae were examined using choice tests. Two hours after introduction to an arena, there were no differences between non-Bt cotton and Bollgard II in the numbers of larvae on different plant structures. However, 24 and 48 h after their introduction, most larvae on Bollgard II were on flowers (mean of 80.5%), whereas on non-Bt cotton, many larvae were also on flowers (58.5%), but there was also a considerable proportion (11%) on squares. In a subsequent experiment, we found similar numbers of larvae on the different structures of Bollgard II plants regardless of whether their parents were collected as survivors on Bollgard II cotton or non-Bt hosts. Cry1Ac and Cry2Ab expression varied among cotton structures, but there were no significant differences between the two popular Bollgard II varieties used in this study. Bt toxin levels did not correlate well with the number of larvae among the structures from Bollgard II plants. Thus, we conclude that although the distribution of Bt-susceptible larvae was somewhat different among plant structures on non-Bt and Bollgard II cotton, history of survival on Bollgard II cotton does not significantly impact on this behaviour. [ABSTRACT FROM AUTHOR]

Hibiscus trionum has generally been regarded as naturalised in Australia and New Zealand. Two varieties are sometimes accepted as occurring in Australia: H. trionum var. trionum and H. trionum var. vesicarius, with the latter occasionally treated as indigenous. Following studies of the variation within H. trionum in Australia and New Zealand we propose that there are three indigenous species in this complex. Of the three species, one, Hibiscus richardsonii, occurs in coastal regions of New South Wales, Australia and the northeastern half of the North Island, New Zealand, Hibiscus tridactylites Lindley occurs in inland southern and eastern Australia, and Hibiscus verdcourtii, described herein, occurs widely in inland Australia, especially north of latitude 28°S. In addition, we provide a description and informally recognise a diploid race of H. trionum s.l. that is widespread in New Zealand. In past treatments of the species in New Zealand this diploid race has either been treated as indigenous or included with H. richardsonii under the name 'H. trionum' as naturalised. A key is provided to identify these taxa. [ABSTRACT FROM AUTHOR]

Chromosome numbers have been determined for plants of Hibiscus trionum L. s.l. from nine locations: two in New Zealand, five in Australia, and two in Africa. Two different numbers were obtained, one diploid with 2n = 28 and the other tetraploid with 2n = 56. The diploids were found in New Zealand and coastal New South Wales, all the other populations were tetraploid. Based on these observations, and plant morphology, especially flower shape and pigmentation patterns, the recent (1988) conclusion that all New Zealand morphs of H. trionum are naturalised is challenged and the morphs present different conservation options. [ABSTRACT FROM AUTHOR]

Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is an important lepidopteran pest of cotton (Gossypium spp.) in Australia and the Old World. From 2002, F2 screens were used to examine the frequency of resistance alleles in Australian populations of H. armigera to Bacillus thuringiensis (Bt) CrylAc and Cry2Ab, the two insecticidal proteins present in the transgenic cotton Bollgard II. At that time, Ingard (expressing CrylAc) cotton had been grown in Australia for seven seasons, and Boilgard H was about to be commercially released. The principal objective of our study was to determine whether sustained exposure caused an elevated frequency of alleles conferring resistance to CrylAc in a species with a track record of evolving resistance to conventional insecticides. No major alleles conferring resistance to CrylAc were found. The frequency of resistance alleles for CrylAc was <0.0003, with a 95% credibility interval between 0 and 0.0009. In contrast, alleles conferring resistance to Cry2Ab were found at a frequency of 0.0033 (0.0017,0.0055). The first isolation of this allele was found before the widespread deployment of Bollgard H. For both toxins the experiment-wise detection probability was 94.4%. Our results suggest that alleles conferring resistance to CrylAc are rare and that a relatively high baseline frequency of alleles conferring resistance to Cry2Ab existed before the introduction of Bt cotton containing this toxin. [ABSTRACT FROM AUTHOR]

A survey of cotton ( Gossypium hirsutum) volunteers was conducted along the 1400 km of a cottonseed transport route in north-east Australia to determine the extent of naturalisation from spilt seed. In each year, 1% of the road distance was inspected for volunteer plants. The survey results were juxtaposed with the eco-climatic suitability predictions from inferential modelling. Over 3 years, 22 cotton plants were found at eight sites. Within the cotton production region, volunteers averaged 2.28 plants km−1 of road; their most likely source was seed cotton spilt during the previous harvest. Further north, three plants were found over 3 years, at an average density of 0.089 plants km−1 of road; all three plants were found in locations with a positive Ecoclimatic Index. No secondary spread was detected. Roadside slashing reduced plant survival and the potential to produce seed. In the wet tropics, weed competition and slashing prevented volunteers establishing. The surveys indicate that roadsides in north-east Australia are a hostile environment for the establishment of cotton plants, with no evidence of naturalisation or secondary spread. Current transport practices utilizing fully covered loads present negligible risk of producing naturalised populations of cotton (either transgenic or non-transgenic) on roadsides in north-east Australia. [ABSTRACT FROM AUTHOR]

The author discusses the local extinction of the Australian species albescens of the Indian Lantern Flower abutilon indicum. Topics discussed include advantages of Abutilon indicum include used as a traditional medicine and its chemicals kills larval mosquitoes, causes of indicum's extinction around Darwin include application of herbicides and fires lit by humans and awaring the members of the Field Naturalists' Club about the plant's extinction.

Information on distribution and relative abundance of species is integral to sustainable management, especially if they are to be harvested for subsistence or commerce. In northern Australia, natural landscapes are vast, centers of population few, access is difficult, and Aboriginal resource centers and communities have limited funds and infrastructure. Consequently defining distribution and relative abundance by comprehensive ground survey is difficult and expensive. This highlights the need for simple, cheap, automated methodologies to predict the distribution of species in use, or having potential for use, in commercial enterprise. The technique applied here uses a Geographic Information System (GIS) to make predictions of probability of occurrence using an inductive modeling technique based on Bayes' theorem. The study area is in the Maningrida region, central Arnhem Land, in the Northern Territory, Australia. The species examined, Cycas arnhemica and Brachychiton diversifolius, are currently being 'wild harvested' in commercial trials, involving sale of decorative plants and use as carving wood, respectively. This study involved limited and relatively simple ground surveys requiring approximately 7 days of effort for each species. The overall model performance was evaluated using Cohen's kappa statistics. The predictive ability of the model for C. arnhemica was classified as moderate and for B. diversifolius as fair. The difference in model performance can be attributed to the pattern of distribution of these species. C. arnhemica tends to occur in a clumped distribution due to relatively short distance dispersal of its large seeds and vegetative growth from long-lived rhizomes, while B. diversifolius seeds are smaller and more widely dispersed across the landscape. The output from analysis predicts trends in species distribution that are consistent with independent on-site sampling for each species and therefore should prove useful in gauging the extent of resource availability. However, some caution needs to be applied as the models tend to over predict presence which is a function of distribution patterns and of other variables operating in the landscape such as fire histories which were not included in the model due to limited availability of data.