Glenthenamines A–F: Enamine pyranonaphthoquinones from the Australian pasture plant-derived Streptomyces sp. CMB-PB042

Chemical investigations into solid phase cultivations of an Australian sheep station pasture plant-derived Streptomyces sp. CMB-PB042, yielded the rare enamine naphthopyranoquinones BE-54238A (1) and BE-54238B (2), together with four new analogues, glenthenamines B–D (4–6) and F (8), and two handling artifacts, glenthenamines A (3) and E (7). Single crystal X-ray analyses of 1–2 resolved configurational ambiguities in the scientific literature, while detailed spectroscopic analysis and biosynthetic considerations assigned structures inclusive of absolute configuration to 3–8. We propose a plausible sequence of biosynthetic transformations linking structural and configurational features of 1–8, and apply a novel Schiff base "fishing" approach to detect a key deoxyaminosugar precursor. These enamine naphthopyranoquinone disclose a new P-gp inhibitory pharmacophore capable of reversing doxorubicin resistance in P-gp overexpressing colon carcinoma cells.

Screening of awnless bromegrass collection samples in the taiga zone of Western Siberia

The paper presents the results of the study of collection samples of awnless bromegrass from the Federal Research Center N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) to identify donors of valuable breeding traits. The study was carried in 2015-2018 in Tomsk region. The soils of the experimental plots were sod-podzolic, sandy loam by granulometric composition, with a humus content in the arable layer of no more than 2%. The recorded area of the plot was 0.5 m2. The trials were repeated two times. Procedures for trial establishment, phenological observations, harvest recording and data processing were performed in accordance with the methodological recommendations of the All-Russian Williams Fodder Research Institute, VIR and the State Variety Testing Methodology. The years of the study were characterized by uneven distribution of heat and moisture during the growing season. This made it possible to identify the most adaptive samples for selective breeding of awnless bromegrass which can be used as a hay and pasture plant in the taiga zone. The following valuable source materials were selected for tall varieties: Khabarovsky, Titan, Vozvyshensky, SibNIISkhoz 88; samples of wild plants Yakutia (K-14215), Vologda (K-14224), Omsk (K-14228), Sverdlovsk (K-14209) regions, a local sample of Tomsk region (K-14226). The following samples resistant to fungal diseases were identified: Morshansky, Khabarovsky and Erkeeni varieties; samples of wild forms of Irkutsk (K-14221, К-14227), Vologda (K-14212, К-14224), Omsk (K-14228) regions, a local sample of Tomsk region (K-14226). The following high-yielding varieties in terms of fodder mass were recognized: wild forms of Vologda region (K-14212, К-14222) and a local population of Tomsk region (K-14214); highly leafy varieties: Primorsky 46, SibNIISKHoz 88, wild forms of Komi (K-14208), Irkutsk (K-14227), Vologda (K14212, К-14224) regions, local samples of Tomsk region (K-14214, К-14226); varieties with high seed yield: Duet, Primorsky 46, Erkeeni, wild forms of Vologda region (K-14212, К-14224), a local sample of Tomsk region (K-14226). Based on the set of the main economically valuable traits for sowing in a polycross nursery, samples of wild plants from Vologda region (K-14212, К-14224), and local samples of Tomsk region (K-14214, К-14226) were selected.

Harvesting subterranean clover seed – current practices, technology and issues

Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.

Severe Insect Pest Impacts on New Zealand Pasture: The Plight of an Ecological Outlier

New Zealand’s intensive pastures, comprised almost entirely introduced Lolium L. and Trifolium L. species, are arguably the most productive grazing-lands in the world. However, these areas are vulnerable to destructive invasive pest species. Of these, three of the most damaging pests are weevils (Coleoptera: Curculionidae) that have relatively recently been controlled by three different introduced parasitoids, all belonging to the genus Microctonus Wesmael (Hymenoptera: Braconidae). Arguably that these introduced parasitoids have been highly effective is probably because they, like many of the exotic pest species, have benefited from enemy release. Parasitism has been so intense that, very unusually, one of the weevils has now evolved resistance to its parthenogenetic parasitoid. This review argues that New Zealand’s high exotic pasture pest burden is attributable to a lack of pasture plant and natural enemy diversity that presents little biotic resistance to invasive species. There is a native natural enemy fauna in New Zealand that has evolved over millions of years of geographical isolation. However, these species remain in their indigenous ecosystems and, therefore, play a minimal role in creating biotic resistance in the country’s exotic ecosystems. For clear ecological reasons relating to the nature of New Zealand pastures, importation biological control can work extremely well. Conversely, conservation biological control is less likely to be effective than elsewhere.

Impact of an arbuscular mycorrhizal fungus on the growth and nutrition of fifteen crop and pasture plant species

The formation of arbuscular mycorrhizas (AM) can result in positive, neutral or negative responses in the growth and mineral nutrition of host plants, particularly that of P, Zn and other micronutrients. This study examined the growth and nutritional responses of 15 agriculturally important plant species, including cereals, legumes and vegetables, with and without inoculation with the AM fungus (AMF) Rhizophagus irregularis. Furthermore, we explored whether the responses differed between different functional groups of plants such as monocots and dicots, C3 and C4 plants, and N-fixing and non-N-fixing plants. We found that that mycorrhizal colonisation of roots, plant growth and plant nutrient responses differed between plant species. Among the species analysed, leek (Allium ampeloprasum L. var. porrum) was the most mycorrhiza-responsive, displaying the highest mycorrhizal colonisation and biomass response, and the greatest increases in most mineral nutrients. In other plant species, the concentration of P, Cu, Zn and S were generally enhanced by inoculation with AMF. Furthermore, ionomes differed more greatly between plant species than in response to inoculation with AMF. This research further improves our understanding of the responses of different and diverse plant species to the formation of AM in terms of growth and ionomics under standardised growth conditions. The results of this study may be used in further studies and to inform agricultural practices.

Does pasture plant diversity influence abundance and diversity of lacewings and Hymenopteran parasitoids?

The lack of plant biodiversity in New Zealand pastoral ecosystems may limit the abundance and diversity of generalist parasitoids and predators, predisposing these ecosystems to pest outbreaks. To test this hypothesis, patches of turf were established in existing pasture during spring 2016. Four treatments of increasing plant complexity were established, commencing with ryegrass alone, and increasing exponentially up to eight species of forage plant per patch. In the summer of 2017, insects were collected from the patches and control plots using suction to assess whether or not plant diversity had influenced the abundance and diversity of lacewings and parasitic Hymenoptera aggregating in the patches. Plant species richness had no impact on lacewing abundance but fewer parasitic Hymenoptera were recovered from the ryegrass-only plots compared with more species rich plots. Also, a wider range of parasitoid families were represented in the more diverse plant treatments compared with the less diverse treatments. Such diversity may have beneficial impacts on the stability of pasture ecosystem and the risk of pest outbreaks.