Brendan J. Lepschi

Leaf essential oils of the genus Leptospermum (Myrtaceae) in eastern Australia. Part 6. Leptospermum polygalifolium and allies.

The leaf essential oils of Leptospermum polygalifolium and related species were isolated and examined. L. morrisonlii produced an essential oil in which the principal component was the β-triketone grandiflorone, while in L. oreophilum the principal component was (E,E)-farnesol. L. variabile gave oils with a spread of composition, the majority of samples being rich in geranyl acetate, β-caryophyllene and humulene, while another sample was rich in 1,8-cineole and a further sample contained comparable amounts of α-pinene, β-caryophyllene and α-, β- and γ-eudesmol. Leptospermum sp. (Mt Maroon, A.R. Bean 6665) appeared to be a chemically variable species; one specimen showed β-caryophyllene and humulene as principal components, while a second gave an oil rich in sesquiterpenes with β-caryophyllene, δ-cadinene, calamenene and an unidentified sesquiterpene hydrocarbon being the major contributors. Of the seven subspecies of L. polygalifolium, ssp. polygalifolium, montanum and howense contained oils which were rich in α-, β, and γ-eudesmol. These were the only subspecies to contain these compounds in more than trace amounts. Of the remaining four subspecies, ssp. cismontanum, transmontanum, tropicum and ‘wallum’, all contained significant amounts of 1,8-cineole. They usually contained larger quantities of spathulenol. All seven subspecies contained α-pinene in significant amounts, while all but spp. howense also contained β-pinene, usually in comparable amounts. Leptospermum madidum spp. sativum gave an oil rich in monoterpenes, with α-pinene, β-pinene, and γ-terpinene being the major components. α-, β-, and γ-eudesmol also made significant contributions to the oil. Copyright

Leaf essential oils of the genus Leptospermum (Myrtaceae) in eastern Australia. Part 7. Leptospermum petersonii, L. liversidgei and allies

Leptospermum amboinense was shown to exist in two chemical varieties, the oil of one chemotype being entirely sesquiterpenoid and that of the second predominantly monoterpenoid, while L. ?amboinense gave an oil which was monoterpenoid in character and contained geranial (13%) and sabinene (13%) as major components. The principal components of the oil of L. emarginatum were α-eudesmol (7 – 17%), β-eudesmol (17 – 26%) and γ-eudesmol (9 – 18%). L. grandiflorum gave an oil which from a coastal location contained up to 50% of α-, β- and γ-eudesmol and from inland locations ca. 5% α-, β- and γ-eudesmol. There is a range of oil compositions within L. liversidgei, varying from oils that are high in citronellal (ca. 44%) and contain virtually no neral/geranial (the more common variety), to oils that contain very little citronellal and high amounts of neral (20%) and geranial (35%). The oil of L. petersonii was found to occur in chemical varieties, with much variation in most of them. Variety 1 contained aldehydes, ranging from high citronellal and low neral/geranial to low citronellal and high neral/geranial. Two oil chemotypes, comprising mainly hydrocarbons, were identified. One chemotype, corresponding to Penfolds ‘variety A’, contained mainly monoterpenes, while a newly discovered chemotype contained mainly sesquiterpenes, with either β-caryophyllene or globulol/viridiflorol/spathulenol as major components. The existence of a further chemotype, corresponding to Penfolds ‘variety B’, containing geranyl acetate (21 – 38%) and geraniol (21 – 29%), was also confirmed. A study of the cotyledon and seedling leaf volatiles of a form of L. petersonii, the parent of which was rich in citronellal and neral/geranial, showed that both cotyledons and seedling leaf volatiles consisted of only sesquiterpene hydrocarbons, being δ-elemene, bicycloelemene, β-elemene, germacrene-D and bicyclogermacrene. It was not until the seedling had 15 nodes (ca. 170 mm tall) that citronellal and neral/geranial were found in the leaves above the fifth node. Leptospermum rotundifolium produced an oil in which the principal components were α-pinene (16 – 25%) and 1,8-cineole (21 – 28%). The oil from L. wooroonooran contained comparable amounts of mono- and sesquiterpenes, the main monoterpenes being α-pinene (4 – 11%), β-pinene (4 – 9%), sabinene (9 – 19%), β-caryophyllene (5 – 7%) and humulene (11 – 20%). Copyright

Genetic congruence with new species boundaries in the Melaleuca uncinata complex (Myrtaceae)

Uninformed management decisions have the potential to create significant problems for conservation programs. In the south-western corner of Australia where conservation initiatives are directed towards restoring large tracts of land degraded by broadscale clearing and increasing levels of dryland salinity, Melaleuca uncinata R.Br. (Myrtaceae) is a species complex of considerable interest for restoration. Although M. uncinata is morphologically uniform across most of southern mainland Australia, there is considerable variation in south-western Australia and a recent morphological evaluation has recognised 11 species. Phylogenetic patterns among populations of seven of these species were examined with nuclear RFLP loci to determine whether morphological and phylogenetic boundaries were congruent before the implementation of any broadscale revegetation programs. The phylogenetic analysis was congruent with the morphological assessment, and populations of different species, including those co-occurring at the same site, clustered according to their correct morphological assignment. Some genetic structuring associated with habitat preference was also evident within two of the species. The taxonomic resolution and knowledge of the phylogenetic relationships among the seven species will facilitate their further assessment for issues relevant to revegetation, such as provenance and local adaptation. It will also enable selection of appropriate germplasm in revegetation programs to maximise the genetic adaptation in restoration and minimise negative impact of plantings on remnant vegetation.

The Leaf Essential Oils of the Australian Members of the Genus Callistemon (Myrtaceae)

Abstract The majority of Australian species (30) of the genus Callistemon gave leaf essential oils with 1,8-cineole as the major component (45–80%). Other compounds present in these species included α-pinene (2–40%, the majority being 2–8%), limonene (2–9%, the majority being 5–8%) and α-terpineol (1–13%, the majority being 5–10%). The species that produced these oils did so in oil yields of 0.1–1.0%. The species giving very low oil yields (<0.1%), viz. C. brachyandrus, C. montanus, C. polandii, C. teretifolius, C. sp. (Walshs Pyramid P.I. Forster 13767), C. sp. nov. “Oakey,” C. pachyphyllus, as a general rule, produced oils in which the amount of 1,8-cineole was low (<20%) and generally there was a preponderance of sesquiterpenes.

Phylogenetic positions of Actites megalocarpa and Sonchus hydrophilus (Sonchinae: Asteraceae) based on ITS and chloroplast non-coding DNA sequences

Phylogenetic positions of the Australian endemic taxa Actites megalocarpa and Sonchus hydrophilus within the subtribe Sonchinae were determined on the basis of ITS sequences of nuclear rDNA and the psbA-trnH (GUG) intergenic spacer of chloroplast DNA. Both ITS and cpDNA phylogenies suggest that the monotypic genus Actites is not closely related to the members of Sonchus section Asperi, as previously suggested. Rather, this study indicates that it is more closely related to the members of Sonchus sections Maritimi (S. maritimus) and Arvenses (S. arvensis). It also suggests that S. maritimus from section Maritimi is one of the closest relatives of Actites in Australia, although an alternative origin from section Arvenses is possible. Actites and Embergeria, once treated as congeneric taxa, appear to have originated independently in Australia and New Zealand, respectively. Sonchus hydrophilus is closely related to the S. asper complex, S. oleraceus and S. kirkii. This study suggests that S. kirkii may be involved in the origin of S. hydrophilus in Australia.

Leaf essential oils of the genus Leptospermum (Myrtaceae) in Eastern Australia. Part 1. Leptospermum brachyandrum and Leptospermum pallidum groups

The essential oils of Leptospermum brachyandrum (F. Muell.) Druce, L. luehmannii F. M. Bailey, L. madidum A. R. Bean subsp. madidum, L. purpurascens Joy Thomps., L. speciosum Schauer, L. whitei Cheel and L. pallidum A. R. Bean have been examined. All species produce α-pinene as the major component. This was accompanied by lesser amounts of β-pinene, β-caryophyllene, aromadendrene, humulene and spathulenol. 1,8-Cineole was present usually in amounts of less than 10%.

Nonindigenous Plant Advantage in Native and Exotic Australian Grasses under Experimental Drought, Warming, and Atmospheric CO2 Enrichment

A general prediction of ecological theory is that climate change will favor invasive nonindigenous plant species (NIPS) over native species. However, the relative fitness advantage enjoyed by NIPS is often affected by resource limitation and potentially by extreme climatic events such as drought. Genetic constraints may also limit the ability of NIPS to adapt to changing climatic conditions. In this study, we investigated evidence for potential NIPS advantage under climate change in two sympatric perennial stipoid grasses from southeast Australia, the NIPS Nassella neesiana and the native Austrostipa bigeniculata. We compared the growth and reproduction of both species under current and year 2050 drought, temperature and CO2 regimes in a multifactor outdoor climate simulation experiment, hypothesizing that NIPS advantage would be higher under more favorable growing conditions. We also compared the quantitative variation and heritability of growth traits in populations of both species collected along a 200 km climatic transect. In contrast to our hypothesis we found that the NIPS N. neesiana was less responsive than A. bigeniculata to winter warming but maintained higher reproductive output during spring drought. However, overall tussock expansion was far more rapid in N. neesiana, and so it maintained an overall fitness advantage over A. bigeniculata in all climate regimes. N. neesiana also exhibited similar or lower quantitative variation and growth trait heritability than A. bigeniculata within populations but greater variability among populations, probably reflecting a complex past introduction history. We found some evidence that additional spring warmth increases the impact of drought on reproduction but not that elevated atmospheric CO2 ameliorates drought severity. Overall, we conclude that NIPS advantage under climate change may be limited by a lack of responsiveness to key climatic drivers, reduced genetic variability in range-edge populations, and complex drought-CO2 interactions.

Population genetics of invasive Citrullus lanatus , Citrullus colocynthis and Cucumis myriocarpus (Cucurbitaceae) in Australia: inferences based on chloroplast and nuclear gene sequencing

To understand the invasion history of the invasive weeds Citrulluslanatus (camel melon), Citrulluscolocynthis (colocynth) and Cucumismyriocarpus (prickly paddy melon) in Australia, we studied a collection of geographically diverse samples from Africa (native range), Asia, North and South America, Europe and Australia (introduced ranges). We sequenced portions of two gene regions, the nuclear G3pdh gene and the chloroplast ycf6–psbM intergenic spacer region, to identify the diversity and relationships of alleles/haplotypes present within and among sampled populations of each species. We found that C. lanatus and C. myriocarpus populations in Australia contain negligible levels of diversity in both genes, indicative of single, genetically impoverished founder events by both species and potentially derived from single source populations in both instances. Together, historical and sequence information point to the north-western region of the Indian subcontinent as the likely source of Australian C. lanatus. Surprisingly, Australian C. myriocarpus plants share the same genetic profile as that observed in all other invasive populations of this species, but differ from that observed in native African plants. This indicates a shared origin of invasive C. myriocarpus populations and potentially a stepping-stone pathway of founder events across the globe, the origins of which are yet unidentified. In contrast, moderate levels of genetic diversity are present among Australian C. colocynthis that can be geographically sorted mainly into eastern and western regions of the continent. This suggests two separate introductions of the species into Australia, from two different source populations, most likely originating from northern Africa and/or southern Europe/Turkey. The evidence of impoverished genetic diversity in Australian populations of C. lanatus and C. myriocarpus indicates they are likely to exhibit similar responses to control measures. In contrast, development of effective chemical or bio-controls for C. colocynthis in Australia may present a greater challenge.

A Comparison of the Leaf Oils of Melaleuca squamophloia with Those of Its Close Relatives, M. styphelioides and M. bracteata

Abstract The chemical composition of the leaf oils of Melaleuca squamophloia was studied for the first time and compared with the oil of two closely related species, M. styphelioides and M. bracteata, to help elucidate their taxonomic relationships. M. squamophloiaoccurs in two chemotypes, in which the major components of the oil are elemicin (up to 96%) or (E)-isoelemicin (up to 78%). The oil yield (w/w% fresh weight) of both chemotypes varied from 0.4% to 3–7%. M. styphelioides produced an oil in 0.05–0.1% yield in which the major compounds were the sesquiterpenes caryophyllene oxide (22–26%) and spathulenol (13–21%). M. bracteata occurs in four chemotypes distinguished by the predominance in the oil of the aromatic ethers elemicin, (E)-isoelemicin, methyl eugenol or (E)-methyl isoeugenol. Oil yields in this species range from 0.2% to 0.8%. Based on oil profiles, M. squamophloia appears to be a taxon distinct from M. styphelioides and unlikely to have been developed from hybridization between this speci...

Evaluation of six candidate DNA barcode loci for identification of five important invasive grasses in eastern Australia

Invasive grass weeds reduce farm productivity, threaten biodiversity, and increase weed control costs. Identification of invasive grasses from native grasses has generally relied on the morphological examination of grass floral material. DNA barcoding may provide an alternative means to identify co-occurring native and invasive grasses, particularly during early growth stages when floral characters are unavailable for analysis. However, there are no universal loci available for grass barcoding. We herein evaluated the utility of six candidate loci (atpF intron, matK, ndhK-ndhC, psbE—petL, ETS and ITS) for barcode identification of several economically important invasive grass species frequently found among native grasses in eastern Australia. We evaluated these loci in 66 specimens representing five invasive grass species (Chloris gayana, Eragrostis curvula, Hyparrhenia hirta, Nassella neesiana, Nassella trichotoma) and seven native grass species. Our results indicated that, while no single locus can be universally used as a DNA barcode for distinguishing the grass species examined in this study, two plastid loci (atpF and matK) showed good distinguishing power to separate most of the taxa examined, and could be used as a dual locus to distinguish several of the invasive from the native species. Low PCR success rates were evidenced among two nuclear loci (ETS and ITS), and few species were amplified at these loci, however ETS was able to genetically distinguish the two important invasive Nassella species. Multiple loci analyses also suggested that ETS played a crucial role in allowing identification of the two Nassella species in the multiple loci combinations.