Academic literature on the topic 'Australian native legumes'

Ascochyta koolunga (Didymellaceae, Pleosporales) was first described in 2009 (as Phoma koolunga) and identified as the causal agent of Ascochyta blight of Pisum sativum (field pea) in South Australia. Since then A. koolunga has not been reported anywhere else in the world, and its origins and occurrence on other legume (Fabaceae) species remains unknown. Blight and leaf spot diseases of Australian native, pasture and naturalised legumes were studied to investigate a possible native origin of A. koolunga. Ascochyta koolunga was not detected on native, naturalised or pasture legumes that had leaf spot symptoms, in any of the studied regions in southern Australia, and only one isolate was recovered from P. sativum. However, we isolated five novel species in the Didymellaceae from leaf spots of Australian native legumes from commercial field pea regions throughout southern Australia. The novel species were classified on the basis of morphology and phylogenetic analyses of the internal transcribed spacer region and part of the RNA polymerase II subunit B gene region. Three of these species, Nothophoma garlbiwalawardasp. nov., Nothophoma naiawusp. nov. and Nothophoma ngayawangsp. nov., were isolated from Senna artemisioides. The other species described here are Epicoccum djirangnandirisp. nov. from Swainsona galegifolia and Neodidymelliopsis tinkyukukusp. nov. from Hardenbergia violacea. In addition, we report three new host-pathogen associations in Australia, namely Didymella pinodes on S. artemisioides and Vicia cracca, and D. lethalis on Lathyrus tingitanus. This is also the first report of Didymella prosopidis in Australia.

Six Spanish legumes, Cytisus balansae, C. multiflorus, C. scoparius, C. striatus, Genista hystrix and Retama sphaerocarpa, were able to form effective nodules when grown in six south-western Australian soils. Soils and nodules were collected from beneath natural stands of six native Australian legumes, Jacksonia floribunda, Gompholobium tomentosum, Bossiaea aquifolium, Daviesia horrida, Gastrolobium spinosum and Templetonia retusa. Four combinations of soils and bacterial treatments were used as the soil treatments: sterile soil (S), sterile inoculated soils (SI), non-treated soil (N) and non-treated inoculated soils (NI). Seedlings of the Australian species were inoculated with rhizobia cultured from nodules of the same species, while seedlings of the Spanish species were inoculated with cultures from each of the Australian species. All Australian rhizobia infected all the Spanish species, suggesting a high degree of 'promiscuity' among the bacteria and plant species. The results from comparing six Spanish and six Australian species according to their biomass and total nitrogen in the presence (NI) or absence (S) of rhizobia showed that all species benefitted from nodulation (1.02–12.94 times), with R.�sphaerocarpa and C. striatus benefiting more than the native species. Inoculation (SI and NI) was just as effective as, or more effective than the non-treated soil (i.e. non-sterile) in inducing nodules. Nodules formed on the Spanish legumes were just as efficient at fixing N2 as were those formed on the Australian legumes. Inoculation was less effective than non-treated soil at increasing biomass but just as effective as the soil at increasing nitrogen content. Promiscuity in the legume–bacteria symbiosis should increase the ability of legumes to spread into new habitats throughout the world.

Australian farming systems have traditionally relied on annual legumes such as subterranean clover (Trifolium subterraneum) and annual medics (Medicago spp.) in either short-term pastures in rotation with crops or permanent pastures to provide low cost biologically fixed N and a high quality forage for livestock. The role of legumes in farming systems is now being reassessed because of the recognition that their extensive use is associated with widespread soil acidification, loss of species diversity in native pastures and increasing dryland salinity. In the future, annual legumes are more likely to be sown in mixtures with deep-rooted perennial pasture species, both in permanent pastures and in rotation with crops, to improve hydrological balance in the landscape. As a result, there is a change of direction in annual legume selection and breeding programs within Australia with a greater focus on the ability of legumes to coexist with perennial species, as well as on characteristics such as an extended growing season and deeper rooting habit to exploit subsoil water. There is also a trend towards increasing the diversity of annual legume species sown in pasture mixes to better exploit paddock variation and variable seasonal conditions.

Considerable uncertainty exists about future climatic predictions but there is little doubt among experts that the future will be warmer. Climate change and the associated elevation in atmospheric CO2 level and temperatures will provide novel challenges and potential opportunities for cultivated plant species. Plant breeding and domestication can contribute to improvements in both yield and quality of native grasses, legumes and forage shrubs. This review explores the use of functional traits to identify native Australian grasses, legumes and forage shrubs suitable for domestication, to meet the challenges and opportunities under a changing climate in pastoral areas in Australia. The potential of these species in terms of life history, regenerative traits, forage quality and quantity, drought tolerance and invasiveness is examined. The paper focuses on three Australian pastoral regions (high-rainfall temperate south, tropical and subtropical grasslands, low-rainfall semi-arid shrublands), in terms of future climate predictions and potential of selected native species to meet these requirements. Selection for adaptation to new climatic environments is challenging but many native species already possess the traits required to cope with the environment under future climate scenarios.

Six Australian native herbaceous perennial legumes (Lotus australis, Swainsona colutoides, Swainsona swainsonioides, Cullen tenax, Glycine tabacina and Kennedia prorepens) were assessed in the glasshouse for nutritive value, soluble condensed tannins and production of herbage in response to three cutting treatments (regrowth harvested every 4 and 6 weeks and plants left uncut for 12 weeks). The Mediterranean perennial legumes Medicago sativa and Lotus corniculatus were also included. Dry matter (DM) yield of some native legumes was comparable to L. corniculatus, but M. sativa produced more DM than all species except S. swainsonioides after 12 weeks of regrowth. Dry matter yield of all native legumes decreased with increased cutting frequency, indicating a susceptibility to frequent defoliation. Shoot in vitro dry matter digestibility (DMD) was high (>70%) in most native legumes, except G. tabacina (65%) and K. prorepens (55%). Crude protein ranged from 21–28% for all legumes except K. prorepens (12%). More frequent cutting resulted in higher DMD and crude protein in all species, except for the DMD of C. tenax and L. australis, which did not change. Concentrations of soluble condensed tannins were 2–9 g/kg DM in the Lotus spp., 10–18 g/kg DM in K. prorepens and negligible (<1 g/kg) in the other legumes. Of the native species, C. tenax, S. swainsonioides and L. australis showed the most promise for use as forage plants and further evaluation under field conditions is now warranted.

This paper reports a study of biological nitrogen fixation in two sand dune regions of New South Wales where planted Acacia spp. had been used in revegetation programmes. At one location (Bridge Hill Ridge), natural regrowth had produced a complex plant community, and native legumes in addition to the planted acacias were present. The other area (Wanda Beach) was a grossly disturbed site which contained only the planted species. Symbiotic fixation in association with Australian legumes occurred at both locations at rates within the range reported by other authors. Distinct seasonal changes were apparent, with higher activities in the cooler months. The legume association seemed the only source of biologically fixed nitrogen at Bridge Hill Ridge, but at Wanda Beach cyanobacteria in an algal mat also made a contribution. Fast and slow-growing bacterial strains were obtained from root nodules of native legumes at both sites and were classed as Rhizobium sp. and Bradyrhizobium sp., respectively. This division was supported by the pattern of serological affinities of the isolates and by differences in their protein profiles demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two atypical types of root-nodule bacteria were found at Bridge Hill Ridge: non-nodulating, fast-growing isolates and an abnormally slow-growing Bradyrhizobium sp.

Mutualisms can be disrupted when non-native plants are introduced into novel environments, potentially impacting their establishment success. Introduced species can reassemble mutualisms by forming novel associations with resident biota or by maintaining familiar associations when they are co-introduced with their mutualists. Invasive Australian Acacia species in South Africa have formed nitrogen-fixing rhizobium mutualisms using both pathways. Here we examined the contributions of novel vs familiar rhizobial associations to the performance of Acacia saligna across different soils within South Africa’s Core Cape Subregion (CCR), and the concomitant impacts of exotic rhizobia on the endemic legume, Psoralea pinnata. We grew each legume with and without Australian Bradyrhizobium strains across various CCR soil types in a glasshouse. We identified root nodule rhizobium communities associating with seedlings grown in each treatment combination using next-generation sequencing (NGS) techniques. Our results show that different CCR soils affected growth performances of seedlings for both species while the addition of Australian bradyrhizobia affected growth performances of A. saligna, but not P. pinnata. NGS data revealed that each legume associated mostly with their familiar rhizobial partners, regardless of soil conditions or inoculum treatment. Acacia saligna predominantly associated with Australian bradyrhizobia, even when grown in soils without inoculum, while P. pinnata largely associated with native South African Mesorhizobium strains. Our study suggests that exotic Australian bradyrhizobia are already present and widespread in pristine CCR soils, and that mutualist limitation is not an impediment to further acacia invasion in the region. The ability of P. pinnata to sanction Australian Bradyrhizobium strains suggests that this species may be a good candidate for restoration efforts following the removal of acacias in CCR habitats.

AbstractMany agricultural systems around the world are challenged by declining soil resources, a dry climate and increases in input costs. The cultivation of plants that are better adapted than current crop species to nutrient poor soils, a dry climate and low-input agricultural systems would aid the continued profitability and environmental sustainability of agricultural systems. This paper examines herbaceous native Australian legumes for their capacity to be developed as grain crops adapted to dry environments. The 14 genera that contain herbaceous species areCanavalia, Crotalaria, Cullen, Desmodium, Glycine, Glycyrrhiza, Hardenbergia, Indigofera, Kennedia, Lotus, Rhynchosia, Swainsona, TrigonellaandVigna. A number of these genera (e.g.,Glycine, Crotalaria, TrigonellaandVigna) include already cultivated exotic grain legumes. Species were evaluated based on the extent to which their natural distribution corresponded to arid and semi-arid climatic regions, as well as the existing information on traits related to harvestability (uniformity of ripening, propensity to retain pod, pod shattering and growth habit), grain qualities (seed size, chemistry, color and the absence of toxins) and fecundity. Published data on seed yield were rare, and for many other traits information was limited. The Australian species ofVigna,CanavaliaandDesmodiummainly have tropical distributions and were considered poorly suited for semi-arid temperate cropping systems. Of the remaining generaGlycyrrhizaandCrotalariaspecies showed many suitable traits, including an erect growth habit, a low propensity to shatter, flowers and fruits borne at the end of branches and moderate to large seeds (5 and 38 mg, respectively). The species for which sufficient information was available that were considered highest priority for further investigation wereGlycine canescens, Cullen tenax, Swainsona canescens, Swainsona colutoides, Trigonella suavissima, Kennedia prorepens, Glycyrrhiza acanthocarpa, Crotalaria cunninghamiiandRhynchosia minima.

Symbiotic relationships between legumes and nitrogen-fixing soil micro-organisms are of ecological importance in plant communities worldwide. For example, nutrient-poor Australian soils are often dominated by shrubby legumes (e.g. species of Acacia). However, relatively few studies have quantified patterns of diversity, host-specificity and effectiveness of these ecologically important plant–microbe interactions. In this study, 16S rRNA gene sequence and PCR-RFLP analyses were used to examine bacterial strains isolated from the root nodules of two widespread south-eastern Australian legumes, Acacia salicina and Acacia stenophylla, across nearly 60 sites. The results showed that there was extensive genetic diversity in microbial populations, including a broad range of novel genomic species. While previous studies have suggested that most native Australian legumes nodulate primarily with species of the genus Bradyrhizobium, our results indicate significant associations with members of other root-nodule-forming bacterial genera, including Rhizobium, Ensifer, Mesorhizobium, Burkholderia, Phyllobacterium and Devosia. Genetic analyses also revealed a diverse suite of non-nodulating bacterial endophytes, only a subset of which have been previously recorded. Although the ecological roles of these endosymbionts are not well understood, they may play both direct and indirect roles in promoting plant growth, nodulation and disease suppression.

ABSTRACT The plant pathogen Phytophthora cinnamomi is having a major negative impact on the biodiversity of native ecosystems in the south west of Western Australia. Acacia pu/chella has previously been shown to suppress P. cinnamomi in the jarrah forest of Western Australia and protect susceptible species from infection. This has management implications for the control of P. cinnamomi in rehabilitated bauxite pits infested with the pathogen and severely diseased forest areas. The objective of this thesis was to determine if other Western Australian native legume species have the potential to biologically control P. cinnamomi. In a rehabilitated bauxite pit trial, five Acacia species were planted with Banksia grandis, to determine their ability to protect this highly susceptible species against P. cinnamomi infection. A. pulchella protected B. grandis from infection for over a year. This protection was not the result of a decrease in soil moisture or soil temperature, as was previously suggested. A. urophylla, A. extensa, A. latericola and A. drummondii did not protect B. grandis in this trial. The trial was replicated in the glasshouse under conditions conducive to the pathogen. The infection of B. grandis by P. cinnamomi was delayed for up to 7 weeks by all of these Acacia species; however, none of them protected B. grandis from eventual mortality. In a glasshouse soil inoculation trial, native legumes other than A. pulchella were able to reduce the soil inoculum potential of P. cinnamomi. Based on these findings, the species with the greatest potential for biological control of P. cinnamomi along with A. pulchella were A. extensa, A. stenoptera and A. a/ata. 11 By assessing the roots of soil inoculated native legumes from the glasshouse trial, P. cinnamomi was found to asymptomatically infect fine lateral roots of some species and sporulate from them. These species can potentially harbour the pathogen and allow for an inoculum increase when environmental conditions are favourable. A. urophylla and Viminaria juncea were the species with the least potential for biological control of P. cinnamomi due to this finding. A possible management tool for bauxite pits in infested areas and in severely diseased forest areas is the ability to influence the density and composition of species used for rehabilitation, by manipulating the seed mix ratio. The implications of this study would be to increase seed in a seed mix of those legume species with the potential for biological control and decrease seed of those species that can harbour the pathogen. However, before rehabilitation management practices are adjusted, further investigation is required to understand how P. cinnamomi suppression occurs and whether it is transferable to a natural environment. The actions of P. cinnamomi suppression by legume species and future research directions are discussed.

Ascochyta blight (synonym: blackspot) is a serious, globally distributed, primarily foliar disease of Pisum sativum L. (field pea). It is typically caused by a combination of three or four fungal species that can exist independently of each other, called a complex. Phoma koolunga, identified in 2009 in South Australia, is the most recent addition in the Ascochyta complex. Despite multiple international studies on Ascochyta blight of field pea, P. koolunga has not been reported anywhere else in the world and the origins of the pathogen, and if it occurs on other legume species remain unknown. This study provides new information on the host range of P. koolunga on leguminous plants in controlled growth room conditions. To establish a host range, disease incidence and severity were assessed on 41 legume species comprising Australian native, weed, crop, pasture legumes and wild type Pisum, Lathyrus and Vicia species, following inoculation using two isolates of P. koolunga. All legumes tested, except Cicer arietinum (chickpea), developed leaf lesions and some also had stem and tendril lesions. Incidence and severity differed significantly among species but not consistently between isolates. The ability of the P. koolunga isolates to cause lesions on a wide range of legumes, including natives, in controlled environment conditions, suggests that it has a broad host range in humid and mild temperature conditions conducive for disease. Although all 17 native species developed some degree of leaf spotting, seven were considered susceptible because disease incidence was greater than 55 percent. This research also details the isolation, identification and classification of Didymellaceae fungi causing leaf spots, collected from legumes during field studies undertaken to investigate a possible native origin of P. koolunga. Samples from plants with leaf spots were collected from field pea growing regions throughout New South Wales, South Australia and Victoria taken back to the laboratory and cultured. The resultant fungal isolates were identified based on both morphology and phylogenetic analyses of the internal transcribed spacer region and part of the RNA polymerase II subunit B gene region. P. koolunga was not detected on native, weed or pasture legumes that had leaf spot symptoms in any of the regions visited, and only one isolate was recovered from field pea in the entire 2-year collection period. However, six novel species from the family Didymellaceae were isolated from Australian native legumes, five were from South Australia and one from New South Wales. The locations are represented by four different Australian Indigenous Peoples native language groups. Representatives of those groups were approached to request permission to use a suitable Aboriginal word for species epithet and permissions granted. These fungi are described here as Didymella djirangnandiri from Swainsona galegifolia, Didymella kaurna from Gastrolobium celsianum, Neodidymelliopsis tinkyukuku from Hardenbergia violaceae, Nothophoma garlbiwalawarda from Senna artemisioides, Nothophoma naiawu, and Nothophoma ngayawang also from S. artemisioides. Additional findings from the field collections were the identification of three new host-pathogen associations for Australia. Didymella pinodes, the primary pathogen responsible for Ascochyta blight of field pea, was isolated from leaf spots on naturalised species Vicia cracca (tufted vetch) in New South Wales and on Senna artemisioides from five different locations across South Australia. The discovery that these legumes may serve as an inoculum reservoir hosts for D. pinodes has implications for epidemiology and management of Ascochyta blight of field pea because both commonly occur in field pea growing regions throughout South Australia. Didymella lethalis was isolated from naturalised species, Lathyrus tingitanus (tangier pea), growing in a creek bed located in a well-used recreation area in Adelaide, South Australia. Phylogenetic analyses indicated that P. koolunga has a close relationship with the recently named species Ascochyta boeremae and supports the re-naming of P. koolunga as Ascochyta. Confirmation of the correction in nomenclature to Ascochyta koolunga comb. nov. was achieved with PCR followed by sequencing at two additional loci, the partial gene regions of ß-tubulin and the partial large subunit nrDNA (LSU). In summary, the controlled growth room results revealing a wide legume host range, and field collection results yielding no isolations from legumes other than field pea, suggest that P. koolunga is unlikely to have originated as a pathogen of Australian native legumes and provides no evidence regarding possible origins.
Thesis (MPhil) -- University of Adelaide, School of Agriculture, Food and Wine, 2020