Hermitage Research Facility

Warwick, Australia

Hermitage Research Facility

Warwick, Australia
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Solomon K.F.,Hermitage Research Facility | Zeppa A.,Hermitage Research Facility | Mulugeta S.D.,North West University South Africa
Plant Breeding | Year: 2012

The objectives of this study were to evaluate the importance of heterosis for agronomic and quality traits in shrunken (sh2) sweet corn, assess the usefulness of combining ability to predict the value of parents and their crosses for further genetic improvement and examine whether genetic divergence can predict heterosis or F 1 performance. Ten genetically diverse shrunken (sh2) sweet corn inbred lines were used to generate 45 F 1s. F 1s and parents were evaluated for agronomic and quality traits across environments. Heterosis was more important for yield-related traits than it was for ear aspects and eating quality. Heterosis for most traits was mostly dependent on dominance genetic effects of parental lines. Parents and F 1per se performance were highly correlated with general combining ability effects and mid-parent values, respectively, for most traits. Hybrid performance for flavour and plant height was significantly but weakly related to simple sequence repeat (SSR)-based genetic distance (GD). Phenotypic distance (PD), estimated from phenotypic traits was correlated with heterosis for total soluble solids, ear length and flavour. © 2012 State of Queensland.

George-Jaeggli B.,Hermitage Research Facility | Jordan D.R.,University of Queensland | Van Oosterom E.J.,University of Queensland | Broad I.J.,Fisheries and Forestry | Hammer G.L.,University of Queensland
Field Crops Research | Year: 2013

Presence of the dw3 sorghum dwarfing gene had negative effects on grain yield in some genetic backgrounds and environments. In a previous study we showed that this was due to a significant reduction in shoot biomass (mainly via reduced stem mass), which in turn negatively affected grain size. The current study examines whether shoot biomass was reduced via effects of dw3 on traits associated with resource capture, such as leaf area index (LAI), light interception (LI), and canopy extinction coefficient (k) or with resource use efficiency, such as radiation use efficiency (RUE). Three pairs of near-isogenic sorghum lines differing only in the presence or absence of the dwarfing allele dw3 (3-dwarfs vs 2-dwarfs) were grown in large field plots. Biomass accumulation and LI were measured for individual canopy layers to examine canopy characteristics of tall and short types. Similar to the previously reported effects on grain yield, the effects of dw3 on RUE, LI and k varied among genetic backgrounds and environments. Interactions between dw3 and genetic background, but also interactions with environment are likely to have modulated the extent to which RUE, LI, or k contributed to biomass differences between tall and short sorghum. © 2013 .

Gilding E.K.,University of Queensland | Frere C.H.,University of Exeter | Cruickshank A.,Hermitage Research Facility | Rada A.K.,University of Gottingen | And 5 more authors.
Nature Communications | Year: 2013

The production of adequate agricultural outputs to support the growing human population places great demands on agriculture, especially in light of ever-greater restrictions on input resources. Sorghum is a drought-adapted cereal capable of reliable production where other cereals fail, and thus represents a good candidate to address food security as agricultural inputs of water and arable land grow scarce. A long-standing issue with sorghum grain is that it has an inherently lower digestibility. Here we show that a low-frequency allele type in the starch metabolic gene, pullulanase, is associated with increased digestibility, regardless of genotypic background. We also provide evidence that the beneficial allele type is not associated with deleterious pleiotropic effects in the modern field environment. We argue that increasing the digestibility of an adapted crop is a viable way forward towards addressing food security while maximizing water and land-use efficiency. © 2013 Macmillan Publishers Limited.

Solomon K.F.,Hermitage Research Facility | Martin I.,Kairi Research Facility | Zeppa A.,Hermitage Research Facility
Euphytica | Year: 2012

The objectives of this study were to quantify the components of genetic variance and the genetic effects, and to examine the genetic relationship of inbred lines extracted from various shrunken2 (sh2) breeding populations. Ten diverse inbred lines developed from sh2 genetic background, were crossed in half diallel. Parents and their F1 hybrids were evaluated at three environments. The parents were genotyped using 20 polymorphic simple sequence repeats (SSR). Agronomic and quality traits were analysed by a mixed linear model according to additive-dominance genetic model. Genetic effects were estimated using an adjusted unbiased prediction method. Additive variance was more important than dominance variance in the expression of traits related to ear aspects (husk ratio and percentage of ear filled) and eating quality (flavour and total soluble solids). For agronomic traits, however, dominance variance was more important than additive variance. The additive genetic correlation between flavour and tenderness was strong (r = 0. 84, P < 0. 01). Flavour, tenderness and kernel colour additive genetic effects were not correlated with yield related traits. Genetic distance (GD), estimated from SSR profiles on the basis of Jaccard's similarity coefficient varied from 0. 10 to 0. 77 with an average of 0. 56. Cluster analysis classified parents according to their pedigree relationships. In most studied traits, F1 performance was not associated with GD. © 2011 Springer Science+Business Media B.V.

Borrell A.K.,University of Queensland | van Oosterom E.J.,University of Queensland | Mullet J.E.,Texas A&M University | George-Jaeggli B.,Hermitage Research Facility | And 3 more authors.
New Phytologist | Year: 2014

Summary: Stay-green is an integrated drought adaptation trait characterized by a distinct green leaf phenotype during grain filling under terminal drought. We used sorghum (Sorghum bicolor), a repository of drought adaptation mechanisms, to elucidate the physiological and genetic mechanisms underpinning stay-green. Near-isogenic sorghum lines (cv RTx7000) were characterized in a series of field and managed-environment trials (seven experiments and 14 environments) to determine the influence of four individual stay-green (Stg1-4) quantitative trait loci (QTLs) on canopy development, water use and grain yield under post-anthesis drought. The Stg QTL decreased tillering and the size of upper leaves, which reduced canopy size at anthesis. This reduction in transpirational leaf area conserved soil water before anthesis for use during grain filling. Increased water uptake during grain filling of Stg near-isogenic lines (NILs) relative to RTx7000 resulted in higher post-anthesis biomass production, grain number and yield. Importantly, there was no consistent yield penalty associated with the Stg QTL in the irrigated control. These results establish a link between the role of the Stg QTL in modifying canopy development and the subsequent impact on crop water use patterns and grain yield under terminal drought. © 2014 New Phytologist Trust.

Mace E.S.,Hermitage Research Facility | Singh V.,University of Queensland | van Oosterom E.J.,University of Queensland | Hammer G.L.,University of Queensland | And 3 more authors.
Theoretical and Applied Genetics | Year: 2012

Nodal root angle in sorghum influences vertical and horizontal root distribution in the soil profile and is thus relevant to drought adaptation. In this study, we report for the first time on the mapping of four QTL for nodal root angle (qRA) in sorghum, in addition to three QTL for root dry weight, two for shoot dry weight, and three for plant leaf area. Phenotyping was done at the six leaf stage for a mapping population (n = 141) developed by crossing two inbred sorghum lines with contrasting root angle. Nodal root angle QTL explained 58.2% of the phenotypic variance and were validated across a range of diverse inbred lines. Three of the four nodal root angle QTL showed homology to previously identified root angle QTL in rice and maize, whereas all four QTL co-located with previously identified QTL for stay-green in sorghum. A putative association between nodal root angle QTL and grain yield was identified through single marker analysis on field testing data from a subset of the mapping population grown in hybrid combination with three different tester lines. Furthermore, a putative association between nodal root angle QTL and stay-green was identified using data sets from selected sorghum nested association mapping populations segregating for root angle. The identification of nodal root angle QTL presents new opportunities for improving drought adaptation mechanisms via molecular breeding to manipulate a trait for which selection has previously been very difficult. © 2011 Her Majesty the Queen in Rights of Australia as represented by The State of Queensland.

George-Jaeggli B.,Hermitage Research Facility | Jordan D.R.,Hermitage Research Facility | Jordan D.R.,University of Queensland | van Oosterom E.J.,University of Queensland | Hammer G.L.,University of Queensland
Field Crops Research | Year: 2011

Positive correlations between plant height and grain yield have been reported for sorghum. The introduction of stay-green in sorghum, and the associated reduction in lodging, has opened the possibility to exploit this positive association. The aim of this study was to analyse the direct effects of the dwarfing gene dw3 (and therefore plant height) on shoot biomass, grain yield, and yield components in pairs of 3-dwarf genotypes and their isogenic 2-dwarf tall mutants. Isogenic pairs with different genetic backgrounds were grown in three field experiments under nutrient and water non-limiting conditions. Tall mutants were significantly taller and produced more shoot and stem biomass than their shorter counterparts. Generally, tall types yielded more grain than short types, but significant interactions between experiment, genetic background and stature affected the consistency of the results. dw3 only affected grain size and not grain number. Increased grain mass of tall types was associated with significantly greater stem mass per grain at anthesis and greater shoot biomass per grain accumulated between anthesis and maturity. The increased biomass of tall plants was therefore important for increased grain yield under optimum conditions. Potential implications of increased biomass production for drought adaptation are discussed. © 2011.

Hickey L.T.,University of Queensland | Lawson W.,Hermitage Research Facility | Platz G.J.,Hermitage Research Facility | Dieters M.,University of Queensland | Franckowiak J.,Hermitage Research Facility
Genome | Year: 2012

Rph20 is the only reported, simply inherited gene conferring moderate to high levels of adult plant resistance (APR) to leaf rust (Puccinia hordei Otth) in barley (Hordeum vulgare L.). Key parental genotypes were examined to determine the origin of Rph20 in two-rowed barley. The Dutch cultivar 'Vada' (released in the 1950s) and parents, 'Hordeum laevigatum' and 'Gull' ('Gold'), along with the related cultivar 'Emir' (a derivative of 'Delta'), were assessed for APR to P. hordei in a disease screening nursery. The marker bPb-0837-PCR, co-located with Rph20 on the short arm of chromosome 5H (5HS), was used to screen genotypes for the resistance allele, Rph20.ai. Results from phenotypic assessment and DNA analysis confirmed that Rph20 originated from the landrace 'H. laevigatum' (i.e., Hordeum vulgare subsp. vulgare). Tracing back this gene through the pedigrees of two-rowed barley cultivars, indicated that Rph20 has contributed APR to P. hordei for more than 60 years. Although there have been no reports of an Rph20-virulent pathotype, the search for alternative sources of APR should continue to avoid widespread reliance upon a single resistance factor. © 2012 Published by NRC Research Press.

Alam M.M.,University of Queensland | Hammer G.L.,University of Queensland | Van Oosterom E.J.,University of Queensland | Cruickshank A.W.,Hermitage Research Facility | And 2 more authors.
New Phytologist | Year: 2014

Summary: Tillering determines the plant size of sorghum (Sorghum bicolor) and an understanding of its regulation is important to match genotypes to prevalent growing conditions in target production environments. The aim of this study was to determine the physiological and environmental regulation of variability in tillering among sorghum genotypes, and to develop a framework for this regulation. Diverse sorghum genotypes were grown in three experiments with contrasting temperature, radiation and plant density to create variation in tillering. Data on phenology, tillering, and leaf and plant size were collected. A carbohydrate supply/demand (S/D) index that incorporated environmental and genotypic parameters was developed to represent the effects of assimilate availability on tillering. Genotypic differences in tillering not explained by this index were defined as propensity to tiller (PTT) and probably represented hormonal effects. Genotypic variation in tillering was associated with differences in leaf width, stem diameter and PTT. The S/D index captured most of the environmental effects on tillering and PTT most of the genotypic effects. A framework that captures genetic and environmental regulation of tillering through assimilate availability and PTT was developed, and provides a basis for the development of a model that connects genetic control of tillering to its phenotypic consequences. © 2014 New Phytologist Trust.

Dreiseitl A.,Agricultural Research Institute Kromeriz Ltd | Dreiseitl A.,Hermitage Research Facility | Platz G.,Hermitage Research Facility
Crop and Pasture Science | Year: 2012

Barley (Hordeum vulgare L.) is a major crop in Australia and powdery mildew (Blumeria graminis f. sp. hordei) is one of its most common diseases. Genes for resistance to powdery mildew were postulated for 86 Australian barley varieties and nine advanced breeding lines using 40 reference isolates of the pathogen. Fifty isolates collected in Australia in 2011 were used for additional tests of some varieties. In total, 22 known resistance genes [mlo, Mla1, MlaAl2, Mla3, Mla6, Mla7, Mla8, Mla9, Mla12, Mla13, Mlat, Mlg, MlGa, Mlk1, MlLa, Mlra, Ml(Ab), Ml(Ch), Ml(Dr2), Ml(He2), Ml(Lo) and Ml(St)] were detected. The most frequent genes were Mla8 and Mlg present in 43 and 34 varieties, respectively, while MlGa was found in 12 varieties. Each of the specific resistance genes Mla1, Mla3, Mla6, Mla9, Mla13, Ml(St) and the non-specific recessive gene mlo was found in one variety only. The varieties Maritime and Stirling appear to carry no specific resistance genes. Fifteen unknown resistances were detected. It is recommended that Australian barley breeding programs exploit European varieties possessing mlo to improve the resistance to powdery mildew in new varieties. © CSIRO 2012.

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