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Glen Osmond, Australia

Hill C.B.,Australian Center for Plant Functional Genomics | Taylor J.D.,Australian Center for Plant Functional Genomics | Edwards J.,University of Melbourne | Mather D.,Waite Research Institute | And 3 more authors.
Plant Physiology | Year: 2013

Drought is a major environmental constraint responsible for grain yield losses of bread wheat (Triticum aestivum) in many parts of the world. Progress in breeding to improve complex multigene traits, such as drought stress tolerance, has been limited by high sensitivity to environmental factors, low trait heritability, and the complexity and size of the hexaploid wheat genome. In order to obtain further insight into genetic factors that affect yield under drought, we measured the abundance of 205 metabolites in flag leaf tissue sampled from plants of 179 cv Excalibur/Kukri F1-derived doubled haploid lines of wheat grown in a field experiment that experienced terminal drought stress. Additionally, data on 29 agronomic traits that had been assessed in the same field experiment were used. A linear mixed model was used to partition and account for nongenetic and genetic sources of variation, and quantitative trait locus analysis was used to estimate the genomic positions and effects of individual quantitative trait loci. Comparison of the agronomic and metabolic trait variation uncovered novel correlations between some agronomic traits and the levels of certain primary metabolites, including metabolites with either positive or negative associations with plant maturity-related or grain yield-related traits. Our analyses demonstrate that specific regions of the wheat genome that affect agronomic traits also have distinct effects on specific combinations of metabolites. This approach proved valuable for identifying novel biomarkers for the performance of wheat under drought and could facilitate the identification of candidate genes involved in drought-related responses in bread wheat. © 2013 American Society of Plant Biologists. All Rights Reserved. Source

Bennett D.,University of Adelaide | Reynolds M.,International Maize and Wheat Improvement Center | Mullan D.,International Maize and Wheat Improvement Center | Izanloo A.,University of Adelaide | And 5 more authors.
Theoretical and Applied Genetics | Year: 2012

A large proportion of the worlds' wheat growing regions suffers water and/or heat stress at some stage during the crop growth cycle. With few exceptions, there has been no utilisation of managed environments to screen mapping populations under repeatable abiotic stress conditions, such as the facilities developed by the International Wheat and Maize Improvement Centre (CIMMYT). Through careful management of irrigation and sowing date over three consecutive seasons, repeatable heat, drought and high yield potential conditions were imposed on the RAC875/Kukri doubled haploid population to identify genetic loci for grain yield, yield components and key morpho-physiological traits under these conditions. Two of the detected quantitative trait loci (QTL) were located on chromosome 3B and had a large effect on canopy temperature and grain yield, accounting for up to 22 % of the variance for these traits. The locus on chromosome arm 3BL was detected under all three treatments but had its largest effect under the heat stress conditions, with the RAC875 allele increasing grain yield by 131 kg ha-1 (or phenotypically, 7 % of treatment average). Only two of the eight yield QTL detected in the current study (including linkage groups 3A, 3D, 4D 5B and 7A) were previously detected in the RAC875/Kukri doubled haploid population; and there were also different yield components driving grain yield. A number of discussion points are raised to understand differences between the Mexican and southern Australian production environments and explain the lack of correlation between the datasets. The two key QTL detected on chromosome 3B in the present study are candidates for further genetic dissection and development of molecular markers. © 2012 Springer-Verlag. Source

Mahjourimajd S.,University of Adelaide | Kuchel H.,Australian Grain Technologies | Langridge P.,University of Adelaide | Okamoto M.,University of Adelaide
Plant and Soil | Year: 2016

Aims: The key aim was to assess the genetic variation for nitrogen (N) response and stability in spring wheat germplasm to determine the scope for improvement of nitrogen use efficiency (NUE) under water-limited, low yielding conditions. A further aim was to evaluate NUE stability and NUE-protein yield (PY) as suitable NUE-related traits for selection. Methods: The traits measured included grain yield (GY, kg ha−1) and NUE (kg GY kg−1 N) under varying N applications at all sites, and NUE for protein yield (NUE-PY), harvest index and plant height at some sites. In addition, two of the trials used two seeding rates to provide an assessment of the impact of plant density on NUE. Results: Genetic variation was significant for all traits studied. Grain yield was affected by both genotype (G) and N rate and the interaction between the two. Interestingly, harvest index and height showed no direct response to varying N applications. However, for these traits, there was a significant G effect and N response (G × N interaction). Conclusions: Increasing N inputs led to variable responses for GY at different sites. Importantly, genetic variation in N response was detected. The information and screening techniques will enable plant breeders to select wheat genotypes that show a consistent response to high N. There is clear scope to improve NUE in spring wheat grown in low yielding environments. © 2015, The Author(s). Source

Bennett D.,University of Adelaide | Izanloo A.,University of Adelaide | Izanloo A.,Birjand University | Reynolds M.,International Maize and Wheat Improvement Center | And 4 more authors.
Theoretical and Applied Genetics | Year: 2012

In the water-limited bread wheat production environment of southern Australia, large advances in grain yield have previously been achieved through the introduction and improved understanding of agronomic traits controlled by major genes, such as the semi-dwarf plant stature and photoperiod insensitivity. However, more recent yield increases have been achieved through incremental genetic advances, of which, breeders and researchers do not fully understand the underlying mechanism(s). A doubled haploid population was utilised, derived from a cross between RAC875, a relatively drought-tolerant breeders' line and Kukri, a locally adapted variety more intolerant of drought. Experiments were performed in 16 environments over four seasons in southern Australia, to physiologically dissect grain yield and to detect quantitative trait loci (QTL) for these traits. Two stage multi-environment trial analysis identified three main clusters of experiments (forming distinctive environments, ENVs), each with a distinctive growing season rainfall patterns. Kernels per square metre were positively correlated with grain yield and influenced by kernels per spikelet, a measure of fertility. QTL analysis detected nine loci for grain yield across these ENVs, individually accounting for between 3 and 18% of genetic variance within their respective ENVs, with the RAC875 allele conferring increased grain yield at seven of these loci. These loci were partially dissected by the detection of co-located QTL for other traits, namely kernels per square metre. While most loci for grain yield have previously been reported, their deployment and effect within local germplasm are now better understood. A number of novel loci can be further exploited to aid breeders' efforts in improving grain yield in the southern Australian environment. © 2012 Springer-Verlag. Source

Bennett D.,University of Adelaide | Izanloo A.,University of Adelaide | Izanloo A.,Birjand University | Edwards J.,University of Adelaide | And 7 more authors.
Theoretical and Applied Genetics | Year: 2012

In southern Australia, where the climate is predominantly Mediterranean, achieving the correct flowering time in bread wheat minimizes the impact of in-season cyclical and terminal drought. Flag leaf glaucousness has been hypothesized as an important component of drought tolerance but its value and genetic basis in locally adapted germplasm is unknown. From a cross between Kukri and RAC875, a doubled-haploid (DH) population was developed. A genetic linkage map consisting of 456 DArT and SSR markers was used to detect QTL affecting time to ear emergence and Zadoks growth score in seven field experiments. While ear emergence time was similar between the parents, there was significant transgressive segregation in the population. This was the result of segregation for the previously characterized Ppd-D1a and Ppd-B1 photoperiod responsive alleles. QTL of smaller effect were also detected on chromosomes 1A, 4A, 4B, 5A, 5B, 7A and 7B. A novel QTL for flag leaf glaucousness of large, repeatable effect was detected in six field experiments, on chromosome 3A (QW. aww-3A) and accounted for up to 52 percent of genetic variance for this trait. QW. aww-3A was validated under glasshouse conditions in a recombinant inbred line population from the same cross. The genetic basis of time to ear emergence in this population will aid breeders' understanding of phenological adaptation to the local environment. Novel loci identified for flag leaf glaucousness and the wide phenotypic variation within the DH population offers considerable scope to investigate the impact and value of this trait for bread wheat production in southern Australia. © 2011 Springer-Verlag. Source

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