Wujun Ma

Optimising Nitrogen fertiliser management and using cultivars with high Nitrogen uptake and utilisation efficiency is a good strategy to improve the Nitrogen use efficiency (NUE). This study investigates the determinants of genetic variation in NUE and develops associations with NAM - A1 and NAM - B1 alleles in Australian wheat cultivars grown under different N treatments in Westonia Australia. The functional NAM - B1 allele improves nitrogen remobilization from the leaf tissue, which led to increasing grain protein content but reduces the grain yield. NAM - A1a allele has the same functional of NAM - B1, but with more influence on the period of grain filling. The Nitrogen fertiliser treatments were applied at rates (0, 50, and 100 kg N ha −1) at three stages (Mid Tillering, Booting, and Flowering) of plant growth. The following parameters were analysed: grain yield, number of head plant - 1, number of seed head - 1, thousand grain weight, Root dry weight, total NAM gene expression, grain protein content, residual N in straw, and Nitrogen content in leaf tissue to determine the Nitrogen accumulation and translocation from the leaves to the grain, and overall NUE and its component. The increase of Nitrogen application also resulted in increased grain yield, number of head plant - 1, and greater root dry weight, which was highest at 100 kg N ha −1. The timing of Nitrogen application had no clear effect on either grain yield or grain protein content. Application of Nitrogen at the late stage (booting and flowering) increased the only number of seed head - 1 and thousand grain weight. The duration of grain filling was critical on Australian wheat cultivars and had a strong impact on grain yield and grain protein content. Our results indicated that NAM - A1 alleles are significantly related to the length of the grain filling period. NAM - A1 allele a is associated with early and early to mid grain filling duration, while NAM - A1 alleles c and d associated with mid and mid to late grain filling duration.

This presentation provides a report on two major investments in wheat molecular biology, namely the sequencing of chromosome 7A and the Australia - China Centre for Wheat Improvement (ACCWI). The sequencing of chromosome 7A project (GRDC/BioPlatforms Australia funded) is supported by the International Wheat genome Sequencing Consortium (IWGSC) and has established the physical assembly of BAC clones prepared from flow sorted ditelocentric chromosomes. The Hiseq sequencing of BAC pools (AGRF) is approximately two thirds completed. The BAC pools being sequenced comprise contigs of 1 - 2 Mb genomic DNA which were assembled using the SNAPshot DNA fingerprinting of individual BACs with 5 restriction endonucleases. Anchoring of the sequence assemblies is being achieved using the 9K and 90K SNP chip based molecular genetic maps as well as the standard deletion maps for chromosome 7A and the published 7A genome sequence for Triticum urartu . The new ACCWI will act as the conduit through which in - depth genome sequence information for chromosome 7A as well as the other chromosomes (through the IWGSC) can be integrated into broader molecular breeding initiatives aimed at increasing the accuracy and efficiency with which wheat phenotypes can be defined. The ACCWI core phenotype targets will focus on grain yield and quality with the characterization of individual quality parameters being undertaken through the use of mass spectroscopy to generate grain protein profiles/signatures, the technology of which is dependent on genome sequences to define genes. The ACCWI - strategy for linking grain protein profiles/signatures to agronomic traits of interest to marketers of grains and breeders will be discussed.

Mixing of lupin flour to wheat in bread making provides a number of health benefits and has major effects on bread properties including protein extractability. The study investigated wheat and lupin protein interaction as influenced by baking process and modification of protein extractability, which is important for the final quality of bread. MALDI-TOF mass spectrometry and 2 dimensional gel electrophoresis followed by MS/MS peptide sequencing were used to study bread protein matrix and wheat and lupin flour proteins. The results demonstrated that many of the wheat and lupin proteins including high molecular weight glutenins remained unchanged in baking as per their elctrophoretic behavior. However, some of the proteins of wheat and lupin became unextractable from the bread, indicating lupin-wheat protein interaction during baking. For the lupin proteins, most of the α-conglutins could be readily extracted from the lupin-wheat bread even at low salt and non-reducing/non-denaturing extraction conditions. In contrast, most of the β-conglutins lost extractability suggesting that they were cross-linked to the wheat gluten network and trapped into the bread matrix. The higher thermal stability of α-conglutins compared to β-conglutins is speculated to account for this difference.

In the current study, we established a fast method to accurately measure the number of cysteine residues in high molecular weight glutenin subunits. An alkylation regent, 4-vinylpyridine (4-vp), was used to treat the proteins during extraction. For every cysteine residue in a protein, such treatment increases its molecular mass value by 105.14 Da, which can be accurately determined by MALDI-TOF equipment. Based on the changes of the molecular mass value after 4-vp treatment, the number of cysteine residue can be reliably determined. We found that this method is also useful in studying non-glutenin proteins such as lupin seed storage proteins. This method is particularly valuable when the number of cysteine residue is of importance.

Nutritional qualities of lupin suggest bread rich in lupin has the potential to provide a number of health benefits. Mixing of lupin flour to wheat has major effects on bread properties including the extractability of proteins that is crucial to define the ultimate attributes of food. Present study investigated the lupin and wheat proteome dynamics as affected by the baking of lupin–wheat bread by using 2-D electrophoresis and direct mass spectrometry. Many of the proteins from both lupin and wheat remained unchanged in baked lupin–wheat bread, while the others were incorporated into the bread matrix and could not be extracted. Most of the alpha-conglutins could be readily extracted from the lupin–wheat bread even at milder extraction. In contrast, most of the beta- conglutins lost extractability. The structural attribute that correlates with this difference in behaviour is the greater in thermal stability of alpha-conglutins relative to Beta- conglutins. Most of the beta and gamma conglutins showed relatively higher peptide sequence coverage of corresponding matched proteins compare to alpha conglutin due to lack of information regarding this group of protein in the database.

Narrow-leafed lupin (NLL) is one of the major legume crops in Australian farming system which is largely used as animal feed. A number of modern cultivars have been developed through breeding making NLL possible to be consumed as human food. Significant health benefits have been recognised when NLL seeds are consumed. This study characterised protein polymorphism among the 25 Australian cultivars through mass spectrometric (MALDI-TOF) with the aim of developing molecular breeding strategies to improve protein quality and content. Altogether, 364 seed storage proteins were identified by the MALDI-TOF profiling and fifty proteins were cultivar specific. Nine common proteins (present in all cultivars) and 61 rare proteins (present in 2–3 cultivars only) were recorded. Phylogenic analysis based on the protein profile clustered the cultivars into 2 major groups and 5 subgroups which are generally supported by the pedigree information. Small number (2.4%) of common proteins among the cultivars suggested a high level of genetic diversity in seed storage protein of NLL.