Jingjuan Zhang

The measurement of the timing, and anatomical features, of spike development in lines from a segregating doubled haploid population derived from a cross between the wheat varieties Westonia x Kauz, has defined a controlling region on chromosome 5B. The region accounted for significant variation in the time to booting, head emergence and floret and spikelet number. Analysis of the gene complement of the region indicated that a Vrn gene was present as well as several genes coding for enzymes that are central to the starch-sugar metabolomic pathway. The observations are discussed in terms of the concepts that argue for the importance of sugars in spike development.

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.

WSM1417, WSM1253 and WSM471 are nodule bacteria that infect Lupinus angustifolius (NLL narrow-leaf lupin) and which have different nodulation and nitrogen fixation profiles. These three strains were sequenced within the JGI GEBA project through the US Department of Energy. To understand the genetic control of the relationship between these three micro-symbionts and their legume host we required both the lupin genome sequence, and transcriptome information. We thus sequenced NLL cv Tanjil using a WGS approach and achieved a 30 fold coverage of the whole genome. We obtained 31 billion base pair high quality sequencing data and are undertaking the lupin genome assembly and annotation with a view to identify candidate genes in nodule formation and function. The transcriptome data was of nodules of three NLL plants inoculated with the three sequenced strains. From the NLL genome sequence we obtained 23,000 contigs, which were assembled into 12,500 scaffolds. The largest contig we have is 149Mb, the N50 size of 13.6 Kb and there is ~80Mb of repeat sequences. Further analysis of the genome sequence data will be provided.

Terminal drought is an increasing risk for wheat production in many parts of the world, especially those with mediterranean type climate. The improvement of drought tolerance has been identified as a research priority. Under terminal drought, the impact of stem carbohydrate remobilization makes significant contributions to grain filling. Our study showed that the stem water soluble carbohydrate (WSC, main components fructan) level is not, on its own, a reliable criterion for the drought tolerance, the performance of the key enzymes involved in the WSC remobilization, which varied among different varieties, were critical in the terminal drought response. The genes involved in the mobilization of stem WSC, 1-FEHs and 6-FEHs (fructan exohydrolases), have been studied in detail to define their role in contributing to water deficit tolerance. The study includes the isolation of mutations where genes of interest have been deleted.

The most common factor affecting wheat production and grain quality in Australia is water deficit - "drought." Drought and heat are considered the top priority among 15 abiotic stresses affecting wheat production in Western Australia (WA). In the WA wheatbelt, water deficit intensifies from anthesis to about 4 weeks later and severe drought usually occurs from a month after anthesis to maturity. Thus, terminal drought is a major problem for wheat production in WA and drought tolerance in wheat is a priority for research. A major limitation in this field is the lack of efficient approaches of drought tolerance screening and availability of drought tolerant germ plasm. Our study has found that stem water soluble carbohydrate (WSC) mobilization has great significance for converting biomass into the grain under terminal water-deficit. However, stem WSC level is not, on its own, a reliable criterion for drought tolerant. The genes involved in the mobilization of stem WSC, 1-FEHs have been studied and the gene expression data, as a potential drought tolerant marker, define their crucial role in contributing to water deficit tolerance. QTL recently discovered provide some evidence for the possible gene function of the contribution to the grain yield components. This and other markers of grain yield components may be useful for wheat breeding in the future. Lack of drought tolerant germplasm significantly slows down drought tolerant breeding in wheat. Introducing new germplasm from China will give great benefit to the Australian wheat breeding program. Hopefully the combination of genes from such diverse environments will enhance the production of new drought tolerant wheat in conventional breeding.

Development of semi-dwarf crop varieties has significantly increased the world food production, which is referred as 18Green Revolution 19. The semi-dwarfing varieties had better lodging resistance, higher harvest index, and more efficient utilization of the environment. The green revolution genes have been isolated from rice (sd1) and wheat (Rht). The sd1 gene encodes a gibberellin acid (GA) 20 oxidase enzyme, which controls a step of biosynthetic pathway of gibberellin, and the Rht is a GA-insensitive gene which controls gibberellin signaling pathway. Two barley semi-dwarf genes sdw and denso have been widely used for barley improvement. The two genes originated from different sources but have been proved to be allelic. The sdw/denso gene was mapped to the long arm of chromosome 3H. Comparative analysis revealed that barley chromosome 3H is syntenic to the rice chromosome 1, to which the rice semi-dwarf gene sd1 was mapped. Further analysis showed that the sdw/denso gene is in the same syntenic region with the rice sd1 gene closely linked with a common RFLP marker R1545. This syntenic relationship was further confirmed through wheat and rice comparative analysis. Both barley sdw/denso and rice sd1 are GA-sensitive semi-dwarf genes. Thus, sdw/denso in barley is the most likely orthologue of sd1 in rice. The rice sd1 orthologous gene (Hv20ox2) was partial isolated from barley based on the conserved sequences between rice, wheat and maize. The barley gene has the same structure as its orthologous gene in rice with three exons and two introns. The barley and rice genes shared 88.3% sequence similarity and 89% amino acid identity. We are in the process to sequence various alleles of this gene from barley to identify the gene mutations for semi-dwarf phenotype and to develop molecular markers marker-assisted selection.