My initial interests were the molecular biology of metabolism, where for my PhD I study anaerobic metabolism and flooding tolerance in cotton (CSIRO, Division of Plant Industry, Canberra) and for my post-doctoral studies, fatty acid and wax biosynthesis in the model plant Arabidopsis (University of British Columbia, Canada). After returning to Plant Industry as a research scientist, my interests shifted to gene regulation, and since my appointment at BaMBi these studies have focused on the regulation of gene expression and plant development by microRNAs.

Contact Details

Email : Tony.Millar@anu.edu.au Ph (+61 2) 6125 2870 Fax : (+61 2) 6125 0313

Main Research interests

MicroRNA control of gene expression and development in Arabidopsis

Teaching Activities

Master of Biotechnology •  BIOL8700: Biochemistry & Molecular Biology Research Proposal •  BIOL8702: Biotechnology Practical Course

Current Research Group

Maria Alonso-Peral – Post-doctoral fellow Robert Allen - PhD Student Jun-Yan (Mary) Li - Honours Student

Research Activities

Until recently it was thought that the majority of regulation was carried out by proteins, and that the DNA between protein-coding genes was nothing other than junk DNA. However this view has changed with the discovery of a new class of gene regulators called small RNAs. These molecules constitute an RNA-centric layer of control whose enormity has only become apparent in the last five years and may provide part of the regulatory requirements needed for the level of complexity observed in higher eukaryotes. The lab focuses on one type of small RNA known as microRNAs (miRNAs), many of which have been shown to play pivotal roles in many developmental and physiological processes, in both plants and animals. MiRNA genes encode a transcript that forms an extensive secondary structure known as a stem-loop (see Fig. A). This stem-loop is then processed into a small 21 nucleotide molecule (Fig. B) known as the ‘mature’ miRNA. This miRNA then guides the RNAi silencing machinery to complementary mRNA molecules, which results in the destruction of those targeted mRNAs, hence silencing gene expression. We have been using mutants in the model plant Arabidopsis, that fails to produce one type of miRNA known as miR159. This has dramatic consequences for the plant’s development, where the miRNA mutant develops curled leaves, smaller fruits and seeds (see below). These traits are a consequence of the de-regulation of a family of genes that code for MYB transcription factors, where each family member has a sequence to which miR159 can bind to and then destroy the gene transcript (mRNAs). This regulation is shown with a reporter gene (gives a blue colour) that has been joined to a MYB gene; in the miRNA mutant there is strong activity (indicating loss of regulation), whereas in the normal wild-type plant no activity can be detected, indicating the gene is being naturally “silenced”. Correlating this gene activity with the mutant traits demonstrates that this natural gene silencing mechanism is critical for proper plant development. Understanding this recently discovered form of gene regulation may provide insights on how to manipulate leaf shape, fruit and seed size, all extremely important agronomic traits. Using molecular genetic approaches to study the miR159 system, we aim to gain a greater understanding of the scope of miRNAs-mediated gene regulation in plants, determining which genes they regulate and the underlying mechanisms they use. Additionally we aim to determine how miRNAs themselves are regulated. This will lead to greater understanding of how miRNA systems operate in eukaryotes, how they regulate developmental and/or physiological processes in the plant and whether, due to their molecular nature, they perform conceptually unique regulatory roles that other known regulatory genes (such as transcription factors) are unable to do. Together this information will not only increase our knowledge on how miRNAs control an organism's form and function, but give us insight on how manipulation of miRNAs may introduce favourable traits into crop species. Some of our recent publications have appeared on the cover:

Publications

Publications Allen RS, Li J, Stahle MI, Dubroué A, Gubler F and Millar AA (2007) Genetic analysis demonstrates functional redundancy and the major target genes of the Arabidopsis miR159 family. Proc. Natl. Acad. Sci. USA, 104, 16371-16376. Millar AA, Jacobsen JV, Ross JJ, Helliwell CA, Poole AT, Scofield G, Reid JB and Gubler F. (2006) Seed dormancy and ABA metabolism in Arabidopsis and barley: the role of ABA 8' hydroxylase. The Plant Journal 45, 942-954. Millar AA and Gubler F (2005) The Arabidopsis GAMYB-like genes, MYB33 and MYB65, are microRNA-regulated genes that redundantly facilitate anther development. The Plant Cell 17, 705-721. Millar AA and Waterhouse PM (2005) Plant and animal microRNAs: similarities and differences. Functional and Integrative Genomics 5, 129-135. Gubler F, Millar AA and Jacobsen JV (2005) Dormancy release, ABA and pre-harvest sprouting. Current Opinion in Plant Biology 8, 183-187. Allen TR, Millar AA, Berch SM and Berbee ML (2003) Culturing and direct DNA extraction find different fungi from the same ericoid mycorrhizal roots. New Phytologist 160, 255-272. Woodger FJ, Millar AA, Murray F, Jacobsen JV and Gubler F (2003) The role of GAMYB transcription factors in GA-regulated gene expression. Journal of Plant Growth Regulation 22, 176-184. Hooker TS, Millar AA, Kunst L. (2002) Significance of the expression of the CER6 condensing enzyme for cuticular wax production in Arabidopsis. Plant Physiology 129, 1568-1580. Ellis MH, Millar AA, Llewellyn DJ, Dennis ES and Peacock WJ (2000) Transgenic cotton (Gossypium hirsutum L.) over-expressing alcohol dehydrogenase shows increased ethanol fermentation but no increase in tolerance to oxygen deficiency. Australian Journal of Plant Physiology 27, 1041-1050. Millar AA, Smith MA and Kunst L. (2000) All fatty acids are not equal: discrimination in plant membrane lipids. Trends in Plant Science 5, 95-101. Millar AA and Kunst L (1999) The natural genetic variation of the fatty-acyl composition of seed oils in different ecotypes of Arabidopsis thaliana. Phytochemistry 52, 1029-1033. Millar AA, Clemens S, Zachgo S, Giblin M, Taylor DC and Kunst L. (1999) CUT1, an Arabidopsis gene required for cuticular wax biosynthesis and pollen fertility, encodes a very-long-chain fatty acid condensing enzyme. The Plant Cell 11, 825-838. Millar AA, Wrischer M and Kunst L (1998) The accumulation of very-long-chain fatty acids in membrane glycerolipids is associated with dramatic alterations in plant morphology. The Plant Cell 10, 1889-1902. Millar AA and Kunst L (1997) Very-long-chain fatty acid biosynthesis is controlled through the expression and specificity of the condensing enzyme. The Plant Journal 12, 121-131. Millar AA and Dennis ES (1996) The alcohol dehydrogenase genes of cotton. Plant Molecular Biology 31, 897-904. Millar AA and Dennis ES (1996) Protein synthesis during oxygen deprivation in cotton. Australian Journal of Plant Physiology 23, 341-348. Millar AA and Kunst L (1995) Isolation of an Arabidopsis cDNA encoding 3-ketoacyl-acyl carrier protein synthase 1 (GenBank U24177) (PGR95-027). Plant Physiology 108, 1747. Millar AA, Olive MR and Dennis ES (1994) The expression and anaerobic induction of alcohol dehydrogenase in cotton. Biochemical Genetics 32, 279-300.