Dr Sarah McKim
Genetic Mechanisms underlying Cereal Architecture
Cereal grain provides more calories to the human diet than any other source. Grain yield is especially influenced by a cereal’s architecture or body plan. In fact, fundamental changes in body plan were hallmark events in cereal domestication. Modern plant breeding continues to select for better yielding crop architectures; however, we still know relatively little about how different genes work together at a molecular level to control cereal body plans, especially in the Triticeae, such as wheat, barley and rye.
Barley as a Model System
I am a plant developmental biologist with extensive experience in Arabidopsis thaliana and its close relatives. I am translating these approaches into crops by using barley as a model. Barley, the fourth largest grown crop worldwide, is a diploid, self-pollinating plant. Recent generation of sophisticated genomic resources enables us to combine the genetic utility of barley with molecular approaches to learn about developmental mechanisms underlying architecture in the Triticeae. This is an exciting time to work in molecular crop genetics!
In contrast to animals, plant architecture is determined after embryogenesis as plants grow, develop and transition through vegetative and reproductive stages. Vegetative phases involve leaf and shoot production while the reproductive phase promotes development of a flower-bearing inflorescence often borne on an elongated stalk. In barley, the inflorescence develops as a terminal spike. Nodes along the central spike stem (rachis) initiate rows of reproductive units called spikelets, each of which can develop into a single kernel of grain.
Developmental phase transitions are controlled by antagonistic activities between two microRNA (miRNA) families that negatively regulate the activity of specific transcription factors. These miRNAs and transcription factors appear deeply conserved across plants and are conspicuously represented in factors regulating agronomically important traits. We are keen to learn how these transcription factors control stage-specific morphologies and architectures in barley and Arabidopsis and the role of miRNA regulation in this process. Given its intimate association with grain production, we are especially interested in growth, development and presentation of the spike.
By deciphering gene function we will learn more about the genetic networks influencing plant architecture and apply this knowledge to molecularly-inform crop breeding.
I am passionate about teaching and greatly enjoy teaching my students.
I manage and teach on the third year Plant Sciences Module. In addition, I contribute to the third year Genetics course.
Zwirek M, Waugh R, and McKim SM (2018) Interaction between row-type genes in barley controls meristem determinacy and reveals novel routes to improved grain. New Phytologist. in press. https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.15548
Monniaux M, Pieper B, McKim SM, Routier-Kierzkowska A-L, Kierzkowski D, Smith R and Hay A (2018) The role of APETALA1 in petal number robustness. eLIFE 2018;7:e39399 DOI:10.7554/eLife.39399. https://elifesciences.org/articles/39399
McKim SM*, Koppolu R, Schnurbusch T (2018) Barley Inflorescence Architecture. In: Stein N., Muehlbauer G. (eds) The Barley Genome. Compendium of Plant Genomes. Springer, Cham. *corresponding author. https://link.springer.com/chapter/10.1007/978-3-319-92528-8_12
Hazel B, Casao MC, Zwirek M, Flavell A, Thomas W, Guo W, Zhang R, Rapazote-Flores P, Kyriakidis S, Russell J, Druka A, McKim SM* and Waugh R* (2017) Barley SIX-ROWED SPIKE3 encodes a putative Jumonji C-type H3K9me2/me3 demethylase that represses lateral spikelet fertility" Nature Communications 8, Article number: 936.*co-corresponding authors.doi:10.1038/s41467-017-00940-7. https://www.nature.com/articles/s41467-017-00940-7
McKim SM, Routier- Kierzkowska A-L, Monniaux M, Kierzkowski D, Pieper B, Smith RS, Tsiantis M and Hay A (2017) Seasonal Regulation of Petal Number in Cardamine hirsuta. Plant Physiology http://www.plantphysiol.org/content/early/2017/08/31/pp.17.00563/tab-article-info
Monniaux M, McKim SM, Cartolano M, Thévenon E, Parcy F, Tsiantis M and Hay A (2017). Conservation vs divergence in LEAFY and APETALA1 functions between Arabidopsis thaliana and Cardamine hirsuta. New Phytologist. doi:10.1111/nph.14419. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.14419
Houston K*, McKim SM*, Comadran J, Bonar N, Druka I, Uzrek N, Cirillo E, Guzy-Wrobelska J, Collins NC, Halpin C, Hansson M, Dockter C, Druka A, Waugh R (2013) “Variation in the interaction between alleles of HvAPETALA2 and microRNA172 determines the density of grains on the barley inflorescence” Proc Natl Acad Sci U S A. 110: 16675–16680, doi: 10.1073/pnas.1311681110 . *co-first authors. http://www.pnas.org/content/110/41/16675.full
Since joining the university in 2012, I have coordinated and developed public and school engagement activities for the Division of Plant Sciences. We have a strong ethos of science outreach with a very high percentage of people from our division volunteering for events held throughout the past year. Much of our work is done in close association with the University of Dundee Botanic Gardens (http://www.dundee.ac.uk/botanic/) which hosts several free, public annual events including Botany Family Fun Day and Fascination of Plants Day.
A major recent effort of Plant Sciences was the development of our Genetics Garden at the Botanic Gardens. Funded from the College of Life Sciences' BBSRC Excellence with Impact Prize, we mounted three installations in the Genetics Garden to highlight the importance of plants in our understanding of genetics and the critical contribution of plant variation in selecting and breeding better crops. Establishing the Genetics Garden involved a massive volunteer effort of over 40 people, both from Plant Sciences and the James Hutton Institute and culminated in the opening of the garden by eminent scientist Dr. Richard Flavell (http://www.lifesci.dundee.ac.uk/news/2013/aug/20/genetics-garden-be-opened-professor-richard-flavell). More than a stand-alone project, the Genetics Garden now acts as a hub for science engagement activities for the Division.