Supervisor
Dr Madelaine Bartlett
Project Summary
Floral sexuality is diverse in the grasses. While many grasses have bisexual flowers, unisexual flowers have evolved many times, including in a lineage leading to maize. In this project, the student will investigate the genetic underpinnings of floral unisexuality in maize. Differential organ suppression drives the development of unisexual maize flowers. Carpels, which develop into fruits after fertilization, normally produce ovules which contain the egg cell. In staminate flowers of the maize tassel, carpel development is suppressed; carpels eventually undergo programmed cell death. This project is focused on identifying the genetic underpinnings of this carpel suppression, using maize as an experimental system.
This work has important translational consequences. Maize is one of more than twenty food crops in the grass subfamily Panicoideae, many of which are climate-resilient, but have not been subject to the intensive breeding that has so drastically improved maize yield. In all panicoid grasses, carpels are suppressed in at least half of all flowers. Only flowers that produce carpels can produce fruits (called grains in the grasses), thus carpel suppression reduces potential crop productivity. It is likely that the genes that regulate carpel suppression in maize also do so in other panicoids, and present promising translational targets for crop improvement using genome editing.
What will the successful applicant do?
The student will use genomic techniques to identify the genes disrupted in novel carpel suppression mutants generated by the Bartlett lab, and will determine how these genes act to control floral development. The student will use classical genetic techniques, molecular biology, microscopy, and quantitative phenotyping to determine how these novel genes interact with known developmental pathways to suppress carpel development and generate unisexual maize flowers.
References
Gallagher JP, Man J, Chiaramida A, Rozza I, Patterson E, Powell M, Schrager-Lavelle A, Multani D, Habben J, and Bartlett ME (2023). Duplicate transcription factors GT1 and VRS1 regulate branching and fertile flower number in maize and Brachypodium distachyon. PNAS. DOI: 10.1073/pnas.2311961120
Klein H, Gallagher J, Demesa-Arevalo E, Abraham-Juárez MJ, Heeney M, Feil R, Lunn JE, Xiao Y, Chuck G, Whipple C, Jackson, DJ, Bartlett, ME (2022). Recruitment of an ancient branching program to suppress carpel development in maize flowers. PNAS. DOI:10.1073/pnas.2115871119