The Generation Gap - Mechanisms of maternal control on grain
Lead Research Organisation:
James Hutton Institute
Department Name: Cell & Molecular Sciences
Abstract
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Technical Summary
This proposal investigates the contribution of pre- and post-fertilisation developmental events in maternal tissues to grain development in barley. We build on our recent discovery that two transcription factors in barley, HvAP2 and HvMADS29, control grain size and shape, and regulate the growth, differentiation and/or death of the hull and ovary tissues. Here, we will evaluate a potential mechanistic relationship of maternal regulators to coordinate tissue growth and survival in the grain.
We hypothesise that tissue transcriptomes will reflect this relationship and predict that these are responsive to regulation by HvAP2 and HvMADS29. To test this prediction we will define, for the first time, cell-specific transcriptomes within pre- and post-fertilisation cereal ovaries by single cell RNAseq (scRNAseq) and computational clustering to build cell populations with similar transcriptomic states and analyse how these states change over time and in response to loss of HvAP2 or HvMADS29 function. Furthermore, we will exploit a heat-inducible Cre-lox gene expression system to restore maternal regulators at specific developmental stages in loss of function mutants to assess responses in the grain size and shape and in cell-specific transcriptomes.
We also hypothesise that grain shape differences in wild compared to cultivated barley may reflect altered maternal tissue developmental processes. We will explore this idea by characterising maternal tissue development by histology approaches followed by scRNAseq on wild barley tissues. Comparative analyses with cultivated grain will reveal conserved and diverged developmental transcriptomic trajectories which may contribute to differences in wild compared to cultivated grain. We will select diverse allelic variation in wild maternal tissue regulators and assess their function in cultivated germplasm by accelerating introgression lines.
We hypothesise that tissue transcriptomes will reflect this relationship and predict that these are responsive to regulation by HvAP2 and HvMADS29. To test this prediction we will define, for the first time, cell-specific transcriptomes within pre- and post-fertilisation cereal ovaries by single cell RNAseq (scRNAseq) and computational clustering to build cell populations with similar transcriptomic states and analyse how these states change over time and in response to loss of HvAP2 or HvMADS29 function. Furthermore, we will exploit a heat-inducible Cre-lox gene expression system to restore maternal regulators at specific developmental stages in loss of function mutants to assess responses in the grain size and shape and in cell-specific transcriptomes.
We also hypothesise that grain shape differences in wild compared to cultivated barley may reflect altered maternal tissue developmental processes. We will explore this idea by characterising maternal tissue development by histology approaches followed by scRNAseq on wild barley tissues. Comparative analyses with cultivated grain will reveal conserved and diverged developmental transcriptomic trajectories which may contribute to differences in wild compared to cultivated grain. We will select diverse allelic variation in wild maternal tissue regulators and assess their function in cultivated germplasm by accelerating introgression lines.
