Genomic Regulation of Seed Development in Brassica

Programmed seed development and maturation underlies consistent yield and quality of Brassica  oilseed crops.  Although the close relative Arabidopsis has provided considerable information about components of such networks, many of the processes occurring during seed development remain to be established. Progress has been confounded by the complexity of seed development, which consists of intricate regulatory networks involving transcriptional, post-transcriptional, translational, post-translational and signalling events in distinct cell and tissue types that change over time. 

Due to their relative size, Brassica seeds have considerable advantages over Arabidopsis, so that the component tissues of integument, embryo and endosperm may be dissected for molecular profiling with relative ease.

We have established that strong parent-of-origin effects have consequences for seed development in Brassica, with a triploid block due to lethal disruption of endosperm development confined to paternal excess. In contrast, maternal excess generates viable seed. Transcriptome analyses demonstrate conservation of some mechanisms controlling aspects of endosperm behaviour in both Arabidiopsis and Brassica oleracea.

We have established a consistent time-line for the early stages of B. rapa.  seed development. This enabled us to characterise by deep sequencing the snRNA and mRNA transcriptomes at two key stages of development, representing the phase change from morphogenetic to biosynthetic program. Identifying snRNA:mRNA differentially expressed pairs provides a baseline for exploring  the role of snRNAs in key regulatory, biochemical and metabolic pathways affecting seed development. We are now combined this information with comparative genome profiling of epigenetic marks at corresponding stages of development in seed and pericarp.