Big data from small tissues: extraction of high-quality RNA for different plant tissue types during oilseed Brassica spp. seed development for RNA-Sequencing

Obtaining high-quality RNA for gene expression analyses from different seed tissues is challenging due to the presence of various contaminants, such as polyphenols, polysaccharides and lipids which interfere with RNA extraction methods. At present, the available protocols for extracting RNA from seeds require high amounts of tissue and are mainly focused on extracting RNA from whole seeds. However, extracting RNA at the tissue level enables more detailed studies regarding tissue specific transcriptome during development. Seeds from heart stage embryo to mature developmental stages of Brassica napus and B. oleracea were sampled for isolation of the embryo, endosperm and seed coat tissues. Ovules and gynoecia wall tissue were also collected at the pre-fertilization stage. After testing several RNA extraction methods, E.Z.N.A. Plant RNA Kit and Picopure RNA Isolation kit extraction methods with some modifications, as well as the use of PVPP for seed coats and endosperms at green stages, resulted in high RNA concentrations with clear 28S and 18S bands and high RIN values. Here, we present efficient and reliable RNA extraction methods for different genotypes of Brassica spp for different tissue types during seed development. The high-quality RNA obtained by using these methodologies is suitable for RNA-Sequencing and gene expression analyses.