The few-celled microspore embryo transcriptome of Brassica napus

Haploid embryos can be induced from cultured immature pollen following a stress treatment. In Brassica napus (B. napus), application of the histone/lysine deacetylase (HDAC/KDAC) inhibitor trichostatin A (TSA) to pollen cultures enhances the production of differentiated embryos and embryogenic callus when applied together with heat stress (Li et al., 2014). To identify genes associated with the induction of B. napus haploid embryogenesis, we employed fluorescence-activated cell sorting on microspore cultures of the LEAFY COTYLEDON1 embryo reporter line (LEC1:LEC1-GFP, Li et al., 2014) to select for embryogenic structures developing in culture, followed by RNA-sequencing. Our transcriptome analysis of the 3-day-old enriched embryo populations and in vitro cultured pollen revealed different regulatory pathways underlying the early development of embryogenic structures. Comparing FACS-sorted embryogenic transcriptomes from cultures treated with heat stress combined with either a low or a high concentration of TSA allowed us to assign transcription profiles to embryogenic structures that have a low or high potential to develop into histodifferentiated embryos. 10 samples were analyzed (3 different treatments). For each condition, three or four biological replicates were analyzed (1 genotype)