DE NOVO TRANSCRIPTOME RECONSTRUCTION OF A THERMO-SENSITIVE MALE STERILITY MUTANT IN RAPESEED (BRASSICA NAPUS; BRASSICACEAE)

Premise of the study: SP2S is a spontaneous thermo-sensitive genic male sterility (TGMS) mutation that facilitates two-line hybrid breeding in Brassica napus (Brassicaceae). De novo assembly of the floral bud transcriptome of SP2S can provide a foundation for deciphering the transcriptional regulation of SP2S in response to temperature change. Methods: mRNAs of the young floral buds of SP2S and its near-isogenic line SP2F grown under cool (16 degrees C)/ warm (22 degrees C) conditions were sequenced on an Illumina Solexa platform, producing 239.7 million short reads with a total length of 19.95 Gbp. Results: The reads were assembled de novo using the Trinity program, resulting in 135,702 transcripts with an average length of 784 bp, an N50 value of 1221 bp, and a total length of 107 Mbp. We identified 24,157 cDNA-derived simple sequence repeats in the assembly. We found 137 and 195 single-nucleotide polymorphisms and 49 and 51 differentially regulated KEGG orthology groups when comparing sample SP2S at 22 degrees C vs. SP2S at 16 degrees C and sample SP2S at 22 degrees C vs. SP2F at 22 degrees C, respectively. Discussion: The numerous differentially expressed genes and the derived single-nucleotide polymorphisms show abnormal transcriptional regulation in the TGMS system. These results outline an intricate transcriptional regulation that occurred in the rapeseed TGMS SP2S when the temperature changed.