2018 ASHS Annual Conference

Gerbera daisy is popular for its attractive flowers available in a wide array of colors. It is also used as a model plant to study flower development and secondary metabolites. Genomic and transcriptomic information and resources are very limited in gerbera, due to a number of factors including a large genome size (5.5 Gb) and a high level of heterozygosity. In this study, we sequenced and assembled the leaf transcriptomes of two gerbera breeding lines with a contrasting phenotype in flower color, flower form, peduncle length, and powdery mildew resistance. We used four different de novo transcriptome assembly pipelines: SOAP, Trinity, Velvet, and TransAbyss and produced a composite assembly of the gerbera daisy leaf transcriptome consisting of 145,348 contigs with a N50 value of 1124 nucleotides and a mean contig length of 761 nucleotides. Our experience showed that the use of multiple assemblers significantly improved the quality of the gerbera daisy leaf transcriptome compared to the assembly produced with Trinity alone. When Trinity was used alone, the assembly consisted of 528,630 contigs with a N50 value of 708 nucleotides. Gerbera daisy leaf transcripts showed highest similarities with Helianthus annus and Cynara cardunculus var. scolmus (both belonging to Asteraceae family), with 13,888 and 13,406 gerbera transcripts similar to the genes of the latter two species, respectively. The high quality gerbera daisy leaf transcriptome assembly should facilitate downstream analyses of gerbera transcriptome including transcript quantification, identification of differentially expressed genes, and identification of candidate genes in gerbera resistance to powdery mildew.