De novo sequencing of Eucommia ulmoides flower bud transcriptomes for identification of genes related to floral development.

Eucommia ulmoides Oliver is a woody perennial dioecious species native to China and has great economic value. However, little is known about flower bud development in this species. In this study, the transcriptomes of female and male flower buds were sequenced using the Illumina platform, a next-generation sequencing technology that provides cost-effective, highly efficient transcriptome profiling. In total, 11,558,188,080 clean reads were assembled into 75,065 unigenes with an average length of 1011 bp by de novo assembly using Trinity software. Through similarity comparisons with known protein databases, 47,071 unigenes were annotated, 146 of which were putatively related to the floral development of E. ulmoides. Fifteen of the 146 unigenes had significantly different expression levels between the two samples. Additionally, 24,346 simple sequence repeats were identified in 18,565 unigenes with 12,793 sequences suitable for the designed primers. In total, 67,447 and 58,236 single nucleotide polymorphisms were identified in male and female buds, respectively. This study provides a valuable resource for further conservation genetics and functional genomics research on E. ulmoides.