Transcriptome Sequencing Determined Flowering Pathway Genes in Aechmea fasciata Treated with Ethylene

Aechmea fasciata is a well-known ornamental flowering plant in the bromeliad family. It is proposed that a small burst of ethylene synthesis in the meristem triggers flowering in pineapple and other bromeliads in response to diverse environmental and endogenous signals. A. fasciata showed an age-dependent response: adult plants were induced to flower successfully under ethylene treatment but juvenile plants did not. To better understand the mechanism of different responses to ethylene in transcriptome and flowering induction by ethylene, we performed a comparative analysis of A. fasciata transcriptome. Four libraries of A. fasciata adult and juvenile plants under water and ethylene treatment were sequenced by Illumina deep sequencing, 55,238,936, 53,797,292, 53,471,812, and 53,485,862 qualified Illumina clean reads, respectively, with 90 bp mean length, respectively. Unigenes of the four libraries were assembled and then merged into an unified library with 86,609 sequences and a mean size of 987 bp. After searching against Nr, KEGG, Swiss-Prot, and COG databases, 28,350 sequences were assigned to 129 KEGG pathways, 28,289 unigenes were categorized into 64 functional groups, and 19,293 sequences were classified into 25 COG categories. Through differential expression analysis, 56 DEGs related to flowering were identified. The critical genes correlated with flowering were selected and confirmed by qRT-PCR analysis. This study provided a global survey of changes in transcriptomes of A. fasciata in response to ethylene. The analyses of transcriptome profiles imply that FT is upregulated in the adult plant and results in flowering. Moreover, the differential expression of GI, DELLA, GAD1, AP2, and so on indicated that a complicated network participated in the induction of flowering by ethylene, which will help in the future studies.