Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Leung, Amy Wing-Sze [1], Kim, Sangtae [2], Lim, Boon Leong [1], Saunders, Richard Mark Kingsley [1].

Transcriptome profiling of Desmos chinesis: Revealing the molecular basis of dipartite perianth evolution in the early-divergent angiosperm family Annonaceae.

While many angiosperm taxa experienced genome duplication and different degrees of transposable element proliferation, the homeotic control of floral development has remained conservative. The MIKC-type MADS-domain proteins are transcription factors that dictate organ identity during floral organogenesis. The classic “ABCDE” MADS-box gene expression model proposed for the core eudicots is not fully applicable to early-divergent angiosperms, in which a gradual transition of floral organ morphology is observed, leading to the proposed “fading-borders” expression model. Flowers in the Annonaceae deviate from other early-divergent angiosperms in possessing a distinctive dipartite perianth. Petals in the Annonaceae (‘bracteopetals’) have furthermore presumably evolved independently from andropetals in core eudicots. The degree of differentiation of petals from sepals in Annonaceae flowers is generally of functional significance (e.g., enabling the evolution of largely or fully enclosed pollination chambers during anthesis). Little is known of the genetic control of floral development in the Annonaceae. The application of massive parallel sequencing techniques such as RNAseq provides opportunities to profile the transcriptomes of non-model organisms. In addition to a developmental study, we characterized the floral and leaf transcriptome of Desmos chinensis, a representative of the Annonaceae that possesses a dipartite perianth and which shares the basic floral Bauplan of the family, in order to understand the genetics of its floral development. Transcriptomes of developing and mature Desmos chinensis floral organs and leaves were sequenced using the high-throughput Illumina sequencing platform. After filtering, 16,098 genes and 22,112 transcripts were recovered from de novo assembly. We identified possible coding regions and compared the assembled transcripts against five public databases. Based on sequence homology against NCBI non-redundant protein database, transcripts were annotated with 3,991 unique gene ontology (GO) terms and categorized into functional groups. Functional group enrichment analysis was used to identify groups with significant expression level changes during organ development. Transcripts that are commonly differentially expressed among developing and mature floral organs and leaves were identified using the digital gene expression data. We identified 40 putative homeotic MADS-box gene homologs and their respective expression levels in order to determine whether Annonaceae flowers are consistent with the MADS-box gene “fading borders” expression model. Other floral developmental regulators of Desmos chinensis were also discovered. While many questions remain unresolved at the transcription level, our data emphasizes the importance and potential of extending further studies into systems biology, and help understand floral developmental biology as biological networks.

1 - The University of Hong Kong, School of Biological Sciences, Hong Kong, China
2 - Sungshin Women's University, Department of Biology, Seoul, Republic of Korea

Keywords:
Transcriptomics
RNAseq
Annonaceae
Dipartite perianth evolution
gene expression.

Presentation Type: Oral Paper
Session: 34, Evo-Devo
Location: Sundance 2/Omni Hotel
Date: Wednesday, June 28th, 2017
Time: 8:00 AM
Number: 34001
Abstract ID:103
Candidate for Awards:Katherine Esau Award