title: A de novo floral transcriptome reveals clues into Phalaenopsis orchid flower development.
abstract: Phalaenopsis has a zygomorphic floral structure, including three outer tepals, two lateral inner tepals and a highly modified inner median tepal called labellum or lip; however, the regulation of its organ development remains unelucidated. We generated RNA-seq reads with the Illumina platform for floral organs of the Phalaenopsis wild-type and peloric mutant with a lip-like petal. A total of 43,552 contigs were obtained after de novo assembly. We used differentially expressed gene profiling to compare the transcriptional changes in floral organs for both the wild-type and peloric mutant. Pair-wise comparison of sepals, petals and labellum between peloric mutant and its wild-type revealed 1,838, 758 and 1,147 contigs, respectively, with significant differential expression. PhAGL6a (CUFF.17763), PhAGL6b (CUFF.17763.1), PhMADS1 (CUFF.36625.1), PhMADS4 (CUFF.25909) and PhMADS5 (CUFF.39479.1) were significantly upregulated in the lip-like petal of the peloric mutant. We used real-time PCR analysis of lip-like petals, lip-like sepals and the big lip of peloric mutants to confirm the five genes' expression patterns. PhAGL6a, PhAGL6b and PhMADS4 were strongly expressed in the labellum and significantly upregulated in lip-like petals and lip-like sepals of peloric-mutant flowers. In addition, PhAGL6b was significantly downregulated in the labellum of the big lip mutant, with no change in expression of PhAGL6a. We provide a comprehensive transcript profile and functional analysis of Phalaenopsis floral organs. PhAGL6a PhAGL6b, and PhMADS4 might play crucial roles in the development of the labellum in Phalaenopsis. Our study provides new insights into how the orchid labellum differs and why the petal or sepal converts to a labellum in Phalaenopsis floral mutants.
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Jian-Zhi
authors.initials: JZ
authors.lastname: Huang
authors.affiliation: Yourgene Bioscience, Shu-Lin District, New Taipei City 23863, Taiwan; Department of Biotechnology, School of Health Technology, Ming Chuan University, Gui Shan District, Taoyuan 333, Taiwan.
authors.forename: Chih-Peng
authors.initials: CP
authors.lastname: Lin
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Ting-Chi
authors.initials: TC
authors.lastname: Cheng
authors.affiliation: Yourgene Bioscience, Shu-Lin District, New Taipei City 23863, Taiwan; Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Bill Chia-Han
authors.initials: BC
authors.lastname: Chang
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Cheng
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Lee
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Shih-Wen
authors.initials: SW
authors.lastname: Chin
authors.affiliation: Department of Plant Industry, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Fure-Chyi
authors.initials: FC
authors.lastname: Chen
mesh_terms: D020451:Contig Mapping; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D059014:High-Throughput Nucleotide Sequencing; D058977:Molecular Sequence Annotation; D009154:Mutation; D029595:Orchidaceae / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D009928:Organ Specificity; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D010940:Plant Proteins