Abstract
The Phalaenopsis orchid is an important potted flower of high economic value around the world. We report the 3.1 Gb draft genome assembly of an important winter flowering Phalaenopsis ‘KHM190’ cultivar. We generated 89.5 Gb RNA-seq and 113 million sRNA-seq reads to use these data to identify 41,153 protein-coding genes and 188 miRNA families. We also generated a draft genome for Phalaenopsis pulcherrima ‘B8802,’ a summer flowering species, via resequencing. Comparison of genome data between the two Phalaenopsis cultivars allowed the identification of 691,532 single-nucleotide polymorphisms. In this study, we reveal that the key role of PhAGL6b in the regulation of labellum organ development involves alternative splicing in the big lip mutant. Petal or sepal overexpressing PhAGL6b leads to the conversion into a lip-like structure. We also discovered that the gibberellin pathway that regulates the expression of flowering time genes during the reproductive phase change is induced by cool temperature. Our work thus depicted a valuable resource for the flowering control, flower architecture development, and breeding of the Phalaenopsis orchids.
Highlights
Phalaenopsis is a genus within the family Orchidaceae and comprises approximately 66 species distributed throughout tropical Asia (Christenson, 2002)
We further examined the expression of PhAGL6b and its alternatively spliced forms in the labellum organs of Phalaenopsis plants with different big lip phenotypes and wild-type plants via realtime PCR (Appendix S1, Table S11)
The genes included in the flowering promotion pathways and floral pathway integrators were generally upregulated in BL (Figs. 5 and 6; Data S11). These findings suggest that the GA pathway may play a crucial role in the regulation of flowering time in Phalaenopsis orchid during cool temperature
Summary
Phalaenopsis is a genus within the family Orchidaceae and comprises approximately 66 species distributed throughout tropical Asia (Christenson, 2002). The predicted Phalaenopsis genome size is approximately 1.5 gigabases (Gb), which is distributed across 19 chromosomes (Lin et al, 2001). Phalaenopsis flowers have a zygomorphic floral structure, including three sepals (in the first floral whorl), two petals and the third petal develops into a labellum in early stage of development, which is a distinctive feature of a. How to cite this article Huang et al (2016), The genome and transcriptome of Phalaenopsis yield insights into floral organ development and flowering regulation. In the ABCDE model, B-class genes play important role to perianth development in orchid species (Chang et al, 2010; Mondragon-Palomino & Theissen, 2011; Tsai et al, 2004). The relationship between the function of genes involved in floral-organ development and morphological features remains poorly understood
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