Transcription analysis of peloric mutants of Phalaenopsis orchids derived from tissue culture.
Tissue culture has been widely used for mass propagation of Phalaenopsis. However, somaclonal variation occurred during micropropagation process posed a severe problem by affecting product quality. In this study, wild type and peloric flower buds of Phalaenopsis hybrids derived from flower stalk nodal culture were used for cDNA-RAPD and cDNA suppression subtractive hybridization analyses in order to study their genetic difference in terms of expressed sequence tags. A total of 209 ESTs from normal flower buds and 230 from mutants were sequenced. These ESTs sequences can be grouped into several functional categories involved in different cellular processes including metabolism, signal transduction, transcription, cell growth and division, protein synthesis, and protein localization, and into a subcategory of proteins with unknown function. Cymbidium mosaic virus transcript was surprisingly found expressed frequently in the peloric mutant of P. Little Mary. Real-time RT-PCR analysis on selected ESTs showed that in mutant flower buds, a bZIP transcription factor (TGA1a-like protein) was down-regulated, while up-regulated genes include auxin-regulated protein kinase, cyclophilin, and TCP-like genes. A retroelement clone was also preferentially expressed in the peloric mutant flowers. On the other hand, ESTs involved in DNA methylation, chromatin remodeling and post-transcriptional regulation, such as DNA methyltransferase, histone acetyltransferase, ERECTA, and DEAD/DEAH RNA helicase, were enriched in normal flower buds than the mutants. The enriched transcripts in the wild type indicate the down regulation of these transcripts in the mutants, and vice versa. The potential roles of the analyzed transcripts in the development of Phalaenopsis flowers are discussed.
Chen
Ya Huei
YH
Institute of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
Tsai
Yi Jung
YJ
Huang
Jian Zhi
JZ
Chen
Fure Chyi
FC
D018076:DNA, Complementary / Q000235:genetics; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development; D015870:Gene Expression; D009154:Mutation / Q000235:genetics*; D029595:Orchidaceae / Q000235:genetics*; D019105:Random Amplified Polymorphic DNA Technique; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017385:Sequence Homology; D046509:Tissue Culture Techniques; D014158:Transcription, Genetic / Q000235:genetics*
D018076:DNA, Complementary