Project description:The study of orchid mycorrhizal interactions is particularly complex because of the peculiar life cycle of these plants and their diverse trophic strategies. Here, large-scale transcriptomics has been applied to investigate gene expression in the mycorrhizal roots of the terrestrial mixotrophic orchid Limodorum abortivum under natural conditions. Our results provide new insights into the mechanisms underlying plant-fungus interactions in orchids and in particular on the plant responses to the mycorrhizal symbiont(s) in adult roots. Comparison with gene expression in mycorrhizal roots of another orchid species, Oeceoclades maculata, suggests that amino acids may represent the main nitrogen source in both protocorms and adult orchids, at least for mixotrophic species. The upregulation, in mycorrhizal L. abortivum roots, of some symbiotic molecular marker genes identified in mycorrhizal roots from other orchids as well as in arbuscular mycorrhiza, suggests a common plant core of genes in endomycorrhizal symbioses. Further efforts will be required to understand whether the specificities of orchid mycorrhiza depend on fine-tuned regulation of these common components, or whether specific additional genes are involved.
Project description:Orchidaceae are renowned for their spectacular flowers as well as other reproductive and ecological adaptations. After the genome of the tropical epiphytic orchid Phalaenopsis equestris was sequenced, we combined Trinity data for de novo assembly and Illumina HiSeq1500 data for RNA-Seq analysis to characterize the transcriptomes of four different organs for a better understanding of the molecular mechanisms driving these characteristics. We present four de novo assembled transcripts reconstructed from RNA collected from the root, stem, leaf, and flower of Phalaenopsis equestris. These sets of transcripts greatly enrich the available data for Phalaenopsis equestris. Here, we present two databases, and each dataset allows for a different type of search for candidate homologues. The first dataset consists of the sets of assembled unigenes, which enable a sequence-based search. A comprehensive analysis of the assembled unigenes revealed the unigenes from root, stem, leaf, and flower with high e-values aligned versus the Nr, Swiss-Port, KEGG, COG, and GO database, respectively. This analysis enabled the production of a second database, which includes sequences correlated with annotated transcript names as well as the confidence of the best hit from BLAST.
