Analysis of Floral Transcriptomes of Lonicera macranthoides ‘Jincuilei' and Its Wild Type

Lonicera macranthoides ‘Jincuilei’ is a mutant producing abundant flower buds that never open, and chlorogenic acid (CGA) content in flower buds reaches up to 6.0%. Its wild type produces open flowers with CGA content less than 4.5%. As a step toward elucidating molecular mechanisms underlying the flower bud non-openness and high CGA biosynthesis, this study compared transcriptomes of flower buds at three developmental stages of ‘Jincuilei’ with those in its wild type using Illumina HiSeq^TM 2000 sequencing system. A total of 69,256,202 sequencing reads corresponding to 5.75 Gb nucleotides were obtained. These reads were assembled into 74,057 sequences, of which 51,038 were homologous with other sequences in DNA database. Whereas 23,019 were unigenes suggesting that these sequences could be specific to L. macranthoides. Using multiple functional classification systems (COG and GO), these sequences could be categorized into 25 or 47 functional groups including energy production and conversion, signal transduction, transcription and translation regulation, and flower development. Comparing the expression level of sequences at different flower developmental stages within a cultivar and/or between cultivars, we found that 510 sequences were down-regulated at least 10 folds and 623 were up-regulated more than 10 folds, of which 154 were probably related to specific flower organ development. To our knowledge, this is the first comprehensive sequence resource available for L. macranthoides, which will permit isolation and characterization of genes related to flower development and CGA biosynthesis in L. macranthoides, an important traditional Chinese medicinal plant.