Regulation Mechanism of MYC Family Transcription Factors in Jasmonic Acid Signalling Pathway on Taxol Biosynthesis

Paclitaxel is an important anticancer drug. The phytohormone jasmonic acid can significantly induce the biosynthesis of paclitaxel in Taxus, but the molecular mechanism has not yet been resolved. To establish the jasmonic acid signalling pathway of Taxus media, based on the gene of the jasmonic acid signalling pathway of Arabidopsis thaliana, sequence analysis was performed to isolate the jasmonic acid signal from the transcriptome, a transcriptional cluster of pathway gene homologs and the full length of 22 genes were obtained by RACE PCR at 5′ and 3′: two EI ubiquitin ligase genes, COI1-1 and COI1-2;7 MYC bHLH type transcription factor (MYC2, MYC3, MYC4, JAM1, JAM2, EGL3, TT8); 12 JAZ genes containing the ZIM domain; and MED25, one of the components of the transcriptional complex. The protein interaction between each were confirmed by yeast two hybridization and bimolecular fluorescence complementation based on similar genes interaction in Arabidopsis. A similar jasmonate signaling pathway was illustrated in T. media. All known paclitaxel biosynthesis genes promoters were isolated by genome walker PCR. To investigate the jasmonate signaling effect on these genes’ expression, the transcription activity of MYC2, MYC3 and MYC4 on these promoters were examined. There are 12, 10 and 11 paclitaxel biosynthesis genes promoters that could be activated by MYC2, MYC3 and MYC4.

Random genomic scans at microsatellite loci for genetic diversity estimation in cold-adaptedLepidium latifolium

Lepidium latifoliumL. (Brassicaceae) grows successfully in a high-altitude cold arid environment. Little molecular data are available for this plant despite its immense ecological importance as a cold- and drought-adapted species. We used a novel approach to identify microsatellite regions using genome walker libraries, called as Random Scans at Microsatellite Regions (RaSMiR), and implemented them on genotypes collected from relatively different topographical conditions within a small geographical area. The success rate of finding a microsatellite sequence using this methodology was 100%, and on developing the RaSMiR technique itself as a molecular marker, 230 electrophoretic bands were obtained using 13 different RaSMiR primers in combination with a microsatellite sequence primer. On an average, 17 bands were obtained for each primer. The electrophoretic profiles generated by RaSMiR markers were distinct from those produced by inter-simple sequence repeat markers. This information has been documented as a dominant marker data, and has been used to construct a neighbour-joining tree that successfully distinguished all genotypes. RaSMiR is an attractive approach for the development of unique and informative microsatellites, or for genome scanning directly as a molecular marker that can potentially be employed for the estimation of genetic diversity or to identify polymorphic loci involved in adaptations particularly in the non-model species, for which sufficient genomic data are not available.