Genome-wide transcriptome profiling is a powerful tool to study global gene expression patterns in plant development. We report the first transcriptome profile analysis of papaya embryogenic callus to improve our understanding on genes associated with somatic embryogenesis. By using 3' mRNA-sequencing, we generated 6,190,687 processed reads and 47.0% were aligned to papaya genome reference, in which 21,170 (75.4%) of 27,082 annotated genes were found to be expressed but only 41% was expressed at functionally high levels. The top 10% of genes with high transcript abundance were significantly enriched in biological processes related to cell proliferation, stress response, and metabolism. Genes functioning in somatic embryogenesis such as SERK and LEA, hormone-related genes, stress-related genes, and genes involved in secondary metabolite biosynthesis pathways were highly expressed. Transcription factors such as NAC, WRKY, MYB, WUSCHEL, Agamous-like MADS-box protein and bHLH important in somatic embryos of other plants species were found to be expressed in papaya embryogenic callus. Abundant expression of enolase and ADH is consistent with proteome study of papaya somatic embryo. Our study highlights that some genes related to secondary metabolite biosynthesis, especially phenylpropanoid biosynthesis, were highly expressed in papaya embryogenic callus, which might have implication for cell factory applications. The discovery of all genes expressed in papaya embryogenic callus provides an important information into early biological processes during the induction of embryogenesis and useful for future research in other plant species.
The PI3K-Akt-mTOR, Wnt/β-catenin and apoptosis signaling pathways have been shown to be involved in genesis of colorectal cancer (CRC). The aim of this study was to elucidate whether combination of Gelam honey and ginger might have chemopreventive properties in HT29 colon cancer cells by modulating the mTOR, Wnt/β-catenin and apoptosis signaling pathways. Treatment with Gelam honey and ginger reduced the viability of the HT29 cells dose dependently with IC50 values of 88 mg/ml and 2.15 mg/ml respectively, their while the combined treatment of 2 mg/ml of ginger with 31 mg/ml of Gelam honey inhibited growth of most HT29 cells. Gelam honey, ginger and combination induced apoptosis in a dose dependent manner with the combined treatment exhibiting the highest apoptosis rate. The combined treatment downregulated the gene expressions of Akt, mTOR, Raptor, Rictor, β-catenin, Gsk3β, Tcf4 and cyclin D1 while cytochrome C and caspase 3 genes were shown to be upregulated. In conclusion, the combination of Gelam honey and ginger may serve as a potential therapy in the treatment of colorectal cancer through inhibiton of mTOR, Wnt/β catenin signaling pathways and induction of apoptosis pathway.