Establishment of a Genomics Tool in Purslane (Portulaca olerceae) to Identify Novel Genes Benefiting Agriculture, Environments and Human Health

Purslane (Portulaca spp) is a xerophyte that can survive severe drought and heat conditions.  It also displays tolerance to high salinity, heavy metals, and other toxins in soil. In addition, Purslane is considered as consumable vegetable and herbal medicine in many parts of the world. Its shoots and leaves contain an abundance of well-known human health-protective bioactive compounds such as omega-3 fatty acids, and antioxidants. It’s anti-inflammation, anti-obesity and anti-diabetes properties made purslane a powerful functional food or nutritional supplement.  Despite that its novel adaptations to stress, heavy metal tolerance and human health beneficial properties, no genomic information is yet available for Purslane. To establish basic genomics tool, we conducted deep sequencing of whole purslane plant cDNA using the Roche 454 FLX-Ti platform. A total of more than 2 million reads were generated with average read lengths of about 460 bases. Clustering analysis using CLC BIO software generated 13,862 unique contigs with average length of 729 bases. Compared to sequences in public databases using B2G software, 57.7% of contigs showed significant similarity to known proteins, while the rest are unknown.  Biological process of these annotated known genes was analyzed. As an example, we used this genomic information in our purslane arsenic tolerance project, and successfully identified homologs of Arabidopsis arsenic transporter, AtABCC2, from purslane genome, designated as PoABCC2. qRT-PCR analysis of this gene on arsenic tolerant and sensitive purslane accessions indicated that PoABCC2 play significantly different functions in arsenic transportation in Purslane comparing to its counterpart in Arabidopsis.