Genetic variation of copper stress tolerance and shoot copper accumulation in Purslane (Portulaca oleracea)

Urban agriculture becomes popular in the United States due to the increasing demands of local foods. However, many urban lands are potentially contaminated by various heavy metals, such as copper, due to human activities and historic use of the lands. These potential contaminations brought up major safety concerns on consumption of the urban produce. Identifying new species or varieties within the species that tolerate heavy metals and accumulate less in their edible part is the key to urban agriculture. Purslane (Portulaca oleracea) is considered as the power food of the future due to its high nutritional properties. In this report, we examined the effects of copper stress on seed germination, seedling development and plant growth, as well as genetic diversity of copper accumulation in its edible part among purslane accessions collected from geographically diverse regions. High concentration of CuSO4 does not affect seed germinations for most of accessions except Tokombia and Egypitum. However, inhibition of hypocotyl elongation by copper stress is dose dependent suggesting that it could be a better trait to quantify copper tolerance at germination stage. The copper tolerance of purslane at adult stage is different from that of germination stage. Three purslane accessions, Egypitum, Golden T and Tokombia, showed increased shoot biomass production, while two of these, Egypitum and Golden T, also had an increased root biomass by 600 ppm CuSO4 treatment compared to the control. Genetic variation in copper accumulation in shoots does exist with accessions Egyptium, Eritrea, Tokombia and Turkey accumulating significant less copper in their edible parts. Our results suggest that some purslane accessions have potential to be used in Urban Agriculture to produce safe products for human consumption. © 2019 Bio Tech System.