Abstract Detail


Burr, Audrey A. [1], Anneberg, Thomas [2], Ashman, Tia-Lynn [1], Turcotte, Martin [1].

Neopolyploid and diploid duckweed fitness converge under heavy metal pollution.

Polyploidy is ubiquitous throughout the tree of life, yet the mechanisms surrounding polyploid establishment remain unclear. Increased stress tolerance has long been postulated as a niche-differentiating mechanism to alleviate competition between nascent polyploids, or “neopolyploids”, and their diploid progenitors. In fact, established polyploids are often found in abiotically more stressful environments that presumably would preclude colonization by their diploid progenitors, including high salinity, harsh temperatures, and high altitudes. With the advent of the Anthropocene, heavy metal pollution has become increasingly common and can have damaging effects on plant health including growth inhibition, reduction in nutrient uptake, and oxidative stress. Yet, it is unclear if neopolyploidy can confer enhanced heavy metal stress tolerance.
Plant species vary greatly in both their tolerance and ability uptake and store heavy metals. Highly metal tolerant plants with large capacities to store metals in their tissues are known as hyperaccumulators and can be employed to remove heavy metal contaminants from polluted environments. One method of heavy metal removal is phytoextraction where plants uptake metals from their environment and are then harvested allowing for safe disposal of non-biodegradable contaminants. It is currently unknown if polyploidy can improve the ability of plants to act as phytoremediators.
Here we use the Greater Duckweed, Spirodela polyrhiza, a small, aquatic, diploid plant commonly used as a phytoremediator, to test 1) if diploid and synthetic neotetraploid multi-generational fitness differs across a gradient of heavy metal pollution, and 2) if heavy metal uptake differs between diploids and neotetraploids. We tested these hypotheses in a growth chamber experiment using six independent, synthetic neotetraploid lineages generated from six diploid genotypes of S. polyrhiza. Diploids and neotetraploids from each lineage were exposed to six concentrations of either cadmium, copper, zinc, or a control with no metal, and were allowed to grow for twelve days before harvesting (approximately 3-4 generations). We selected these metals because they are common pollutants that differ in their toxicity and represent both essential and non-essential metals.
Preliminary results indicate that diploids have faster population growth rates in benign conditions, but high levels of heavy metal pollution cause the growth rates of neopolyploids and their diploid ancestors to converge, although the strength of this trend depends on the type of metal and genetic lineage. These findings imply that neotetraploid S. polyrhiza have greater heavy metal tolerance relative to their diploid progenitor. We will further investigate metal tolerance and uptake capacity in neotetraploids using inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS analysis will allow us to compare neopolyploid and diploid duckweed’s ability to remove metals from the environment and concentrate them in their tissues. We assess these results in the context of bioremediation to explore the effect of neopolyploidy on the capacity for duckweed to act as wastewater phytoremediators.

1 - University of Pittsburgh, Biological Sciences, 4249 Fifth Ave, Pittsburgh, PA, 15260, USA
2 - University of Pittsburgh, Biological Sciences, 4249 Fifth Ave, Pittsburgh, PA, 15260, United States

whole genome duplication
Heavy Metal

Presentation Type: Oral Paper
Number: EC07005
Abstract ID:740
Candidate for Awards:None

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