Polyploid Plants Become Generalists by Developing Differently than Their Parents

Researchers have found that polyploid plant offspring tend to have different features than their parents, potentially making them more adaptable to ecological changes. The findings are in a paper just published in the journal Nature Plants.

Humans, along with most animals, are diploids. Diploid organisms inherit two sets of chromosomes (and therefore two copies of every gene) from each parent. Polyploid organisms, on the other hand, inherit three or more sets of chromosomes. Polyploidy is uncommon in eukaryotes but there are many polyploid plants. Polyploid plants tend to produce hybrids but unlike animal hybrids, these hybrids are fertile.

Researchers from the School of Biological and Chemical Sciences at the Queen Mary University of London studied flowering plants in the genus Nicotiana. Plants in the Nicotiana genus, which includes tobacco plants, are polyploids. The team compared flower shapes of offspring plants to their parents. They measured the corolla tube, a set of fused petals that forms a long structure and increases pollinator contact. The researchers measured the length of the tube as well as the shape of the petals and opening.

The researchers found that the offspring plants had different morphology than their parents. The length of the corolla tube and the size of the opening varied. The tube opening was generally significantly shorter or wider than the parents’. The researchers speculate that this would allow for a separate set of pollinator species to enter the flower opening. By attracting a different set of pollinators, the flowers could adapt to a changing environment. If the plants became too specialized, they would run into trouble if the necessary pollinator animal went extinct.

The problem with a specialist strategy for pollination is that if the pollinator species disappears, the plant can’t be pollinated at all. Polyploid plants in the Nicotiana genus avoid this issue by developing differently than their parents. By adapting the size of their corolla tube opening, Nicotiana plants attract a greater variety of pollinator species and become less vulnerable to extinction.

REFERENCE

Elizabeth W. McCarthy et al. Transgressive phenotypes and generalist pollination in the floral evolution of Nicotiana polyploids. Nature Plants (2016).

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