Jumping genes!

This spring, I noticed this striped flower in a stand of feral Hesperis matronis
hesperistransposonStripey flowers! And like almost all striped flower variants, almost certainly caused by transposons, aka jumping genes.

To understand transposons, you can think of genes as instructions. So when making a flower, a plant may be following a gene that says:

MAKE PURPLE PIGMENT

And so it does, and the flower is purple.

You can think of a transposon as a gene that says:

COPY ME!

And so the cell makes a copy of the transposon, and then that copy gets dropped somewhere else in the genome. And sometimes, that new copy of the transposon lands in the middle of a gene that does something important. Like, for example, a gene involved in pigment production. So you get this:

MAKE PUR COPY ME! LE PIGMENT

Which doesn’t make any sense. So now the gene for making the purple pigment doesn’t work. And if that happens in a cell in a flower petal, that part of the flower will be white. And as that cell divides, the new cells resulting from it will also have the transposon in place, making more white cells, producing a white patch or stripe in the flower.

When transposons were first discovered in corn by the great geneticist Barbara McClintock, they were thought to be an oddity, something unusual. As we’ve learned more, it turns out they are ubiquitous. Some 40% of the human genome is thought to be transposons. Usually they are invisible, and have been silenced to prevent their moving around and disrupting other genes. But sometimes they pop up in a flower and make themselves visible, in a beautiful, interesting way.

Joseph Tychonievich

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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

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