Researchers report cell-to-cell movement of mitochondria through a graft junction of two plant species

March 8, 2016 by Bob Yirka, Phys.org report

Mitochondria. Credit: Wikipedia commons
(Phys.org)—A team of researchers with Rutgers University has found an example via experimentation, of cell-to-cell movement of mitochondria through a graft junction of two tobacco species. In their paper published in Proceedings of the National Academy of Sciences, the team describes their experiments with grafting tobacco plants and what they learned about cells swapping mitochondria during the aftermath.

Human beings have been grafting for centuries, cutting a branch from one plant and pressing it against an exposed part of another has resulted in fruit trees that bear more than one type of fruit, for example. But, what has not been clear is what else happens during grafting—to the human eye it appears a grafted branch produces the type of fruit it originally would have, but not much else. But genetic research over the past decade has shown that chloroplasts can be exchanged between cells on either side of a graft, and in some cases an entire cell nucleus can be exchanged as well. In this new effort, the researchers have found that cells can exchange also which means that plants mix their DNA together when grafting takes place.

To find out more about what happens during grafting the researchers grafted one species of tobacco plant onto another, one of which had a mutation that prevented male flowers from growing in a normal way. Next, they sliced off pieces of the plant from the side of the graft that had come from a male sterile plant and planted it resulting in new plants growing individually from the ground. As those plants grew, the researchers found that some of them developed normal male flowers, which showed that mitochondrial transfer had occurred between the two species. When the team looked at the mitochondrial genomes of the plants, they found recombination of the two and were also able to identify the gene that was likely responsible for the male sterility.

This new evidence blurs the line between genetically modified plants, or crops that come about due to man-made processes and those that occur naturally, because natural grafting sometimes occurs when two plants grow close to one another. Those who insist that GMOs are harmless will now have another argument to back them up because it now appears that plants have been swapping DNA naturally all along.

Explore further: Can trees really change sex?

More information: Csanad Gurdon et al. Cell-to-cell movement of mitochondria in plants, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1518644113

Abstract
We report cell-to-cell movement of mitochondria through a graft junction. Mitochondrial movement was discovered in an experiment designed to select for chloroplast transfer from Nicotiana sylvestris into Nicotiana tabacum cells. The alloplasmic N. tabacum line we used carries Nicotiana undulata cytoplasmic genomes, and its flowers are male sterile due to the foreign mitochondrial genome. Thus, rare mitochondrial DNA transfer from N. sylvestris to N. tabacum could be recognized by restoration of fertile flower anatomy. Analyses of the mitochondrial genomes revealed extensive recombination, tentatively linking male sterility to orf293, a mitochondrial gene causing homeotic conversion of anthers into petals. Demonstrating cell-to-cell movement of mitochondria reconstructs the evolutionary process of horizontal mitochondrial DNA transfer and enables modification of the mitochondrial genome by DNA transmitted from a sexually incompatible species. Conversion of anthers into petals is a visual marker that can be useful for mitochondrial transformation.

Related Stories

Can trees really change sex?

November 5, 2015

The revelation that the UK's oldest tree is showing signs of switching sex has sparked much excitement in the world of horticultural science. The Fortingall yew (main image) in Perthshire, Scotland, having apparently spent ...

Grafted plants' genomes can communicate with each other

January 19, 2016

Agricultural grafting dates back nearly 3,000 years. By trial and error, people from ancient China to ancient Greece realized that joining a cut branch from one plant onto the stalk of another could improve the quality of ...

Making new species without sex

June 10, 2014

Occasionally, two different plant species interbreed with each other in nature. This usually causes problems since the genetic information of both parents does not match. But sometimes nature uses a trick. Instead of passing ...

Grafted watermelon plants take in more pesticides

January 25, 2012

The widely used farm practice of grafting watermelon and other melon plants onto squash or pumpkin rootstocks results in larger amounts of certain pesticides in the melon fruit, scientists are reporting in a new study. Although ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

fidh
5 / 5 (2) Mar 08, 2016
Interesting subject I hadn't heard of before. Definitely going to waste the rest of my day reading more about it.
Though, I'm pretty sure there isn't that much objections againt GMOs themselves/the concept, just how it's done currently and how it has spread from plants to shrimp to etc.
By the way, I've no opinion of GMOs, just pointing out what I have read before.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.