Can you do a paternity test on a tree?

eLife features editor SarahShailestook on Michael's seedy question...

Sarah - Yeah, we can actually. Like us, plants do produce children that have a mixture of genes from two parents so in that respect you do maternity/paternity testing. There are a few things that make that quite tricky with plants. So when we do paternity testing in humans we generally have a shortlist of people who could possibly be the father of the child so you are only testing a certain number of people’s DNA. With plants you can’t actually talk to them. Well, you can talk to plants but the don’t necessarily talk back.

Chris - Prince Charles does. He swears by it.

Sarah - I used to sometimes talk to my plants when I was working with them but they don’t generally… I just be looking at them wondering why they weren't being all nice and tidy when I needed them to be. I worked with a plant that crept all over the surfaces because it generally grows across the ground and you’d get tangled and get annoyed with them but they don’t generally answer when you ask them questions.

Chris - … funnily enough. But back to the family tree question then. You were saying that humans have a limited number of potential partners to trawl through but with trees, what are you saying, they’re a bit promiscuous and they’re sort of having sex in the air with so many other possible tree fathers that it’s very hard to work out who the dad is?

Sarah - Yes, exactly. Pollen can travel quite large distances. If you think of trees that are pollinated by insects, a bumble bee can travel a mile so you’d be looking at a whole bunch of trees in a mile radius potentially of the plant you’re interested in. But also seeds can travel quite a long way as well because seeds can survive for a long period of time and they can travel quite big distances.

Chris - Inside birds and things. Because birds will fly off and poop them out somewhere else and a new plant will grow there.

莎拉-是的,你也会携带种子by the wind and all sorts of other ways. So you have a massive pool of potential mothers and fathers to work from. The other problem as well is that a lot of trees produce both pollen and eggs, so they’re both male and female. So even if you have narrowed it down to which plants you’re looking at it’s potentially going to be hard to tell whether they’re male or female.

Although it’s tricky to do maternity/paternity testing it plants, it is possible, especially in orchard situations. So, if you’re growing plants for breeding, you've got a bit better idea of what plants you’ve got in your orchards to do testing with. You can identify the top parents, so they’re the ones producing the best plants that you most interested in. This is also being used for conservation purposes with wild tree populations because you can use it to study how pollen moves and disperses within a wild population.