Phytochromes: the most important twitch on the planet – Audio
Phytochromes helping plants use light
Richard Vierstra, Professor
Department of Genetics
UW-Madison College of Agricultural and Life Sciences
vierstra@wisc.edu
(608) 262-8215, (608) 262-0307
3:03 – Total Time
0:16 – A definition of phytochromes
0:44 – How phytochromes work
1:05 – How plants interpret light
1:29 – What is shade avoidance
1:50 – Managing plants for higher yields
2:04 – What a new corn field will look like
2:54 – Lead out
TRANSCRIPT
Sevie Kenyon: Rick, can you tell us what this molecule is that you work with?
Richard Vierstra: I work on this amazing photoreceptor that’s called phytochrome, and plants have really adopted great ways for them to live and grow in a light environment. So they know when spring comes, when summers around, and eventually when fall, so they know when to germinate, grow, flower, and eventually die; so they attrain all this to the light environment, using these amazing photoreceptors.
Sevie Kenyon: And Rick, can you tell us what goes on at that point in the plant?
Richard Vierstra: Phytochromes, what they have, is they have a pigment inside them. And so when that pigment absorbs light it twitches, and I would argue this is probably the most important twitch on the planet. Because when that twitch happens, plants turn green. They germinate, they become photosynthetic, they flower, and eventually they senesce.
Sevie Kenyon: So what are these molecules actually doing?
Richard Vierstra: It is a ripple effect upon this twitch that tells the plant that the light’s on or the light’s off. It can also tell the plant how long the light’s been on, it can tell the plant how long the light’s been off, and it can also tell the plant whether it’s being shaded by other plants. And it turns out that is a really important process in agriculture. It’s called shade avoidance.
Sevie Kenyon: And Rick, can you further describe what shade avoidance means?
Richard Vierstra: Take plants and you put them in a dark corner, they will grow tall and spindly, and what the plant is trying to do is it’s trying to grow towards situations in which there’s better light. And it does this by measuring the twitch of phytochromes, and so it can then sense that there’s competition, then what’ll happen, it will start growing taller.
Sevie Kenyon: Are you also looking at ways to manage this process?
Richard Vierstra: I think your going to see some of this engineering soon, and so we should be starting next fall, and we’re going to be engineering the phytochrome system in corn, in lines that will eventually be used for breeding.
Sevie Kenyon: What might this new cornfield look like?
Richard Vierstra: Hopefully they’d be very short. So they’d be very packed rows, and the plants would be short, but each one would produce the same ear, and the same size ear. We’re also hoping that we’ll eventually develop lines of different species, for example, that will flower at different times of the year. So we might be able to get Chrysanthemums to bloom in the summer rather than the spring, or we might be able to get Poinsettias to bloom at different times of year. Spinach is a big issue; you know spinach will only make spinach leaves in the spring and the fall because they like short days. And you won’t get spinach in the summer, and it turns out the measurement of day is caused by phytochromes. So one thing we’d love to be able to do is build a spinach that will not sense the long days of summer, by manipulating the phytochrome system. So we’ll be able to grow a really nice leafy spinach all year round.
Sevie Kenyon: We’ve been visiting with Rick Vierstra, Department of Genetics, University of Wisconsin and the College of Agricultural and Life Sciences, Madison, Wisconsin, and I’m Sevie Kenyon.