The last story revealed that when seeds were first sent to space and exposed, mysteriously, 60% of them made it without any severe damages. And this story being the follow up of SS #32: Seeds in Space reveals the reason behind it and much more. The story is brought to you by Satyashree, who is a seed scientist by profession.
All the inquisitive souls, catch more stories on seeds below:
Hey, this is Aasif, and you are listening to Hello Educator.
Today’s episode is from Mango Science Radio and it is from Satyashree, who is a seed scientist. This is a follow up of the previous episode and in the previous episode, Satyashree mentioned about seeds in space. This episode is around gravity and seeds.
00:42 Hi, you’re listening to Satyashree. We were speaking about seeds in space, and I left the previous episode without revealing the results of Tepfer and Leach experiment. I think you are curious to know the results. Here are the results –
01:03 Tepfer and Leach, through their experiments, concluded that flavonoids in seed coats protect from UV radiation damage. However, genetic redundancy did not have a greater role to play in protecting the DNA damage in space. They predicted that there should be some other molecules like proteins playing an important role in preventing DNA damage in space. This is still under research. Now, let’s discuss an even more interesting topic: the effect of gravity on plants germinating in space.
01:51 As Stephen Hawking quoted, “It’s the gravity that shapes the large-scale structure of the universe even though it is the weakest of four categories of forces.” So gravity is vital, and has huge importance. Until you stand with legs fixed on the ground, you can’t stand against gravity. Now, let us see how our tiny little champs, seeds, interact with gravity.
02:27 We all know that once the seed is sown in the soil the root grows towards the soil while the shoot grows upwards. They call the root growth as a GeoTropic response while the shoot growth as a phototropic response. Geotropism is the growth of a plant in response to the force of gravity, and our consciousness is fixed with the fact that the root grows down responding to gravity.
03:02 Scientists have been wondering what would happen if seeds were made to germinate in space, where there is zero gravity. They were thinking whether the roots will grow upside down. We all have seen images of scientists floating in space, and water droplets hanging in space without gravity. There were huge expectations on what would happen if seeds were made to germinate in space. I know you are also wondering. Let your imagination race until we know the actual fact.
03:40 Seeds of small white flowers called arabidopsis thaliana were the subject of an experiment to study how plant roots developed in a weightless environment, that is, in space. These flowers were orbiting some 220 miles, nearly 350 kilometres above the Earth at the time under a NASA funded project, and the seeds were made to germinate there.
04:13 We know that gravity has an important influence on root growth but the scientists found that the space plants didn’t need gravity to flourish. The seeds produced roots exactly in a similar pattern as that it would do on our Earth, even in space. Surprising, right? Not only love defies the laws of gravity, but the seeds too! Jokes apart, seeds germinated on the International Space Station sprouted roots that behave as they do on Earth, growing away from the seed to sip nutrients and water in exactly the same pattern observed with gravity. These roots emerging from seeds do not get affected by gravity. This is just an observation. But science? I believe observations turn to science when we tag a ‘why’ to the phenomenon. So, why was the seed germination not affected by gravity as expected? This is science.
05:29 The research team led by Paul and Ferl from the University of Florida thinks this is related to a plant’s inherent ability to orient itself as it grows. Also, the new study suggests that features of the plant growth we thought were the result of gravity acting on plant cells and organs do not actually get affected by gravity. Researchers have always thought that root skewing was a result of gravity’s effect on how the root tip interacts with the surface it encounters. But Paul and Ferl, who are working on the effect of gravity on root establishment, suspect that in the absence of gravity other cues take over. Those cues include moisture, nutrients, and light avoidance. Roots don’t need gravity to orient their directional skewing. They will grow away from a light source regardless of gravitational forces.
06:38 In the December 2012 issue of the journal, BMC Plant Biology, lead artist Paul and Ferl wrote –
‘Though plants on Earth do use gravity to help determine the direction of their growth, it is clear that gravity is neither essential for root orientation, nor is it the only factor influencing the pattern of root growth. We can only guess the cues for root and shoot growth unless nature reveals it as science.’
Paul also added –
‘There’s really no impediment to growing plants in microgravity such as on a long-term mission to Mars or in reduced gravity environments such as in specialized greenhouses on Mars or on the moon. This boosts our hope of growing plants in space.’
07:37 It is now clear that seeds and plants can help us even in space. We should be grateful to these tiny little superstars defying gravity for our present and even future survival, in space, if any. Einstein once quoted ‘You can’t blame gravity for falling in love’. From now on, you can also not blame gravity for pulling the roots down. This clearly shows the strength of these tiny seeds and plants. I think you all now understand why I quote seeds as superheroes. So, next time when you see seeds, remember, those are not just seeds, they are superheroes. Thank gravity for making you stay on this fantastic planet but never blame gravity for pulling you back from your paths to success. I think if I’m let to speak further, I will forget my purpose of science communication and turn into a motivational speaker. So, let’s stop now and until we meet again with more intruding seed facts, keep wondering.
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Music by Karthikeyan KC