(Lightly edited for readability)
Speakers: P. V. Shivaprasad, Shuchishweta Kendurkar, Subhra Priyadarshini
Support Announcement 00:01: This episode is produced with support from the National Center for Biological Sciences.
Subhra Priyadarshini 00:31: Welcome back to Biolore. This is a Nature India podcast series where we unravel fascinating stories from the history of biological sciences in India. I’m Subhra Priyadarshini.
Packed into lunchboxes, blended into smoothies, and stocked in nearly every Indian grocery store, bananas reign supreme on the superfood list. But did you know that behind every perfectly grown banana, there’s a fascinating science at play?
A science called plant tissue culture that can speed up plant breeding to develop high-yielding, disease-resistant crops in record time. It may sound like science fiction, but it’s a reality. Plant tissue culture is a powerful biotechnology technique that has been around for decades, allowing scientists to grow plants in a laboratory using just a tiny piece of tissue — a leaf, stem, or even pollen — in a controlled environment.
This allows scientists to create genetically identical plantlets, free from diseases and environmental limitations. Unlike traditional propagation methods that rely on seeds, plant tissue culture can produce millions of identical plants in a fraction of the time.
Today, we delve into two pioneering plant tissue culture techniques — haploid culture and meristem culture — that are transforming agriculture and forestry. Our journey takes us from the labs of Delhi University, where Sipra Guha and S. C. Maheshwari stumbled upon shoots growing out of Datura anthers while culturing tissue to study cell division, to the research at the National Chemical Laboratory in Pune, where two 100-year-old teak trees stand solid testimony to these developments.
P. V. Shivaprasad 02:54: Plants are very different from animals, because any, literally, any part of the plant can make a new plant. So this is called totipotency. Unfortunately, animals don't have this and this is important for plants, because while in animals, our gem cells are pre designed, they are already there even before we are born, plants can make germ cells from anywhere.
Subhra Priyadarshini 03:17: That's biotechnologist P. V. Shivaprasad joining us from the National Center for Biological Sciences in Bengaluru.
The 1920s set the stage for experimental embryology in plants. Scientists realized that by providing the right nutrients in a sterile environment, they could grow plant tissues without contamination. This idea took off in Europe, where researchers optimized artificial media with salts, vitamins, and hormones. In the 1950s when Indian botanist Panchanan Maheshwari entered the field, key discoveries had already been made—like the role of auxins and cytokinins in growth. But the precise balance of these hormones was still unclear. In his Delhi University lab, Maheshwari, originally a taxonomist, turned his focus to embryo sac development, exploring how female gametophytes formed and how sperm cells fused with egg cells—laying the groundwork for breakthroughs in plant development. His work on embryo culture, induced parthenogenesis, and haploid production sparked a new era in plant development research. Back then, plant breeders around the world were deep into researching haploids—plants that only have a single set of unpaired chromosomes.
P. V. Shivaprasad 05:04: So in this setup of Delhi University, there is also Professor B.M. Johri who was the student of Panchanam Maheshwari. He and Sipra Mukherjee were really interested in finding whether we can study the pollen grains, what they are made up of, what kind of nuclei fused and they ended up keeping this pollen in the media. And it turned out that this plant accidentally could become a new plant.
So the outcome was quite surprising. They just kept the pollen and it ended up making a new plant. And this is a haploid plant because there is no future with the female axil.The advantage was not immediate at that time, but we knew that anybody can make a haploid plant and it's easy to then convert it into deploid by treating with colchicine. One can fix anything that is made or seen in nature or created in nature and there will not be loss of this character in the subsequent generation. So if there is, let's say, a plant somebody observes making big fruit or better flower. And if we now end up crossing with another plan, they won't inherit properly, they will not be truly same in the offsprings. But if you take your plant's, let's say, pollen and make a haploid then this plant can now mimic exactly what one has seen in nature or one has created in the lab. So without this haploid generation, one needs maybe 10 to 12 years to make a proper plant, but with this one can generate with half the time, let's say five years. One can make a plant which has the right trait which somebody has created or observed and put it into the plant, and make it stably inherited when it is grown in the in the soil.
Subhra Priyadarshini 06:52: In India, Shipra Guha applied the technique to rice breeding at the behest of MS Swaminathan, didn't she?
P. V. Shivaprasad 07:01: Initially, when Professor Shipra did this work, it was in Datura, and nobody knew what exactly one can do with Datura. Only making very strong chemicals, which we now know we can use for diseases such as Parkinson (but that time, it was not a model) could not yield a product, which could yield a new line that people could use. So Prof. Swaminathan saw the potential, and also there was enormous work on this line going on in China. So he thought, why not do the same thing with rice, which is obviously our number one crop. And he invited her, and they worked together, and Prof. Shipra could generate haploid plants in rice. These are some of the first ones. We can see how the Chinese pursued this, because Chinese really respected Prof. Shipra for this discovery. And over the next many, maybe decades or so, China started producing these lines, hybrids, for the first time, started growing commercially. And these hybrids were behaving way better than anything else that was grown. Until then, without tissue culture, one could not raise transgenic lines in rice and many other plants.
Subhra Priyadarshini 08:14: Since then, researchers have made huge strides in developing anther culture for all kinds of crops -- wheat, rice, potatoes, maize, peppers, you name it. This technique has been applied to a wide range of economically important plants making a real impact on agriculture. And were there any landmark success stories that stood out, or even stand out today, in how haploid culture contributed to crop improvement in India?
P. V. Shivaprasad 08:45: There are a couple of examples. The best example is Indian mustard. You have to retain the oil content but you have to reduce its nasty smell. I think this technology was very useful in making plants which can now have less smell, but have equal or better oil content.
Subhra Priyadarshini 09:03: Today, plant tissue culture provides the essential platform for introducing and regenerating genetically edited plants.
P. V. Shivaprasad 09:16: Yeah, so currently, the most interesting application is to use it to edit the genome. So it has been discovered that one can use a protein called CAS9. Its origin is from a bacteria, and it needs a RNA of a specific type. And if one can insert this into a plant, there will be change in the digits, i. e. ATGC can be changed, sometimes to the specific residue, or sometimes to any other type of residue. And this means, if somebody can manipulate the genome like this, one can make the gene to make more protein, or completely remove the gene. Basically, one can tinker with this massive recipe book called the genome that we have. The most common way of doing it is through Agrobacterium. Introduce this protein, and then with this guide RNA use tissue culture to make a new plant. Now what people are trying to do is somehow introduce, reduce the tissue culture step to a minimum. Or introduce in such a way that you can still make a new plant by maybe picking up specific cells, or the tissue culture itself will be of a different type, where you somehow in the growing media itself introduce this protein, make it go through the roots. With nanoparticles we edit the genome. So the advantage of these methods is that we will be able to change anything, modify, make better crops, both that can produce more yield or better nutritive capabilities, or sometimes make more of medicinally important compounds. All this is possible, and this is where most of the work is going on right now. And people are trying this in different crops in India as well. Many groups are trying to improve these crops with editing.
Subhra Priyadarshini 11:05: And can it make agriculture more resilient to diseases and climate extremes?
P. V. Shivaprasad 11:10: If anybody can find a disease resistant gene and introduce it to a plant, or if there is a natural variant of a plant already quite capable of dealing with climate or weather, or is disease resistance, one can simply use anther culture to fix this character and get the offspring out. So this is the advantage of using anther culture and similar technologies, where one can fix this trait, one can also use this to screen large number of germplasm to see which of the ones is better, then fix that character in the subsequent generation. So that kind of work is again, very popular in many countries, especially in countries such as Australia. Climate resilience is the keyword, and this kind of research is being done.
Subhra Priyadarshini 11:58: After Maheshwari's team developed pollen embryo culture, another big breakthrough that really pushed plant tissue culture research forward in India was micropropagation. This technique involves growing tiny plantlets in a controlled environment before transplanting them into the field. Some of the early pioneers in this field, included Narayanaswami at the Bhabha Atomic Research Center, along with H. Y. Mohan Ram, N. S. Rangaswami and K R Shivana at Delhi University. Their work was crucial. It helped speed up plant breeding by cutting down the time between generations and increasing the number of plants that could be grown from a single parent. A business model around plant tissue culture began to take root. Meanwhile, at NCL Pune, under Jagannathan's watchful eyes, another story was unfolding, and it started with Ram and Lakshman, two iconic teak plants, they were over 100 years old, standing tall in the Allapalli forest of Maharashtra's Gadchiroli district. Now, what made them special? They were completely resistant to termites and diseases and had impressive girth and produced top quality wood. But the problem? They were too old to regenerate naturally, and despite multiple attempts, officials from the Maharashtra Forest Development Corporation could not successfully propagate trees like them. That's when they turned to scientists at NCL for help, sometime around 1975-76.
Shuchishweta Kendurkar 13:44: Those people, they approached that now that tissue culture has come to India, why don't you try this type of thing rather than haploid culture. And that is having more academic value, rather why don't you go for application-oriented problem? And when they approached us, we had at that time in NCL prepared through our NCL workshop aluminum hoops, which used to have perspex sheet on the top. You could see from the top, and you could put your hands in from below. And at other times you could close those boxes. It used to be sterilized with spirit and all that. And those boxes, along with the test tubes containing our artificial media, we guided them to the locations. And there in the guest house, all these inoculations were done. But the problem is, of course, heavy contamination. So we had to work on it and to get the sterile and green culture.
And that is how in 1980 it was the first report of matured meristem tip culture of teak.
Subhra Priyadarshini 14:59: That was Suchishweta Kendurkar, former NCL researcher who worked on meristem tip culture for two decades. Meristem is the fresh actively dividing tissue around the tips of roots and shoots. And NCL scientists proved that even mature trees could be regenerated in a lab using these tissues. In fact, this breakthrough made NCL the birthplace of successful mature forestry tissue culture, something that had never been done before on a global scale. And it didn't stop with teak as the forest department's needs grew. The same technique was applied to other valuable trees like eucalyptus and salvadora. This was the turning point in forestry and conservation, proving that even ancient trees could have a second life through science.
Shuchishweta Kendurkar 15:51: And another problem was rooting of those plants, because they are hardwood species, so they don't root easily. So that was also standardized. We tried continuous oxygen treatment, we tried pulse treatment. Many things were tried, and we got the plant. And once we got the plant, they approached us that, why don't you go for the upscaling of the technology. Not at a very large scale, up to 1000 level or 2000 level -- that was also big number at that time. And that is how we entered this micropropagation and scaling. Then NABARD came up with the proposal that, why don't you take other species also, like eucalyptus and salvador and then some agricultural industries were there.
Subhra Priyadarshini 16:40: One of the major success stories in plant tissue culture commercialization in India today is bananas, like we mentioned before. Small labs have replaced the costly foreign models, and businesses in places like Pune are thriving using efficient, locally adapted techniques. Farmers can now grow stronger, healthier banana plants with confidence. But it wasn't always a smooth journey. In fact, the early days of tissue culture in India were full of challenges.
Shuchishweta Kendurkar 17:18: See initially when tissue culture industries came up in India, mostly they were based on the foreign technology, and they had come up with very big green houses and very big special laboratories. But in banana, another problem is that (on this also NCL has worked and helped DBT to come up with the solutions) if you go after certain subcultures, those plants start showing variation. That is their genetic problem. And most important, or the most serious problem, was virus.
Subhra Priyadarshini 17:51: One of the most devastating was the banana bunchy top virus. If a single infected plant was used as an explant, it could silently multiply across thousands of plants in a lab. When these infected plants were transferred to farms, entire banana crops were wiped out. A major outbreak in the late 1990s near Jalgaon in Maharashtra was a wake up call for the industry.
Shuchishweta Kendurkar 18:25: We had worked on this problem, particularly because we were approached by many small scale industries and many farmers also, and DBT also intervened. But now DBT has come up with national certification system for tissue culture raised plants. There, we have come up with the protocols at every step, which is virus indexing, and how many subcultures these cultures have gone to. See, what happens for industries is, it is easy to take it to a higher subculture source. But then these plants start showing variation. So that type of certification system is there in place. There are committees who visit, they check all the data which is there. They check the plant and then labels are provided. Before selling, those labels are put on those boxes, and then only they are sold. So basically, banana, it is a success story in India.
Subhra Priyadarshini 19:19: But Suchishweta emphasizes the need for crop diversification in banana farming to avoid the risks associated with monoculture.
Shuchishweta Kendurkar 19:29: But unfortunately, at the moment, people are market-driven. So market is for banana, not for sugarcane also that much. But it is a success story for banana. But another thing that I am observing now (I am out of this market) is that they are going for Grand Nain (a banana variety), mostly. They should go for other varieties also, they should be cultured, otherwise there will be a threat of monoculture. So future is bright. Only it has to be taken up in a different manner.
Subhra Priyadarshini 20:03: But to immerse oneself in plant tissue culture is like raising a child.
Shuchishweta Kendurkar 20:11: It requires continuous monitoring. Yes, see like you are bringing up your child, that kind of attention it requires.
Subhra Priyadarshini 20:19: She hopes the banana success story can be replicated with teak. Going back to Tadoba was an incredible experience for her. Visiting the very spots where she and her colleagues had planted the trees. felt like reconnecting with long lost siblings.
Shuchishweta Kendurkar 20:40: See, I tell you, first time, after 3-4 years, we had visited Tadoba and we went to the places where our plants were planted. It was a really exciting moment to see our plants, like they are our siblings. Only another thing now, after when the technology was upgraded and these plants were put in different fields, and then farmers used to insist, "Madam, please come and see your plants. They are growing beautifully." And when you go to those fields and you see them, you say, "Oh, thank God, you gave me such a beautiful opportunity to work on these plants and add to nature." Similarly, in case of Salvadora also, nothing grows except for that plant there, and those seeds are the source of income. For them, conditions are very harsh -- 50 degrees and shade also. 2-3 times I have fainted there. But looking at our plants and all those things, we used to be really motivated that, yes, we are doing something for the society. And this is what I feel, rather than publishing many papers and all those things.
What I feel is that our plants are standing high in the field. I don't know now, some of them must have come for rotation also, 20 years old and all that, since 1993. But that is the real moment that you feel, yes, you have contributed something to the nature, to the system. Also see, national certification system, we have come up with all those small things which we worked with, they are really very exciting. And I'm really satisfied with my career. It is my dream that somebody should take up peak technology and make thousands and thousands of plants.
Subhra Priyadarshini 22:33: And as you can see, Indian scientists have been at the forefront of this movement, playing a major, major role in solving food and nutrition challenges on a global scale. That brings us to the close of the Biolore series. We hope you enjoyed it as much as we did bringing it to you. Please tune in to the other episodes of Biolore, and I hope to bring you another fascinating series very soon on the Nature India podcast. Till then, this is Subhra Priyadarshini signing off.
Support Announcement 23:39: This episode was brought to you with support from the National Center for Biological Sciences.
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