Plant tissue culture (PTC) is a term most biotechnologists are well-acquainted with. This technology exploits what is known as the totipotency of Plant cells. Totipotency is the inherent capacity of each and every living plant cell, whether it originates from a leaf or stem or root of a plant to be able to give rise to an entire plant on its own. In short, I don’t need a seed to grow a plant. If I can  extract a set of totipotent cells from a plant and give it the right set of nutrients, the right temperature and day-night cycle and of course an optimal cocktail of hormones (Plant growth promoting), I can grow a complete plant out of those few cells. So I excise a small portion of the plant (leaf, stem, node, root etc) which is called the explant and then after carefully treating it with the proper set of disinfectants (to get rid of contaminating microbes) I inoculate it into media (liquid or solid) and provide it with all optimal growth parameters. Within a reasonable period of time I should be able to obtain plantlets out of my original explant. This is a very simplistic explanation of plant tissue culture.

From the time Gautheret worked with encouraging results in the young field of PTC in 1934 and the problem of tissue culture of plant cells was definitely solved in 1939, independently by Gautheret, Nobécourt and White, the field has come a long way. With more than ten thousand researchers actively engaged in this field of research1 the technique has undergone massive changes in method and application. From the more academic applications of trying to demonstrate totipotency and wound healing effects to generation of entirely new plants with the view to transplanting them in fields, we have witnessed the growth of an important tool of biotechnology.

Consider that PTC has the potential to be used for solving various different problems of our lives. For example, one could select out plants with superior qualities such as productivity or hardiness from a tissue culture set using the principle of Additive Genetic effects. Since a certain amount of genetic variation can be induced during plant tissue culture, such selection is made possible. Similarly, PTC could be used for Genetic Engineering too. Engineer a mother plant and then simply tissue culture it in the lab. The Advantage? In a shorter time span and with considerable lesser space investment, one can grow hundreds of genetically identical plants and then transplant them to the fields. The potential is endless, one can culture rare plants, plants on the brink of extinction under controlled conditions and replant them.

Another application that has caught my attention is the use of this technology for reforestation or forest regeneration programs. A very interesting article on the latter outlines a program carried out by S.C. Grossnickle, D. Cyr, and D.R. Polonenko (the Director of forestry and manager of tissue culture research, BCRl Forest Biotechnology Centre, and the director of operations, Silvagen, BCRI, Vancouver, BC, Canada) The paper details an effort at genetic improvement of Spruce pines as a part of an operational forest regeneration program. This work was carried out using a PTC technique of Somatic embryogenesis in order to reforest areas of the forest. To quote from the introductory passage of the paper, “There have been major advances over the past 25 years in the development of operational vegetative propagation systems for conifer species used in plantation forestry programs. These propagation systems provide a means of bringing new genetic material into forestry programs through the capture of a greater proportion of the gain from additiveand non-additive genetic components inherent within a selected tree species (Libby and Rauter 1984). Vegetative propagation systems also provide a method for multiplying superior families identified in tree improvement programs (Gupta and Grob 1995; Zobel and Talbert 1984).”

Deforestation has become a concern globally. We are faced with an alarming decrease in the total forest cover in the world. The Food and Agriculture Organization of the United Nations (FAO) in its 2005 Global Forest Resources Assessment, concludes that some 13 million hectares of the world’s forests are still lost each year, including 6 million hectares of primary forests. Primary forests are forests with no visible signs of past or present human activities and are considered the most biologically diverse ecosystems on the planet. For a detailed split-down of stats in various continents/ countries see this site. Reasons for this range from Industrialization to over-exploitation of forest resources by the rural poor for want of any other means of sustenance. One scarcely needs to be reminded of the reasons why forests are important to save the millions of species that are now endangered and ultimately to ensure our own survival on this planet.

Given this background, reforestation efforts are being doubled across the world. Reforestation as the term suggests is the process of repopulating forests with trees and other secondary flora to restore the vigor of the area. This will in time result in the restoration of the entire ecosystem dependent on the forests in question. The process used to be a long and tedious one. In the initial stages of the reforestation programs, work used to be done essentially using manual labour. Hundreds of acres used to be seeded or planted using saplings or plantlets and the process of reforestation used to take a substantial number of years. This process is useful though in hard rocky inaccessible areas where mechanical is still not possible. The next stage was to use simple mechanical planters which essentially consist of a modified tractor, bearing a planting device. As the tractor is pulled, the device plants a seedling/ plantlet in the furrow created, and then the furrow is sealed by the tractor itself. Additional attachments include herbicide spraying devices for better weed control. For additional information on the two techniques outlined above, read this article.

But the cutting edge in this array of techniques is to use what is now known variously as Aerial Reforestation or Aerial Seeding. Conservationists have visualized using advanced military air-plane technology for the purpose of reforestation. In the 1930s planes were used to air-drop seeds of plants over the vast areas that were rendered barren. The idea was innovative, but fraught with difficulties. Many of the seed simply became food for pests and rodent son the ground and out of those that did not survival rates were low. Recent developments however, have seen a drastic improvement in the success rate of this technology. While traditional methods are expensive and time-consuming, Aerial reforestation can result in the planting of as many as 100,000 trees. This is in a single day. Further, instead of only dropping seeds one can now actually air-drop plantlets, saving more time.

Moshe Alamaro Moshe Alamaro

Moshe Alamaro, a graduate student in Mechanical Engineering at MIT, pioneered a method wher he developed tiny little canisters made up of biodegradable, starch matter to house the plantlets. The conical canisters are filled with nutrients and soil that safely encase the plantlets. These packages are then dropped from a low-flying plane onto the soil where the canisters eventually break-up and decompose allowing the plantlet within to take root. The system combine ballistics and navigation technology to place the saplings accurately and is overseen by a airborne surveillance system, which guarantees safety and also monitors the early growth of the trees.

Using this path breaking method, one can examine the possibilities of using tissue culture plants to reforest large areas in a relatively shorter period of time. Rare plants or tree species can be tissue cultured in labs and then replanted in nature using this unique technology. Similar efforts can be undertaken for plants on the verge of extinction.

Cannisters Designed for Aerial Reforestation Cannisters Designed for Aerial Reforestation

Our problem of reforestation as well as preservation of rare and unique flora around the world can be efficiently solved by using powerful technologies coming from the fields of Biotechnology and Engineering. So, the next time you take that flight to your workplace or travel destination; do think about the marvelous potential of the Bird to reforest our planet.




3.  Image (Moshe Alamaro as well as text matter)

4. Somatic Embryogenesis Tissue Culture for the Propagation of Conifer Seedlings: ATechnology Comes of Age, S.C. Grossnickle, D. Cyr, and  D.R. Polonenko  Tree Planters Notes, 1996.

5 .Image credit for the schematic representation of Aerial reforestation: