Polyploids: Getting And Using Colchicine At Home

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Experimental polyploidy in the kitchen

There are many plants grown in our gardens, which are essentially poisonous - aconite, lumbago (dream-grass), lily of the valley, colchicum - colchicum, etc. But no one is in a hurry to refuse them - after all, obtaining pure chemicals from these plants is a complicated process, and we do not use them for food. What is so interesting about the alkaloid colchicine, which is contained, for example, in everyone's favorite colchicum?

Let's start with the basics of biology from the school curriculum, which we have probably already forgotten. When a cell divides, DNA first doubles, and then the cell divides into two with the same set of chromosomes. So this very colchicine interferes with normal cell division. DNA doubles, quadruples, etc., and the cell is delayed in its division.

When it was divided, then in the process of growth in the cells of a new plant these same sets of chromosomes are no longer 2n (standard diploid), but 4n, 8n, etc. This is our polyploid. It has now been established that 1/3 of all angiosperms on earth are polyploids. These natural mutations occurred for various reasons - temperature shock, trauma, illness, solar radiation.

Man has been using polyploidy for a long time to develop highly productive varieties of agricultural plants. At first this was done unconsciously: they simply multiplied the largest specimens, giving a lot of grain or especially large fruits. With the advent of genetics, it became clear that such giants are polyploids. More than 500 polyploids are known in plant growing (beets, grapes, radishes, onions, etc.).

A wide variety of polyploids is observed in floriculture: if one original form in 2n = 18 chromosomes, then cultivated plants of this species can have 36, 54 and up to 198 chromosomes. You can get a very miraculous chimera, this is when, in the process of disrupting normal division with colchicine, we get cells with different sets of chromosomes in one plant.

Such plants are unusual, and in adulthood, different parts of the plant carry different characteristics. People have long noticed such natural mutations, and a detached part of a plant with interesting traits gave rise to a new variety. Thus, for example, columnar apple trees were first obtained, and the shattered genetic fund of the host itself is the basis of countless varieties of this plant. Natural mutations, together with endless cross-pollination and selection, were, in fact, the basis of selection at all times of mankind.

But we live in the 21st century - science has stepped far ahead, and time seems to fly faster and faster. Well, we do not have several generations in reserve for the so-called "folk" selection, now and faster I want to see something new, and even more interesting - to try to experiment and proudly see the results of our own work.

Serious science for experimental, accelerated selection has a huge number of possibilities in its arsenal - laser treatment, radiation, X-rays, mutagens and supermutagens. What about an inquisitive and enthusiastic gardener? Where can I get pure colchicine for my experiments?

Let's go dig the crocus

We will still be in time in this weather, and the sowing time is not far off. The content of colchicine in the bulb is 0.25%, in flowers - 0.8%, in seeds - 1.2%. Naturally, it is more convenient to work with the bulb. Then everything is simple - get the juice (grate, grind in a meat grinder, mortar, whatever you like), squeeze, filter, put in the refrigerator. It is better to prepare the juice just before sowing. Don't forget about safety measures! A mask, gloves are required; wash hands and tools - do not drink juice!

The optimal percentage of colchicine in the solution to obtain polyploids is 0.1-0.2% - accordingly, our solution (juice) must be diluted with water by half or a quarter. The time of soaking seeds in a solution for different plants is different, but usually for dry plants - a day, for seedlings - 8-12 hours. But these are only general principles. Experiment.

From experience I can say that the looser the skin of the seed, the less time it takes. For example, for primroses, an hour is enough, and the solution is weaker. Naturally, do not start your experiments on expensive (purchased) seeds: colchicine is a strong mutagen, and some of the seeds will die. Use your own seeds that you know are fresh and of the kind you want to work with.

The most interesting thing is that the result of our "kitchen" science is visible quickly enough. At the seedling stage, the hypocotyl (the place between the root and the leaf primordium is the hypocotyl knee) thickens and becomes like a tiny barrel, and the seedlings in polyploids are distinguished by a brighter and darker green color; leaflets are more rigid, leaf petioles are shortened. These are clearly noticeable differences, allowing already at the stage of seedlings on the windowsill during a pick to make primary selection.

Be prepared for the most severe selection at all stages, otherwise the overstocking of experimental plants in your summer cottage cannot be avoided. Indeed, to obtain promising seedlings, which may turn into a new variety, you need to wait for the plant to bloom or fructify, depending on what you are fond of.

Well, why do we need all this - ruined crocus bulbs, graters, masks, window sills, occupied not with the usual seedlings, but with some (it is not yet known whether the resulting polyploids)? Oh, if everything were so simple - multiply the number of chromosomes - and here's a giant terry bells, irises, gladioli, raspberries with a fist or currants with an egg … But the eternal itch of the inventor-experimenter: what if? Others succeed, but why am I worse?

Polyploids give different offspring - this is gigantism (mostly) and dwarfism. Well, let's put it in our favor - you give a 20 cm high slope for slides or a 3-meter high gooseberry - formed it as a tree - and no problems with thorns … Is dwarf terry lilac for a flower garden - weak? Polyploids are both enlargement (mainly), and a decrease, and deformities of a flower. There is only one recipe - selection.

Polyploids are both enlargement (mainly) and a decrease in the size of the fetus. Here, too, everything is decided by selection. By the way, all of us beloved garden strawberries (strawberries) normally have 2n = 14 chromosomes, and we grow cultivars, which almost all have 7n = 98 chromosomes.

Polyploids are both an increase (mainly) in the number of flowers on a peduncle, and a decrease. Grew up, appreciated, took away - the rest was ruthlessly thrown away. Remember the overstocking.

Polyploids are a change in the winter hardiness of plants - almost always upward. Well, this is definitely for us - for St. Petersburg and other northern regions! Stop licking your lips at Western catalogs - you give roses without shelter, and more - I want peaches!

By the way, the most winter-hardy birch species, with a natural advancement to the north due to natural polyploidy, have 84 chromosomes (unlike their southern counterparts with 2n = 28 chromosomes).

Polyploids are also changes in the life cycle of plants - biennials often turn into juveniles (3-4 years). For example, we got a pyramidal bell (C. pyramidalis) in our nursery. By its appearance, he belongs to two-year-olds, but he has been living with us for four years, we continue to work with him.

Polyploids often have reduced fertility - seed formation. And therefore - forward for the seedless gooseberries - how are our northern grapes (as gooseberries are often called) worse than the southern kish-mish ?!

Polyploids are both a change in the number of petals, both underdeveloped and terry beauties. The recipe is the same - selection.

In any case, polyploids are definitely not new genera in the sense in which the word is used in the Bible. Irises and raspberries remained irises and raspberries instead of palms and kiwis.

This article gives a very simplified idea of such a complex phenomenon as polyploidy (yes, professionals will forgive me), but we don't need to go deeper, we would like to experiment, get our own variety and rejoice - boast. By the way, how would you name your own variety of giant terry gladiolus or apple-sized raspberries - have you already decided?