On February 8, 1865, the Augustinian monk Gregor Mendel presented the first part of his papers to his colleagues at the Brünn (now Brno, Czech Republic) Natural History Society. “The experience in artificial fertilization, – he said – as it is used to obtain varieties of new colors, has served as the basis for the experiments that we are going to present today.” None of those present suspected that this work would go down in history as one of the most important scientific events of the century. XIXMendel was about to reveal the laws that govern the genetic inheritance of creatures.
A month later, the monk Gregor Mendel, appeared again before his colleagues and the following year, his work was reflected in an article published in the magazine of the Society under the title Experiments in the hybridization of plants.
Hybridization
With the word “hybridization” Mendel referred to the fertilization between individuals that belong to different varieties of the same species. During the eight years prior to the publication of the work, the monk had experimented in the monastery garden with different varieties of peas. They were years of painstaking work, selecting different characteristics of the leaves, stems and seeds, years dedicated to planting, artificially pollinating, collecting seeds and replanting, crossing some varieties with others with exquisite care and following a rigorously established plan. All this to find the laws that govern the transmission of these characteristics between parents and children, for several generations.
The task in the garden of the monastery was arduous but the meticulous work of compilation and analysis of the results obtained was not less. Mendel himself made it clear that this methodology is what had been lacking in previous studies.
“Those who review previous work in this field -says Mendel in his writing- will come to the conviction that, among all the numerous experiments carried out, none was carried out in such a way that it was possible to determine the number of different forms in which that the descendants of the hybrids appear, neither have such forms been grouped into separate generations, nor have their statistical relationships been definitively obtained. It takes, of course, a certain courage to face such extensive work (…) The work now presented exposes the results of such a detailed experiment.”
variety selection
The article describes in great detail the criteria for the selection of the varieties used in the investigation.
“The plants in the experiment must necessarily: 1) Possess differentiating characteristics that are constant. 2) Hybrids of such plants must, during the flowering period, be protected from the influence of foreign pollen and be easy to protect…”
Mendel describes in detail the methods used to artificially pollinate the flowers of the different varieties of peas, selecting the pollen of the variety chosen as a parent and fertilizing the chosen flower, protecting it from any other pollen that could ruin the experiment.
The varieties of the experiment were chosen in such a way that they presented clear and perfectly differentiated characters. He chose seven main characters, among them, different shape of the seeds, differences in internal and external color, roughness of the external skin, the length of the stems, etc. Plants with two different characters were crossed with each other under controlled conditions.
“The plants grew in the ground, some in pots, and were held in their natural upright position by stakes, tree branches, and rope. In each experiment, a number of potted plants were placed in a greenhouse during the flowering period, to serve as a control for the main experiment due to possible insect interference.
Control of pollinating insects
The control of certain species of insects occupied not a few energies of the monk. In his writing, Mendel explains how it was important to avoid the attack of a kind of beetle that tends to pierce flowers and deposit their eggs in them, because these beetles usually fly from flower to flower carrying grains of pollen that facilitate natural fertilization.
Every year, for eight in a row, Mendel obtained a new generation of plants that were meticulously studied and whose seeds and characteristics were scrupulously noted. Here’s an example:
“Experiment 1: Shape of the seed. – Of 253 hybrids, 7,324 seeds have been obtained in the second year of the experiment. Among them were 5,474 round or rounded and 1,850 wrinkled and angular. Then it follows that the ratio is 2.96:1.”
He verified that certain characters remained from generation to generation while others disappeared or remained latent and were losing presence. The former are called “dominant” and the latter “recessive”. The different proportions of offspring that showed the characteristics of the parents were outlining a behavior that allowed the monk to think that Nature follows certain simple mathematical rules when distributing genetic inheritance.
If a pure variety with a dominant character -let’s say that its seeds have smooth skin- is crossed with another variety that is also pure but with a recessive character -wrinkled skin-, all the offspring show the dominant character – they all have smooth skin – and, on the other hand, when the children cross with each other, the second generation presents the dominant character in a proportion of 3 to 1, that is, one in four grandchildren recovers the character lost from their grandfather or grandmother. These relationships have been reflected in what we now know as Mendel’s Laws for genetic inheritance. As the complete explanation would take too long to expose here, we invite you to visit the following page
Unfortunately, as sometimes happens with great discoveries, that work had little impact. Although Mendel sent copies to the most important botanists of the time, none of them paid attention to his research. Father Gregor Mendel died on January 6, 1884 without realizing the enormous impact his work would have on the future.
The history of the manuscript
Sixteen years after his death, in 1900, three researchers: the Dutchman Hugo de Vries, the German Carl Correns, and the Austrian Tschermak-Seysenegg, simultaneously and independently rediscovered Mendel’s work. Subsequently, Thomas Hunt Morgan discovered that the characters are closely linked to the chromosomes and specifically to certain areas of these that have been called genes.
After the death of Gregor Mendel the precious original manuscript of his work slept the sleep of oblivion in the archives of the Brünn Natural History Society. The lack of recognition reached such a point that in 1911, during the cleaning work of the library, Mendel’s work was discontinued and thrown away. Luckily, a high school teacher from the institution found it among the mountain of discarded papers and got it refiled.
During the German occupation of World War II, a professor in charge of the Natural History Society rescued the manuscript and carried it with him for a while. In 1945 Mendel’s work disappeared without a trace. For more than 40 years nothing was known about it and, when everyone considered it lost, in 1988, an Augustinian monk descendant of Mendel, Father Clemens, informed the rest of the family that he had the manuscript in his possession. After a long dispute between Mendel’s descendants and the congregation to which he belonged, the original work was deposited with the Wahlert law firm in Stuttgart, where it remains to this day.
We invite you to listen to his biography.
REFERENCES
Experiments in the hybridization of plants. gregor mendel
Mendel’s Experiments