Gregor Johann Mendel was the first to demonstrate the scientific basis of inheritance and variation by conducting hybridisation experiments. He is best known today for his work on Pisum sativum (Garden pea) and proposal for the laws of inheritance in living organisms. But it should be very much clear that he was not the first to conduct these experiments, rather he perhaps the first to consider several characters of the parental generation at once. His experiments were in fact, the extension and development of experiments on the pea done by workers like Knight and Goss.
Progeny receives the characters from the parents in form of genetic information in gametes. This can be summed up in a phrase ‘like begets like‘. The transfer of characters from the parents to the offsprings is inheritance and the degree by which offsprings differ from the parents is variation. The branch of science which deals with inheritance as well as the variation of characters is Genetics.
Mendel was born in a poor peasant family of village Silisian, Austria on June 22, 1822. He received early education at home and in a preparatory school. He was a brilliant student and studied philosophy for several years. At the age of 21, he joined the Augustinian monastery of St. Thomas in Brunn (Brno), where he received his further education. He was made priest in 1847 and took up teaching assignment in 1849.
Mendel was sent to the University of Vienna for studying Physics and Botany in 1851 and returned in 1854 to become a science teacher. His attention was drawn to the regular occurrence of two different types of seeds in garden pea plants growing in his monastery. Mendel performed hybridization experiments on the pea plants from 1856-1863.
Initially, he collected 34 varieties of pea plants and allowed them to breed to obtain pure lines. Later, he took 7 varieties for his experiments where each variety had two types of plants showing different traits of the same character. He maintained records of each crossing and selfing. He had a large sampling size of about 10,000 plants.
Mendel used statistical analysis and mathematical logic for the first time in biological calculations, which were ahead of his time. The results of these breeding experiments were presented in two sittings of Natural History Society of Brunn in 1865. The same were published in 1866 in the 4th volume of “Proceedings of Brunn Natural History Society” under the title “Experiments on Plant Hybridization”. Mendel showed his results to Naegeli who asked him to perform the similar experiments on Hawkweed (Hieracium).
Selection of Pea Plant
- Pea was in cultivation for long had many distinct alternative traits / contrasting characters.
- It produced a large number of seeds to give a large sampling size.
- It completes its life cycle in one season as it is an annual plant. It did not require much after care.
- Pea flowers are bisexual and show self pollination (bud pollination) and hence were true breeding.
- It was easy to artificially cross pollinate the pea flowers by employing hybridization techniques such as emasculation and bagging.
Reasons for Mendel’s Failure/Non-recognition
Mendels’s work was not taken seriously by contemporary scientists. Many of them did not know about his experiments and the conclusions drawn from them. Therefore, Mendel could not get recognition during his life time. The main reason’s for Mendel’s non-recognitions were:
- He was not attached to any major seat of learning and preoccupied in his duties as an abbot of the monastery.
- Mendel used statistical calculations in biological context which were beyond the comprehension of the scientists of that time.
- His faith was reduced and he was demotivated as he was unable to reproduce his results in Lab lab beans and Hawkweed.
- The biological world was already rocked with Darwin’s theory of natural selection.
- He did not have any physical proof for the existence of factors.
- His concept of state, blending and discrete units did not find acceptance.
- He was not scientifically aggressive.
It was unfortunate that Mendel died in 1884 due to kidney failure, without getting any recognition or appreciation for his work. It was 16 years after his death in 1900 that similar experiments were performed by Hugo de Vries, Carl Correns and Erich von Tschermak independently. de Vries found out the original paper of Mendel and got it published in Flora (1901). We should really thank Mendel for his contribution to the understanding of genetics.
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