Rivista di Biologia / Biology Forum 97 ( 2004), pp. 483-498.
1. Lysenko's Contributions to Plant Physiology
2. Lysenko's Contributions to Genetics
3. Lysenko's Achievements in Agro-biology
4. Lysenko's Work in Evolutionary Biology
5. Lysenko's Tragedies and Mistakes
Lysenko; Vernalization; Phasic development of plants; The inheritance of acquired characters; Epigenetic inheritance; Graft hybridization; Intra-varietal crossing; Mentor pollination; Agro-biology; Sudden species transformation; Horizontal gene transfer; Intraspecific competition.
Trofim Denisovich Lysenko's life and work have been much analyzed and discussed in the world's literature. It is well known that Lysenko is notorious and has been regarded as a charlatan. Less well known is that he once made greater contributions to Biology and has been misunderstood in some aspects. In this paper, Lysenko's contributions to plant physiology, genetics, agro-biology and evolutionary biology are briefly reviewed. His tragedies and mistakes, such as mixing science and politics, denying the existence of genes, failing to build up suitable scientific collectives for the metabolism-biochemical studies of heredity, as well as his theoretical one-sidedness, are also discussed, thus reconsidering the case of Lysenko from a comprehensive and objective viewpoint.
In 1977, the famous British cytogeneticist and evolutionist, C. D. Darlington, asked a question: was Lysenko a charlatan? In his book The Lysenko Affair, Joravsky [1970] depicted Lysenko as a pseudo-scientist from the beginning: “The painful truth is that Lysenko was never seriously involved in any genuine scientific problem”. Roll-Hansen [1985] argued that Joravsky did not recognize the considerable difference between Lysenko's credentials in plant physiology and in genetics, by pointing out that Lysenko's work in genetics may well be considered pseudo-science as a whole. Until recently, Lysenko's work in genetics was still regarded as charlatanism and fraud (Hagemann [2002]; Hossfeld and Olsson [2002]; Wobus and Schubert [2002]; Muller-Hill [2002]; Witkin [2002]), though Flegr [2002] correctly pointed out that Lysenko was partly right. As a matter of fact, Vavilov once placed a high value on Lysenko's work: “Lysenko is a careful and highly talented researcher. His experiments are irreproachable” (Soyfer [1989]), though he later regarded Lysenko as “an angry man” (Darlington [1977]). The respected British biologist, J.B.S. Haldane, before his death, passed the fairest judgment on Lysenko. He believed that Lysenko was a very fine biologist and some of his ideas were right, though he also realized that some of Lysenko's ideas were wrong and badly wrong (Haldane [1964]). Frankly speaking, Lysenko's own contributions had been outstanding, and had covered several important fields of biology, whereas his mistakes were also evident. In this paper, I try to distinguish between Lysenko's rightness and wrongness, and make a concrete analysis of his contributions to biology and his tragedies, thus reconsidering him from a comprehensive and objective viewpoint.
One of Lysenko's greatest contributions in plant physiology is that he put forward the concept of vernalization and the theory of phasic development of plants, which have been recognized internationally, and were highly praised even by his strongest critics among geneticists, such as Vavilov (Roll-Hansen [1985]; Soyfer [1989]). Vernalization is a cold treatment that induces or accelerates flowering and insures that temperate-zone plants will not flower until after winter. Lysenko's work on vernalization caused a great stir in 1932-33. Until now Lysenko was one of the main references in textbooks of plant physiology. Vernalization is not only of great interest theoretically, but also effective in agricultural practice since it ensures fructification while forestalling frost damage. The term vernalization, which derives from Lysenko, is still an extant scientific term and frequently appears in many prestigious journals (Sherman and Talbert [2002]; Bastow et al. [2004]; Yan et al. [2004]; Sung and Amasino [2004]).
From his study of vernalization, Lysenko built his famous theory of phasic development of plants. He investigated the effects on the development not only of low and high temperatures, but also of various regimes of light, moisture, and other environmental factors on a number of cultivated plants. He discovered that the requirements of plants as to life conditions are not identical at different periods in their individual lives. At each phase of its development, a plant requires determinant conditions of life. Thus autumn wheat and rye require fairly low temperatures in the first phase of their development and are indifferent to light. Once the phase of vernalization is terminated, the plant acquires new characteristics. Then begins the second phase of development, the “luminous” phase. At this phase autumn wheat already requires higher temperatures and a fairly long light day. If these requirements are not met, the plant does not pass through the “luminous” phase and cannot move on to the next phase of development (Stoletov [1953]). Lysenko's theory of phasic development of plants has gradually evolved into a general framework for plant science including not only plant physiology and development but also genetics (Roll-Hansen [1985]).
Based on the works of Michurin and other Soviet scientists (including Lysenko himself), Lysenko founded the Michurinist genetics school. In the course of his life, Michurin not only produced more than 300 strains of horticultural plants, but also made a great many observations and studies of plant life. The basic principle of Michurin's operations was the changing of heredity by means of environmental changes acting on the early developmental stages of plants. It was in this spirit that Lysenko formulated the basic theses of the Michurinist genetics school. According to this, the external environment plays a leading role in the development of the organic world. Only by competently changing the life conditions and by skilled preparation of the organisms that ensures the reception of these conditions through assimilation and dissimilation processes, is it possible to change the living body and its properties. This assumption cannot be considered as gratuitous and improbable because it is consistent with Darwin's ideas. Throughout his career, Darwin consistently linked the cause of variation with changes in the environment. This is the reason why Lysenko also took Darwin's theory as their basis and regarded Michurinist genetics as Soviet creative Darwinism.
It is well known that Lysenko was a keen supporter of the inheritance of acquired characters, which is a central tenet of Michurinist genetics and is also associated with the name of Lamarck and Darwin. Recently, Lamarck's name has been creeping back into scientific literature. The main reason is that some of the epigenetic changes can be passed on to offspring in ways that appear to violate Mendelian genetics (Balter [2000]). The conversion of winter wheat and spring wheat is cogent evidence for the inheritance of acquired characters. Darwin [1868] mentioned Monnier's experiments in which winter wheat was sown in the spring and spring wheat in the autumn to produce spring or winter wheat respectively. In the middle of the 1930s, Lysenko reposed the problem of conversion and proved that the conversion of winter wheat and spring wheat could be realized by skillful training (Lysenko [1954]). Recently, the relationship between vernalization and epigenetics has been extensively documented. It has been indicated that environmental factors, such as temperature, can influence epigenetic marks such as methylation (Balter [2000]). There is evidence that vernalization results in DNA demethylation that induces flowering, thus shedding new light on the epigenetic basis of vernalization (Sung and Amasino [2004]; Sherman and Talbert [2002]). It has been accepted that the epige-netic inheritance system enables the environmentally induced phenotypes to be transmitted between generations. Jablonka and Lamb [1998] described the properties of the epigenetic inheritance systems that underlie cell memory and enable environmentally induced cell phenotypes to be transmitted in cell lineages, and argued that transgenerational epigenetic inheritance is an important and neglected part of heredity. Therefore, the conversion of winter wheat and spring wheat cannot be regarded as Lysenko's fraud.
Graft hybridization is the main content of Michurinist genetics. Based on the works of Darwin and Michurin, Lysenko not only recognized the existence of graft hybrid, but also applied graft hybridization to the practice of plant breeding. According to incomplete statistics, there were about 500 papers on graft hybridization published in Soviet Union during 1950-1958 (Zu and Li [1964]). Unfortunately, these were largely thought to be fraudulent results (Crane [1949]; Hagemann [2002]). Over the past decades, however, several independent groups of scientists repeatedly showed that graft-induced variant characteristics were stable and inheritable (Shinoto [1955]; Frankel [1956]; Zu and Li [1964]; Ohta [1991]; Taller et al. [1998], [1999]; Fan [1999]; Hirata et al. [2003]). All of these grafting experiments proved the existence of graft hybrid, and ruled out chimaerism, the only explanation so far considered, as being the basis of graft hybrid. It has been indicated that graft hybridization is not only a simple and powerful means of plant breeding (Taller et al. [1999]; Liu [2001]), but also striking evidence for Darwin's pangenesis – a developmental theory of heredity (Liu [2004a]), and plays a crucial role in revealing the hereditary mystery of fruit trees (Liu [2004b]). Recently, grafting experiments proved that endogenous mRNA enters and moves the phloem long-distance translocation system (Lucas et al. [2001]). With the establishment that novel mRNA species may move between cells and around the plant, and the ability of retroviruses or retrotransposons to reverse transcribe mRNA into cDNA capable of being integrated into the genome (Kumar and Bennetzen [1999]), mechanisms exist for the horizontal gene transfer from stock to scion and vice versa by grafting. Although Lysenko's explanation for the formation of graft hybrid might be flawed, in the point of recognizing the existence of graft hybrid and applying it to plant breeding, at any rate, Lysenko was right.
It was known to Darwin that the ill effects of inbreeding both in animals and plants could be partly or wholly removed by raising them in different environmental conditions (Darwin [1868]). Inspired by Darwin, Lysenko proposed the renovation of wheat seed by intravarietal crossing. This was based on the assumption that other plants of the same self-fertilizing variety would nevertheless show slightly different environmental conditions, and that crossing them should lead to an increase in vigour. This assumption was brilliantly justified in practice. Within a very few years, extensive comparative trials on many collective farms demonstrated the effectiveness of the technique in raising yields (Morton [1951]). Recently, Flegr [2002] has proved the validity of intravarietal crossing theoretically.
Wide hybridization is an important content of Michurinist genetics. Prior to the work of Michurin, hybridization rarely went beyond close intraspecific crossing because of the difficulties of wide hybridization. One of the important barriers to wide hybridization is rejection of pollen by a foreign style. Either the pollen is unable to germinate or the pollen tube is inhibited in the pistil before reaching the egg. A thorough study of pollination biology in fruit plants enabled Michurin to introduce the method of mentor pollination to breeding, thus overcoming the difficulties in wide hybridization. Mentor pollination is the use of a small amount of pollen that is highly compatible with the seed parent mixed with a large amount of pollen from the intended pollen parent to increase the possibility of success in wide hybridization. The application of mentor pollination has been well confirmed and recognized by Western scientists (Stettler [1968]; Pandey [1977]; Wenslaff et al. [2000]).
It is worthwhile noting that Japan and China are the few countries where Michurinist genetics had been taken seriously. The Japanese Society for Michurin Biology was set up in 1954, and the Japanese Journal of Michurin Biology was launched in 1965 and still continued in the 1980s (Halstead [1987]). China's policy is that “hundred flowers bloom, hundred schools contend”, therefore, both Mendelian genetics and Michurinist genetics could coexist (Li [1987]). When I was an undergraduate student in Henan Agricultural University, China, during 1982 and 1986, I was taught two genetics – Mendelian genetics and Michurinist genetics. In my opinion, Michurinist genetics cannot be regarded as pseudoscience because it provides many scientific phenomena and explanations that Mendelian genetics conspicuously lacks.
Lysenko's practical achievements in agriculture were very impressive. His first achievement in agricultural practice was the use of Vernalization method. In regions of poor summer rainfall, seed planted in the spring may not achieve sufficient growth before the dry season. For some crops, notably wheat, a winter variety had been developed. The seeds are planted and begin to grow in the fall, over-winter as very young seedlings, and then start to grow again immediately in the spring, thus achieving a longer total growing season. Winter varieties, however, are subject to catastrophic loss if the winter is unduly severe. Vernalization is a process of chilling and wetting the seeds of winter varieties, then planting them in the spring. The seeds complete their growth cycle without the hazard of severe winter conditions. Lysenko adopted vernalization and expanded its use to a whole variety of crops and situations. It is no accident that the first wholesale trials of vernalization were carried out after the two severe winters of 1927-28 and 1928-29, in which 32 million acres of winter wheat were lost in the extraordinary cold (Levins and Lewontin [1985]). It was widely felt that vernalization was a promising method. Roll-Hansen [1985] once asked a very good question: “If Lysenko's tests for vernalization were so poor, why was the method not criticized and rejected by agricultural experts?”
The technique of summer planting of potatoes was proposed by Lysenko in 1935 to solve the problem of the cultivation of potatoes in the steppes of Southern Russia. This cultivation had long been abandoned because of the “degeneration” of the tubers in these hot dry regions. In addition he created a variety of spring wheat suitable for Southern Steppes, which had been a standard variety; he brought about phenomenal increases in the yield of millet, which played an important part in feeding the Red Army during the war; he increased the yields of kok-sagyz by cluster-planting; solved the problem of over-wintering wheat in Siberia by sowing in the autumn stubble; developed a branched wheat of great promise; and laid down the principles and practice of seed production, which had revolutionary effects in raising yields. These achievements won him the respect and affection of the Soviet people [Morton 1951].
Haldane argued that, from a practical standpoint, Lysenkoism was a great success. He assumed, probably correctly, that communists and non-communists alike would find it hard to believe that the Soviet regime would support Lysenko if his policies had been practical failures (Paul [1983]). Eric Ashby, a respected plant physiologist, who had lived in the Soviet Union and visited Lysenko's institute on several occasions, wrote that “his scientific theories may be rubbish, but his practical ideals do in fact work; it is what Lysenko does on the farm, not what he says in the Academy”. This is essentially the way Ashby judged Lysenko's personality in 1947: “He is not a charlatan. He is not a showman. He is not personally ambitious. He is extremely nervous and conveys the impression of being unhappy, unsure of himself, shy, and forced into the role of leader by a fire within him. He believes passionately in his own theories, and he is not convinced by cold reasoning” (Roll-Hansen [1985]).
Throughout his career, Lysenko can be regarded as a Darwinist because most of his ideas are consistent with Darwin's ideas. Lysenko recognized that Darwin was a great naturalist, the founder of scientific biology. He believed that only on the basis of Darwinism could the science of the life of plants and animals develop successfully. However, it is true that Lysenko challenged Darwin at least in the formation of species and intraspecific competition, which he thought to be erroneous aspects of Darwinian theory.
Darwin's theory of evolution proceeds from the recognition of quantitative changes only, thus there should be no natural border lines, no discontinuity between species in nature. Lysenko did not hesitate to oppose Darwin directly: “No continuous, unbroken series of forms between species – different qualitatively definite states of living matter – have been found. This is so not because the intermediate forms in a continuous range have died out as a result of mutual competition, but because there is no such continuity in nature, nor can there be. A species is a distinct, qualitatively definite state of living matter. We must realize that spe-ciation is a transition – in the course of the historical process – from quantitative to qualitative variations. Such a leap is prepared by the vital activity of organic forms themselves, as the result of quantitative accumulation of response to the action of definite conditions of life, and that is something that can definitely be studied and directed. The conversion of one species into another takes place by a leap” (Lysenko [1954]). Lysenko's assumption is based on the following facts: In 1948, V.I. Karapetian observed in his experiments that if 28-chromosome durum wheat (Triticum durum) is sown late in the autumn, some of the plants are converted rather quickly, in two or three generations, into another species, into 42-chromosome soft wheat (T. vulgare). In addition, a number of Soviet agronomists found single grains of rye in durum-wheat and soft-wheat spikes. The facts Lysenko described might be true, and can be well explained by horizontal gene transfer, though his idea of sudden jumps in evolution was supported only by a few scientists, such as Imanishi (Halstead [1987]). Horizontal gene transfer is the transfer of genes across species including those in different kingdoms. It goes counter to both modern genetics and the theory of evolution. The passage of DNA from plants to soil bacteria has been proposed as a force in evolution. Soil bacteria could thus provide a genetic link between distant plant species. High rates of gene transfer are known to be associated with the plant root system, the rhizosphere, where conjuga-tive are most likely. There, Agrobacterium could multiply and transfer transgenetic DNA to other bacteria, and to the next crop (Ho [2003]).
Inspired by Malthus, Darwin explained the gap between species by using intraspecific competition. Based on a practical farming method of raising kok-saghyz plants, Lysenko argued that there exists no intraspecific competition but mutual assistance among individuals within a species, and there does exist interspecific competition and also mutual assistance between different species. Lysenko had done a service to biology by pointing out how rarely intraspecific competition happens, though he had stated his case too strongly. Haldane expressed partial sympathy with Lysenko over the significance of intraspecific competition. Like Lysenko, Haldane also rejected the Malthusian element in this Darwinian schema. That is, he rejected the notion that overpopulation, leading to conflict within species, was the rule in nature. He did not deny its existence, but thought its extent generally exaggerated. Animal populations, Haldane insisted, are typically kept down, not by resources in short supply but by conflict with other species; direct struggle among members of the same species is rare. He proceeded to make a more general point, about which there is today no disagreement: natural selection can occur in the absence of competition among members of the same species, in fact even when they are actively cooperating (Haldane [1948]). Despite its significant theoretical utility, there is little empirical support for the idea that intraspecific competition generates disruptive selection. Indeed one major proponent has recently written that “at present, this mechanism for fitness-minimizing equilibria is only a theoretical possibility, but a wide variety of ecological circumstances should lead to fitness functions with the necessary type of frequency-dependent … [including] a number of models of competition” (Bolnick [2004]). Obviously, Lysenko's claim of nonex-istence of intraspecific competition in nature is too one-sided, as Haldane [1948] correctly pointed out. However, the facts he described might be true. Recently, Cresswell et al. [2001] demonstrated that attributes of individual flowers of Brassica napus L. are affected by defoliation but not by intraspecific competition, which is similar to Lysenko's experimental result. Bossdorf et al. [2004] formulated a new ERCA (Evolutionary Reduced Competitive Ability) hypothesis: if there is less competition in the invasive range and competitive ability involves traits that have a fitness cost, then selection might act against it, thereby reducing intra-specific competition too. Nevertheless, competition between relatives can reduce, and even totally negate, the kin-selected benefits of altruism toward relatives (West et al. [2002]). Mutualism may play a more important role in the evolution of specialized cooperative societies than has previously been supposed (Clutton-Brock [2002]), thus supporting Lysenko's claim of mutual assistance within and between species.
Lysenko's biggest mistake is mixing science and politics. As Lindegren [1966] correctly point out, Vavilov's tragic death led to an emotional reaction against Lysenko in which much of the emphasis was placed on the wrongness of Lysenkoism rather than upon the wrongness of using political procedures to liquidate a scientific opponent. Lysenko used to regard Mendelian genetics as “bourgeois science” and “pseudoscience” and forced Soviet geneticists to accept Michurin's teaching or be banned from doing research, for which he became notorious. In his self-obituary, Haldane [1964] said: “I think it was extremely unfortunate both for Soviet agriculture and Soviet biology that he was given the powers that he got under Stalin, and that he used to suppress a lot of what I believe, and what most geneticists believe, to be valuable work, much of which has been started up again but with a considerable lag”. Soyfer [2001] claimed that “Stalin decided to show his support for Lysenko by allowing him to officially declare that genetics was a bourgeois perversion”, which actually is not the case. Stalin, contrary to expectations, did reject some of Lysenko's wrong ideas. For instance he removed all mention of “bourgeois biology”, and crossed out the section entitled “The false basis of bourgeois biology” from Lysenko's report. In the margin next to Lysenko's statement that “any science is based on class” Stalin wrote, “HA-HA-HA!!! AND WHAT ABOUT MATHEMATICS? AND WHAT ABOUT DARWINISM?” (Rossianov [1993]; Medvedev [2000]). The reason why most western scientists did not believe Lysenko's scientific claims is probably because of his political views and the obvious political content of his arguments as presented in The State of Biology in the Soviet Union. People outside the Soviet Union, except for a few Communists, cannot accept the statement that insight into a scientific problem has been achieved by a study of the principles laid down by Marx, Engels and Stalin. Even the finest scientific date would find an unreceptive audience with such an introduction. No politician, no matter how well respected, would be an acceptable mentor for a scientific presentation to a Western scientific audience. Lysenko probably lost his Western audiences through his acceptance of a political mentor (Lindegren [1966]). It is worth noting that, unlike Lysenko, Michurin recognized the significance of the genetic laws of Mendel and the existence of genes. He wrote: “I by no means deny the merits of Mendelian laws. On the contrary, I merely insist on the need to introduce amendments and addenda into it, for it is evident to everybody that his calculations are not applicable to cultivated varieties of fruiters…” (Michurin [1955]). But Lysenko denied both the significance of Mendelian laws and Morgan's theory of chromosome. According to Morgan's theory of chromosome, genes are located in the chromosome of the cell nuclei. Morganists thought that the scion and the stock could not have exchanged chromosomes of the cell nuclei; therefore, they did not think it possible to obtain hybrids by means of grafting. On the contrary, Lysenko denied Morgan's theory of chromosome according to the existence of graft hybrid. He wrote: “Thus experiments in graft hybridization provide unmistakable proof that any particle of a living body, even the juices exchanged between scion and stock, possesses hereditary qualities. Does this detract the role of the chromosomes? Not in the least. Is heredity transmitted through the chromosomes in the sexual process? Of course it is. We recognize the chromosomes. We do not deny their presence. But we do not recognize the chromosome theory of heredity. We do not recognize Mendelism-Morganism”. Morganists should not have denied the existence of graft hybrid and Lysenko should not have denied the existence of genes. The word gene was coined in 1909 by Johanssen, and was derived from De Vries' term pangen, itself a derivative of the word pangenesis which Darwin had coined. Now most biologists have accepted that certain genes routinely move around – within a chromosome, between chromosomes, within a species, between species. Movable genes torpedoed the idea of the gene as a site on a chromosome (Comfort [2001]). It seems likely that both Morganists and Lysenko were one-sided.
Lysenko's failure to build up suitable scientific collectives for the metabolism-biochemical studies of heredity at a time when he could have done it is a much more serious mistake. Lysenko is correct in stating that he has on several occasions acknowledged both orally and in writing the importance of the physical, chemical, etc., studying of living body, but he failed to organize these investigations at a time when he, as a leader, had all possibilities to do so (Rajki [1966]).
It is true that sometimes Lysenko forgot to mention the names of his predecessors in his publications. For example, many people mistook the conversion of winter wheat and spring wheat for Lysenko's discovery because of his neglect of his predecessors. In addition, Lysenko forgot a very important kind of conflict between members of the same species, to which Darwin drew attention. This is the struggle, often with horns and teeth, which takes place between males of polygamous species for the possession of females. In such species the males are larger than the females. Darwin explained such facts by sexual selection (Haldane [1948]). Being a famous biologist, Lysenko should have been proficient in Darwin's works, but he was not, as he himself said: “[Prezent] showed me that the roots of the work I am doing lie in Darwin. And I, comrades, must confess here straightforwardly in the presence of Iosif Vissarionovich [Stalin] that of my shame I have not studied Darwin properly” (Jukes [1995]).
Department of Horticulture, Henan Institute of Science and Technology, Xinxiang,
China, 453003
Current address: Department of Biochemistry, University of Alberta, Edmonton,
Canada, T6G 2H7
E-mail: ysliu63@yahoo.ca
I wish to thank Professor Xiang-ming Wang for providing me with research materials and Ms. Helen Aitken Ritzer for language corrections.