Frederick Charles Bawden: Plant Pathologist and Pioneer in Plant ...

Annu. Rev. Phytopathol. 1994.32:39-47. Downloaded from www.annualreviews.org Access provided by Academia Sinica - Taipei on 11/03/15. For personal use only.

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CHARLES BAWDEN

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1994.32:39-47 e 1994 by Annual Reviews Inc. All rights

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FREDERICK CHARLES BAWDEN: Plant Pathologist and Annu. Rev. Phytopathol. 1994.32:39-47. Downloaded from www.annualreviews.org Access provided by Academia Sinica - Taipei on 11/03/15. For personal use only.

Pioneer in Plant Virus Research B.D. Harrison Department of Biological Sciences, University of Dundee, Dundee DDI 4HN, U.K. KEY WORDS:

plant pathologist, plant virologist, pioneer plant virologist, Rothamsted Experimental Station, virologist

Fred Bawden was the dominant figure in plant pathology in Britain during the 1950s when I was fortunate to be one of his few research students. Later I was a member of staff of his department at Rothamsted Experimental Station and altogether had close contact with him for more than ten yearS. His research and writings on plant viruses and virus diseases, first at Cambridge and later at Rothamsted, gave him an international reputation dating from the late 1930s. At the time of his death in 1972, he had been director of Rothamsted for 14 years and was probably the most distinguished agricultural scientist in the British Commonwealth. Bawden was born at North Tawton, Devon, in 1908 and spent most of his childhood and school years at nearby Okehampton, where his father and mother were the master and matron of the workhouse. He was the youngest of their three children. As a boy he became interested in potatoes and other crops, perhaps those growing in the workhouse garden (11). Another key influence was the enthusiasm his grammar school headmaster had for botany. He was later awarded a Ministry of Agriculture and Fisheries scholarship, which en abled him to pursue a degree in natural sciences at Cambridge University. He also took, as required by his scholarship, the Diploma in Agricultural Science. His diploma thesis, on cereal rusts, described work done under the supervision of FT Brooks and was an important step toward his career in plant pathology. In 1930 he took a relatively low paid job as research assistant at the recently established Potato Virus Research Station in Cambridge. Positions in research were, as now, not easy to obtain. The head of the station, RN Salaman, was qualified in medicine, an enthusiast and man of culture, and an authority on 39 0066-428619410901-0039$05.00

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many aspects of the evolution and economic history of the potato. Bawden is

said to have regarded him with affection and respect. While at the Potato Virus Research Station, Bawden concentrated on finding methods, especially sero

logical ones (perhaps suggested and no doubt approved of by Salaman), that could be used to detect, quantify, and identify potato viruses. These methods would end the reliance on symptoms as the main indicators of which virus or combination of viruses occurred in a particular plant. After six years of this


research, which yi elded several publications, Bawden became a "virus physi ologist" in the Plant Pathology Department at Rothamsted, where he remained on the staff for the rest of his life.

RESEARCH ON PLANT VIRUSES When Bawden moved to Rothamsted, he had already been collaborating with NW (Bill) Pirie for a couple of years. It was to become a famous scientific partnership, lasting for another 36 years. They had been fellow students, and had begun working together after chance meetings in the Department of Pa thology at Cambridge, where Bawden had come to do his serological experi

ments on potato virus X with ETC Spooner. To have such a long and productive collaboration, facilitated by Pirie's move to Rothamsted in 1939, required a remarkable degree of personal and scientific compatibility. On the surface, they had different backgrounds, personalities, and habits: Bawden, a botanist with a strong Devon accent, was fond of company, a great talker, politically

left-of-center, and he worked long hours that did not, however, include the early morning; Pirie, a biochemist and a Scot, was more self-contained, less

talkative, politically left wing, and was often met going home for breakfast when others were arriving for work. However, they both had keen minds, were scrupulous about interpreting evidence correctly, were attracted by work on viruses, could bring different scientific backgrounds to bear on a problem,

shared an interest in the correct and skillful use of words, and obviously enjoyed each other's company. Interestingly, neither of them felt the need to obtain a PhD. At Cambridge, Bawden and Pirie had attempted to purify potato virus X. This was no easy task in the 1930s and they made only moderate progress. When Bawden moved to Rothamsted, he was not restricted to potato viruses and they decided to try tobacco mosaic virus (TMV). The result was dramatic. Pirie (10) recorded that "in a few weeks using the methods that had been standard in protein chemistry for half a century, [we) got liquid-crystalline preparations of an infective nucleoprotein." Their work was described in detail in 1937 in the Proceedings of the Royal Society (2). The paper was the most renowned of their many joint publications. Not only were their observations

and conclusions correct, but, more remarkably, the accuracy of their quantita-


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tive estimates have scarcely been bettered by more modem techniques after more than 50 years. Their results, together with those of their collaborators, JD Bernal and I Fankuchen (6), showed that TMV particles contain about 95% protein and 5% ribonucleic acid, and that they are rod-shaped, can form liquid crystals, and have a regular substructure detectable by X-ray diffraction. Plainly, viruses were not very small bacteria, as had been commonly thought, but rather, they were entities of a totally different kind. Although WM Stanley, working at the Rockefeller Institute for Medical Research in New York, was the first to claim that TMV particles contained protein (12), he had not detected nucleic acid in his preparations and at first disputed the evidence for its presence. Perusal of the correspondence between Bawden and Stanley, now held by the Royal Society, is instructive. Bawden is assiduous in pointing out the inaccuracies and inconsistencies in Stanley's data and conclusions. Indeed Stanley admitted in 1938 that he had been misled by "incorrect phosphorus determinations" and wrote that he now agreed with Bawden and Pirie. However, this admission was not much aired in public and some of Bawden's further comments seem tart. On hearing in 1941 that Stanley had received a medal, Bawden wrote "what does it feel like (to be reward ed) ...for discovering that tobacco mosaic virus was a liquid crystalline nucleo protein after the stubborn fight you put up to maintain that it was a... crystalline globulin?" Stanley seems not to have taken offense. His replies were polite and in 1940, after the outbreak of the war in Europe, he offered to look after Bawden's children in his own home if Bawden wanted to send them to the United States. Bawden and Pirie progressed from their seminal studies on TMV to work showing that particles of cucumber viruses 3 and 4 (now known to be strains of another tobamovirus), potato virus X, and tomato bushy stunt virus were ribonucleoproteins. They also obtained evidence that particles of tomato bushy stunt virus were spherical and produced true crystals of them (3). Particles of tobacco necrosis viruses were also purified and a variety of crystals were produced. Stanley and his colleagues eventually confirmed several of these findings. With their emphasis on the ribonucleic acid content of virus particles, why did Bawden and Pirie fail to discover the infectivity of isolated virus nucleic acid? Indeed, they prepared TMV RNA using a variety of procedures similar to those used by others in the late 1950s, but they found it was not infective. The most likely explanation is that, at the time, virus inocula had to be transported about 50 miles from Pirie's laboratory in Cambridge to Baw den's at Rothamsted for infectivity testing, and the RNA, which is labile, became inactivated in transit. Molecular biology might have begun much earlier but for this unlucky circumstance. It was about another 20 years before the infectivity of plant viral RNA was established (8). This golden period of research was ended by the war. Bawden mobilized

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his colleagues to do work of more practical importance, for example, on restricting the spread of potato viruses in crops, studying varietal differences in virus resistance in potato and differences among virus strains, and investi gating the effects of factors such as light and plant nutrition on the susceptibility of plants to virus infection (with B Kassanis and FM Roberts). His interest in laboratory phenomena with possible practical applications extended from work on inactivators of infectivity, such as urea and alkali (with Pirie), to inhibitors


of virus infection and/or replication: ribonuclease (with A Kleczkowski), tri chothecin (with G Freeman), and thiouracil (with Kassanis). However, these approaches have yet to be of much value in agriculture. Another finding, the consequences of which gave him particular pleasure, was that paracrinkle disease is caused not, as suggested by CD Darlington, by a "plasmagene", but by a conventional virus (now known to be a carlavirus) that occurred in every King Edward potato plant (5). Kassanis used meristem-tip culture some years later to produce a virus-free stock of this widely grown variety with enhanced tuber yield. Bawden and Kassanis visited the Scottish seed-potato farm where the first field of virus-free King Edward was growing and are reported to have shown great pride when standing in the magnificent crop.

Bawden and Pirie's work on the tobacco necrosis viruses (4) also provided much of the groundwork for the discovery of satellitism. They showed that the Rothamsted culture contained ribonucleoprotein components of two or three sizes, and at least two serological specificities. The smallest of these particles (50S) was not infective; infectivity was associated with a larger particle (115S). Their colleagues Kassanis and Nixon (9), who separated the particle types by density gradient centrifugation, which had just been intro duced, showed that the smallest of the particles were those of a second virus that could multiply only in tissues infected with tobacco necrosis virus, which produced the larger ones. They coined the name satellite virus for the depen dent virus. In later years, Bawden's research contributions decreased as his administra tive responsibilities grew. Few others would have been able to maintain any research at all. However, he discovered photoreactivation of ultraviolet-irra diated plant viruses and nucleic acids (with Kleczkowski). He also continued his series of studies, which he now described as his hobby, on the activity and inactivation of tobacco necrosis and tobacco mosaic viruses (with Pirie). Bawden's influence on the emerging science of plant virology was not confined to his research work. In 1939 he produced the first comprehensive book (1) embracing both the chemical and biological properties of plant vi ruses. It was written in a particularly lucid style and provided both facts and viewpoints, with a clear distinction between the two. It became the standard text for aspiring plant virologists and appeared in three more editions. I par ticularly valued the third edition, which was authoritative and taught the need



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to think about and question the interpretations of others. Bawden was not reticent about questioning conclusions he thought were derived from inade� quate evidence. For example, he pointed out that the initial experiments of LM Black and associates in the United States did not establish beyond doubt that some viruses multiplied in their insect vectors. This objection stimulated the Americans to do further work, which proved the point to the satisfaction of all. Bawden also questioned, quite correctly, the initial evidence of A Gierer and K-W Mundry that nitrous acid caused mutations in TMV, and suggested other interpretations. However, in this instance he seems to have persisted in his objections too long, probably because he had not followed some of the key evidence, which was published in Gennan. Bawden contributed much to thinking on virus classification and nomencla ture. He advocated the use of chemical and serological properties of viruses as taxonomic characters and poked fun at the views of those who preferred to use symptom types (which he argued had relatively little value in virus tax onomy) as a basis for latinized binomial names. He probably would have approved of modem trends in virus taxonomy, which emphasize genome organization, and would have welcomed the evidence for modular evolution of viral genomes. He would have been less enthusiastic about adoption of the categories of species, genus, and family in virology. As a leading research worker and gifted writer, Bawden was also in demand as an author of more general articles on plant viruses. He produced many such reviews for a variety of publications and, as a result, brought to a wide audience new knowledge on the structure of virus particles and the nature of the bor derline between the living and non-living. LEADERSHIP IN PLANT PATHOLOGY AT ROTHAMSTED Bawden became head of the Plant Pathology Department in 1940 at the age of 32 and led it with distinction for 18 years. The war and its aftennath may have truncated his research on the properties of virus particles but it also had some beneficial effects. It enabled him to gather (and retain) in the department several talented individuals such as Kassanis (a Greek research student), Kleczkowski (a Polish medical doctor of Russian extraction), and Nixon (a Quaker conscien tious objector from the Chemistry Department). Indeed, when I went to Roth amsted as a research student in the 1950s, the names on the doors read like a directory of prominent plant virologists, and included those of these wartime acquisitions as well as Marion Watson and L Broadbent. Pirie was head of the Biochemistry Department, which was housed in an adjacent building. Bawden coordinated this diverse group with great success. He believed in selecting able people, pointing them in a particular direction, and allowing

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them to develop their own lines of work. However, he collaborated actively with several of them, and particularly fruitfully with Kassanis and Klecz kowski. Though he did not do field experiments on virus diseases, he recog nized the importance of virus epidemiology and control, and encouraged work in these areas, especially in sugar beet (by R Hull and Marion Watson) and potatoes (by Broadbent). As a result of Bawden's high reputation and the all-around expertise in plant virology at Rothamsted, the department became


something of a training center, with people from many countries coming to work in the laboratories. Bawden also encouraged work on fungal pathogens. PH Gregory's studies on the air spora led him to develop the science of aerobiology. JM Hirst applied micrometeorology and the technique of spore trapping to his analysis of the development of fungal disease epidemics. Ff Last studied microorganisms on the leaf surface (the phylloplane) and showed the importance of cereal powdery mildews. Mary Glynne conducted pioneering studies on the development and control of eyespot disease of cereals. These researchers benefited from Baw den's comments and suggestions and, like those of the virologists, their papers were subject to the discipline imposed by Bawden's editorial pencil. He rig orously pruned unnecessary verbiage, punctured pomposity, ironed out ambi guities, and encouraged the correct use of words in direct, grammatically sound sentences. Bawden's comments were made in his minute hand writing. Almost invariably they were improvements and, even when illegible, they were a sure indication that revision was needed. They provided a schooling in scientific writing that was valued by most of the recipients, five of whom were or later became Fellows of the Royal Society. During this period, departmental sem inars under Bawden's informal chairmanship were often lively, sometimes hilarious. One speaker, replying to a Bawden question and attempting a mild rebuff with "Well Fred, if you had read my last paper ..." was cut off by the expostulation "Read it, X,-I wrote it." This was indeed a real possibility in some instances, although subsequent language analysis has shown relatively little evidence of Bawden's writing style in the papers of departmental col leagues who were not his coauthors. In contrast, the introductions of the Bawden and Pirie papers are mostly in Bawden's style and he confirmed that he wrote most of these (AJ Gibbs, personal communication). Bawden believed in informality and his door was always open to those with something plant pathological to discuss. One would typically find him in his office. wreathed in cigarette smoke. and bent over an ancient portable type writer, drafting an article on the back of scrap paper. Alternatively, in the late afternoon, or on Saturday mornings, he would be found in the glasshouse. counting local lesions on inoculated leaves or, surrounded by watchglasses containing virus inocula prepared by Pirie, holding an animated conversation with a colleague, interspersed with gusts of his characteristic laughter.


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WIDER RESPONSIBILITIES Others have recorded Bawden's role in the development and expansion of Rothamsted during his 14 years as director: a near doubling in staff, new buildings and additional farm land, extra equipment, and a new approach to the classical field experiments (7). His introductions to the published annual reports were highly valued for their general comments as well as for their specific references to work at Rothamsted. He applied his high scientific standards and


editorial pencil when commenting on more than 300 papers produced per year by Rothamsted staff, and so compelled many of them to think more deeply ( 13). He had a strong interest in the land and the practical impact of science on farming, perhaps in part a result of having been brought up in an agricultural area. He took a personal interest in the field experiments at Rothamsted and, during his time as director, helped to keep himself well informed about them by taking Sunday afternoon walks on the Rothamsted farm. After his first experience of the tropics in 1947-a visit to West Africa in connection with cocoa swollen shoot disease-Bawden made many other foreign visits, especially to developing countries in the British Commonwealth. He realized that the problems caused by plant pathogens in Britain were relatively minor compared with those in many tropical regions. To help tackle some of these problems, he arranged for various members of staff to be seconded, for example, to West Africa to study cocoa swollen shoot disease, to East Africa to investigate diseases of coffee or cloves, and to the Sudan to study cotton diseases. He was also in demand for committees and to advise on agricultural research in the tropics, where his visits seem to have been greatly appreciated, especially by the working scientists he tried to meet whenever possible. However, despite his strong commitment to those in de veloping countries, Bawden's greatest loyalty was to Rothamsted, the suc cesses of which gave him enormous satisfaction. Yet he also recognized all that still needed to be done. Bawden fought hard to minimize the adverse effects of moves in the early 1970s toward greater governmental control of research. He was firm in his belief that committees and administrators were unlikely to bring the best out of research scientists. Most certainly he would have been even more scathing about the accountancy-dominated environment that is inflicted on government funded research in Britain today. Bawden received many honors. He was elected to Fellowship of the Royal Society in 1949 and was its Treasurer from 1968 to 1972. He served as President of at least six learned societies in Britain and was awarded several honorary degrees. He was elected to honorary membership of numerous soci eties, both British and foreign, and to fellowship of several foreign academies of science. He was knighted in 1967.

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QUALITIES OF CHARACTER Few who met Fred Bawden would forget the experience or his force of character. He was totally informal and had wide interests, for example, in music, rugby football, and cricket, as well as in science and scientists. His brain worked extremely fast, he had a superb memory, and he got through mountains of paper work with remarkable speed. A few other characteristics stand out. His strong commitment to the need for evidence, and for logical


deduction, made it difficult for him to sit still or keep quiet when he thought someone was speaking nonsense. In such circumstances he was apt to give a commentary of criticism to those around him and, on occasion, he would voice his opinion more loudly. In seminars, a typical comment to a colleague who was indulging in unjustified speCUlation was "I'm old fashioned, just give me the facts." Fred was a highly articulate, persuasive, and humorous speaker, and he was also particularly interested in the written form of language. For him, WS Gilbert's words in the Gilbert and Sullivan comic operas were a far more crucial contribution than Arthur Sullivan's music. Fred enjoyed injecting witticisms into scientific meetings of staff at Rothamsted. On one occasion an eminent statistician was explaining, somewhat lugubriously, the merits of the newly introduced electronic computer, which would be able, he claimed, to do as much work as several hundred female operators with mechanical calcu lators. Moreover, he added, working with such operators had caused problems of staffing continuity "because all the good girls get married." "Do you mean," interjected Fred from the chair, "that the bad ones don't bother?" His infectious sense of humor also came into full play when he recounted stories of his travels and the incidents that occurred during them, especially when they involved well-known people in unlikely situations. But underneath this exterior lay a man with serious purpose and steadfast aims, which included the maintenance of scientific standards and the use of science to discover practical ways of improving agriculture in Britain and developing countries. This was particularly apparent to the staff and research students involved in the informal Saturday-morning discussions in the glasshouse laboratory, where a mixture of stories, scientific talk, and analysis of ideas and results left an indelible impression. In the first part of Fred's career, his research transformed the way people thought about viruses. In the second part, he had a strong influence on devel opments in plant pathology, not only in Britain but also, through his committee and advisory work, and the training of future practitioners from many other countries, on the study and control of plant diseases worldwide. In all these endeavors he was stoutly supported by his wife Marjorie, a school friend from Okehampton who was also a fellow student at Cambridge, where she too had become a plant pathologist before they married.


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ACKNOWLEDGMENTS

I am indebted to Lady Bawden for helpful comments and for granting me access to Sir Frederick Bawden's papers held by the Royal Society, and to former colleagues at Rothamsted, especially Professors AJ Gibbs and JM Hirst, for their help on numerous points. In addition, lowe a special debt to the


authors of references 7, 10, 1 1, and 13. Any Annual Review chapter, as well as any article cited In an Annual Review chapter, may be purchased from the Annual Reviews Preprlnts and Reprints service. 1-800-347-800 7; 41S-259-S017; email: [email protected]

Literature Cited 1.

Bawden Fe. 1939. Plant Viruses and Virus Diseases. Leiden: Chronica Botanica. 272 pp. 2. Bawden FC, Pirie NW 1937. The iso lation and some properties of liquid crys talline substances from solanaceous plants infected with three strains of to bacco mosaic virus. Proc. R. Soc. Lon don Ser. B 123:274-320 3. Bawden FC, Pirie NW 1938. Crystalline preparations of tomato bushy stunt virus. Br. J. Exp. Pathol. 19:251...(i3 4. Bawden FC, Pirie NW. 1945. Further studies on the purification and properties of a virus causing tobacco necrosis. Br. J. Exp. Pathol. 26:277-85 5. Bawden FC, Kassanis B, Nixon HL. 1950. The mechanical transmission and some properties of potato paracrinkle virus. J. Gen. Microbiol. 4:210--19 6. Bawden FC, Pirie NW Bernal 10, Fankuchen I. 1936. Liquid crystalline substances from virus-infected pl ants . Nature 138:1051-52 .

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7.

Cooke GW. 1972. Frederick Charles Bawden. A review of Rothamsted during his directorship, 1958-1972. Rep. Roth amsted Exp. Stn. for 1971, 1:26-30 8. Gierer A, Schramm G. 1956. Infectivity of ribonucleic acid from tobacco mosaic virus. Nature 177:702-3 9. Kassanis B, Nixon HL. 1961. Activation of one tobacco necrosis virus by another. J. Gen. Microbiol. 25:459-71 10. Pirie NW 1972. Frederick Charles Baw den. Thirty-eight years of collaboration. Rep. Rothamsted Exp. Stn. for 1971, 1:34-39 11. Pirie NW 1973. Frederick Charles Bawden (1908-1972). Biogr. Mem. Fel lows R. Soc. 19:19...(i3 12. Stanley WM. 1935. Isolation of a crys talline protein possessing the properties of tobacco-mosaic virus. Science 81: 644-45 13. Watson 01. 1972. Frederick Charles Bawden. Rep. Rothamsted Exp. Stn. for 1971. 1:31-33 .

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