A Tribute to Vernon Ahmadjian (19 May 1930–13 March 2012)

The Lichenologist 45(2): 133–136 (2013) 6 British Lichen Society, 2013 doi:10.1017/S0024282912000795

A tribute to Vernon Ahmadjian (19 May 1930–13 March 2012)

Dr Vernon Ahmadjian was the ﬁrst person to sity, Massachusetts, he served two years on develop consistently successful techniques military service with the US Army Combat for the laboratory synthesis of a variety of dif- Medical Corps in Korea. He returned to ferent lichen species from their isolated algal Clark University, obtaining an M.A. in 1956. and fungal components. His research led to A key event for him was meeting the lichenol- some penetrating discoveries concerning the ogist I. MacKenzie Lamb on a marine botany factors that regulate the early development of course in the summer of 1955. Lamb, then lichens. Director of the Farlow Herbarium at Harvard The son of Armenian immigrants to the University, was taking the course in order to USA, Ahmadjian was born and raised in better curate and enlarge the Farlow collec- Whitinsville, Massachusetts, and lived most tions. Their common keen interest in lichens of his life in Worcester, Massachusetts. After led to Ahmadjian becoming Lamb’s ﬁrst obtaining a B.A. in 1952 from Clark Univer- Ph.D. student at Harvard. Lamb taught him

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Wareń’s micropipette technique for isolating the initial stages were often observed, these lichen symbionts into laboratory culture, and mostly died off or proceeded no further. He introduced him to the unknowns of phyco- concluded that the methodological difficulties biont taxonomy, on which Ahmadjian was were so great that his objectives could only also later to become one of the world’s lead- be realised to a very small degree. ing experts. Most importantly, Lamb passed This was the situation confronting Ahmad- on his own fascination with the experimental jian when his experimental work on lichen synthesis of lichens and the difficulties in synthesis began in the late1950s. His success achieving it to Ahmadjian, and this became was due to his early appreciation of the im- one of his key lifelong interests. After obtain- portance for the initiation of a lichen synthe- ing his Ph. D. at Harvard, he held brief posts sis that the level of available nutrients should at the University of Massachusetts and the Uni- be low (if symbionts are inoculated together versity of California, Berkeley, before returning on nutrient-rich agar they show no tendency to Clark University where he spent most of to associate and grow quite independently). the rest of his career researching lichens. Synthesis progresses further if the cultures At that time, there were confusing reports are subjected to slow, alternate periods of on attempts at the laboratory synthesis of li- wetting and drying. Even better results are chens. A decade or so after it was discovered obtained if more natural substrata such as in the 1860s that a lichen was composed of rock, wood or soil are used instead of agar. two separate organisms, the French biologist Ahmadjian described how the laboratory Gaston Bonnier reported the successful arti- synthesis of Cladonia cristatella proceeded in ficial synthesis of quite a number of lichens the following stages. First, the hyphae en- from their component algal and fungal sym- circle the symbiont – a non-specific stage bionts; he used small stones or pieces of since they would encircle in a similar manner bark hung over water in a current of sterilised a variety of non-symbiotic algae and even air. However, all subsequent attempts by glass beads of a similar size. Secondly, the various scientists to repeat these experiments hyphae branch and continue to envelop sym- failed, and Bonnier’s work became the target bionts to form soredia; the symbionts be- of criticism and doubt. Thus, the Dutch li- come surrounded by a gelatinous matrix of chenologist Quispel, in his classic 1943 re- fungal origin and penetration of them by view of the mutual relations between algae fungal haustoria commences. Thirdly, tissue and fungi in lichens, wrote of Bonnier: ‘‘. . . he differentiation by the fungus into cortex and was the only investigator who pretended to have medulla begins, with the algal symbionts synthesised these lichens in pure culture . . . ’’. confined to a distinct layer. Fourthly, in a Quispelnotedthatallthosescientistswhohad few samples, synthesis proceeds as far as the attempted such synthesis could at best only formation of podetia and the initiation of occasionally obtain the very beginnings of a fungal fruit bodies. Furthermore, transport thallus and no lichen was formed. The Swiss of products of photosynthesis from algal to lichenologist E. A. Thomas imputed the fail- fungal symbionts commenced at about 12 ure of many attempts at synthesis to the use weeks after their first contact. of the wrong substrata with overly high con- Ahmadjian also made extensive studies tents of water and/or of food substances. of the phycobionts of lichens, especially the Thomas developed a technique involving the various species of Trebouxia and Pseudotre- partial insertion of pieces of wood into 1% bouxia. Identical phycobionts were isolated Knop agar inside flasks, and then inoculating from widely different lichen species, indicat- those parts not submerged in the agar with ing that algae are not specific to particular pure cultures of fungus and alga. In only one mycobionts. In a study of the specificity of of the 800 flasks used in these experiments the fungus Cladonia cristatella for its Tre- was a successful complete synthesis observed. bouxia symbionts, for example, he found Quispel himself made numerous attempts at that of nine Trebouxia spp. inoculated with the laboratory synthesis of lichens: although the fungus, three were killed, but four pro-

ceeded as far as thallus formation. However, in 1986, together with Surindar Paracer, he no association was initiated with any of published a more general text, Symbiosis. An 12 Pseudotrebouxia spp. He considered the Introduction to Biological Associations,asecond added problem that Trebouxia spp. are ap- edition appearing in 2000. parently rare in the free-living state. This Sadly, opportunities to meet up with Vernon raised the question of how lichens which do Ahmadjian have been all too few, but on those not form symbiotic propagules such as sore- occasions when each of us did have the plea- dia but only have fungal fruit bodies re- sure of his company they were both memora- produce in nature. With his co-workers, he ble and illuminating. Like us, those who have observed zoosporogenesis in the Trebouxia dealt with him over the years have deeply gelatinosa symbiont of Parmelia (Xantho- appreciated his thoughtfulness, courtesy and parmelia) conspersa. These observations sug- generosity, and can testify to his outstanding gested that zoospores may be released within and unique contributions to our understand- the thallus, escaping to form free-living micro- ing of lichens. colonies. These colonies could potentially then unite with spores from the same or Selected Publications genetically different mycobionts. Such natural Over 90 lichenological and phycological papers and resyntheses could be the cause for the ob- books are attributed to Vernon Ahmadjian, some of the served heterogeneity characterizing the fungi more notable being: of many lichen populations. Ahmadjian, V. (1958) A guide for the identification Ahmadjian’s interests were not confined of algae occurring as lichen symbionts. Botaniska to the laboratory. He knew where the rare Notiser 111: 632–644. lichens grew in his county in Massachusetts, Ahmadjian, V. (1959) A contribution toward lichen synthesis. Mycologia 51: 56–60. and campaigned to have these locations pro- Ahmadjian, V. (1960) The lichen association. Bryologist tected from development. In 1967 the Na- 63: 250–254. tional Science Foundation awarded him the Ahmadjian, V. (1961) Studies on lichenized fungi. Antarctic Medal for his work on lichens at Bryologist 64: 168–179. the McMurdo station in Antarctica, and an- Ahmadjian, V. (1962) Investigations on lichen synthesis. American Journal of Botany 49: 277–283. nounced that an ice-covered, 2900 m peak in Ahmadjian, V. (1966) Artificial reestablishment of the the Queen Alexandra Range of the Transan- lichen Cladonia cristatella. Science 15: 199–201. tarctic had been named ‘Ahmadjian Peak’ in Ahmadjian, V. (1966) Cultural and physiological aspects his honour. He was the first co-editor with of the lichen symbiosis. In Plant Biology Today. Ad- vances and Challenges 2nd ed. (W. A. Jensen & L. G. Ernie Brodo (1967–1974) of the Interna- Kavaljian, eds): 148–163. Belmont, California: Wads- tional Lichenological Newsletter, and in 1996, worth Publishing. for his lifetime achievements in lichenology, Ahmadjian, V. (1966) Lichens. In Symbiosis, Volume 1. particularly for his pioneering research, he (S. M. Henry, ed.): 35–97. New York: Academic was awarded the Acharius Medal. Nor were Press. Ahmadjian, V. (1967) The Lichen Symbiosis. Waltham, his botanical interests and achievements con- Mass.: Blaisdell Publishing. fined to lichenology: he was a champion for Ahmadjian, V. (1967) A guide to the algae occurring as his local natural plant communities and a lichen symbionts: isolation, culture, cultural physi- member of the Tower Hill Botanic Garden ology, and identification. Phycologia 6: 127–160. Ahmadjian, V. (1970) The lichen symbiosis: its origin in Boylston, and in 1979 published a book and evolution. In Evolutionary Biology, Volume 4. on the Flowering Plants of Massachusetts. His (T. Dobzhansky, M. K. Hecht & W. C. Steere, eds): students thoroughly enjoyed the field trips 163–184. New York. Appleton-Century Crofts. he led, for he was an excellent teacher. Ahmadjian, V. (1980) Separation and artificial synthesis Apart from publishing numerous research of lichens. In Cellular Interactions in Symbiosis and Parasitism (C. B. Cook, P. W. Pappas & E. D. Ru- papers, Ahmadjian was the author of a highly dolph, ed.): 3–29. Columbus: Ohio State University significant textbook published in 1967, The Press. Lichen Symbiosis (152 pages), a second edi- Ahmadjian, V. (1982) Algal/fungal symbioses. In Progress tion appearing in 1993 (250 pages). In 1973, in Phycological Research. Volume 1 (F. E. Round & D. J. Chapman, eds): 179–233. Amsterdam: Elsevier he co-edited with Mason Hale the highly in- Biomedical Press. fluential book The Lichens (697 pages), and

Ahmadjian, V. (1988) The lichen alga Trebouxia: does Ahmadjian, V. & Jacobs, J. B. (1987) Studies on the de- it occur free-living? Plant Systematics and Evolution velopment of synthetic lichens. Bibliotheca Licheno- 158: 243–247. logica 25: 47–58. Ahmadjian, V. (1989) Studies on the isolation and syn- Ahmadjian, V. & Paracer, S. (1986) Symbiosis: an In- thesis of bionts of the cyanolichen Peltigera canina troduction to Biological Associations. Hanover, N.H: (Peltigeraceae). Plant Systematics and Evolution 165: University Press of New England. 29–38. Ahmadjian, V., Russell, L. A. & Hildreth, K. C. (1980) Ahmadjian, V. (1990) What have synthetic lichens told Artiﬁcial reestablishment of lichens. I. Morphologi- us about real lichens? Bibliotheca Lichenologica 38: cal interactions between the phycobionts of different 3–12. lichens and the mycobionts of Cladonia cristatella Ahmadjian, V. (1993) The Lichen Symbiosis. 2nd edition. and Lecanora chrysoleuca. Mycologia 72: 73–89. New York: John Wiley. Jacobs, J. B. & Ahmadjian, V. (1969) The ultrastructure Ahmadjian, V. & Hale, M. E. (ed.) (1973) The Lichens. of lichens. I. A general survey. Journal of Phycology New York: Academic Press. 5: 227–240. Ahmadjian, V. & Jacobs, J. B. (1981) Relationship be- Jacobs, J. B. & Ahmadjian, V. (1971) The ultrastructure tween fungus and alga in the lichen Cladonia crista- of lichens. II. Cladonia cristatella: the lichen and its tella Tuck. Nature, London 289: 169–172. isolated symbionts. Journal of Phycology 7: 71–82. Ahmadjian, V. & Jacobs, J. B. (1982) Artiﬁcial re-estab- Paracer, S. & Ahmadjian, V. (2000) Symbiosis: an Intro- lishment of lichens. III. Synthetic development of duction to Biological Associations. 2nd edition. Oxford: Usnea strigosa. Journal of the Hattori Botanical Labo- Oxford University Press. ratory 52: 393–399. Ahmadjian, V. & Jacobs, J. B. (1983) Algal-fungal re- David C. Smith and Mark R. D. Seaward lationships in lichens: recognition, synthesis, and development. In Algal Symbiosis (L. J. Goff, ed.): 147–172. Cambridge: Cambridge University Press.