Mikhail Khristoforovich Chailakhyan: The fate of the scientist under the sign of florigen

The more significant is a discovery made by the scientist, the greater influence it exerts on the fate of its author. The theory of florigen, a hormone of flowering, put forward by M.Kh. Chailakhyan in 1936 initially was inconvenient for Soviet authorities and brought severe trials to the scientist. However, as distinct from many others, Chailakhyan did not deny his scientific beliefs but continued to defend them in spite of harassment and threats. Later, on the contrary, this theory promoted the worldwide fame of its creator, although during Chailakhyan lifetime florigen has not been definitely identified chemically. Chailakhyan was close to the establishing of florigen protein nature, but even his long life was not enough to identify this elusive substance.     

Phytohormones in Plant Biotechnology and Agriculture. Proceedings of the NATO-Russia Workshop held in Moscow, 12-16 May 2002. * Machackova I. and Romanov GA, eds. 2004. * Dordrecht: Kluwer Academic Publishers. {euro}95 (hardback).280 pp

This book contains articles writtenby speakers and selected participants who attended the AdvancedResearch Workshop in 2002. The workshop was dedicated to thecentenary of the birth of the distinguished Russian plant physiologistMikhail Khristoforovich Chailakhyan who is best known for proposingthe existence of a universal flowering hormone that he namedflorigen. The opening article by N.     

"Florigen ": an intriguing concept of plant biology.

"Florigen" is the name that Mikhail Chailakhyan coined in 1937 for the putative hormone regulating flowering. At this concept, plant physiologists arrived following early research concerning the effects of temperature and day length on the transition from vegetative to reproductive stages of plants. The existence of florigen was postulated on the experimental backgrounds involving i) the response of plants to inductive conditions; ii) transmission of a flowering stimulus by grafting; iii) extraction of this stimulus from induced plants. This experimental results showed the existence of florigen at least as concept because they always failed to offer the experimental evidence of its chemical existence. The myth of florigen persisted as long as the end of the Seventies, when physiologists began to consider flowering as a complex process in which various classes of hormones might variously interplay.     

Florigen goes molecular: Seventy years of the hormonal theory of flowering regulation

As early as in 1936, the comprehensive studies of flowering led M.Kh. Chailakhyan to the concept of florigen, a hormonal floral stimulus, and let him establish several characteristics of this stimulus. These studies set up for many years the main avenues for research into the processes that control plant flowering, and the notion of florigen became universally accepted by scientists worldwide. The present-day evidence of genetic control of plant flowering supports the idea that florigen participates in floral signal transduction. The recent study of arabidopsis plants led the authors to conclusion that the immediate products of the gene FLOWERING LOCUS I, its mRNA and/or protein, move from an induced leaf into the shoot apex and evoke flowering therein.     

Promotory effect of GA13 on flowering ofAmaranthus — a short day plant

Abstact The three plant types ofAmaranthus namely,A. caudatus f.albiflorus, A. caudatus f.caudatus andA. tricolor var.tristis are qualitative short day plants with critical photoperiods 16.0, 15.5 and 15.0 h, respectively. Gibberellins A₃, A₄₊₇ and A₁₃ affect extension growth, leaf differentiation and floral induction differently. Thus, in all the three plant types ofAmaranthus, whereas, GA₃ and G₄₊₇ enhanced extension growth, GA₁₃ was completely ineffective under both, 24- and 8-h photoperiods. None of the three gibberellins could affect the leaf differentiation. In all the three plant types, flowering was promoted by GA₁₃ and not by other gibberellins tried. GA₁₃ caused promotion was manifested in two manners, firstly by lowering the critical dark period requirement in each inductive cycle, and secondly by shortening the total period taken for the initiation of inflorescence primordia under inductive photoperiods. The floral induction by gibberellins inAmaranthus is contrary to the gibberellin-anthesin concept of Chailakhyan. It is suggested that gibberellins other than GA₃ may be playing an important role in floral morphogenesis of short day plants.     

Philip R. White (1901–1968)—a tribute

The groundbreaking research carried out by Philip R. White in the 1930s and 1940s played a critical early role in the development of modern plant biotechnology and the production of biotech crops. He gained instant fame and became a historical figure early in his career by becoming the first person to attain unlimited growth of cultured plant tissues. White was one of the best known and most influential figures of his generation in plant cell culture research. His tireless and lifelong efforts to promote the use of plant cell culture systems inspired a generation of scientists and stimulated much scientific activity. White was not only a brilliant and visionary scientist but also a highly principled man who spoke courageously about the great moral and political issues of his day. He was admired as much for his science as for his humanity. His belief that plant cell culture research was not well represented at national and international meetings, and his deeply held conviction that science had to be international and without borders in order to be of service to humankind led to the founding of the International Association for Plant Biotechnology in 1963, currently the largest forum for the international plant biotechnology community. This tribute honors and celebrates Philip R. White for his inspiring science, for his kind and generous mentoring of young scientists, for his advocacy of plant cell culture research and its applications, for his promotion of international scientific exchange and cooperation, and for his leadership in the founding of the International Association for Plant Biotechnology.     

Intercellular interactions through gap junctions in embryonic stem cells

The minireview considers the structure and function of gap junctions, their role in embryonic stem cell persistence and differentiation, and in this context, the first data of the last research project launched by Levon M. Chailakhyan.     

Somatic hybrids of Datura innoxia Mill.+Datura discolor bernh. and of Datura innoxia Mill.+Datura stramonium L. var. tatula L.

Summary Three sexual generations of the somatic hybrids from Datura innoxia+Datura stramonium (Datura straubii) and from Datura innoxia+Datura discolor (Datura hybrida) were investigated (Schieder, 1978). Self fertility of the somatic hybrids proved to be comparable to that of the parental plant species. The good fertility is attributed to the low number of quadrivalents formed in meiosis I. The growth rate of the somatic hybrids is superior to the parental plant species and also to the autotetraploid somatic hybrids of Datura innoxia. Datura innoxia is the species showing the best growth rate of all species used for the hybridization experiments. In addition, some irregularities in the sexual generations are described.Dedicated to my teacher, Prof. Dr. J. Straub, on the occasion of his 70^th birthday.     

The genius of Wilhelm Hofmeister: the origin of causal-analytical research in plant development

Friederich Wilhelm Benedikt Hofmeister (1824-1877) stands as one of the true giants in the history of biology and belongs in the same pantheon as Darwin and Mendel. Yet by comparison, he is virtually unknown. If he is known at all, it is for his early work on flowering plant embryology and his ground-breaking discovery of the alternation of generations in plants, which he published at age 27 in 1851. Remarkable as the latter study was, it was but a prelude to the more fundamental contributions he was to make in the study of plant growth and development expressed in his books on plant cell biology (Die Lehre von der Pfanzenzelle, 1867) and plant morphology (Allgemeine Morphologie der Gewächse, 1868). In this article we review his remarkable life and career, highlighting the fact that his scientific accomplishments were based largely on self-education in all areas of biology, physics, and chemistry. We describe his research accomplishments, including his early embryological studies and their influence on Mendel's genetic studies as well as his elucidation of the alternation of generations, and we review in detail his cell biology and morphology books. It is in the latter two works that Hofmeister the experimentalist and biophysicist is most manifest. Not only did Hofmeister explore the mechanisms of cytoplasmic streaming, plant morphogenesis, and the effects of gravity and light on their development, but in each instance he developed a biophysical model to integrate and interpret his wealth of observational and experimental data. Because of the lack of attention to the cell and morphology books, Hofmeister's true genius has not been recognized. After studying several evaluations of Hofmeister by contemporary and later workers, we conclude that his reputation became eclipsed because he was so far ahead of his contemporaries that no one could understand or appreciate his work. In addition, his basically organismic framework was out of step with the more reductionistic cytogenetic work that later came in vogue. We suggest that the translation of the cell and morphology books in English would help re-establish him as one of the most notable scientists in the history of plant biology.     

Otto kuntze,botanist. I. Biography,bibliography and travels

Otto Kuntze (1843–1907) is renowned for hisRevisio generum plantarum in which he changed thousands of plant names in accordance with his revision of the 1867 Paris Code of Botanical Nomenclature. His contributions to plant taxonomy, based on his world-wide collecting trips, and his monographs are not as well known. A short biographical sketch and bibliography of Kuntze’s natural history and plant taxonomy publications are included with detailed enumeration of localities and dates for trips around the world in 1874–1876 and 1904, to southern U.S.S.R. in 1886, to the Canary Islands and Madeira in 1887–1888, to South America in 1891–1893 and to southern Africa in 1894. Herbaria housing Kuntze specimens are cited. The majority of the type specimens are at the New York Botanical Garden.     

Molecular Genetics Returns to Basic Postulates of the Florigen Theory

The florigen theory, also known as the hormonal theory of flowering in plants, was put forward by M.Kh. Chailakhyan more than 65 years ago. This theory, reviewed here in its historical progress, gave an impetus to a number of modern genetic and molecular studies of flowering in plants. In turn, results of recent investigations restored to a new level Chailakhyan's ideas about florigen, the hormonal stimulus of flowering.     

Induction of abiotic stress tolerance in plants by endophytic microbes

Endophytes are micro‐organisms including bacteria and fungi that survive within healthy plant tissues and promote plant growth under stress. This review focuses on the potential of endophytic microbes that induce abiotic stress tolerance in plants. How endophytes promote plant growth under stressful conditions, like drought and heat, high salinity and poor nutrient availability will be discussed. The molecular mechanisms for increasing stress tolerance in plants by endophytes include induction of plant stress genes as well as biomolecules like reactive oxygen species scavengers. This review may help in the development of biotechnological applications of endophytic microbes in plant growth promotion and crop improvement under abiotic stress conditions.

Significance and Impact of the Study

Increasing human populations demand more crop yield for food security while crop production is adversely affected by abiotic stresses like drought, salinity and high temperature. Development of stress tolerance in plants is a strategy to cope with the negative effects of adverse environmental conditions. Endophytes are well recognized for plant growth promotion and production of natural compounds. The property of endophytes to induce stress tolerance in plants can be applied to increase crop yields. With this review, we intend to promote application of endophytes in biotechnology and genetic engineering for the development of stress‐tolerant plants.     

植物种群的繁殖对策

植物种群的繁殖对策钟章成（西南师范大学,重庆６３０７１５）ＲｅｐｒｏｄｕｃｔｉｖｅＳｔｒａｔｅｇｉｅｓｏｆＰｌａｎｔＰｏｐｕｌａｔｉｏｎｓ．￥ＺｈｏｎｇＺｈａｎｇｃｈｅｎｇ（ＳｏｕｔｈｗｅｓｔＣｈｉｎａＴｅａｃｈｅｒｓＵ－ｎｉｖｅｒｓｉｔｙ,Ｃｈｏｎ...     

Ethylene hormone receptor action in Arabidopsis.

Small gaseous molecules play important roles in biological signaling in both animal and plant physiology. The hydrocarbon gas ethylene has long been known to regulate diverse aspects of plant growth and development, including fruit ripening, leaf senescence and flower abscission. Recent progress has been made toward identifying components involved in ethylene signal transduction in the plant Arabidopsis thaliana. Ethylene is perceived by five receptors that have similarity to two-component signaling proteins. The hydrophobic amino-terminus of the receptors binds ethylene, and mutations in this domain both prevent ethylene binding and confer ethylene insensitivity to the plant; the carboxyl-terminal portion of the receptors has similarity to bacterial his tidine protein kinases. Genetic data suggest a model in which ethylene binding inhibits receptor signaling, yet precisely how these receptors function is unclear. Two of the receptors have been found to associate with a negative regulator of ethylene responses called CTR1, which appears to be a mitogen-activated protein kinase (MAPK) kinase kinase.     

Constant hybrids in Mendel's research

The persisting controversial interpretation of constant hybrids and of the term Entwicklungsgeschichte, mentioned by Mendel in the Pisum paper, is elucidated in the context of his experiments with other plant species and of the growth of knowledge in scientific animal and plant breeding in Moravia.     

Lorenz Hiltner, a pioneer in rhizosphere microbial ecology and soil bacteriology research

Lorenz Hiltner is recognized as the first scientist to coin the term “rhizosphere” in 1904. His scientific career and achievements are summarized in this essay. Most of his research he performed in the Bavarian Agriculture–Botanical Institute (later named the “Bavarian Institute of Plant Growth and Plant Protection”) in Munich, where he was the director from 1902 to 1923. Beginning with intensive and thorough investigations on the germination and growth of different crop plants (legumes and non-legumes) Hiltner became convinced, that root exudates of different plants support the development of different bacterial communities. His definition of the “rhizosphere” in the year 1904 centered on the idea, that plant nutrition is considerably influenced by the microbial composition of the rhizosphere. Hiltner observed bacterial cells even inside the rhizodermis of healthy roots. In analogy with fungal root symbionts, Hiltner named the bacterial community that is closely associated with roots “bacteriorhiza.” In his rhizosphere concept, Hiltner also envisioned, that beneficial bacteria are not only attracted by the root exudates but that there are also “uninvited guests,” that adjust to the specific root exudates. Based on his observations he hypothesized that “the resistance of plants towards pathogenesis is dependent on the composition of the rhizosphere microflora.” He even had the idea, that the quality of plant products may be dependent on the composition of the root microflora. In addition to his scientific achievements, Hiltner was very dedicated to applied work. Together with F. Nobbe he had the first patent on Rhizobium inoculants (Nitragin). He continuously improved formulations and the effectivity of the Rhizobium preparations and he also initiated seed dressing with sublimate for plant protection of seedlings. Thus, Hiltner tightly linked breakthroughs in basic research to improved rhizosphere management practices. In addition, he wrote a pioneering monograph on plant protection for everybody’s practical use. His emphasis on understanding microbes in the context of their micro-habitat, the rhizosphere, made him a pioneer in microbial ecology. Even now, in the era of genome and postgenome analysis with our better understanding of plant nutrition and soil bacteriology, his ideas and contributions are as fresh as they were more than 100 years ago.     

N. I. Vavilov-the man and his work

A brief sketch is presented of Vavilov's career, his main contributions to science and personal qualities. The imporatnce of his work in genetics, agro-ecology, plant breeding, the experimental taxonomy of crop plants and genetic resources conservation is also emphasized.     

Effect of simulated microgravity on auxin polar transport in inflorescence axis of Arabidopsis thaliana.

The morphology, growth and development of higher plants are strongly influenced by environmental stimuli on the earth, which affect the changes in the dynamics of plant hormones in plants. Qualitative and quantitative changes in plant hormones are the most important internal factor to regulate plant growth and development. Among them, auxin (IAA) is of most significant. There are numerous reports concerning the physiological roles of auxin in plant growth and development (Matthysse and Scott 1984). One of the characteristics of auxin is to have the ability of polar transport along the vector of gravity on the earth (Schneider and Wightman 1978), suggesting that the activity of auxin polar transport is also important for the growth and development of plants. It has recently been reported that the normal activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana was required for flower formation (Okada et al. 1991, Ueda et al. 1992). Considering the above evidence together with the fact that gravity affects the morphology, growth and development of higher plants, gravity might affect the qualitative and quantitative changes in plant hormones including the activity of auxin polar transport. In this paper, we report the effect of microgravity condition simulated by a three-dimensional (3-D) or a horizontal clinostat on the activity of auxin polar transport in inflorescence axis of Arabidopsis thaliana.