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Life and work of an Indian botanist (1904–1966) of the 20th century

Ramesh Maheshwari

In an e-mail dated 21 November 2010, angiosperms and the gymnosperms pro- have written remembrance articles on P. Balaram said ‘It would be wonderful duce seeds, whereas the seeds in the for- him in this very journal5–8. He gave talks to have a scholarly, yet personal, biogra- mer are enclosed inside the ovary (e.g. and wrote newspaper articles on various phy of your father’. Though it seemed mango, papaya), the seeds in the latter topics in . He gave talks on topics odd to write a biography of one’s father, are not, as for example, the cycads and such as the life and work of Sir J. C. nonetheless here was an opportunity to the pines. Rather, in the latter group of Bose, or Nurture? Among the review and learn about a discipline of plants the seeds are borne on the surface popular articles written by him were botany that is assuming increasing of scales, not enclosed inside the fruit. ‘The plants that India gave to the world’, importance for generating the next- The latter book was to deal with the ‘What seeds must be preserved in the generation inter-generic hybrid crops morphology of the reproductive structure event life is destroyed by a holocaust?’, producing high-quality seeds by over- and seed development in species of Gym- ‘Botany in ancient India’, ‘Plants, history coming incompatibility barriers between nosperms, chiefly the species found in and politics’. He was a complete bota- parents. Having grown up in P. Mahesh- the Himalayan mountain ranges. Unfor- nist. wari (hereafter PM) household, I had the tunately this work remained unpublished fortune of some plant embryology rubbed as PM died a couple of weeks prior to the onto me although I went on to specialize submission of the manuscript to the pub- Professional development differently. Googling led to an article by lisher. PM himself1 published in Nature way Tall, broad-shouldered, always well- PM was born in 1904 in Jaipur, Raja- back in 1952. This article tells about a dressed and generally sporting a stern sthan, where his father was an office sensational claim made by a Russian look, PM worked from pre-dawn to sun- superintendent in the SMS Medical Col- agricultural botanist of conversion of seeds set all seven days in the week, at home or lege. His father had wished that his only of one plant species into that of another in his office (Figure 1) in the Botany surviving son would enter the medical species merely by a change in environ- Department of Delhi University. One of profession. However, since PM wore ment (temperature)2. his former students described him as a thick glasses, he was denied admission in A voracious reader, a hard worker and ‘karmayogi’4. Though a strict disciplinar- the medical programme. PM took up a master in laboratory skills with scien- ian, PM was a kind-hearted person who botany instead. Who mentored him in tific temper, the insight and ability to enjoyed telling jokes and humorous an- specializing in plant embryology is not identify promising research topics, PM ecdotes. His large personal library com- known. Some of his clan was seed or was a multitasker and a stickler for punc- prised of original and rare titles acquired grain merchants; perhaps the seeds tuality. Although always immersed in during his several visits abroad. The col- sprouting during the monsoon rains work, he was generous with his time for lection of books and reprints served as a aroused his curiosity to dissect the seeds any research worker who wished to show valuable resource not just for his own re- to find out which parts emerge and grow and tell microscopic observations. He search students, but also for out-of- as the root and the shoot axes. After a was the founder-editor of an interna- station faculty and students from other D Sc from the Ewing Christian College tional journal, Phytomorphology; served parts of India in need to access to the lit- in Allahabad, under an American mis- on the editorial boards of some interna- erature. Some of his former students sionary teacher Dr Winfield Dudgeon, tional journals; edited textbooks for the higher secondary students; cor- rected theses and manuscripts of his Ph D students; frequently accompanied res- earch students on botanical forays; con- tributed articles for BOTANICA – an in- house journal of the Delhi University Botanical Society – that he had founded; organized national and international symposia; workshops for high-school biology teachers; trained Ph D students in all-round abilities; and when called upon to do so advised the Government on science policy matters; and played host to out-of-station colleagues and visi- tors at his home. Following the publica- tion in 1950 of his highly successful 3 Figure 1. P. Maheshwari at about 1960 in his office room in Delhi University. A major book on embryology of angiosperms , effort was collection of scholastic reference material through postal exchange with sci- PM was working on his second book, entists. These were classified and stored in reprint boxes in the background. From Curr. Morphology of Gymnosperms. Both the Sci., 2004, 87, 1738.

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PM taught botanical disciplines at the resulting in seed formation. Stated thus laboratory for histochemical processing universities in Agra, Lucknow and Alla- the ‘book’ created an entire new field of and microscopic examination of - habad, where he established himself as enquiry with focus on the fine events in logical oddities. This would allow a an innovative and committed teacher seed development. The book met with steady publication of papers, earn the re- who inspired and aroused curiosity of immediate success throughout the world, search workers recognition, and give students. He was a born teacher. Using including USSR, where it was quickly them a feeling of accomplishment lead- the reverse psychology method he gave translated into Russian, as Embriologia ing to growth of science in general and popular talks such as ‘How to give a pokritocemmenikh rastenii or the ‘Em- botany in particular. PM and/or his poor lecture?’, ‘How to write a research bryology of the covered seeded plants’. research students undertook regular for- paper for outright rejection by the jour- The ‘covered seeded plants’ are the ays for collection of botanicals and their nal’ and the ‘Ten commandments for bad Angiosperms in the original book title. processing in the laboratory. Careful writing’. These were among the most examination and documentation of hilarious talks in the department. He embryological features led to the discov- wrote articles on a variety of botanical Impact of the ‘book’ ery of different types of embryo sacs, topics for BOTANICA under the pseudo- variations in the number and the distribu- name IDLER. Publishing a book may seem a small tion of nuclei in them, intercarpellary thing, but PM’s book had wide implica- pollen grains, multiple , modi- tions. It opened an entire new field of re- fied suspensor cells, endosperm haus- A highly cited textbook search that investigated the correlations toria, polyembryony and apomictic between sex in plants and seed develop- plants, enabling observations to be pub- Since during PM’s early days the scien- ment. In 1980, in an editorial Eugene lished in high-ranking journals (see tific literature was almost wholly in Garfield (ISI) ranked the book as among Selected bibliography). He investigated German, there was an acute need of sci- the 20 biology texts most quoted in the embryological features of doubtful taxa entific literature in English for the re- century! With the current emphasis on and showed that in conjunction with search workers. Recognizing this, with reproductive structures, the last ten years morphology, and , embryology the aim of bringing out a textbook on have seen resurgence in plant embryol- could be useful in identification of taxa plant embryology in English, at the age ogy using the tools of modern molecular and phylogeny of taxa with uncertain of 34 PM undertook visits to Kiel and biology. PM’s book continues to be cited affinities. Vienna where he became fluent in Ger- more than 50 years after its publication. The plant embryo develops rapidly fol- man and worked with German experts. A discipline which has simple research lowing fertilization of the and He discussed the scope of embryology requirements is likely to take roots and becomes differentiated into a suspensor and its interfaces with cytology, taxon- flourish in India where the facilities for cell and conspicuous cotyledon. It prompts omy, and plant . Dur- research are rudimentary or even non- how a single fertilized egg cell is con- ing 1945–1947, he worked at Harvard existent, Plant embryology offered a verted into a mass of cells organized into University in Cambridge. He visited sev- field of enquiry in which India could a basal and apical pole that differentiate eral laboratories in USA, met a number become a leader. With its diversity of into the root and the shoot? This is the of botanists, did intensive library work exotic plants, modest requirements of a fundamental problem of polarity or the for rare literature and finalized the manu- microtome for serial sectioning of wax- establishment of a basal and an apical script for publication by the McGraw- embedded flowers, ovaries or ovules, and end. PM recognized that embryology and Hill Book Company, New York. In his staining of sections, followed by their morphogenesis are linked and should be 3 seminal work , An Introduction to the light microscopic examination and the studied together. With the major events 3 Embryology of Angiosperms (hereafter camera-lucida sketches would provide in seed development – from the time pol- referred to as the ‘book’), he stated the research results of adequate quality and len grains land and germinate on stigma scope of plant embryology as the study quantity and be a competitive area of identified, and new examples discovered of embryo and endosperm and the deve- scientific research. Botanical material wherein for one or the other reason seed lopment of the male and female struc- could be collected from different cli- development fails, practical solutions tures that participate in fertilization matic regions, fixed and brought to the could be conceived for overcoming the bottlenecks under controlled conditions using the emerging technique of Box 1. Plants named after Panchanan Maheshwari. and , or experimental em- bryology. Around 1950, PM embarked P. Maheshwari has been commemorated by naming plants after him: on ‘experimental embryology’. This work involved the aseptic culturing of Panchanania jaipuriensis, a hypomycetous fungus; Isoetes panchananii, a excised reproductive parts on chemically new species of quillworts; Maheshwariella bicornuta, a Palaeozoic seed from defined nutrient media for determining the lower Gondwanas of Karaharbari coal field, India; and Oldenlandia the nutritional and hormonal substances maheshwarii, a new rubiaceous taxon are some examples. Names of up to that the globular or the pre-globular em- 10 taxa ranging from microbes to angiosperms commemorate his interest in bryo receives from the maternal (female) several fields of botanical research. ovarian tissue for them to grow and de- velop into plantlet. With the enthusiastic From: Rangaswamy4 support of his former student and later a

528 CURRENT SCIENCE, VOL. 104, NO. 4, 25 FEBRUARY 2013 PERSONAL NEWS colleague, B. M. Johri, who had received the spikes of the spring-planted crop of (a cell in an ovule formed by meiotic training in plant tissue culture in the UK, rye (Secale cereale) are converted into division) has two female cells of which laboratories were set up at Delhi for plant wheat (Triticum vulgare) and wheat into one is the egg cell attached at one end of cell and tissue culture. Plant embryos rye and barley (Hordeum vulgare) by ex- the embryo sac, whereas another female from a variety of flowers of parasitic and posing the plants to near freezing tem- cell called the secondary cell is posi- non-parasitic plants, of terrestrial and peratures at the time of inflorescence tioned at the centre of the embryo sac aquatic plants were cultured and their development (flowering). Lysenko called (Figure 3). In plants, fertilization entails chemical requirements for growth deter- the low temperature-induced phenotypic a pollen grain germinating on the stigma mined. With experimental and descrip- change in plants as ‘jarovization’. If a of the ovary bringing in two male nuclei tive studies side by side, the Delhi school species of plant could be converted into a (cells) through the pollen tube inside the established itself as the leading centre of different species simply by a change in embryo sac. Whereas one male cell fuses research on plant reproductive biology. It the environment, then this could be with the egg cell to produce the began attracting research scholars from translated into practical agriculture for and embryo, the other male cell fuses all over the world. Reminiscing about solving the problem of food shortage that with the secondary cell to form en- this period, a former student, Guha- was plaguing Russia. Lysenko shot into dosperm – a cellular tissue which accu- Mukherjee7, a co-discoverer of andro- fame. A web photo shows Lysenko giv- mulates starch, lipids and proteins filling genic haploids9,10, said: ing a speech at the Kremlin with Joseph the embryo sac. Until when the mature Stalin on the dais, suggesting that Lysenko seed falls on the ground and the seedling ‘My major inspiration came from Prof. had the backing and support of Stalin. turns green and is able to synthesize its P. Maheshwari, a world-renowned Lysenko’s challengers lived in fear. own food by the chemical process of plant embryologist, who headed the Since Lysenko’s claims were against photosynthesis, the endosperm provides department. P. Maheshwari made it his the tenets of plant embryology and the food to the developing embryo. The mission to inculcate students’ interest genetics, PM considered Lysenko’s data embryo and the endosperm are the basis in Botany by applying various teaching as faked or false. How could a plant spe- of our dependency on the plant seeds as a innovations. The whole department cies distinguishable on the basis of the source of . It is remarkable that was in the birth pangs of the plant tis- number of its chromosomes – the bearer a Russian plant embryologist, Sergius sue culture. The intellectual ferment of DNA – the chemical substance deter- Nawaschin, had at about 1898 seen the had a major effect on all of us.’ mining heredity – be converted into nuclei in the act of fusion in whole some other species? Lysenko’s ‘discov- mounts of ovules or fine serial sections, Today, with finer and finer techniques ery’ found way in the newspapers. PM and reconstructing the picture from care- this area of botanical science is increas- felt that teaching of to ful examination of the sections of the ingly gaining importance, offering new young research students would not be embryo sac. A photograph of Nawaschin challenges for fundamental research and acceptable. He published a strong scien- is given in PM’s book. opportunities for breeding new varieties tific criticism of Lysenko in a widely of crop plants. read journal1 that circulates internation- ally (Figure 2), drawing the curtain on Unique features of embryo Lysenko. development in plants Debunking Lysenko To recapitulate, in plants, the develop- Prior to 1950, PM was at the University Impact of the ‘book’ ment of a seed involves two separate of Dacca (now Dhaka, Bangladesh), male nuclei (cells) fusing with two sepa- where he founded the Department of The Nature article1 must have created rate female nuclei (cells) inside the em- Biology. In 1949, Maurice Gwyer, the confusion among the minds of the bota- bryo sac. This unique event of double Vice-Chancellor of Delhi University, nists in Russia as to how to react to PM’s fertilization was discovered by Nawaschin. invited PM to the new Botany criticisms of Lysenko, who had domina- Perhaps, as said above, one of PM’s in- Department. ted the Russian botanical and agriculture terests in visiting Russia was to pay Soon after taking charge, a situation scene. Not very long after, PM was invi- homage to the memory of Nawaschin for developed in the department that required ted to visit Russia, perhaps at the stance his epochal discovery of double fertiliza- to be expertly tackled. A faculty member of the academicians who wished to ex- tion in the 19th century. with a formidable personality had press their appreciation and gratitude to Although PM did not get to meet returned from visits to USSR and had him for his campaign against Lysenko’s Lysenko in USSR, he had the opportu- begun teaching Michurin biology, which pseudoscience. nity to visit a few research institutions in is essentially the discredited Lamarck’s PM welcomed the opportunity to visit Moscow, Leningrad and Kiev. A Russian ‘theory of inheritance of acquired char- USSR, but for a different reason as well. botanist, V. Poddubnaya-Arnoldi (see acters’. Ivan Michurin (1855–1935) had In 1898, a Russian botanist, Sergius her contributions to plant embryology in propounded his view that the genotype of Nawaschin, had made an epochal discov- the ‘book’) fluent in English, offered to a plant can be changed by the variation ery. This discovery, called ‘double fer- the Academy to serve as PM’s official of environmental condition. This view tilization’, is a crucial event in the life of interpreter during his entire visit. During was vigorously championed by his disci- seed-formng plants. It is unique to flow- this visit a surprised PM was presented a ple Trofim Denisovitch Lysenko2 (1898– ering plants (in botanical terminology Russian translation of his own book – 1976), who claimed that some grains in called the angiosperms). The embryo sac titled Embryologia pokritocemmenikh

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Figure 2. Excerpts from an article questioning the claims of T. D. Lysenko on conversion of wheat grains into rye, barley and oats.

rastenii. In scientific English, ‘pokrito- am in agreement with this wider compre- the botanists attracted international cemmenikh rastenii’ refers to the angio- hension of the subject and have therefore acclaim. which comprise the large group included in this volume not only an Though small to be seen by the of plants in which the seeds are covered account of the embryo and endosperm, unaided human eye, the embryo is a (in contrast to the group gymnosperms in but also an account of the development miniature plant, differentiated into a mi- which the seeds are not covered by of the male and female gametophytes and cropylar or the root end, and a chalazal integument). fertilization.’ PM recognized that smaller or the shoot end. This is a classic exam- With a reference book on plant em- structures would offer greater chance of ple of ‘polarity’ or a ‘top and bottom’ bryology available, it entered into the discovering microscopic structures that axes in plants. A plethora of fascinating curricula of botany in all universities, at are new to science and their characteriza- questions came to the fore: how does fer- home as well as in countries where Eng- tion would yield academic satisfaction. tilization occur of two female cells inside lish is spoken. In the preface of the Indeed, more than any other branch of the embryo sac by two male cells ‘book’, PM defined the scope of embry- botany, descriptive plant embryology brought inside the embryo sac by the pol- ology as: ‘In a strict sense, embryology entered into the curricula in all institu- len tube? The male cells were originally is confined to a study of the embryo, but tions in India and became popular. The inside the pollen grain that germinated most botanists also include under it embryological findings from studies of on the stigma of the ovary in the flower. events which lead on to fertilization. I the diversity of the extant flora by The germinating pollen grain produces a

530 CURRENT SCIENCE, VOL. 104, NO. 4, 25 FEBRUARY 2013 PERSONAL NEWS tube that works its way through the stylar Embryologie der Angiospermen (1929) the pollen tube working its way inside tissue to (chemotropically?) enter into and Vergleichende Embryologie der An- the tissue of the style to reach the egg the embryo sac contained in the ovule giospermen (1931) are the most impor- cell for discharging the male cells (pollen wherein the two male (nuclei) cells are tant and exhaustive treatises in the field, contains two male cells) inside the em- discharged. While one male cell fuses and still serve as valuable works of ref- bryo sac to produce a zygote. The zygote with the female egg cell, the other male erence.’ A handwritten letter by Schnarf (or the fertilized egg cell) then undergoes cell fuses with a secondary cell inside the in his calligraphic handwriting in Ger- cell divisions, the first division is almost embryo sac. Several figures in the ‘book’ man was the only memorabilia at home. always in a transverse direction that results illustrate that polarity in the zygote cell The handwriting was so beautiful that the in asymmetric segregation of cytoplasm is established after the first cell division publisher is said to have accepted into a large basal cell and a small apical which is invariably in the transverse di- Schnarf’s entire hand-written manu- cell, and each time the cell divides the rection. Thus the central question: what scripts without requiring a typed copy. rule of segregation in specific planes rules of shape or size, i.e. geometry ac- Two slogans – descriptive and experi- apply, forming a species-specific embryo. count for the plane of cell division or the mental – embryology have come in vogue. That seeds produce recognizable species- localization of the new cell wall? The former is the description of all the specific plants implies that the embryo – The side of the zygote cell attached to various ways and contrivances that occur a structure comprising thousands of cells – the embryo sac at the micropylar end in a flower from the time the egg cell is has emergent patterns of shoot and root develops into a root, whereas the oppo- fertilized by a male cell brought in by a that divide mitotically and enlarge to site chalazal end develops into a shoot. pollen germinating on the stigma, with form the shoot and root (Figure 4). Further, the embryo has symmetry, viz. root and shoot are alike on either side of a vertical plane of symmetry. The em- bryo sac is mostly a seven-celled, eight- nucleate structure, comprising one egg cell, two synergid cells, three antipodal cells, and two polar nuclei that fuse to form one (n + n) diploid nucleus in the central cell (Figure 3). Why a plant embryo sac needs this cellular organiza- tion is unknown. Neither is it known if the extant primitive plants have a seven- cell organization of the embryo sac?

Descriptive embryology

PM greatly encouraged collections, ob- servations and descriptions of botanical materials from different countries. He recognized that morphology would offer the chance of discovering structures that are new to science and their characteriza- tion would, as said before, provide aca- demic satisfaction. Indeed, more than any other branch of botany, plant embry- ology became popular in almost all teaching and research institutes in India. Several botanists, notably B. G. L. Swamy, M. A. Rau, B. M. Johri, H. Y. Mohan Ram and S. C. Maheshwari, to name just a few, made important contribu- tions to the embryology of exotic plants. As was said before, the original work in plant embryology was in Germany and the literature was in German. Among the Figure 3. Camera lucida drawings of stages in embryo development in the plant names of prominent embryologist cited Capsella bursa-pastoris following fertilization of egg cell. Note that the first division in in the ‘book’ is that of Karl Schnarf the transverse direction with the basal cell cb larger and showing vacuolation. The about whom PM commented as: ‘Among polarity and body plan of the embryo of a flowering plant are established during early embryogenesis, but the rules controlling the order of cell divisions are not known. Draw- the modern students of the subject, the ing made in 1914 by C. R. Soueges, University of Paris, shows highly ordered sequence name of the late Karl Schnarf of Vienna of invariant cell divisions to generate a multicellular embryo with differentiation of two stands preeminent. His two works entitled cotyledons.

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Experimental embryology fuses with two polar nuclei in a central of plant cells, i.e. virtually any cell of cell in the unique process of double plant from almost any part, diploid or Experimental embryology is cell and fertilization? What signalling events haploid, will develop into embryo. By development biology encompassing the occur for triple nuclear fusion inside the comparison, totipotency of animal cells mechanisms by which pollination occurs, embryo sac for formation of a nutritive is not yet demonstrated. The animal sci- the biochemical conditions that control tissue called the endosperm which sur- entists have coined a term ‘pluripotency’ pollen germination on stigma and the rounds the growing embryo until it is which is defined as the potential of a cell mechanisms by which the pollen tube consumed by the embryo? Embryology to develop into more than one type of grows through the style and finds the thus has great relevance to the science of mature cells, depending on the environ- female cell inside the embryo sac for dis- improving the nutritional quality of crop ment (http://groups.molbiosci.northwestern. charging the two free male cells inside plants – not by Lysenko’s ‘jarovization’ edu/holmgren/Glossary/Definitions/Def-P/ the embryo sac. Further, what mecha- method, but through sexual crosses Pluripotency.html). The numerous figures nisms determine that only one of the two between selected parents. in the ‘book’ depict development of em- male nuclei (cells) fuses with the egg In his ‘book’ PM discussed examples bryos from single fertilized cells, estab- cell, whereas the second male nucleus where inter-generic or inter-specific lishing the tenet that plant embryology is crosses for creating new varieties of about what determines the plane in which crops had failed – either because of the the cell wall is laid down after each cell failure of pollen to germinate on foreign division to form a species-specific em- stigma, or the failure of pollen tubes to bryo. Published in 1950, two generations grow in the foreign style of the ovary, or of botany students have read the ‘book’. the failure of pollen tube to enter into the ovule through the micropyle (an open- ing), or the of embryo following Seeds formed without fertilization fertilization? Identifying the precise block and carrying out remedial opera- Tuned to the knowledge that a seed is tion might help circumvent the problem. formed by the fertilization of The plant embryo is formed inside an involving fusion of male and the female embryo sac (Figure 4) is attached to nucleus, one of PM’s students, Prem maternal tissue by a long suspensor cell. Murgai, discovered a herbaceous plant This raises the question about what Aerva tomentosa growing in the botani- chemical substances does the embryo re- cal research garden of Delhi University ceive from the maternal tissue until it can that surprisingly produced seeds even 11 grow independently into an adult plant though the male plants were not found . by absorption of mineral nutrients from Neither pollen grains were seen on the Figure 4. Diagram of a seven-celled, the soil and carbon dioxide fixation by stigma, nor pollen tubes in longitudinal eight-nucleate embryo sac of a flowering photosynthesis? This study required that sections of the style. It was inferred that plant (angiosperm). The egg apparatus consisting of two synergids and one egg smaller and smaller embryos be manu- this plant is an apomict – the embryo (n) cell is towards the upper (micropylar) ally dissected out from the ovules and arises without fertilization. Identification pole of the embryo sac. The chalazal pole cultured in nutrient media of defined of apomicts is important, for if the genes contains three ephemeral antipodal cells. chemical compositions. Requiring keen controlling this trait can be transferred Fertilization involves the fusion of one by genetic transformation technique into male cell brought in by pollination to form eyes, immense patience and steady hands diploid embryo. Double fertilization in- for dissecting out the minute embryos a crop plant the transformed plant can volves fusion of one (n) of the two haploid from flowers under a dissecting micro- produce generations of genetically iden- male cells brought in by pollen tube with scope a new research worker was quickly tical plants without forming seeds. the two haploid polar nuclei (n + n) in the transformed into a having pa- centre of embryo sac fusing with one male cell to effect triple fusion, producing tience, precision and determination. The triploid endosperm tissue. Apparently tri- results caught the imagination of new Artificial induction of fruiting ple fusion of nuclei signals the female workers entering into botany8. plant to accumulate food material as a With tissue culture laboratories estab- Since seed development is at the core of source of nutrition for the developing em- bryo. The mechanism of cell signalling re- lished, the Delhi School expanded embryology, PM was always thinking sulting in triple fusion is not known. The research on plant embryology. Experi- of the ways in which embryology could mature seed containing a diploid embryo, mental embryology with its modest be put into practical uses. His ‘book’ a triploid multicellular endosperm tissue is research requirements caught on at sev- gives examples of plants where inter- surrounded by a hard seed coat for pro- eral places in India and even displaced generic or inter-specific crosses for cre- tection from infection by in soil. The synergid cell presumably descriptive embryology. With proximity ating new varieties of crops had failed guides the pollen tube towards the egg to a diversity of native flora, the workers for lack of precise knowledge of embry- apparatus. The function of antipodal cells chose and collected different plant mate- ology. Where exactly is the embryologi- is not known. The embryo sac and the rials for in vitro cultivation and exam- cal block – in pollen germination on endosperm are surrounded by maternal tissue which hardens into a protective ined their potentialities for regenerating foreign stigma, or the failure of pollen covering as the mature seed falls on the into complete plants. Overall, the results tubes to grow in the foreign style of the ground to begin new growth. strengthened the concept of totipotency ovary, failure of pollen tube to enter into

532 CURRENT SCIENCE, VOL. 104, NO. 4, 25 FEBRUARY 2013 PERSONAL NEWS the ovule through the micropylar open- the developing seed to accumulate nutri- finding out, I begin to worry that eve- ing, or the abortion of embryo following ents (that is, become a ‘sink’)? Clearly rything about botany will be known, fertilization? Guided by the precise un- the traditional botany will have to be re- and then what will botanists do? Any- derstanding of the block in embryogenesis, oriented towards physiology and bio- one who has visited the University of corrective operations could be devised to chemistry and genetics and the new California at Davis in the past few circumvent the problem. For example, students will have to be given practical years knows the sense of excitement one of PM’s students, Kusum Kanta, cir- experience in techniques of which pervades the anatomy laborato- cumvented incompatibility and achieved and . With his personal ries, as Katherine Esau, Vernon seed set by intraovarian pollination in contacts, PM helped young colleagues to Cheadle, and their allies work out in some plants belonging to the family secure postdoctoral research fellowships detail the anatomical facts of plant Papaveraceae12,13. In this technique a abroad with doing cutting edge development. The same may be said of suspension of pollen grains is directly in- research in plant embryology. He main- Professor Maheshwari’s group in jected into the ovary using a hypodermic tained contacts and invited some scien- Delhi and of other groups throughout syringe. The technique is analogous to tists to visit India and give lectures, and the world.’ artificial insemination (AI) in which se- stay for short periods to hold workshop men is directly installed in the . and demonstrate new techniques to the And, an English biophysicist R. D. Pre- This work underscores that knowledge of research workers. ston, FRS, Professor of Plant the diversity of plants, and thoughtful One of the problems that fascinated and Head of the Astbury Department of choice of a plant material for experiments, and challenged PM was to extract a live Biophysics at University of Leeds (au- is very important for success. It also re- plant egg from the embryo sac, fertilize it thor of Physical Biology of Plant Cell minds us that excessive dependency on a in a test tube with a cell extracted Walls) who had reviewed some published model plant such as Arabidopsis thaliana from a pollen grain, the two mixed on work by PM commented as19: which is widely used today, may not an- some artificial medium, and the zygote swer all questions in biology. Diversity reared into a complete plant! Recently ‘One of the most remarkable develop- of plant life must at least dimly reflect (2010), R. G. Edwards (b. 1925) and Pat- ments of our time in plant sciences has the diversity of research problems. rick Steptoe were awarded the Nobel been the way in which hitherto purely Because the plant embryo is attached Prize in Physiology or for suc- observational regions are progressively to the maternal plant tissue by a long cessful creation of the world’s first test becoming experimental or even mathe- suspensor cell, an unanswered question tube baby. The similarity in the aims of matical. One case of the former is the is what chemical substances does the both human and plant embryology is remarkable developments in embryo- embryo receive from the plant until the striking, although in the plants the pre- logy at the hands of Professor seed falls on the ground and the embryo sence of a cell wall that binds the adjacent Maheshwari and his colleagues and can grow independently? This investiga- plant cells together, making manipula- students.’ tion required that smaller and smaller tions of separating live cells very embryos be manually dissected out from difficult if not impossible. Recently, live ovules and cultured in nutrient media of egg cells and were isolated using Honours and awards defined chemical composition14. With microcapillary connected micropump expertise gained in designing nutrient from enzyme-treated ovule of Alstroe- PM rarely, if ever, talked of the honours media, the work on culturing a variety of meria16. Kranz and Lorz17 in Germany and awards bestowed upon him. We tissues from plants was expanded with isolated single sperm and egg cells from learned about these only through reports rewarding results. I select two examples: maize embryo sac and fused these cells in the newspapers. During the Interna- Culture of anthers of a weed Datura in vitro by applying an electric shock. tional Botanical Congress held at Paris in innoxia growing in the campus resulted Following fusion, the in vitro-produced 1954, PM was conferred the Honorary in production of haploid embryos9,10. The embryo underwent similar pattern of em- degree of Doctor of Science. Five years culture of floral buds of another weed bryogenesis and produced multicellular later, in 1959, the McGill University in Ranunculus scleratus gave crop of em- embryo just as in the normal maize plant. Montreal honoured him for his contribu- bryos arising from the epidermis of the Plant embryology is poised for exciting tions to plant embryology. In 1966, PM explants15. These observations reinforced advances. was elected a Fellow of the Royal Society, the concept of totipotency of plant cells. London. He died shortly thereafter. Accolades A vision for the future Concluding remarks Following a visit to Delhi, the Caltech In the 1960s, biology was becoming plant biochemist, James Bonner, known Plant embryology developed from obser- molecular. Traditional plant embryology for his researches on chromatin biology vations by the ancient naturalists that a required a paradigm shift to answer out- in plants visited the Delhi School. Bon- non-fruit bearing female date palm standing questions, for example, would ner wrote an article18 in which he sum- would set seeds only if dusted by the the seed germinate without double ferti- marized his impressions: inflorescence from a male palm. This lization and the formation of endosperm? observation led to the discovery of sex in How does double fertilization repro- ‘Each time I go to a meeting of bota- plants, of fertilization of gametes, of the grams cellular biochemistry and trigger nists and hear the many things they are formation of an embryo with a root and a

CURRENT SCIENCE, VOL. 104, NO. 4, 25 FEBRUARY 2013 533 PERSONAL NEWS shoot end, and the formation of nutrient- central cell containing polar nuclei and 3. Maheshwari, P., An Introduction to the rich endosperm tissue by the unique the antipodal cells. Embryology of Angiosperms, McGraw- process of double-fertilization. The core Endosperm: The nutritive tissue in a Hill, New York, 1950. of plant embryology encompasses know- seed for the developing embryo formed 4. Rangaswamy, N. S., Resonance, 2003, 8, 1–5. ledge of the male and the female ga- as a result of double fertilization. The 5. Maheshwari, N., Curr. Sci., 2001, 87, metophytes, of the process by which endosperm id formed by multiple divi- 1756–1769. fertilization occurs to produce single- sions of primary endosperm nucleus. 6. Raghavan, V., Curr. Sci., 2004, 87, celled zygote, of the programmed cell Experimental embryology: In vitro modi- 1660–1665. divisions that occur to form a multicellu- fication of processes underlying the 7. Guha-Mukherjee, S., In vitro Cell Dev. lar species-specific embryo. Today, with development and differentiation of the Biol., 1999, 35, 357–360. the basic events in seed development embryo. 8. Shivanna, K. R. and Mohan Ram, H. Y., elucidated17,21,22, plant research has entered Gymnosperm: A group of plants in Curr. Sci., 2005, 89, 1820–1834. into a new era in which genetics, mole- which the seeds are not enclosed inside 9. Guha, S. and Maheshwari, S. C., Nature, cular and approaches offer the seed coat. 1964, 204, 497. 10. Guha, S. and Maheshwari, S. C., Nature, guidance for developing crops producing Haploid: A plant containing half the 1966, 212, 97–98. better quality seeds. P. Maheshwari was number of chromosomes (n) in each nu- 11. Murgai, P., Nature, 1959, 184, 72–73. ahead of his time. cleus of the cell than normal diploid (2n). 12. Maheshwari, P. and Kanta, K., Nature, Intraovarian pollination: Injection of 1961, 191, 304. pollen grains suspended in a suitable liq- 13. Kanta, K., Rangaswamy, N. S. and Glossary uid nutrient medium into the ovary and Maheshwari, P., Nature, 1962, 194, achieving pollen germination, pollen 1214–1217. Androgenic haploids: Haploid embryos tube entry into ovule and fertilization. 14. Maheshwari, P. and Johri, B. M., Nature, produced from microspore mother cell Male cells: Male gametes formed in 1950, 165, 978–979. by culturing anthers. pollen and transmitted into embryo sac 15. Konar, R. N. and Nataraja, K., Phyto- morphology, 1965, 15, 132–137. Angiosperm: Plants producing seeds through pollen tube. 16. Hoshino, Y., Murata, N. and Shinoda, covered by integuments that harden to Nucellus: The central portion of a seed form the seed coat. K., Ann. Bot., 2006, 97, 1139–1144. in which embryo sac develops. 17. Kranz, E. and Lorz, H., Plant Cell, 1993, Apomixis: Formation of seeds by a Pollen tube: A tubular structure formed 5, 739–746. process not involving fertilization of egg by the germinating pollen that penetrates 18. Bonner, J., AIBS Bull., 1963, 13, 20–21. cell. into stylar tissue for delivery of male 19. Preston, R. D. (ed.), Advances in Botani- Chromosomes: Condensed form of gametes inside embryo sac. cal Research, Academic Press, London, chromatin visible under microscope. Seed: Propagule of a flowering plant vol. II, 1965. Contain DNA. containing an embryo, endosperm and 20. Berger, F., Hamamura, Y., Ingouff, M. Descriptive embryology: Study of de- the seed coat. and Hagayashima, T., Trends Plant Sci., 2008, 13, 437–443. velopmental processes that take place in Somatic embryo: Embryo (as opposed 21. de Smet, I., Lau, S., Mayer, U. and Jür- a plant from the initiation of sex organs to zygotic embryo) produced from any to the maturation of embryo. gens, G., Plant J., 2010, 61, 959–970. cell other than egg cell without involving Double fertilization: The act of fusion fertilization. of one of two male gametes (cell) Zygote: Fertilized egg cell. ACKNOWLEDGEMENT. I thank N. B. brought inside the embryo sac by pollen Raju for scanning PM’s 1952 Nature article

tube with the egg and the second from the archives of Stanford University male gamete with the fused polar nuclei, Selected bibliography: Library. resulting in the formation of endosperm. 1. Maheshwari, P., Nature, 1952, 170, 66–

Embryo culture Growth of excised 68. globular embryos on artificial nutrient 2. Lysenko, T. D., Foreign Languages Pub- Ramesh Maheshwari lives at 53/13 medium. lishing House, 1951; first published in Sriteertha Apts, 4th Main, 17th Cross, Embryo sac: A cell in the developing Agrobiologia, 1950, No. 6 (not seen in Malleswaram, Bangalore 560 055, India. seed containing the egg apparatus, the original). *e-mail: [email protected]

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