Education and Professional experience:
Retired as a Professor & Head, Department of Botany, University of Delhi in June 2002 and joined ATREE in August 2002. Studied up to M.Sc. (Botany) in Karnataka and Ph.D. (Botany) (1969) from the University of Delhi. Spent the entire academic career at the Department of Botany, University of Delhi as Lecturer (1969-81), Reader (1981-1991) and Professor (1991-2002). Carried out research in many internationally reputed laboratories such as Royal Botanic Gardens, Kew, UK; Welsh Plant Breeding Station, UK; University of Melblourne, Australia; University of Siena, Italy and University of Saskatoon, Canada as a Royal Society Fellow/ Visiting Scientist/Visiting Professor. Collaborated with internationally renowned researchers such as Professor J. Heslop-Harrison, Professor B.R. Knox and Professor M. Cresti in the area of Reproductive Biology. Have supervised 9 M.Phil. and 23 Ph.D. students. Authored many books on pollen biology and biotechnology and published over 150 original research articles and reviews in refereed journals. Participated in a number of National and International Scientific Meetings, chaired technical sessions and delivered invited lectures.
Major areas of interest are reproductive biology particularly pollen biology and biotechnology, and conservation biology.
Ongoing Research Programs
Studies on reproductive ecology for effective conservation
The Western Ghats, one of the megadiversity centers in India, harbors over 4000 species of flowering plants of which over 30 per cent are endemic. A number of endemic species are of great economic importance and have been in trade for decades. However, extensive deforestation, fragmentation of habitats and indiscriminate extraction has led to sparse distribution and reduced population size of many of the endemic species. Reduction in population size would result in inbreeding that leads to narrowing of genetic variability and eventual extinction of the populations.
Despite serious threats to biodiversity, very few programs have addressed the conservation concerns of endemic and critically endangered species in the Western Ghats. Even these limited conservation efforts have been arbitrary and there are very few success stories. The survival of a species becomes threatened when deaths exceed births for a prolonged period. Thus the ultimate cause that pushes a species to endangered status is the prevalence of some constraint(s) for sustainable reproduction/regeneration of its populations. For developing any rational conservation strategy for threatened species, it is therefore important to study the details of reproductive ecology to identify these constraints. An understanding of reproductive constraints would facilitate development of effective strategies to mitigate the problems and thus facilitate recovery of populations. In the absence of data on reproductive ecology, conservation efforts remain arbitrary and are less effective.
Under one of the DBT research projects (2004-2007) on studies on reproductive ecology and population enrichment of some endemic and endangered species of Western Ghats, we studied reproductive ecology of six endangered species of the Western Ghats (Nothapodytes nimmoniana, Myristica dactyloides, Garcinia indica, Dysoxylum malabaricum, Embelia ribes and Vateria indica) which are of great economic importance. Apart from generating baseline information on reproductive ecology of these plants, these studies showed that there are no basic constraints for reproduction and regeneration of these species; overexploitation is the main constraint for their sustainability.
Reproductive Biology of Cardamoms:
Under a DST research programme (2004-2007) studies were conducted on reproductive ecology of cardamums, Eletteria cardamomum and Amomum subulatum (large cardamum) covering the entire flowering period (early, peak and late flowering) and at different locations. These studies have shown for the first time that bumblebee is the major pollinator of Amomum and honey bee (Apis cerana) is the pollen robber. Apart from confirming A. dorsata and A. cerana as the pollinators of Elettaria, we have documented five additional pollinators for this species. More importantly we have shown that pollination is a dynamic event and the pollinators show temporal and spatial variation.
Recently we have initiated studies on reproductive ecology of some endemic/endangered species of Syzygium in Western Ghats under a DST research project.
Established a school of Reproductive Biology at the Department of Botany, University of Delhi. The techniques of cytochemistry, fluorescence microscopy, ultrastructure, cell and tissue culture, physiology and biochemistry were integrated with traditional methods to understand the structure of the pollen and the pistil in relation to their function. The outcome of these efforts has been a wealth of new fundamental knowledge on pollen biology, pollen-pistil interaction, incompatibility, pollination biology, breeding systems and their applications in crop improvement programs.
The following are some of the major research contributions during 38 years of research in Delhi University:
Reproductive biology of tree species of economic importance: Comprehensive studies on reproductive biology of tree species such as Sterculia urens, Boswellia serrat and Commiphora wightii, important sources of non-timber forest products of India (gums and gum-resins), have highlighted many constraints in their natural regeneration and have led to the development of technologies to overcome them for their conservation and sustainable utilization. Our studies have shown that C. weightii (salai guggul) is an obligate apomict. Studies on many other tree species such as Dalbergia sissoo, Acacia senegal and Butea monosperma have brought out many unique features. Just to mention a few: contrary to the earlier belief that D. sissoo is an inbreeder, we have shown that the species is an obligate outbreeder; this has important implications in the breeding program of this species for desirable traits such as straight bole and heartwood formation. Our group has also established the unusual instance of squirrel as an effective pollinator in Butea monosperma, beside the purple sunbird. Detailed studies on oil palm (Elaeis guineensis) have shown the feasibility of using assisted pollination as a means of sustaining fruit yield when pollination becomes a constraint.
Self-incompatibility: Studies carried out on the structural and functional aspects of self-incompatibility in both homomorphic and heteromorphic systems were the first comprehensive studies to be initiated in the country. An in vitro technique termed placental pollination was devised and applied to overcome self-incompatibility in Petunia. This technique has been used subsequently to overcome interspecific incompatibility by other workers. Fundamental studies on self-incompatibility have provided much new information and have led the group to propose a new hypothesis that ‘heteromorphic self-incompatibility’ is the result of a combination of lack of morphological complementation between the pollen and the stigma, and active physiological inhibition. Similarly in homomorphic incompatibility also, requirement of both transcription and translation for inhibition of self-pollen tubes in gametophytic systems was shown for the first time.
Wide hybridization: A notable achievement has been on wide hybridization in an Brassica, an important oil and vegetable species of our country. We have been able to raise over 40 intergeneric hybrids between the cultivars of Brassica and many wild species such as species of Diplotaxis, Erucastrum, Enorthocarpus and Sinapis through the use of embryo rescue technique, and to develop six new cytoplasmic male sterile (CMS) lines in Brassica cultivars. These hybrids and CMS lines provide extensive genetic variability to Brassica breeders, and many of them have been registered for further research with the National Bureau of Plant Genetic Resources (NBPGR), New Delhi.
Pollen viability and vigour: First to provide experimental evidences for the role of plasma membrane in pollen viability. Breakdown of membrane phospholipids has been shown to be the primary cause for the loss of pollen viability. Our group has also highlighted, for the first time, the importance of pollen vigour in assessing the quality of pollen, particularly of stored pollen.
Classification of stigma types: While working with Prof. J. Heslop-Harrison and Y. Heslop-Harrison at the Royal Botanic Gardens, Kew, UK during 1970’s, the stigmas of over 1000 species of flowering plants were screened and classified. Apart from documenting all the prevailing morphological variations of the stigma, this study brought to light significant correlations between structural and functional aspects of the stigma. The classification of the stigma proposed by the group is being used uniformly by Botanists through out the world The paper [Annals of Botany (1977) Vol: 41: 1233-1258] which has reported these findings has turned out to be the most cited paper ever published in Annals of Botany.
Honours and Awards
Publications (excluding communications to scientific meetings)