Are plants with anti-cancer activity resistant to crown gall? : A test of hypothesis

The Crown gall tumour assay (CGTA) is one of several bench top bioassays recommended for the rapid screening of plants with anti-cancer activity. The rationale for the use of the bioassay is that the tumorogenic mechanism initiated in plant tissues by _Agrobacterium tumefaciens_ is in many ways similar to that of animals. Several plant species with anti-cancer activity have already been discovered using this bioassay. However till date no explicit test of an association between anti-cancer activity of plants and their resistance to crown gall formation has been demonstrated. Demonstration of an association could have exploratory potential when searching for plants with anti-cancer activity. In this paper, we determined whether or not a statistically significant association between crown gall resistance and anti-cancer activity exists in plants found in existing published data sets. Our results indicate that plants with anti-cancer activity have a higher proportion of their species resistant to crown gall formation compared to a random selection of plants. We discuss the implications of our results especially when prospecting for newer sources of anti-cancer activity in plants

Playing with the forest: invasive alien plants, policy and protected areas in India

Protected areas (PAs) are inviolate and invaluable landscapes that promote the in situ conservation of endangered, threatened and rare species. Accordingly, and in keeping with this definition, PA managers ensure that PAs are free from fire, poaching, grazing, non-timber forest products collection, mining, etc. In India, following the Indian Wildlife (Protection) Act (1972), there are today 102 and 515 National Parks and Wildlife Sanctuaries respectively. Many of these have in recent decades been heavily threatened by the spread of invasive alien plant species, notable among them being Lantana and Eupatorium. These species may have usurped as yet unestimated number of native plants and fauna, besides depressing the reproduction of native plant species. In fact, it is realized that the threat to biodiversity by invasive alien species (IAS) may only be second to that of fragmentation. Yet there seems to be no major attempts to eradicate, contain or manage IAS in PAs. Ironically, the justification for the lack of action lies in the definition of PAs – that they need to be kept inviolate and therefore above any active intervention. In this article we bring home this serious contradiction in the approach to management of PAs in India and discuss the philosophical origins of this practice. We argue that if we are to protect our PAs from the serious scourge of invasive species, we would have to relook at the policy governing PA management and revise it to be more inclusive than exclusive

In pursuit of a universal barcode of plants: peril of followers?

In May 2007, during the early days of the DNA bar coding project in India, we published an article, ‘DNA barcoding: an exercise in futility or utility’1. As the title reflects, we were literally at crossroads, caught between the cross-fire of traditional taxonomists (we think it is disrespectful to call them traditional; they are as much modern as are archaeologists and molecular biologists) and molecular systematists and not knowing which way to go forward. After a reasonable amount of brain-storming that took us through well-trodden criticisms of the DNA barcoding initiative, we concluded that while debates can go on, the tool itself can be effectively used in complementing conventional taxonomic studies and in securing Intellectual Property Rights (IPRs) for important taxa. We also felt at that time that it would be important for the country to develop skills and infrastructure to undertake barcoding of at least some of the important taxa, both for conservation and commerce

Floral resources of Karnataka: a geographic perspective

We compiled the data on the floral resources of Karnataka from diverse published sources and analysed the geographic patterns of distribution of floral diversity. Our database shows that Karnataka harbours 4758 species from 1408 genera and 178 families and accounts for about 27 per cent of the country's floral diversity. We computed the 'endemicity value' of different districts based on the number of endemic species (those restricted to a maximum of five districts) harboured by them and found that the most species-rich districts (viz. Uttara Kannada, Dakshina Kannada, Mysore, Hassan, Udupi and Kodagu) were also characterized by high values of endemicity while the species-poor districts had low values of endemicity. However, the relation between the species richness and endemicity of the districts was not linear; the species richness increases abruptly at lower levels of endemicity but plateaus off later at high levels of endemicity. Based on the number of species packed into the families, all the 27 districts segregated distinctly into three clusters that geographically correspond with the three major agro-climatic zones of the state. Our analysis showed that though the districts along the Western Ghats are florally rich, those along the dry tracts also harbour certain unique elements of the flora; thus these dry zone districts appear to be as important as those along the Western Ghats in conserving the floral resources

Frequency distribution of seed number per fruit in plants: a consequence of self organizing process?

Plants exhibit wide variation in the frequency distribution of seed number per fruit. These distributions have been explained on the basis of proximate factors such as limitation of pollen and resource, lethal alleles, and developmental abnormalities. However, such explanations are inadequate and are not parsimonious in explaining the wide range of distributions of seed number per fruit. In this paper we propose an alternative model based on the process of self-organization, involving simple rules of resource flow into ovules. We show that the wide range of observed frequency distributions of seed number per fruit can be generated as a function of resource-drawing ability of ovules, which interact stochastically during their development

Diversity of species assemblages of islands: predictions and their test using tree species composition of shola fragments

Based on all possible combinations of species that can theoretically exist on islands of different sizes, we estimated similarities among islands of equal size in their species compositions. We found that similarity coefficients among islands of equal sizes increases and the coefficients of variation for similarities decreases with increase in the size of islands. Accordingly, it can be predicted that the species compositions of small fragments shall be more diverse compared to large fragments. We tested this prediction using the tree species composition of the shola fragments at BR Hills, Western Ghats. Similarities among sholas were measured as coefficients of correlation between the frequencies of species in them and also as proportions of species shared among sholas. Small sholas were less similar and shared fewer species among themselves, compared to medium and large sholas. Also, small sholas showed higher coefficient of variation for the correlation coefficients and for proportion of species shared than medium or large sholas. In other words, species assemblage diversity among sholas was found to decrease with their size and large islands appeared to converge towards a common assemblage of species. Based on our results, we argue that small fragments add structural and functional heterogeneity to the ecosystem and hence are as important as are the large fragments in conserving biodiversity

Does forest type classification reflect spatial dynamics of vegetation? Analysis using GIS techniques

The existing methods of classification of forest vegetation rely more on the structure and composition of tree vegetation with little information derived from other layers. We suggest that any classificatory process of forest vegetation should consider the spatial dynamics of all the three layers namely, tree, shrub and herb. In this paper we have attempted to offer an objective method of classifying the vegetation at all the three layers utilizing GIS and multivariate statistical tools. Unlike the existing techniques, our method views the forest as a continuously changing mosaic of vegetation and not as an assemblage of discrete patches. Our study suggests that understanding the spatial dynamics of vegetation at one layer may not reflect that at others. Further, as an alternate to the existing methods, we also develop a continuum map of biodiversity of the forest that offers the conservation value of each patch, an element that is not conveyed in the existing classificatory processes. Discover the world's researc

Changes in genetic diversity parameters in unimproved and improved populations of teak (Tectona grandis L.f.) in Karnataka state, India

Teak (Tectona grandis L. f.; family Verbanaceae) is an important plantation tree species in the tropics and in India one of the first species to be prioritized for improvement. Improvement efforts for the last 50 years have essentially concentrated on augmenting quality seed production by establishing seed production areas (SPA) and clonal seed orchards (CSO). Presently, these two form the main sources of quality planting material for teak throughout the country. However, there is no information on the genetic quality of such sources nor information on the progeny used in plantation programmes. Reports of studies based on coniferous and tropical species provide conflicting results on the impact of domestication on the genetic diversity of populations (Chaisurisri and El Kassaby 1994; Rajora 1999; Moran et al. 2000; Godt et al. 2001; Icgen et al. 2006). Also the impact of domestication on the genetic diversity of progeny populations is poorly understood (Stoehr and El-Kassaby 1997; Schmitdtling and Hiplins 1998). Such studies become pertinent not only for gauging the impact of selection on reforestation stock, but also for effective genetic conservation of existing breeding populations. We therefore address two issues in the present study: (i) the change in genetic diversity with increasing levels of improvement, and (ii) the impact of the above change on genetic diversity of progeny populations

War of hormones over resource allocation to seeds: strategies and counter-strategies of offspring and maternal parent

It is suggested that maternal parent and offspring have conflicting interests over the extent of resource allocation to developing seeds. While maternal parent would be selected to allocate her resources optimally among her offspring, the latter would be selected to demand more. In animals, offspring are known to demand additional resources either visibly (through intense vocal calls) or subtly through the production of hormones. In plants though parent offspring conflict over resource allocation has been invoked, the mechanism through which the parent and offspring interact in regulating resource allocation into developing seeds is not yet clear. In this paper, we propose that the strategies and counter-strategies of the offspring and mother during the development of seeds might be manifested through the production of appropriate growth hormones. Accordingly, we predict (i) hormones that mobilize resources into seeds (e.g. auxins and gibberellic acid) shall be synthesized exclusively by the offspring tissue and (ii) hormones that inhibit resource flow in to seeds (e.g. abscisic acid) be produced exclusively by the maternal tissue. We show that these predictions are supported by existing literature on the temporal dynamics and source of production of growth hormones during seed development. Finally, we suggest that such analysis viewing the production of different hormones during early seed development, as strategies and counter-strategies of mother and offspring tissue, helps ofer a meaningful interpretation of the otherwise complex dynamics of hormone fluxes

Age-specific sex ratio in a monoecious species Croton bonplandianum Baill

The ratio of male to female flowers (sex ratio) in the monoecious Croton bonplandianum Baill decreased as plants aged in three habitats. Two major forces, male and female gametic success and intra-sexual selection, have been invoked to explain the decrease in sex ratio. While increasing female gametic success at successive stages of growth might be responsible for the enhanced allocation of resource to the females and hence for the absolute increase in number of female flowers at a later age, increasing male gametic success does not change the absolute number of male flowers but merely causes an increase in the number of pollen grains deposited on the stigma. Differences in the sex ratio between habitats was influenced by the differential fitness gained by the two sexes in the various habitats