Bir Bahadur

Nectar types in Indian plants

Nectar composition (sugars and amino acids) of 100 species representing 83 genera from 34 families of angiosperms have been studied. The distribution of the 3 common sugars viz., sucrose, fructose and glucose in nectars of the species studied can be broadly divided into 6 types, based on the presence or absence of any one of the sugars viz sucrose-glucose-fructose, sucrose-glucose, sucrose-fructose, glucose-fructose, glucose and sucrose types with some variations. α-Amino acids were processed in 85 species. Distribution of amino acids was studied in some species and was found to be useful in detecting flower visitors.

Plant Biology and Biotechnology

We present a comprehensive compilation of genomic structure evolution that should help the reader who is not familiar with genomics to understand the mechanisms that are shaping its structures over time. We believe that this understanding is essential to work with genomics in the sense that it should help to formulate productive hypothesis for new original works. We believe that the mechanism by which the extant genomic structures arose is more important than the shape of these structures since evolution is continuously at work. In addition, taking genomics under the evolution perspective gives the possibility to release a unifi ed picture of its unlimited natural complexity to the reader without fair to be incomplete. It is amazing to realize how fast complex biological structures arose in the early time of Earth, and it has been our aim to try to give a constructive view of the life journey to the reader.

Seedling handedness in Fabaceae

Seedling handedness has been studied in 76 genera and 137 species of of the Fabaceae out of which 35 genera and 78 species exhibit handedness. Its presence is more common or sporadic in some tribes and completely absent in other tribes. The taxonomic implications of this character is discussed. The possible causes for the existence of seedling handedness are discussed.

Interspecific Hybridization in the Genus Jatropha

Jatropha curcas L. has assumed importance in tropical and subtropical countries as a potential biofuel crop. The limitations with the currently used germplasm are the lack of knowledge of the genetic base, poor yields, low genetic diversity and vulnerability to a wide array of insect pests and diseases under monoculture. Few varieties are reported in different countries but the cultivars are a result of selection from locally available ‘wild’ material. The crop has not been domesticated so far and there is an urgent need to initiate systematic breeding programmes for developing elite genotypes in order to transform the low yielding wild J. curcas into a high yielding cultivable crop. Assessment of genetic diversity in J. curcas germplasm indicated modest levels of variability for various agronomically desirable traits. However, vast scope exists for genetic improvement of the crop through alien gene transfer via interspecific hybridization. Hybridizations between sexually compatible species facilitates introgression of desirable genes for characters, such as, high oil content, oil quality, resistance to insect pests and diseases, reduced toxicity of endosperm proteins and improved growth on problematic sites. With a modest estimate of 6–8 years of research programme and the involvement of both national and international organizations in the activities on assemblage and evaluation of germplasm including wild species, identification of divergent material, interspecific hybridization, selection and generation advancement, development of molecular tools and genetic map of the crop, besides improved germplasm with desirable attributes can be accomplished.

Karyology and Genomics of Jatropha: Current Status and Future Prospects

Global warming, population, environmental degradation and food production are serious concerns to the well being of mankind. Development of sustainable energy resources is an essential component to many of these problems. Bioenergy holds great promise to contribute significantly to reduce petroleum consumption and emission of green house gases. Biodiesel derived from the oil of Jatropha curcas seed is emerging as an alternative to fossil fuel, since it has the desirable physiochemical characteristics and performance even superior to conventional petroleum diesel. In addition, the plant is able to grow on marginal lands, which eliminates the “food versus fuel” dilemma. However, large scale cultivation of J. curcas remains the single most important issue that will ultimately decide of its success. Despite the availability of a vast germplasm with wide variability, not much progress has been made in developing varieties or hybrids for higher oil yield, better agricultural and economic features. Additional information about the karyology, genetic diversity and genomics is necessary to generate mapping populations, marker assisted selection and to develop superior genotypes. In this review, we discuss the state of the art of genetic improvement research for J. curcas.

Seedling handedness in Gramineae

Seedling handedness with regard to first seedling leaf above the coleoptile has been studied in 67 genera and 93 species spread over 11 tribes of Gramineae. In general the tribes Paniceae, Andropogoneae, Festuceae, Hordeae, Aveneae, Bambuseae, Oryzeae and Chlorideae show seedling handedness whereas it is absent in Agrostideae, Phalarideae and Poaceae. Some tribes contain species that show handedness. Seedling handedness may be used for taxonomic purposes for delimiting the various tribes of Gramineae.

Pollen of Jatropha L. Taxonomic and Phylogenetic Considerations

We present a comprehensive review of the inaperturate (omniaperuturate) pollen by light and scanning electron microscopy of the various wild and cultivated species in the genusJatropha. The genus division in the sub-generaJatrophaandCurcasas well as in sections and sub-sections is discussed in this paper. This survey has brought out the taxonomic value of subtle variations in pollen exine features in the “crotonoid pattern” according to (1) size, shape, ornamentation types and density of clava or pila processes; and (2) presence or absence of free processes in lumina and their number, and details of brochi and muri. We also discuss the application of these features to taxonomic and phylogenetic classifications of theJatrophaspecies investigated so far. Pollen related aspects such as pollen viability, pollen germination, pollen conservation/banks, pollen as model in vitro system, pollen haploids and use of pollen in transformation are also contemplated for Jatropha improvement.

Genetic Affinities of Jatropha with Other Euphorbiaceous Taxa

The genetic relatedness of Jatropha with other economically important members of the family Euphorbiaceae has been studied. Keeping in view the morphological resemblances of different species of the genus Jatropha, particularly with Ricinus, attempts were made at intergeneric hybridization between the two genera. Protein and molecular profiles showed that Ricinus is genetically distant to Jatropha. Intergeneric crosses and pollen-pistil interactions revealed that the sexual crossability between members of these two genera is limited by incongruity rather than a genetically-controlled incompatibility mechanism. Genome sequencing and molecular phylogenetic studies of different Euphorbiaceous genera indicated the relatedness of Jatropha with cassava (Manihot esculenta). In the recent past, molecular markers and microsatellite markers viz., genic and genomic SSRs developed for Hevea, Manihot, Ricinus and Jatropha are being tested for cross-taxa transferability to facilitate marker-assisted breeding programmes. Likewise, with the draft genomes in place for castor and jatropha – besides the framework linkage maps of Hevea and cassava – it should be feasible to analyze and unravel the various regulatory mechanisms through structural and functional genomics.

Fruit, Seed and Seedling Characters in Jatropha L.

The fruit, seed, caruncle and seedling characters of Jatropha species are reviewed. The capsule shape and size varies considerably with ridges and furrows of various depths in different species while in some species the fruits are glabtous. The pericarp characters under light and scanning electron microscope are also described for nine species. The seed and caruncle size and shape also show considerable variation from species to species. SEM studies of these structures in the species studied showed diversity in structure and hence, are of taxonomic value. The seed shape as also the seed colour and testa are variously ornamented with mottling pattern, with vertical stripes often with a median ridge on the ventral side. Testa (spermoderm) microcharacters of some Indian Jatropha species exhibit various patterns that are taxonomically useful. Seedling characters in some species studied are of two types with three or five major cotyledon veins. The role of caruncle in seed dispersal (mymechory) is also discussed.

Breeding System and Pollination in Jatropha curcas: An Overview

Jatropha curcas L. is a monoecious pantropical shrub or treelet and grows everywhere in tropical and sub-tropical areas without any human care. It is entomophilous with sticky pollen that does not disperse by wind, but only by insects carrying it from male to female flowers. Honeybees can be employed for pollination purpose; they are efficient and manageable pollinators. Fruit and seed sets are dependent from soil nutrient content, but also from fruiting rate since genetically inferior fruits may abort before maturity. Wide crossings between different landraces of native or exotic collections are to be performed to develop genetically superior cultivars in order to produce quality seeds with enhanced oil content. Alternative strategies to boost female flower induction and warrant uniform fruit yield, such as cytokinin application, molecular manipulation of the genes involved in flower development and homeotic regulation are also contemplated.