Sundip Kumar

Transfer of useful variability of high grain iron and zinc from Aegilops kotschyi into wheat through seed irradiation approach

Abstract Purpose To transfer the 2S chromosomal fragment(s) of Aegilops kotschyi (2Sk) into the bread wheat genome which could lead to the biofortification of wheat with high grain iron and zinc content. Materials and methods Wheat-Ae. kotschyi 2A/2Sk substitution lines with high grain iron and zinc content were used to transfer the gene/loci for high grain Fe and Zn content into wheat using seed irradiation approach. Results Bread wheat plants derived from 40 krad-irradiated seeds showed the presence of univalents and multivalents during meiotic metaphase-I. Genomic in situ hybridization analysis of seed irradiation hybrid F2 seedlings showed several terminal and interstitial signals indicated the introgression of Ae. kotschyi chromosome segments. This proves the efficacy of seed radiation hybrid approach in gene transfer experiments. All the radiation-treated hybrid plants with high grain Fe and Zn content were analyzed with wheat group 2 chromosome-specific polymorphic simple sequence repeat markers to identify the introgression of small alien chromosome fragment(s). Conclusion Radiation-induced hybrids showed more than 65% increase in grain iron and 54% increase in Zn contents with better harvest index than the elite wheat cultivar WL711 indicating effective and compensating translocations of 2Sk fragments into wheat genome.

Physical localization and probable transcriptional activity of 18S-5.8S-26S rRNA gene loci in some Asiatic Cymbidiums (Orchidaceae) from north-east India.

Fluorescence in situ hybridization based physical localization of 45S ribosomal DNA in eight horticulturally important species of Cymbidium (Orchidaceae) from north-east India (South-East Asia) has been carried for the first time. Observations revealed only one pair of chromosomes had NOR loci. Three, out of eight Cymbidiums showed decondensed, dispersed, extended form of hybridization signals of rDNA as dots of fluorescence (transcriptionally active), where as the rest of the Cymbidiums revealed condensed (non-active) forms, hence demonstrated the heteromorphism in size, intensities and their appurtenance which may be under epigenetic control. Except for the ribosomal genes, no other active genes have been reported to reside within the nucleoli. Such observations provide useful chromosome landmarks and provide valuable evidence about the genome evolution, speciation and ploidy both at molecular and chromosomal levels which is more or less highly ambiguous in family Orchidaceae.

Fate of Aegilops speltoides-Derived, Repetitive DNA Sequences in Diploid Aegilops Species, Wheat-Aegilops Amphiploids and Derived Chromosome Addition Lines

The present study reports the cloning and characterization of an Aegilopsspeltoides-derived subtelomeric repeat, designated as pSp1B16. Clone pSp1B16 has 98% sequence homology with the previously isolated Ae. speltoides repeat Spelt1. The distribution of pSp1B16 and another Ae. speltoides repeat, pGc1R1, was analyzed in diploid Aegilops species, tetra- and hexaploid wheats, wheat-Aegilops amphiploids and derived chromosome addition lines by fluorescence in situ hybridization (FISH). Clones pSp1B16 and pGc1R1 revealed FISH sites in Ae. speltoides, Ae. sharonensis and Triticumtimopheevii, whereas additional pGc1R1 FISH sites were observed in Ae. longissima and Ae. caudata. The pSp1B16 and pGc1R1 FISH patterns of the Aegilops chromosomes in the wheat-Aegilops amphiploids and chromosome addition lines are similar to those present in the Aegilops parent accession. We did not observe any evidence of pSp1B16 and pGc1R1 sequence elimination, which is in contrast to previous studies using similar hybrids and repeats. The presented data suggest that the genomic changes in synthetic amphiploids observed in previous studies might be caused by homoeologous recombination, which was suppressed in the amphiploid analyzed in this study.

Micro-determination of uranium(VI) based on the formation of a ternary complex with pyrogallol red and cetylpyridinium chloride

A sensitive spectrophotometric method has been developed for the microdetermination of uranium(VI) based on the formation of a blue ternary complex with pyrogallol red and cetylpyridinium chloride. The ternary complex is stable over the pH range 5.2–6.4, and the wavelength of maximum absorption is at 580 nm. The ternary system obeys Beers law between 0.23 and 9.52 p.p.m. of uranium. A high molar absorptivity (Iµ= 36 500 l mol–1 cm–1) and Sandells sensitivity (0.001 µg cm–2) have been obtained. The complex has the composition UO22+(PGR)2(CP)4, as established by Jobs method of continuous variation and the molar ratio method. The method has been tested in the presence of several other cations and anions. The structure of the ternary complex is discussed.

Evaluation of iron and zinc in grain and grain fractions of hexaploid wheat and its related species for possible utilization in wheat biofortification

Iron (Fe) and zinc (Zn) contents in hexaploid wheat are very low and are further reduced because of the removal of micronutrient-rich bran of wheat grains during milling and processing. Therefore, hexaploid wheat, its wild species and wheat– Aegilops kotschyi substitution lines were evaluated to identify the genome(s) carrying gene(s) for high Fe and Zn concentrations in bran and endosperm fractions of grains. It is reflected from the results that Triticum monococcum (acc. W463) may serve as a promising donor for biofortification of Fe, and Aegilops speltoides (acc. 3804) may serve as a promising donor for biofortification of Zn in the endosperm of cultivated wheat. Further, among the three wheat– Ae. kotschyi substitution lines, the higher concentration of Fe and Zn in endosperm fraction was observed in BC 2 F 4 63-2-13-1. The work on precise transfer of useful gene(s) from 7U k chromosome of this line is in progress to reduce linkage drag.

Genetic Improvement of Sugarcane Through Conventional and Molecular Approaches

In recent years, efforts to improve sugarcane have focused on the development of biotechnology tools for this crop. It has become clear that sugarcane lacks tools for the biotechnological route of improvement and that the initial efforts in sequencing ESTs had limited impact on breeding. Until recently, the models used by breeders in statistical genetic approaches have been developed for diploid organisms, which are not ideal for a polyploid genome such as that of sugarcane. Breeding programs deal with decreasing yield gains. The contribution of multiple alleles to complex traits such as yield is a basic question underlining the breeding efforts that could only be addressed by the development of specific tools for this grass. However, functional genomics has progressed, and gene expression profiling leads to the definition of gene networks. The sequencing of the sugarcane genome, which is underway, will greatly contribute to numerous aspects of research on grasses. We expect that both the transgenic and the marker-assisted routes for sugarcane improvement will contribute to increased sugar, stress tolerance, and higher yield and that the industry for years to come will be able to rely on sugarcane as the most productive energy crop.

Curcumin profiling and genetic diversity of different accessions of Curcuma longa L.

Abstract Objective To investigate the genetic diversity and variation in active compound of turmeric rhizomes collected from different niches of Uttarakhand. Methods Genetic diversity and relationship of Curcuma longa accessions was evaluated by random amplification polymorphism DNA analysis and curcumin profiling was evaluated by high performance liquid chromatography method. Results The curcumin contents in 20 accessions of turmeric rhizomes were found to be in the range of 0.90% to 3.26%. All accessions were separated into six groups (92% genetic similarity) by using 10 decamer oligonucleotide primers for the amplification of genomic DNA. Conclusions The results indicated the possibility of selecting high quality clones for large scale production.