Satya Narayan Jena

Development and characterization of genomic and expressed SSRs for levant cotton ( Gossypium herbaceum L.)

Four microsatellite-enriched genomic libraries for CA(15), GA(15), AAG(8) and ATG(8) repeats and transcriptome sequences of five cDNA libraries of Gossypium herbaceum were explored to develop simple sequence repeat (SSR) markers. A total of 428 unique clones from repeat enriched genomic libraries were mined for 584 genomic SSRs (gSSRs). In addition, 99,780 unigenes from transcriptome sequencing were explored for 8,900 SSR containing sequences with 12,471 expressed SSRs. The present study adds 1,970 expressed SSRs and 263 gSSRs to the public domain for the use of genetic studies of cotton. When 150 gSSRs and 50 expressed SSRs were tested on a panel of four species of cotton, 68 gSSRs and 12 expressed SSRs revealed polymorphism. These 200 SSRs were further deployed on 15 genotypes of levant cotton for the genetic diversity assessment. This is the first report on the successful use of repeat enriched genomic library and expressed sequence database for microsatellite markers development in G. herbaceum.

Large‐scale resource development in Gossypium hirsutum L. by 454 sequencing of genic‐enriched libraries from six diverse genotypes

The sequence information has been proved to be an essential genomic resource in case of crop plants for their genetic improvement and better utilization by humans. To dissect the Gossypium hirsutum genome for large-scale development of genomic resources, we adopted hypomethylated restriction-based genomic enrichment strategy to sequence six diverse genotypes. Approximately 5.2-Gb data (more than 18.36 million reads) was generated which, after assembly, represents nearly 1.27-Gb genomic sequences. We predicted a total of 93,363 gene models (21,399 full length) and identified 35,923 gene models which were validated against already sequenced plant genomes. A total of 1,093 transcription factor-encoding genes, 3,135 promoter sequences and 78 miRNA (including 17 newly identified in Gossypium) were predicted. We identified significant no. of molecular markers including 47,093 novel simple sequence repeats and 66,364 novel single nucleotide polymorphisms. In addition, we developed NBRI-Comprehensive Cotton Genomics database, a web resource to provide access of cotton-related genomic resources developed at NBRI. This study contributes considerable amount of genomic resources and suggests a potential role of genic-enriched sequencing in genomic resource development for orphan crop plants.

Analysis of genetic diversity, population structure and linkage disequilibrium in elite cotton (Gossypium L.) germplasm in India

An understanding of the level of genetic diversity is a prerequisite for designing efficient breeding programs. Fifty-one cultivars of four cotton species (Gossypium hirsutum, G. barbadense, G. herbaceum and G. arboreum) representing core collections at four major cotton research stations with a wide range of eco-geographical regions in India were examined for the level of genetic diversity, distinct subpopulations and the level of linkage disequilibrium (LD) using 1100 amplified fragment length polymorphism (AFLP) markers with 16 primer pairs combinations. The AFLP markers enabled a reliable assessment of inter- and intra-specific genetic variability with a heterogeneous genetic structure. Higher genetic diversity was noticed in G. herbaceum, followed by G. arboreum. The genetic diversity in tetraploid cotton species was found to be less than that in the diploid species. The genotypes VAGAD, RAHS14, IPS187, 221 557, Jayhellar of G. herbaceum and 551, DLSA17, 221 566 of G. arboreum were identified as the most diverse parents, useful for quantitative trait loci (QTL) analysis in diploid cotton. Similarly, LRA 5166, AS3 and MCU5 of G. hirsutum and B1, B3, Suvin of G. barbadense were most diverse to develop mapping populations for fibre quality. The internal transcribed spacer sequences were sufficient to resolve different species and subspecies of diploid cotton. Low level of genome-wide LD was detected in the entire collection (r2 = 0.07) as well as within the four species (r2 = 0.11–0.15). A strong agreement was noticed between the clusters constructed on the basis of morphological and genotyping data.

Genetic diversity and population structure of Arabidopsis thaliana along an altitudinal gradient.

In this study Tyagi et al. determined the genetic diversity and population structure of the model plant, Arabidopsis thaliana. These populations inhabit west Himalaya, an undersampled region. Using 19 genomic SSR and 11 chloroplast markers they determined that these populations are highly structured and genetically distinct from the rest of the world populations. They also observed that the populations were structured at the altitudinal level. Additionally their molecular clock analysis showed that these populations are not recent introductions and have inhabited the Himalayan region for about 130,000 years.

Gene actions for yield and its attributes and their implications in the inheritance pattern over three generations in opium poppy (Papaver somniferum L.).

The gene actions for yield and its attributes and their inheritance pattern based on five parameter model have been explored in four single crosses (NBIHT-5 × NBIHT-6, NBIHT-5 × NBMHT-1, NBMHT-1 × NBIHT-6 and NBMHT-2 × NBMHT-1) obtained using thebaine rich pure lines of opium poppy (Papaver somniferum L.) for three consecutive generations. All the traits showed nonallelic mode of interaction, however, dominance effect (h) was more pronounced for all the traits except thebaine and papaverine. The dominance × dominance (l) effects were predominant over additive × additive (i) for all traits in all the four crosses except for papaverine. The seed and opium yield, and its contributing traits inherited quantitatively. The fixable gene effects (d) and (i) were lower in magnitude than nonfixable (h) and (l) gene effects. The estimates of heterosis were also higher in comparison to the respective parents which suggested preponderance of dominance gene action for controlling most of the traits. The phenotypic coefficient of variation was marginally higher than those of genotypic coefficient of variation for all the traits. The traits thebaine, narcotine, morphine and opium yield had high heritability coupled with high genetic advance. The leaf number, branches per plant and stem diameter showed positive correlation with opium and seed yields. The selection of plants having large number of leaves, branches and capsules with bigger size would be advantageous to enhance the yield potential.

Microarray-based large scale detection of single feature polymorphism in Gossypium hirsutum L.

Microarrays offer an opportunity to explore the functional sequence polymorphism among different cultivars of many crop plants. The Affymetrix microarray expression data of five genotypes of Gossypium hirsutum L. at six different fibre developmental stages was used to identify single feature polymorphisms (SFPs). The background corrected and quantile-normalized log 2 intensity values of all probes of triplicate data of each cotton variety were subjected to SFPs call by using SAM procedure in R language software. We detected a total of 37,473 SFPs among six pair genotype combinations of two superior (JKC777 and JKC725) and three inferior (JKC703, JKC737 and JKC783) using the expression data. The 224 SFPs covering 51 genes were randomly selected from the dataset of all six fibre developmental stages of JKC777 and JKC703 for validation by sequencing on a capillary sequencer. Of these 224 SFPs, 132 were found to be polymorphic and 92 monomorphic which indicate that the SFP prediction from the expression data in the present study confirmed a ∼58.92% of true SFPs. We further identified that most of the SFPs are associated with genes involved in fatty acid, flavonoid, auxin biosynthesis etc. indicating that these pathways significantly involved in fibre development.

In Vitro Clonal Propagation of Musa Sp. Cultivar Gopi: A Palatable Banana of Tripura, India

The present investigation has been concentrated on the establishment of an efficacious method for in vitro regeneration of a Musa cultivar Gopi of Tripura. Focus has been greatly anchored to the sterilization procedure for assuring successful aseptic culture establishment of this cultivar. The culture protocol for shoot induction and proliferation comprised of four different treatments in basal MS medium fortified with 6-Benzylaminopurine of varying concentrations. The optimum response was encountered in the treatment of BAP in MS medium at concentration of 8mg l -1 for shoot bud induction and multiplication. Subsequent shoot growth and multiplication was achieved through repeated subcultures in media containing lower concentration (4 mg l -1 ). Root initiation was stimulated and brought about by treatments with two different concentrations of Indole butyric acid. The best rooting was manifested in treatment with IBA at concentration of 2mg l -1 . The present study is an approach towards successful establishment of a simple and rapid clonal propagation of a potent Musa cultivar Gopi having traditional and commercial value from this region of Tripura, North-east India.