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    Breeding and biotechnological interventions for trait improvement: status and prospects
    (Springer Nature Publishing AG, 2020) Singh, Roshan Kumar; Prasad, Ashish; Muthamilarasan, Mehanathan; Parida, Swarup K.; Prasad, Manoj
    Crop improvement relies on modulating the genes and genomic regions underlying key traits, either directly or indirectly. Direct approaches include overexpression, RNA interference, genome editing, etc., while breeding majorly constitutes the indirect approach. With the advent of latest tools and technologies, these strategies could hasten the improvement of crop species. Next-generation sequencing, high-throughput genotyping, precision editing, use of space technology for accelerated growth, etc. had provided a new dimension to crop improvement programmes that work towards delivering better varieties to cope up with the challenges. Also, studies have widened from understanding the response of plants to single stress to combined stress, which provides insights into the molecular mechanisms regulating tolerance to more than one stress at a given point of time. Altogether, next-generation genetics and genomics had made tremendous progress in delivering improved varieties; however, the scope still exists to expand its horizon to other species that remain underutilized. In this context, the present review systematically analyses the diferent genomics approaches that are deployed for trait discovery and improvement in major species that could serve as a roadmap for executing similar strategies in other crop species. The application, pros, and cons, and scope for improvement of each approach have been discussed with examples, and altogether, the review provides comprehensive coverage on the advances in genomics to meet the ever-growing demands for agricultural produce.
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    Development, characterization and cross-species transferability of genomic SSR markers in berseem (Trifolium alexandrinum L.), an important multi-cut annual forage legume
    (Springer, 2015) Verma, Priyanka; Chandra, Amaresh; Roy, Ajoy Kumar; Malaviya, Devendra Ram; Kaushal, Pankaj; Pandey, Dinesh; Bhatia, Sabhyata
    Egyptian clover (Trifolium alexandrinum), a multi-cut forage legume, is widely grown as an annual feed crop. Genetic improvement in this legume is largely hampered due to limited availability of genomic resources. Hence, a genomic library enriched for GA/CT motif was constructed to develop SSR primers. As a result, 667 SSR primer pairs were developed and 111 were validated in T. alexandrinum cv. Wardan s-99-1. Among these, 45 primer pairs were used for the analysis of genetic diversity among 86 Trifolium accessions, resulting in 220 alleles with an average of 4.88 alleles per locus. Polymorphic information content for these markers ranged from 0.040 to 0.819 with an average of 0.445. The observed and expected heterozygosity for individual loci ranged from 0.39 to 0.89 and 0.368 to 0.80 with an average of 0.675 and 0.659, respectively. The markers exhibited varied levels of cross-species transferability ranging from 93.33 % across T. resupinatum to 40.0 % across T. balansae. Phylogenetic relationships were analyzed using the unweighted pair group method with arithmetic averages (UPGMA)-based dendrogram which was able to establish the uniqueness of each genotype and grouped them into two major clusters. To the best of our knowledge, the SSR markers reported here are among the first to be reported in this important yet neglected forage legume. They were assessed to be highly efficient and polymorphic and found to be useful for distinguishing the closely related genotypes of Trifolium. This large resource of SSR markers would therefore facilitate new avenues for T. alexandrinum genomics.
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    Review on different mechanisms of sex determination and sex-linked molecular markers in dioecious crops: a current update
    (Springer, 2015) Heikrujam, Monika; Sharma, Kuldeep; Prasad, Manoj; Agrawal, Veena
    Flowering plants are known to exhibit vast diversity of sexual systems encompassing bisexual, monoecious and dioecious conditions. Dioecy offers opportunities to explore separately the male and female programmes giving an insight to the evolutionary, developmental and molecular processes leading to separate mechanisms for sex expression. Mechanisms controlling sex can either be genetic or epigenetic (physiological and environmental). Plant hormones too influence sex expression. An active Y sex determination system and an X to autosomes ratio systems are common amongst the flowering plants. Advances in our understanding of sex determination has been addressed both by conventional as well as molecular approaches. Using conventional techniques mainly cytogenetics, sex chromosomes in some dioecious plants have been identified and characterized. Surprisingly, the presence of well defined sex chromosomes was found in only few species. Some sex linked genes have also been identified and characterized using molecular approaches but none of these genes have a direct link to sex determination. Molecular markers have been employed to resolve the enigma associated with dioecism to a certain extent. Its application in plant breeding is immensely beneficial. Positively, it would be beneficial for validation of sex prior their sex expression at larger perspectives. The present review therefore emphasizes the mode of sex determination among dioecious plants vis-a-vis summarizes the works related to gender specific markers generated using male and female plants from agriculturally important dioecious crops.
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    Generation of expressed sequence tags under cadmium stress for gene discovery and development of molecular markers in chickpea
    (Springer, 2014) Gaur, Rashmi; Bhatia, Sabhyata; Gupta, Meetu
    Chickpea is the world's third most important legume crop and belongs to Fabaceae family but suffered from severe yield loss due to various biotic and abiotic stresses. Development of modern genomic tools such as molecular markers and identification of resistant genes associated with these stresses facilitate improvement in chickpea breeding towards abiotic stress tolerance. In this study, 1597 high-quality expressed sequence tags (ESTs) were generated from a cDNA library of variety Pusa 1105 root tissue after cadmium (Cd) treatment. Assembly of ESTs resulted in a total of 914 unigenes of which putative homology was obtained for 38.8 % of unigenes after BLASTX search. In terms of species distribution, majority of sequences found similarity with Medicago truncatula followed by Glycine max, Vitis vinifera and Populus trichocarpa and Pisum sativum sequences. Functional annotation was assigned using Blast2Go, and the Gene Ontology (GO) terms were categorized into biological process, molecular function and cellular component. Approximately 10.83 % of unigenes were assigned at least one GO term. Moreover, in the distribution of transcripts into various biological pathways, 20 of the annotated transcripts were assigned to ten pathways in KEGG database. A majority of the genes were found to be involved in sulphur and nitrogen metabolism. In the quantitative real-time PCR analysis, five of the transcription factors and three of the transporter genes were found to be highly expressed after Cd treatment. Besides, the utility of ESTs was demonstrated by exploiting them for the development of 83 genic molecular markers including EST-simple sequence repeats and intron targeted polymorphism that would assist in tagging of genes related to metal stress for future prospects.
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    EST-derived single nucleotide polymorphism markers for assembling genetic and physical map of the barley genome
    (Springer, 2008) Kota, R.; Varshney, R. K.; Prasad, M.; Zhang, H.; Stein, N.; Graner, A.
    In a panel of seven genotypes, 437 expressed sequence tag (EST)-derived DNA fragments were sequenced. Single nucleotide polymorphisms (SNPs) that were polymorphic between the parents of three mapping populations were mapped by heteroduplex analysis and a genome-wide consensus map comprising 216 EST-derived SNPs and 4 InDel (insertion/deletion) markers was constructed. The average frequency of SNPs amounted to 1/130 bp and 1/107.8 bp for a set of randomly selected and a set of mapped ESTs, respectively.