• Kuldeep Singh

      Articles written in Journal of Genetics

    • Introgression of a leaf rust resistance gene from Aegilops caudata to bread wheat

      Amandeep Kaur Riar Satinder Kaur H. S. Dhaliwal Kuldeep Singh Parveen Chhuneja

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      Rusts are the most important biotic constraints limiting wheat productivity worldwide. Deployment of cultivars with broad spectrum rust resistance is the only environmentally viable option to combat these diseases. Identification and introgression of novel sources of resistance is a continuous process to combat the ever evolving pathogens. The germplasm of nonprogenitor Aegilops species with substantial amount of variability has been exploited to a limited extent. In the present investigation introgression, inheritance and molecular mapping of a leaf rust resistance gene of Ae. caudata (CC) acc. pau3556 in cultivated wheat were undertaken. An F2 population derived from the cross of Triticum aestivum cv.WL711 – Ae. caudata introgression line T291-2 with wheat cultivar PBW343 segregated for a single dominant leaf rust resistance gene at the seedling and adult plant stages. Progeny testing in F3 confirmed the introgression of a single gene for leaf rust resistance. Bulked segregant analysis using polymorphic D-genome-specific SSR markers and the cosegregation of the 5DS anchored markers (Xcfd18, Xcfd78, Xfd81 and Xcfd189) with the rust resistance in the F2 population mapped the leaf rust resistance gene (LrAC) on the short arm of wheat chromosome 5D. Genetic complementation and the linked molecular markers revealed that LrAC is a novel homoeoallele of an orthologue Lr57 already introgressed from the 5M chromosome of Ae. geniculata on 5DS of wheat.

    • A substitution mutation in OsCCD7 cosegregates with dwarf and increased tillering phenotype in rice

      Krishnanand P. Kulkarni Chandrapal Vishwakarma Sarada P. Sahoo John M. Lima Manoj Nath Prasad Dokku Rajesh N. Gacche Trilochan Mohapatra S. Robin N. Sarla M. Seshashayee Ashok K. Singh Kuldeep Singh Nagendra K. Singh R. P. Sharma

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      Dwarf plant height and tillering ability are two of the most important agronomic traits that determine the plant architecture, and have profound influence on grain yield in rice. To understand the molecular mechanism controlling these two traits, an EMS-induced recessive dwarf and increased tillering1 (dit1) mutant was characterized. The mutant showed proportionate reduction in each internode as compared to wild type revealing that it belonged to the category of dn-type of dwarf mutants. Besides, exogenous application of GA3 and 24-epibrassinolide, did not have any effect on the phenotype of the mutant. The gene was mapped on the long arm of chromosome 4, identified through positional candidate approach and verified by cosegregation analysis. It was found to encode carotenoid cleavage dioxygenase7 (CCD7) and identified as an allele of htd1. The mutant carried substitution of two nucleotides CC to AA in the sixth exon of the gene that resulted in substitution of serine by a stop codon in the mutant, and thus formation of a truncated protein, unlike amino acid substitution event in htd1. The new allele will facilitate further functional characterization of this gene, which may lead to unfolding of newer signalling pathways involving plant development and architecture.

    • Molecular mapping of CLCuD resistance introgressed from synthetic cotton polyploid in upland cotton


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      Cotton leaf curl disease (CLCuD), caused by a geminivirus complex, is the most serious disease of upland cotton in northwest India and Pakistan. It results in substantial losses in cotton yield and fibre quality. Due to continuous appearance of new viral strains, all the established CLCuD resistant stocks, extant and obsolete cultivars of upland cotton have become susceptible. Therefore, it became crucial to explore the novel sources of CLCuD resistance, as development of CLCuD resistant varieties is the most practical approach to manage this menace. Here, for the first time, we report introgression and mapping of CLCuD resistance from a ‘synthetic cotton polyploid’ to uplandcotton. A backcross population (synthetic polyploid / Gossypium hirsutum Acc. PIL 43/G. hirsutum Acc. PIL 43) was developed for studying inheritance and mapping of CLCuD resistance. Dominance of CLCuD resistance was observed over its susceptibility. Two dominant genes were found to confer resistance to CLCuD. Molecular analysis through genotyping-by-sequencing revealed that chromosomes A01 and D07 harboured one CLCuD resistance gene each.

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