Biology subjects

Chhuneja, P.

Publications and source records attributed to Chhuneja, P..

7 recordsLinked to original sources

bioRxiv2026

"Editing the conserved IPA1-TB1 regulatory module reshapes plant architecture and enhances tillering in wheat

Plant architecture is a major determinant of yield potential in cereal crops, where tiller number directly influences spike production and grain yield. The transcriptional regulators Ideal Plant Architecture 1 (IPA1) and Teosinte Branched1 (TB1) constitute a conserved genetic module controlling axillary bud activity and branching in grasses; however, their functional contribution to wheat architecture remains largely unexplored. Here, we employed CRISPR/Cas9-mediated genome editing to investigate the roles of TaIPA1 and TaTB1 in regulating tillering in hexaploid wheat (Triticum aestivum L.). Comparative genomic analysis identified conserved IPA1 orthologs across the wheat A, B, and D sub-genomes, with strong conservation of the SQUAMOSA-binding protein domain. Sequencing analysis confirmed targeted mutations, including nucleotide substitutions and insertions that generated frameshift mutations and premature stop codons. Genome-edited lines exhibited enhanced tillering compared with wild-type plants. Several TaIPA1 mutant lines produced up to two-fold higher tiller numbers, while TaTB1 knockout lines showed earlier tiller initiation and [~]50% increased tillering. Notably, enhanced tillering was associated with increased grain weight without affecting spikelet number per spike. Together, these results demonstrate that the conserved TaIPA1-TaTB1 regulatory module plays a pivotal role in shaping wheat plant architecture. Targeted manipulation of this pathway using CRISPR/Cas9 provides a promising strategy for optimizing tillering and developing high-yielding wheat ideotypes.

molecular biology↗

bioRxiv2024

Guava cv. Allahabad Safeda Chromosome scale assembly and comparative genomics decodes breeder choice marker trait association for pink pulp colour

Deciphering chromosomal length genome assemblies has the potential to unravel an organisms evolutionary relationships and genetic mapping of traits of commercial importance. We assembled guava genome using a hybrid sequencing approach with [~]450x depth Illumina short reads, [~]35x PacBio long reads and Bionano maps to [~]594 MB Scaffold length on 11 pseudo chromosomes ([~]479 MB contig length). Maker pipeline predicted 17,395 genes, 23% greater from earlier draft produced in same cultivar Allahabad Safeda. The genome assembly clarified guava evolutionary history, for example revealing predominance of gene expansion by dispersed duplications, in particular contributing to abundance of monoterpene synthases; and supporting evidence of a whole genome duplication event in guava as in other Myrtaceae. Guava breeders have been aiming to reduce screening time for selecting pink pulp colour progenies using marker-trait associations, but a previous comparative transcriptomics and comparative genomics approach with draft genome assembly to identify the effector gene associated with pink pulp was unsuccessful. Here, genome re-sequencing with Illumina short reads at [~]25x depth of 20 pink fleshed and/or non-coloured guava cultivars and comprehensive analysis for genes in the carotenoid biosynthesis pathway identified structural variations in Phytoene Synthase 2. Further, ddRAD based association mapping in core-collection of 82 coloured and non-coloured genotypes from Indian sub-continent found strong association with the same causal gene. Subsequently, we developed PCR based Indel/SSR breeder friendly marker that can readily be scored in routine agarose gels and empowers accurate selection for seedlings that will produce fruits with pink pulp.

plant biology↗

bioRxiv2023

Origin and evolution of the bread wheat D genome

Bread wheat (Triticum aestivum) is a globally dominant crop and major source of calories and proteins for the human diet. Compared to its wild ancestors, modern bread wheat shows lower genetic diversity caused by polyploidisation, domestication, and breeding bottlenecks1,2. Wild wheat relatives represent genetic reservoirs, harbouring diversity and beneficial alleles that have not been incorporated into bread wheat. Here, we establish and analyse pangenome resources for Tauschs goatgrass, Aegilops tauschii, the donor of the bread wheat D genome. This new pangenome facilitated the cloning of a disease resistance gene and haplotype analysis across a complex disease resistance locus, allowing us to discern alleles from paralogous gene copies. We also reveal the complex genetic composition and history of the bread wheat D genome, involving previously unreported contributions from genetically and geographically discrete Ae. tauschii subpopulations. Together, our results reveal the complex history of the bread wheat D genome and demonstrate the potential of wild relatives in crop improvement.

genomics↗

bioRxiv2021

Whole genome resequencing and comparative genome analysis of three Puccinia striiformis f. sp. tritici pathotypes prevalent in India

Stripe rust disease of wheat, caused by Puccinia striiformis f. sp. tritici, (Pst) is one of the most serious diseases of wheat worldwide. In India, virulent stripe rust races have been constantly evolving in the North-Western Plains Zone leading to the failure of some of the most widely grown resistant varieties in the region. With the goal of studying the recent evolution of virulent races in this region, we conducted whole-genome sequencing of three prevalent Indian Pst pathotypes Pst46S119, Pst78S84 and Pst110S119. We assembled 58.62, 58.33 and 55.78 Mb of Pst110S119, Pst46S119 and Pst78S84 genome, respectively. Pathotypes were found to be highly heterozygous. Comparative phylogenetic analysis indicated the recent evolution of pathotypes Pst110S119 and Pst78S84 from Pst46S119. Pathogenicity-related genes classes (CAZyme, proteases, effectors, and secretome proteins) were identified and found to be under positive selection. Higher rate of gene family expansion was also observed in the three pathotypes. A strong association between the effector genes and transposable elements may be the source of the rapid evolution of these strains. Phylogenetic analysis differentiated the Indian races in this study from other known US, European, African and Asian races. Diagnostic markers developed for the identification of different Pst pathotypes will help tracking of yellow rust at farmers field and strategizing resistance gene deployment.

bioinformatics↗

bioRxiv2021

Targeted resurrection of chromosomal arm 1RS in two elite wheat lines with 1BL/1RS translocation for improved end-use quality

1BL/1RS translocation is widely used around the world to enhance wheat yield potential, resistance to various diseases, and adaptation. However, the translocation is combined with inherent quality problems associated with reduced dough strength and dough stickiness due to the presence of Sec-1 on proximal end and absence of GluB3/GliB1 on distal end. Two NILs, one carrying the distal (1RSRW) and the other carrying the proximal (1RSWR) fragment from 1BS, in background of Pavon were used for transferring these two loci in yellow rust resistant version of two elite wheat varieties PBW550+Yr5 and DBW17+Yr5. Foreground and background marker assisted selection was done for the Sec-1- and GluB3+ alongwith Lr26/Yr9/Sr31, Pm8 and 1RS loci in the advancing generation. BC2F5:6 NILs with absence of Secalin and presence of GluB3/GliB1 loci were evaluated for two years in replicated yield trial. A positive correlation of thousand grain weight (TGW), harvest index (HI), and tiller number per meter (TNpM) with yield (YD) with significant GxE effect was observed. Further multivariate analysis of these traits contributed maximum to the effective yield. Thirty promising NILs were identified with Sec-1-/GluB3+ alongwith with high yield contributing parameters.

genetics↗

bioRxiv2018

Efficient curation of genebanks using next-generation sequencing reveals substantial duplication of germplasm accessions

Genebanks are valuable resources for crop improvement through the acquisition, ex-situ conservation and sharing of unique germplasm among plant breeders and geneticists. With over seven million existing accessions and increasing storage demands and costs, genebanks need efficient characterization and curation to make them more accessible and usable and to reduce operating costs, so that the crop improvement community can most effectively leverage this vast resource of untapped novel genetic diversity. However, the sharing and inconsistent documentation of germplasm often results in unintentionally duplicated collections with poor characterization and many identical accessions that can be hard or impossible to identify without passport information and unmatched accession identifiers. Here we demonstrate the use of genotypic information from these accessions using a cost-effective next generation sequencing platform to find and remove duplications. We identify and characterize over 50% duplicated accessions both within and across genebank collections of Aegilops tauschii, an important wild relative of wheat and source of genetic diversity for wheat improvement. We present a pipeline to identify and remove identical accessions within and among genebanks and curate globally unique accessions. We also show how this approach can also be applied to future collection efforts to avoid the accumulation of identical material. When coordinated across global genebanks, this approach will ultimately allow for cost effective and efficient management of germplasm and better stewarding of these valuable resources.

genomics↗

bioRxiv2017

Development and molecular characterization of wheat-Aegilops peregrina Introgression Lines with resistance to leaf rust and stripe rust

A wild non-progenitor species from wheat tertiary gene pool Aegilops peregrina accession pau3519 (UUSS) was used for introgression of leaf rust and stripe rust resistance in bread wheat. It was crossed and backcrossed with hexaploid wheat line Chinese Spring PhI to develop two homozygous BC2F6 wheat-Ae. peregrina introgression lines (ILs) viz. IL pau16058 and IL pau16061 through induced homoeologous recombination. Homozygous lines were screened against six Puccinia triticina and two Puccinia striiformis f. sp. tritici pathotypes at the seedling stage and a mixture of prevalent pathotypes of both rust pathogens at the adult plant stage. IL pau16061 showed resistance to leaf rust only while IL pau16058 was resistant to both leaf and stripe rust pathotypes throughout plant life. Molecular characterization of these ILs aided in defining the introgressed regions. Identification of linked markers with advance genomic technologies will aid in marker assisted pyramiding of alien genes in cultivated wheat background.

genetics↗