Biology subjects

Jayakodi, M.

Publications and source records attributed to Jayakodi, M..

9 recordsLinked to original sources

bioRxiv2026

Haplotype-resolved genetic mapping using selfed progeny enables simultaneous genome assembly validation and trait dissection in a heterozygous plant

Genetic linkage maps are essential for genome analysis and molecular breeding, but developing suitable mapping populations remains challenging in many plant species. Approaches requiring inbred parental lines are particularly difficult to implement in plants with long generation times or severe inbreeding depression. We developed haplotype-resolved genetic mapping (HRGM) to construct linkage maps from a single heterozygous individual and its selfed progeny without requiring inbred parental lines. HRGM combines haplotype-resolved unitig assemblies from the S0 parent with genotype data from its S1 progeny, using sequence differences between the two haplotypes to define phased SNP markers. Application to Cynanchum wilfordii generated a high-density genetic map comprising 8,147 SNP markers consolidated into 464 bins across 11 linkage groups, spanning 786.4 cM. The map enabled the detection of two loci associated with root development. Recombination patterns derived from the S1 population showed strong concordance with the chromosome-scale genome assembly and exhibited recombination suppression in putative centromeric regions. HRGM integrates recombination-based genome assembly validation and trait mapping within a single framework. By using one generation of selfed progeny and obtaining linkage-phase information directly from phased assemblies, it simplifies mapping population development and extends the utility of genomic resources for genetic analysis and molecular breeding, particularly in species where selfed progeny can be obtained but conventional mapping populations are difficult to establish.

genomics↗

bioRxiv2026

Global Sesame Germplasm Harbors Untapped Genetic Potential for Crop Improvement

Background Sesame (Sesamum indicum L.) is one of the oldest oilseed crops. Its seeds accumulate lignans and antioxidants that determine their nutritional value. Global demand for sesame is rising rapidly, but climate change increasingly threatens sesame yields and seed quality. Here, we analyzed a worldwide panel of 300 sesame accessions to explore the genetic basis of key adaptive and quality traits, specifically flowering time, seed lignan content, and seed antioxidant capacity. Results Whole-genome resequencing revealed previously unreported genetic diversity, expanding the resources available for sesame breeding. By integrating k-mer-based genome-wide association analysis with a graph-based sesame genome, we identified structural variants associated with differences in flowering time and lignan accumulation. A 9.4-kb deletion on chromosome 6 that disrupted SIN_1018434 (an ortholog of Arabidopsis PHOTOPERIOD-INDEPENDENT EARLY FLOWERING 1) and a 6.2-kb Copia-type retrotransposon insertion upstream of SIN_1004470 on chromosome 11 were associated with early flowering. The intact alleles at both loci were associated with delayed flowering and were predominant in low-latitude accessions. High seed lignan content was associated with non-synonymous mutations and copy number variants in glycosyl hydrolase genes on chromosome 6 and an 8.2-kb deletion spanning SIN_1019378 on chromosome 13. Association signals for seed antioxidant traits coincided with loci involved in abiotic stress responses and seed-coat pigmentation. Conclusions These findings highlight the importance of exploring diverse germplasm to uncover previously unrecognized adaptive and quality-associated genomic variation. The loci identified here provide molecular targets for developing climate-adapted cultivars with improved seed quality.

genomics↗

bioRxiv2025

A near gap-free haplotype-resolved genome assembly of Zoysia japonica uncovers intra-subgenomic gene expression and regulatory variation

Zoysiagrass is a warm-season allotetraploid turfgrass valued for stress tolerance, but high heterozygosity and polyploidy have impeded accurate genome assembly. Here, a near gap-free, allele-aware, fully phased genome of Zoysia japonica cv. Palisades was assembled using PacBio HiFi and Hi-C data. The assembly resolves 20 chromosome pairs (317.2 and 317.0 Mb for haplotypes 1 and 2) with telomeric repeats at both ends of all chromosomes, attains 98.3% BUSCO completeness and 99% completeness by Merqury, and comprises approximately 50% repetitive DNA and about 40,000 protein-coding genes per haplotype. Comparative analysis identified roughly 2.9 million SNPs and numerous structural variants. Hemizygous genes were widespread (4,863 in hap-1 and 4,519 in hap-2), enriched within insertion regions, highly divergent regions, and haplotype-unique sequences, and showed elevated expression relative to homozygous genes. Among 539 one-to-one coding-identical homologs, 29 exhibited haplotype-biased expression associated with upstream promoter variants. This phased genome enables marker development, genetic mapping, and trait dissection in heterozygous polyploids.

genomics↗

bioRxiv2024

A haplotype-based evolutionary history of barley domestication

Barley is an old crop with a complex history. Its evolution and the molecular basis of domestication have been intensely studied. This research has ruled out a single origin of the crop and motivated a model of mosaic genomics ancestry. As more and better genome sequences have become available, this concept can be refined: where do the building blocks of the mosaic, that is, the haplotypes come from? Were all cultivated barleys created equal or did some wild barley populations contribute more to some domesticated lineages? To answer these and other questions, we pursue a haplotype-based approach to connect diversity and population structure in wild and domesticated barley. We sequence the genomes of 628 genebank accessions and 23 archaeological specimens. Using these data, we infer the spatiotemporal origins of haplotypes and map the contributions of different wild barley populations either during the initial phase of domestication or through later gene flow. Ancient DNA sequences corroborate our genome-wide analysis in present-day samples. Our results indicate that an early domesticated founder population formed in the Fertile Crescent during an extended period of pre-domestication cultivation. A practical implication of our findings is that the high haplotype differentiation between barley populations, which arose possibly without, and most likely on top of, selective forces, complicates the mapping of adaptive loci.

plant biology↗

bioRxiv2024

Whole-Genome Sequencing of the Wild Barley Diversity Collection: A Resource for Identifying and Exploiting Genetic Variation for Cultivated Barley Improvement

To exploit allelic variation in Hordeum vulgare subsp. spontaneum, the Wild Barley Diversity Collection was evaluated for several agronomic traits and subjected to paired-end Illumina sequencing at [~]9X depth, generating 109.5 million single nucleotide polymorphisms after alignment to the Morex V3 assembly. A genome-wide association study of lemma color identified one marker-trait association (MTA) on chromosome 1HL close to HvBlp, the cloned gene controlling black lemma. Four MTAs were identified for stem rust resistance: one co-locating to the complex RMRL1-RMRL2 locus on 5HL, and three novel loci on 1HS, 1HL, and 5HL. Six MTAs for days to heading (DTH) on vernalized plants were identified on all chromosomes except 1H and 6H. Two MTAs for DTH on non-vernalized plants were identified on chromosomes 1HL and 2HS. All MTAs for DTH were novel. The whole genome sequence data described herein will facilitate the identification and utilization of new alleles for barley improvement.

genomics↗

bioRxiv2024

Adaptive diversification through structural variation in barley

Pangenomes are collections of annotated genome sequences of multiple individuals of a species. The structural variants uncovered by these datasets are a major asset to genetic analysis in crop plants. Here, we report a pangenome of barley comprising long-read sequence assemblies of 76 wild and domesticated genomes and short-read sequence data of 1,315 genotypes. An expanded catalogue of sequence variation in the crop includes structurally complex loci that have become hot spots of gene copy number variation in evolutionarily recent times. To demonstrate the utility of the pangenome, we focus on four loci involved in disease resistance, plant architecture, nutrient release, and trichome development. Novel allelic variation at a powdery mildew resistance locus and population-specific copy number gains in a regulator of vegetative branching were found. Expansion of a family of starch-cleaving enzymes in elite malting barleys was linked to shifts in enzymatic activity in micro-malting trials. Deletion of an enhancer motif is likely to change the developmental trajectory of the hairy appendages on barley grains. Our findings indicate that rapid evolution at structurally complex loci may have helped crop plants adapt to new selective regimes in agricultural ecosystems.

plant biology↗

bioRxiv2023

Dynamic phytomeric growth contributes to local adaptation in barley

Vascular plants segment their body axis with iterative nodes of lateral branches and internodes. Appropriate node initiation and internode elongation are fundamental to plant fitness and crop yield formation; but how they are spatiotemporally coordinated remains elusive. We show that in barley (Hordeum vulgare L.), selections under domestication have extended the apical meristematic phase to promote node initiation, but constrained subsequent internode elongation. In both vegetative and reproductive axes, internode elongation displays a dynamic proximal - distal gradient, and among subpopulations of domesticated barleys at the global range, node initiation and proximal internode elongation are associated with latitudinal and longitudinal gradients, respectively. Genetic and functional analysis suggest that, in addition to their converging roles in node initiation, flowering time genes are repurposed to specify the dynamic internode elongation. Our study provides an integrated view of barley node initiation and internode elongation, and suggests that plant architecture has to be recognized as dynamic phytomeric units in the context of crop evolution.

plant biology↗

bioRxiv2022

The giant diploid faba genome unlocks variation in a global protein crop

Increasing the proportion of locally produced plant protein in currently meat-rich diets could substantially reduce greenhouse gas emission and loss of biodiversity. However, plant protein production is hampered by the lack of a cool-season legume equivalent to soybean in agronomic value. Faba bean (Vicia faba L.) has a high yield potential and is well-suited for cultivation in temperate regions, but genomic resources are scarce. Here, we report a high-quality chromosome-scale assembly of the faba bean genome and show that it has grown to a massive 13 Gb in size through an imbalance between the rates of amplification and elimination of retrotransposons and satellite repeats. Genes and recombination events are evenly dispersed across chromosomes and the gene space is remarkably compact considering the genome size, though with significant copy number variation driven by tandem duplication. Demonstrating practical application of the genome sequence, we develop a targeted genotyping assay and use high-resolution genome-wide association (GWA) analysis to dissect the genetic basis of hilum colour. The resources presented constitute a genomics-based breeding platform for faba bean, enabling breeders and geneticists to accelerate improvement of sustainable protein production across Mediterranean, subtropical, and northern temperate agro-ecological zones.

plant biology↗

bioRxiv2021

Dosage of duplicated and antifunctionalized homeobox proteins influences spikelet development in barley

Illuminating the mechanisms of inflorescence architecture of grain crops that feed our world may strengthen the goal towards sustainable agriculture. Lateral spikelet development of barley (Hordeum vulgare L.) is such an example of a floral architectural trait regulated by VRS1 (Vulgare Row-type Spike 1 or Six-rowed Spike 1, syn. HvHOX1). Its lateral spikelet-specific expression and the quantitative nature of suppressing spikelet development were previously shown in barley. However, the mechanistic function of this gene and its paralog HvHOX2 on spikelet development is still fragmentary.Here, we show that these duplicated transcription factors (TFs) have contrasting nucleotide diversity in various barley genotypes and several Hordeum species. Despite this difference, both proteins retain their basic properties of the homeodomain leucine zipper class I family of TFs. During spikelet development, these genes exhibit similar spatiotemporal expression patterns yet with anticyclic expression levels. A gene co-expression network analysis suggested that both have an ancestral relationship but their functions appear antagonistic to each other, i.e., HvHOX1 suppresses whereas HvHOX2 rather promotes spikelet development. Our transgenic promoter-swap analysis showed that HvHOX2 can restore suppressed lateral spikelets when expression levels are increased; however, at its low endogenous expression level, HvHOX2 appears dispensable for spikelet development. Collectively, this study proposes that the dosage of the two antagonistic TFs, HvHOX1 and HvHOX2, influence spikelet development in barley.

plant biology↗