Yang Jae Kang

Bio: Yang Jae Kang is an academic researcher from Gyeongsang National University. The author has contributed to research in topics: Genome & Gene. The author has an hindex of 17, co-authored 34 publications receiving 1309 citations. Previous affiliations of Yang Jae Kang include Seoul National University & Technische Universität München.

Genome sequence of mungbean and insights into evolution within Vigna species

Abstract: Mungbean (Vigna radiata) is a fast-growing, warm-season legume crop that is primarily cultivated in developing countries of Asia. Here we construct a draft genome sequence of mungbean to facilitate genome research into the subgenus Ceratotropis, which includes several important dietary legumes in Asia, and to enable a better understanding of the evolution of leguminous species. Based on the de novo assembly of additional wild mungbean species, the divergence of what was eventually domesticated and the sampled wild mungbean species appears to have predated domestication. Moreover, the de novo assembly of a tetraploid Vigna species (V. reflexo-pilosa var. glabra) provides genomic evidence of a recent allopolyploid event. The species tree is constructed using de novo RNA-seq assemblies of 22 accessions of 18 Vigna species and protein sets of Glycine max. The present assembly of V. radiata var. radiata will facilitate genome research and accelerate molecular breeding of the subgenus Ceratotropis.

Whole-genome sequencing and intensive analysis of the undomesticated soybean (Glycine soja Sieb. and Zucc.) genome

Abstract: The genome of soybean (Glycine max), a commercially important crop, has recently been sequenced and is one of six crop species to have been sequenced. Here we report the genome sequence of G. soja, the undomesticated ancestor of G. max (in particular, G. soja var. IT182932). The 48.8-Gb Illumina Genome Analyzer (Illumina-GA) short DNA reads were aligned to the G. max reference genome and a consensus was determined for G. soja. This consensus sequence spanned 915.4 Mb, representing a coverage of 97.65% of the G. max published genome sequence and an average mapping depth of 43-fold. The nucleotide sequence of the G. soja genome, which contains 2.5 Mb of substituted bases and 406 kb of small insertions/deletions relative to G. max, is ∼0.31% different from that of G. max. In addition to the mapped 915.4-Mb consensus sequence, 32.4 Mb of large deletions and 8.3 Mb of novel sequence contigs in the G. soja genome were also detected. Nucleotide variants of G. soja versus G. max confirmed by Roche Genome Sequencer FLX sequencing showed a 99.99% concordance in single-nucleotide polymorphism and a 98.82% agreement in insertion/deletion calls on Illumina-GA reads. Data presented in this study suggest that the G. soja/G. max complex may be at least 0.27 million y old, appearing before the relatively recent event of domestication (6,000∼9,000 y ago). This suggests that soybean domestication is complicated and that more in-depth study of population genetics is needed. In any case, genome comparison of domesticated and undomesticated forms of soybean can facilitate its improvement.

Genome-wide mapping of NBS-LRR genes and their association with disease resistance in soybean

Abstract: R genes are a key component of genetic interactions between plants and biotrophic bacteria and are known to regulate resistance against bacterial invasion. The most common R proteins contain a nucleotide-binding site and a leucine-rich repeat (NBS-LRR) domain. Some NBS-LRR genes in the soybean genome have also been reported to function in disease resistance. In this study, the number of NBS-LRR genes was found to correlate with the number of disease resistance quantitative trait loci (QTL) that flank these genes in each chromosome. NBS-LRR genes co-localized with disease resistance QTL. The study also addressed the functional redundancy of disease resistance on recently duplicated regions that harbor NBS-LRR genes and NBS-LRR gene expression in the bacterial leaf pustule (BLP)-induced soybean transcriptome. A total of 319 genes were determined to be putative NBS-LRR genes in the soybean genome. The number of NBS-LRR genes on each chromosome was highly correlated with the number of disease resistance QTL in the 2-Mb flanking regions of NBS-LRR genes. In addition, the recently duplicated regions contained duplicated NBS-LRR genes and duplicated disease resistance QTL, and possessed either an uneven or even number of NBS-LRR genes on each side. The significant difference in NBS-LRR gene expression between a resistant near-isogenic line (NIL) and a susceptible NIL after inoculation of Xanthomonas axonopodis pv. glycines supports the conjecture that NBS-LRR genes have disease resistance functions in the soybean genome. The number of NBS-LRR genes and disease resistance QTL in the 2-Mb flanking regions of each chromosome was significantly correlated, and several recently duplicated regions that contain NBS-LRR genes harbored disease resistance QTL for both sides. In addition, NBS-LRR gene expression was significantly different between the BLP-resistant NIL and the BLP-susceptible NIL in response to bacterial infection. From these observations, NBS-LRR genes are suggested to contribute to disease resistance in soybean. Moreover, we propose models for how NBS-LRR genes were duplicated, and apply Ks values for each NBS-LRR gene cluster.

Draft genome sequence of adzuki bean, Vigna angularis.

Abstract: Adzuki bean (Vigna angularis var. angularis) is a dietary legume crop in East Asia. The presumed progenitor (Vigna angularis var. nipponensis) is widely found in East Asia, suggesting speciation and domestication in these temperate climate regions. Here, we report a draft genome sequence of adzuki bean. The genome assembly covers 75% of the estimated genome and was mapped to 11 pseudo-chromosomes. Gene prediction revealed 26,857 high confidence protein-coding genes evidenced by RNAseq of different tissues. Comparative gene expression analysis with V. radiata showed that the tissue specificity of orthologous genes was highly conserved. Additional re-sequencing of wild adzuki bean, V. angularis var. nipponensis and V. nepalensis, was performed to analyze the variations between cultivated and wild adzuki bean. The determined divergence time of adzuki bean and the wild species predated archaeology-based domestication time. The present genome assembly will accelerate the genomics-assisted breeding of adzuki bean.

Highly efficient homology-directed repair using CRISPR/Cpf1-geminiviral replicon in tomato

Abstract: Genome editing via the homology-directed repair (HDR) pathway in somatic plant cells is very inefficient compared with error-prone repair by nonhomologous end joining (NHEJ). Here, we increased HDR-based genome editing efficiency approximately threefold compared with a Cas9-based single-replicon system via the use of de novo multi-replicon systems equipped with CRISPR/LbCpf1 in tomato and obtained replicon-free but stable HDR alleles. The efficiency of CRISPR/LbCpf1-based HDR was significantly modulated by physical culture conditions such as temperature and light. Ten days of incubation at 31 °C under a light/dark cycle after Agrobacterium-mediated transformation resulted in the best performance among the tested conditions. Furthermore, we developed our single-replicon system into a multi-replicon system that effectively increased HDR efficiency. Although this approach is still challenging, we showed the feasibility of HDR-based genome editing of a salt-tolerant SlHKT1;2 allele without genomic integration of antibiotic markers or any phenotypic selection. Self-pollinated offspring plants carrying the HKT1;2 HDR allele showed stable inheritance and germination tolerance in the presence of 100 mm NaCl. Our work may pave the way for transgene-free editing of alleles of interest in asexually and sexually reproducing plants.

Dependent Protein Kinase Required for Bacterial and Fungal Symbioses

Abstract: Legumes can enter into symbiotic relationships with both nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. Nodulation by rhizobia results from a signal transduction pathway induced in legume roots by rhizobial Nod factors. DMI3 ,a Medicago truncatula gene that acts immediately downstream of calcium spiking in this signaling pathway and is required for both nodulation and mycorrhizal infection, has high sequence similarity to genes encoding calcium and calmodulin-dependent protein kinases (CCaMKs). This indicates that calcium spiking is likely an essential component of the signaling cascade leading to nodule development and mycorrhizal infection, and sheds light on the biological role of plant CCaMKs.

Resequencing 302 wild and cultivated accessions identifies genes related to domestication and improvement in soybean

Abstract: Resequencing of 302 soybean accessions and GWAS provide a comprehensive resource for soybean geneticists and breeders.

Crop genomics: advances and applications

Abstract: The completion of reference genome sequences for many important crops and the ability to perform high-throughput resequencing are providing opportunities for improving our understanding of the history of plant domestication and to accelerate crop improvement. Crop plant comparative genomics is being transformed by these data and a new generation of experimental and computational approaches. The future of crop improvement will be centred on comparisons of individual plant genomes, and some of the best opportunities may lie in using combinations of new genetic mapping strategies and evolutionary analyses to direct and optimize the discovery and use of genetic variation. Here we review such strategies and insights that are emerging.

The sunflower genome provides insights into oil metabolism, flowering and Asterid evolution

Abstract: The domesticated sunflower, Helianthus annuus L, is a global oil crop that has promise for climate change adaptation, because it can maintain stable yields across a wide variety of environmental conditions, including drought Even greater resilience is achievable through the mining of resistance alleles from compatible wild sunflower relatives, including numerous extremophile species Here we report a high-quality reference for the sunflower genome (36 gigabases), together with extensive transcriptomic data from vegetative and floral organs The genome mostly consists of highly similar, related sequences and required single-molecule real-time sequencing technologies for successful assembly Genome analyses enabled the reconstruction of the evolutionary history of the Asterids, further establishing the existence of a whole-genome triplication at the base of the Asterids II clade and a sunflower-specific whole-genome duplication around 29 million years ago An integrative approach combining quantitative genetics, expression and diversity data permitted development of comprehensive gene networks for two major breeding traits, flowering time and oil metabolism, and revealed new candidate genes in these networks We found that the genomic architecture of flowering time has been shaped by the most recent whole-genome duplication, which suggests that ancient paralogues can remain in the same regulatory networks for dozens of millions of years This genome represents a cornerstone for future research programs aiming to exploit genetic diversity to improve biotic and abiotic stress resistance and oil production, while also considering agricultural constraints and human nutritional needs

De novo assembly of soybean wild relatives for pan-genome analysis of diversity and agronomic traits

Abstract: Wild relatives of crops are an important source of genetic diversity for agriculture, but their gene repertoire remains largely unexplored. We report the establishment and analysis of a pan-genome of Glycine soja, the wild relative of cultivated soybean Glycine max, by sequencing and de novo assembly of seven phylogenetically and geographically representative accessions. Intergenomic comparisons identified lineage-specific genes and genes with copy number variation or large-effect mutations, some of which show evidence of positive selection and may contribute to variation of agronomic traits such as biotic resistance, seed composition, flowering and maturity time, organ size and final biomass. Approximately 80% of the pan-genome was present in all seven accessions (core), whereas the rest was dispensable and exhibited greater variation than the core genome, perhaps reflecting a role in adaptation to diverse environments. This work will facilitate the harnessing of untapped genetic diversity from wild soybean for enhancement of elite cultivars.