Genome Assembly and Annotation of Soft-Shelled Adlay (Coix lacryma-jobi Variety ma-yuen), a Cereal and Medicinal Crop in the Poaceae Family.
ABSTRACT: Coix lacryma-jobi, also called adlay or Job's tears, is an annual herbal plant belonging to the Poaceae family that has been cultivated as a cereal and medicinal crop in Asia. Despite its importance, however, genomic resources for better understanding this plant species at the molecular level and informing improved breeding strategies remain limited. To address this, we generated a draft genome of the C. lacryma-jobi variety ma-yuen (soft-shelled adlay) Korean cultivar, Johyun, by de novo assembly, using PacBio and Illumina sequencing data. A total of 3,362 scaffold sequences, 1.28 Gb in length, were assembled, representing 82.1% of the estimated genome size (1.56 Gb). Genome completeness was confirmed by the presence of 91.4% of the BUSCO angiosperm genes and mapping ratio of 98.3% of Illumina paired-end reads. We found that approximately 77.0% of the genome is occupied by repeat sequences, most of which are Gypsy and Copia-type retrotransposons, and evidence-based genome annotation predicts 39,574 protein-coding genes, 85.5% of which were functionally annotated. We further predict that soft-shelled adlay diverged from a common ancestor with sorghum 9.0-11.2 MYA. Transcriptome profiling revealed 3,988 genes that are differentially expressed in seeds relative to other tissues, of which 1,470 genes were strongly up-regulated in seeds and the most enriched Gene Ontology terms were assigned to carbohydrate and protein metabolism. In addition, we identified 76 storage protein genes including 18 seed-specific coixin genes and 13 candidate genes involved in biosynthesis of benzoxazinoids (BXs) including coixol, a unique BX compound found in C. lacryma-jobi species. The characterization of those genes can further our understanding of unique traits of soft-shelled adlay, such as high seed protein content and medicinal compound biosynthesis. Taken together, our genome sequence data will provide a valuable resource for molecular breeding and pharmacological study of this plant species.
Project description:<i>Coix lacryma-jobi</i> is a cereal and medicinal crop belonging to the Poaceae family. This study characterized complete chloroplast genome sequence of a Korean cultivar Johyun of <i>C. lacryma-jobi</i> var. <i>ma-yuen</i> through the <i>de novo</i> hybrid assembly with Illumina and PacBio genomic reads. The chloroplast genome is 140,863?bp long and composed of large single copy (82,827?bp), small single copy (12,522?bp), and a pair of inverted repeats (each 22,757?bp). A total of 123 genes including 87 protein-coding genes, 32 tRNA genes, and four rRNA genes were predicted in the genome. Phylogenetic analysis confirmed a close relationship of <i>C. lacryma-jobi</i> with species in the Panicoideae subfamily of the Poaceae family.
Project description:Coix lacryma-jobi L. is an important minor cereal with a high nutritional and medicinal value in Asian countries. The hilly region of South China is the secondary center of diversity of Coix lacryma-jobi L. In the present study, we took a sample of 139 Coix lacryma-jobi L. genotypes from four geographical regions in Southwest China and analyzed the genetic diversity and population structure using AFLP markers. Six primer combinations detected a total of 743 (89.52%) polymorphic loci. The percentage of polymorphic bands within the four geographical populations ranged from 56.02% (Guangxi) to 86.75% (Guizhou). The overall genetic diversity of 139 Coix lacryma-jobi L. was relatively low (h ranged from 0.1854 to 0.2564). The neighbor-joining method grouped all Coix lacryma-jobi L. genotypes into two clusters with no geographical affinity observed among genotypes within the same group. The Fst indicated the two clusters existed great genetic differentiation. AMOVA analysis showed the molecular variation within populations was much higher than that among populations of geographical regions and subpopulations derived from STRUCTURE. Human activities and the natural outcrossing system of Coix lacryma-jobi L. may have a great influence on its distribution, genetic diversity, and population structure. Our study provides useful information for local breeding programs of Coix lacryma-jobi L. as well.
Project description:BACKGROUND: Coix, Sorghum and Zea are closely related plant genera in the subtribe Maydeae. Coix comprises 9-11 species with different ploidy levels (2n = 10, 20, 30, and 40). The exclusively cultivated C. lacryma-jobi L. (2n = 20) is widely used in East and Southeast Asia for food and medicinal applications. Three fertile cytotypes (2n = 10, 20, and 40) have been reported for C. aquatica Roxb. One sterile cytotype (2n = 30) closely related to C. aquatica has been recently found in Guangxi of China. This putative hybrid has been named C. aquatica HG (Hybrid Guangxi). The genome composition and the evolutionary history of C. lacryma-jobi and C. aquatica HG are largely unclear. RESULTS: About 76% of the genome of C. lacryma-jobi and 73% of the genome of C. aquatica HG are repetitive DNA sequences as shown by low coverage genome sequencing followed by similarity-based cluster analysis. In addition, long terminal repeat (LTR) retrotransposable elements are dominant repetitive sequences in these two genomes, and the proportions of many repetitive sequences in whole genome varied greatly between the two species, indicating evolutionary divergence of them. We also found that a novel 102 bp variant of centromeric satellite repeat CentX and two other satellites only appeared in C. aquatica HG. The results from FISH analysis with repeat probe cocktails and the data from chromosomes pairing in meiosis metaphase showed that C. lacryma-jobi is likely a diploidized paleotetraploid species and C. aquatica HG is possibly a recently formed hybrid. Furthermore, C. lacryma-jobi and C. aquatica HG shared more co-existing repeat families and higher sequence similarity with Sorghum than with Zea. CONCLUSIONS: The composition and abundance of repetitive sequences are divergent between the genomes of C. lacryma-jobi and C. aquatica HG. The results from fine karyotyping analysis and chromosome pairing suggested diploidization of C. lacryma-jobi during evolution and C. aquatica HG is a recently formed hybrid. The genome-wide comparison of repetitive sequences indicated that the repeats in Coix were more similar to those in Sorghum than to those in Zea, which is consistent with the phylogenetic relationship reported by previous work.
Project description:Adlay (Coix lacryma-jobi) is a tropical grass that has long been used in traditional Chinese medicine and is known for its nutritional benefits. Recent studies have shown that vitamin E compounds in adlay protect against chronic diseases such as cancer and heart disease. However, the molecular basis of adlay's health benefits remains unknown. Here, we generated adlay gene sets by de novo transcriptome assembly using long-read isoform sequencing (Iso-Seq) and short-read RNA-Sequencing (RNA-Seq). The gene sets obtained from Iso-seq and RNA-seq contained 31,177 genes and 57,901 genes, respectively. We confirmed the validity of the assembled gene sets by experimentally analyzing the levels of prolamin and vitamin E biosynthesis-associated proteins in adlay plant tissues and seeds. We compared the screened adlay genes with known gene families from closely related plant species, such as rice, sorghum and maize. We also identified tissue-specific genes from the adlay leaf, root, and young and mature seed, and experimentally validated the differential expression of 12 randomly-selected genes. Our study of the adlay transcriptome will provide a valuable resource for genetic studies that can enhance adlay breeding programs in the future.
Project description:Coix lacryma-jobi, commonly known as job's tear, is a tall grain-bearing tropical plant of the family Poaceae. The ethanolic root extract (ERE) of the plant was investigated for the first time for anti-venom activity against Indian cobra Naja naja venom. In-vitro studies were conducted to determine neutralization of phospholipase A2 (PLA2) activity of the Naja naja venom by the ERE. ERE showed significant inhibition of PLA2 activity, which was further confirmed from effective neutralization of human red blood cells (HRBC) lysis induced by the venom. In addition, venom-induced proteolysis, fibrinogenolysis, DNase activity were also neutralized by the ERE, which contained carbohydrates, glycolides, resins and tannins. Oral administration of ERE at doses levels 100, 200 and 400 mg/kg effectively inhibited Naja naja venom-induced lethality in mice. Myotoxicity induced by Naja naja venom, measured by creatine kinase activity in rats was significantly neutralized by the ERE at a dose of 200 mg/kg. Stigmasterol, as one of the component isolated from the ERE, was found to have venom phospholipase A2 inhibition potential, which was confirmed by molecular docking studies with PLA2. In summary, these studies indicate the ability of ERE of Coix lacryma-jobi to effectively neutralize the toxic effects of the venom is, in part, contributed by the inhibition of PLA2 activity among other venom-derived factors.