First Complete Genome Sequence of Barley Virus G Identified from Proso Millet (Panicum miliaceum) in South Korea.
ABSTRACT: The complete genome sequence of an Uiseong isolate of barley virus G (BVG) on proso millet plants in a field in South Korea was determined by RNA sequencing and Sanger sequencing. To our knowledge, this is the first complete genome sequence report of BVG infecting proso millet in South Korea.
Project description:PREMISE OF THE STUDY:Proso millet (Panicum miliaceum; Poaceae) is a minor crop with good nutritional qualities and strong tolerance to drought stress and soil infertility. However, studies on genetic diversity have been limited due to a lack of efficient genetic markers. METHODS:Illumina sequencing technology was used to generate short read sequences of proso millet, and de novo transcriptome assemblies were used to develop a de novo assembly of proso millet. Genic simple sequence repeat (SSR) markers were identified and used to detect polymorphism among 56 accessions. Population structure and genetic similarity coefficient were estimated. RESULTS:In total, 25,341 unique gene sequences and 4724 SSR loci were obtained from the transcriptome, of which 229 pairs of SSR primers were validated, which resulted in 14 polymorphic genic SSR primers exhibiting 43 total alleles. According to the ratio of polymorphic markers (6.1%, 14/229), there are potentially 288 polymorphic genic SSR markers available for genetic assay development in the future. Bayesian population analyses showed that the 56 accessions comprised two distinct groups. DISCUSSION:A genetic structure and cluster assay indicated that the accessions from the Loess Plateau of China shared a high genetic similarity coefficient with those from other regions and that there was no correlation between genetic diversity and geographic origin. The transcriptome sequencing data and millet-specific SSR markers developed in this study establish an excellent resource for gene discovery and may improve the development of breeding programs in proso millet in the future.
Project description:BACKGROUND:Drought stress is a major abiotic stress that causes huge losses in agricultural production. Proso millet (Panicum miliaceum L.) can efficiently adapt to drought stress and provides important information and gene resources to improve drought tolerance. However, its complex drought-responsive mechanisms remain unclear. RESULTS:Among 37 core Chinese proso millet cultivars, Jinshu 6 (JS6) was selected as the drought-sensitive test material, whereas Neimi 5 (NM5) was selected as the drought-tolerant test material under PEG-induced water stress. After sequencing, 1695 differentially expressed genes (DEGs) were observed in JS6 and NM5 without PEG-induced water stress (JS6CK and NM5CK). A total of 833 and 2166 DEGs were found in the two cultivars under simulated drought by using 20% PEG-6000 for 6 (JS6T6 and NM5T6) and 24?h (JS6T24 and NM5T24), respectively. The DEGs in JS6T6 and JS6T24 treatments were approximately 0.298- and 0.754-fold higher than those in NM5T6 and NM5T24, respectively. Compared with the respective controls, more DEGs were found in T6 treatments than in T24 treatments. A delay in the transcriptional responses of the ROS scavenging system to simulated drought treatment and relatively easy recovery of the expression of photosynthesis-associated genes were observed in NM5. Compared with JS6, different regulation strategies were observed in the jasmonic acid (JA) signal transduction pathway of NM5. CONCLUSION:Under PEG-induced water stress, NM5 maintained highly stable gene expression levels. Compared with drought-sensitive cultivars, the different regulation strategies in the JA signal transduction pathway in drought-tolerant cultivars may be one of the driving forces underlying drought stress tolerance.
Project description:BACKGROUND:Proso millet is a highly nutritious cereal considered an essential component of processed foods. It is also recognized with high water-use efficiency as well as short growing seasons. This research was primarily aimed at investigating the genetic diversity among genotypes based on evaluating those important traits proposed in previous researches under both normal and salinity- stress conditions. Use of Amplified fragment length polymorphism (AFLP) molecular markers as well as evaluating the association between markers and the investigated traits under both conditions was also another purpose of this research. RESULTS:According to the phenotypic correlation coefficients, the seed yield had the highest correlation with the forage and biological yields under both conditions. By disintegrating those traits investigated under normal and salinity-stress conditions into principal component analysis, it was found that the first four principal components justified more than 59.94 and 62.48% of the whole variance, respectively. The dendrogram obtained by cluster analysis displayed three groups of genotypes under both normal and salinity- stress conditions. Then, association analyses were conducted on 143 proso millet genotypes and 15 agronomic traits as well as 514 polymorphic AFLP markers (out of 866 created bands) generated by 11 primer combinations (out of the initial 20 primer combinations) EcoRI/MseI. The results obtained by mixed linear model (MLM) indicated that under normal conditions, the M14/E10-45 and M14/E10-60 markers had strong associations with seed yield. A similar trend was also observed for M14/E10-45 and M14/E11-44 markers in relation to forage yield. On the other hand, M14/E10-14, M14/E10-64 markers (for seed yield) and M14/E10-64 marker (for forage yield), had significant and stable association in all environments under salinity-stress conditions. Moreover, a number of markers showed considerable associations and stability under both normal and salinity stress conditions. CONCLUSIONS:According to the analysis of phenotypic data, the wide germplasm of Iranian proso millet has significant variation in terms of measured traits. It can be concluded that markers showing strong associations with traits under salinity-stress conditions are suitable candidates to be used in future marker-assisted selection (MAS) studies to improve salinity-resistance genotypes of Panicum miliaceum in arid and semiarid areas.
Project description:The origin of millet from Neolithic China has generally been accepted, but it remains unknown whether common millet (Panicum miliaceum) or foxtail millet (Setaria italica) was the first species domesticated. Nor do we know the timing of their domestication and their routes of dispersal. Here, we report the discovery of husk phytoliths and biomolecular components identifiable solely as common millet from newly excavated storage pits at the Neolithic Cishan site, China, dated to between ca. 10,300 and ca. 8,700 calibrated years before present (cal yr BP). After ca. 8,700 cal yr BP, the grain crops began to contain a small quantity of foxtail millet. Our research reveals that the common millet was the earliest dry farming crop in East Asia, which is probably attributed to its excellent resistance to drought.
Project description:Broomcorn millet (Panicum miliaceum L.) is one of the world's oldest cultivated cereals, with several lines of recent evidence indicating that it was grown in northern China from at least 10,000 cal bp. Additionally, a cluster of archaeobotanical records of P. miliaceum dated to at least 7000 cal bp exists in eastern Europe. These two centres of early records could either represent independent domestications or cross-continental movement of this cereal that would predate that of any other crop by some 2 millennia. Here, we analysed genetic diversity among 98 landrace accessions from across Eurasia using 16 microsatellite loci, to explore phylogeographic structure in the Old World range of this historically important crop. The major genetic split in the data divided the accessions into an eastern and a western grouping with an approximate boundary in northwestern China. A substantial number of accessions belonging to the 'western' genetic group were also found in northeastern China. Further resolution subdivided the western and eastern genepools into 2 and 4 clusters respectively, each showing clear geographic patterning. The genetic data are consistent with both the single and multiple domestication centre hypotheses and add specific detail to what these hypotheses would entail regarding the spread of broomcorn millet. Discrepancies exist between the predictions from the genetic data and the current archaeobotanical record, highlighting priorities for investigation into early farming in Central Asia.
Project description:Broomcorn millet (Panicum miliaceum L.), one of the first domesticated crops, has been grown in Northern China for at least 10,000 years. The species is presently a minor crop, and evaluation of its genetic diversity has been very limited. In this study, we analyzed the genetic diversity of 88 accessions of broomcorn millet collected from various provinces of China. Amplification with 67 simple sequence repeat (SSR) primers revealed moderate levels of diversity in the investigated accessions. A total of 179 alleles were detected, with an average of 2.7 alleles per locus. Polymorphism information content and expected heterozygosity ranged from 0.043 to 0.729 (mean = 0.376) and 0.045 to 0.771 (mean = 0.445), respectively. Cluster analysis based on the unweighted pair group method of mathematical averages separated the 88 accessions into four groups at a genetic similarity level of 0.633. A genetic structure assay indicated a close correlation between geographical regions and genetic diversity. The uncovered information will be valuable for defining gene pools and developing breeding programs for broomcorn millet. Furthermore, the millet-specific SSR markers developed in this study should serve as useful tools for assessment of genetic diversity and elucidation of population structure in broomcorn millet.
Project description:Broomcorn millet (Panicum miliaceum L.) is an important nutritious ancient minor-cereal food crop. However, this crop is little explored in the food processing arena to improve its functionality. In this context, different processing methods were applied to enhance the secondary compounds of broomcorn millet. Four different individual methods such as roasting, steaming, puffing, and extrusion were applied at 110 °C to enhance the functional attributes of millet flour. It was observed that the significantly highest content of total phenolic (TP) (670 mg/100 g of ferulic acid equivalent) and total flavonoid (TF) (391 mg/100 g of rutin equivalent ) was attained in the roasted whole millet followed by steaming (315 mg/100 g, 282 mg/100 g), puffing (645 mg/100 g, 304 mg/100 g), extrusion (455 mg/100 g, 219 mg/100 g), and control (295 mg/100 g, 183 mg/100 g). The chromatographic analysis showed a greater content of single phenolic acids such as syringic acid, gallic acid, 4-hydroxy benzoic acid, ferulic acid, sinapic acid, and catechin in roasted millet compared to control, and the content of each acid was higher in whole millet than dehulled. Results also indicated that the content of ferulic acid was relatively higher among the quantified single phenolic acid from broomcorn millet. Likewise, in comparison with dehulled millet, the roasted whole millet showed higher total antioxidant capacity, measured by the 2,2-diphenyl-1 picryl hydrazyl (DPPH), the ferric reducing antioxidant power assay (FRAP), the phosphomolybdenum method (PPMD), and the hydroxyl radical scavenging capacity (HRSC) method. Lastly, it is concluded that the roasting method should be taken into consideration in the processing of broomcorn millet to enhance the content of nutraceutical compounds and improve its functionality.
Project description:BACKGROUND:Broomcorn millet is a drought-tolerant cereal that is widely cultivated in the semiarid regions of Asia, Europe, and other continents; however, the mechanisms underlying its drought-tolerance are poorly understood. The NAM, ATAF1/2, and CUC2 (NAC) transcription factors form a large plant-specific gene family that is involved in the regulation of tissue development and abiotic stress. To date, NAC transcription factors have not been systematically researched in broomcorn millet. RESULTS:In the present study, a total of 180 NAC (PmNAC) genes were identified from the broomcorn millet genome and named uniformly according to their chromosomal distribution. Phylogenetic analysis demonstrated that the PmNACs clustered into 12 subgroups, including the broomcorn millet-specific subgroup Pm_NAC. Gene structure and protein motif analyses indicated that closely clustered PmNAC genes were relatively conserved within each subgroup, while genome mapping analysis revealed that the PmNAC genes were unevenly distributed on broomcorn millet chromosomes. Transcriptome analysis revealed that the PmNAC genes differed greatly in expression in various tissues and under different drought stress durations. The expression of 10 selected genes under drought stress was analyzed using quantitative real-time PCR. CONCLUSION:In this study, 180 NAC genes were identified in broomcorn millet, and their phylogenetic relationships, gene structures, protein motifs, chromosomal distribution, duplication, expression patterns in different tissues, and responses to drought stress were studied. These results will be useful for the further study of the functional characteristics of PmNAC genes, particularly with regards to drought resistance.
Project description:Panicum miliaceum (broomcorn millet) is a tetraploid cereal, which was among the first domesticated crops, but is now a minor crop despite its high water use efficiency. The ancestors of this species have not been determined; we aimed to identify likely candidates within the genus, where phylogenies are poorly resolved. Nuclear and chloroplast DNA sequences from P. miliaceum and a range of diploid and tetraploid relatives were used to develop phylogenies of the diploid and tetraploid species. Chromosomal in situ hybridization with genomic DNA as a probe was used to characterize the genomes in the tetraploid P. miliaceum and a tetraploid accession of P. repens. In situ hybridization showed that half the chromosomes of P. miliaceum hybridized more strongly with labelled genomic DNA from P. capillare, and half with labelled DNA from P. repens. Genomic DNA probes differentiated two sets of 18 chromosomes in the tetraploid P. repens. Our phylogenetic data support the allotetraploid origin of P. miliaceum, with the maternal ancestor being P. capillare (or a close relative) and the other genome being shared with P. repens. Our P. repens accession was also an allotetraploid with two dissimilar but closely related genomes, the maternal genome being similar to P. sumatrense. Further collection of Panicum species, particularly from the Old World, is required. It is important to identify why the water-efficient P. miliaceum is now of minimal importance in agriculture, and it may be valuable to exploit the diversity in this species and its ancestors.
Project description:Broomcorn millet (Panicum miliaceum L.) is one of the world's oldest cultivated cereals, which is well-adapted to extreme environments such as drought, heat, and salinity with an efficient C4 carbon fixation. Discovery and identification of genes involved in these processes will provide valuable information to improve the crop for meeting the challenge of global climate change. However, the lack of genetic resources and genomic information make gene discovery and molecular mechanism studies very difficult. Here, we sequenced and assembled the transcriptome of broomcorn millet using Illumina sequencing technology. After sequencing, a total of 45,406,730 and 51,160,820 clean paired-end reads were obtained for two genotypes Yumi No. 2 and Yumi No. 3. These reads were mixed and then assembled into 113,643 unigenes, with the length ranging from 351 to 15,691 bp, of which 62,543 contings could be assigned to 315 gene ontology (GO) categories. Cluster of orthologous groups and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses assigned could map 15,514 unigenes into 202 KEGG pathways and 51,020 unigenes to 25 COG categories, respectively. Furthermore, 35,216 simple sequence repeats (SSRs) were identified in 27,055 unigene sequences, of which trinucleotides were the most abundant repeat unit, accounting for 66.72% of SSRs. In addition, 292 differentially expressed genes were identified between the two genotypes, which were significantly enriched in 88 GO terms and 12 KEGG pathways. Finally, the expression patterns of four selected transcripts were validated through quantitative reverse transcription polymerase chain reaction analysis. Our study for the first time sequenced and assembled the transcriptome of broomcorn millet, which not only provided a rich sequence resource for gene discovery and marker development in this important crop, but will also facilitate the further investigation of the molecular mechanism of its favored agronomic traits and beyond.