Browsing by Author "Nie, Gang"

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    Genome assembly provides insights into the genome evolution and flowering regulation of orchardgrass
    Huang, Linkai; Feng, Guangyan; Yan, Haidong; Zhang, Zhongren; Bushman, Bradley Shaun; Wang, Jianping; Bombarely, Aureliano; Li, Mingzhou; Yang, Zhongfu; Nie, Gang; Xie, Wengang; Xu, Lei; Chen, Peilin; Zhao, Xinxin; Jiang, Wenkai; Zhang, Xinquan (2020-02)
    Orchardgrass (Dactylis glomerata L.) is an important forage grass for cultivating livestock worldwide. Here, we report an similar to 1.84-Gb chromosome-scale diploid genome assembly of orchardgrass, with a contig N50 of 0.93 Mb, a scaffold N50 of 6.08 Mb and a super-scaffold N50 of 252.52 Mb, which is the first chromosome-scale assembled genome of a cool-season forage grass. The genome includes 40 088 protein-coding genes, and 69% of the assembled sequences are transposable elements, with long terminal repeats (LTRs) being the most abundant. The LTRretrotransposons may have been activated and expanded in the grass genome in response to environmental changes during the Pleistocene between 0 and 1 million years ago. Phylogenetic analysis reveals that orchardgrass diverged after rice but before three Triticeae species, and evolutionarily conserved chromosomes were detected by analysing ancient chromosome rearrangements in these grass species. We also resequenced the whole genome of 76 orchardgrass accessions and found that germplasm from Northern Europe and East Asia clustered together, likely due to the exchange of plants along the 'Silk Road' or other ancient trade routes connecting the East and West. Last, a combined transcriptome, quantitative genetic and bulk segregant analysis provided insights into the genetic network regulating flowering time in orchardgrass and revealed four main candidate genes controlling this trait. This chromosome-scale genome and the online database of orchardgrass developed here will facilitate the discovery of genes controlling agronomically important traits, stimulate genetic improvement of and functional genetic research on orchardgrass and provide comparative genetic resources for other forage grasses.
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    Integration of small RNAs and transcriptome sequencing uncovers a complex regulatory network during vernalization and heading stages of orchardgrass (Dactylis glomerata L.)
    Feng, Guangyan; Xu, Lei; Wang, Jianping; Nie, Gang; Bushman, Bradley Shaun; Xie, Wengang; Yan, Haidong; Yang, Zhongfu; Guan, Hao; Huang, Linkai; Zhang, Xinquan (2018-10-03)
    Background Flowering is a critical reproductive process in higher plants. Timing of optimal flowering depends upon the coordination among seasonal environmental cues. For cool season grasses, such as Dactylis glomerata, vernalization induced by low temperature provides competence to initiate flowering after prolonged cold. We combined analyses of the transcriptome and microRNAs (miRNAs) to generate a comprehensive resource for regulatory miRNAs and their target circuits during vernalization and heading stages. Results A total of 3,846 differentially expressed genes (DEGs) and 69 differentially expressed miRNAs were identified across five flowering stages. The expression of miR395, miR530, miR167, miR396, miR528, novel_42, novel_72, novel_107, and novel_123 demonstrated significant variations during vernalization. These miRNA targeted genes were involved in phytohormones, transmembrane transport, and plant morphogenesis in response to vernalization. The expression patterns of DEGs related to plant hormones, stress responses, energy metabolism, and signal transduction changed significantly in the transition from vegetative to reproductive phases. Conclusions Five hub genes, c136110_g1 (BRI1), c131375_g1 (BZR1), c133350_g1 (VRN1), c139830_g1 (VIN3), and c125792_g2 (FT), might play central roles in vernalization response. Our comprehensive analyses have provided a useful platform for investigating consecutive transcriptional and post-transcriptional regulation of critical phases in D. glomerata and provided insights into the genetic engineering of flowering-control in cereal crops.
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    Pangenomic analysis identifies structural variation associated with heat tolerance in pearl millet
    Yan, Haidong; Sun, Min; Zhang, Zhongren; Jin, Yarong; Zhang, Ailing; Lin, Chuang; Wu, Bingchao; He, Min; Xu, Bin; Wang, Jing; Qin, Peng; Mendieta, John Pablo; Nie, Gang; Wang, Jianping; Jones, Chris S. S.; Feng, Guangyan; Srivastava, Rakesh K. K.; Zhang, Xinquan; Bombarely, Aureliano; Luo, Dan; Jin, Long; Peng, Yuanying; Wang, Xiaoshan; Ji, Yang; Tian, Shilin; Huang, Linkai (Nature Portfolio, 2023-03)
    Pearl millet is an important cereal crop worldwide and shows superior heat tolerance. Here, we developed a graph-based pan-genome by assembling ten chromosomal genomes with one existing assembly adapted to different climates worldwide and captured 424,085 genomic structural variations (SVs). Comparative genomics and transcriptomics analyses revealed the expansion of the RWP-RK transcription factor family and the involvement of endoplasmic reticulum (ER)-related genes in heat tolerance. The overexpression of one RWP-RK gene led to enhanced plant heat tolerance and transactivated ER-related genes quickly, supporting the important roles of RWP-RK transcription factors and ER system in heat tolerance. Furthermore, we found that some SVs affected the gene expression associated with heat tolerance and SVs surrounding ER-related genes shaped adaptation to heat tolerance during domestication in the population. Our study provides a comprehensive genomic resource revealing insights into heat tolerance and laying a foundation for generating more robust crops under the changing climate. A graph-based pan-genome constructed using de novo genome assemblies of ten pearl millet accessions adapted to different climates worldwide identifies structural variations and their contribution to heat tolerance in pearl millet.
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    Reference Gene Selection for Quantitative Real-Time Reverse-Transcriptase PCR in Annual Ryegrass (Lolium multiflorum) Subjected to Various Abiotic Stresses
    Liu, Qiuxu; Qi, Xiao; Yan, Haidong; Huang, Linkai; Nie, Gang; Zhang, Xinquan (MDPI, 2018-01-16)
    To select the most stable reference genes in annual ryegrass (Lolium multiflorum), we studied annual ryegrass leaf tissues exposed to various abiotic stresses by qRT-PCR and selected 11 candidate reference genes, i.e., 18S rRNA, E2, GAPDH, eIF4A, HIS3, SAMDC, TBP-1, Unigene71, Unigene77, Unigene755, and Unigene14912. We then used GeNorm, NormFinder, and BestKeeper to analyze the expression stability of these 11 genes, and used RefFinder to comprehensively rank genes according to stability. Under different stress conditions, the most suitable reference genes for studies of leaf tissues of annual ryegrass were different. The expression of the eIF4A gene was the most stable under drought stress. Under saline-alkali stress, Unigene14912 has the highest expression stability. Under acidic aluminum stress, SAMDC expression stability was highest. Under heavy metal stress, Unigene71 expression had the highest stability. According to the software analyses, Unigene14912, HIS3, and eIF4A were the most suitable for analyses of abiotic stress in tissues of annual ryegrass. GAPDH was the least suitable reference gene. In conclusion, selecting appropriate reference genes under abiotic stress not only improves the accuracy of annual ryegrass gene expression analyses, but also provides a theoretical reference for the development of reference genes in plants of the genus Lolium.