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Zhang X, Zhu Y, Kremling KAG, Romay MC, Bukowski R, Sun Q, Gao S, Buckler ES, Lu F. Genome-wide analysis of deletions in maize population reveals abundant genetic diversity and functional impact. Theor Appl Genet 2022; 135:273-290. [PMID: 34661697 DOI: 10.1007/s00122-021-03965-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
Two read depth methods were jointly used in next-generation sequencing data to identify deletions in maize population. GWAS by deletions were analyzed for gene expression pattern and classical traits, respectively. Many studies have confirmed that structural variation (SV) is pervasive throughout the maize genome. Deletion is one type of SV that may impact gene expression and cause phenotypic changes in quantitative traits. In this study, two read count approaches were used to analyze the deletions in the whole-genome sequencing data of 270 maize inbred lines. A total of 19,754 deletion windows overlapped 12,751 genes, which were unevenly distributed across the genome. The deletions explained population structure well and correlated with genomic features. The deletion proportion of genes was determined to be negatively correlated with its expression. The detection of gene expression quantitative trait loci (eQTL) indicated that local eQTL were fewer but had larger effects than distant ones. The common associated genes were related to basic metabolic processes, whereas unique associated genes with eQTL played a role in the stress or stimulus responses in multiple tissues. Compared with the eQTL detected by SNPs derived from the same sequencing data, 89.4% of the associated genes could be detected by both markers. The effect of top eQTL detected by SNPs was usually larger than that detected by deletions for the same gene. A genome-wide association study (GWAS) on flowering time and plant height illustrated that only a few loci could be consistently captured by SNPs, suggesting that combining deletion and SNP for GWAS was an excellent strategy to dissect trait architecture. Our findings will provide insights into characteristic and biological function of genome-wide deletions in maize.
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Affiliation(s)
- Xiao Zhang
- Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, China.
- Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Chengdu, Sichuan, China.
- Institute for Genomic Diversity, Cornell University, 175 Biotechnology Building, Ithaca, NY, USA.
| | - Yonghui Zhu
- Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, Sichuan, China
| | - Karl A G Kremling
- Institute for Genomic Diversity, Cornell University, 175 Biotechnology Building, Ithaca, NY, USA
| | - M Cinta Romay
- Institute for Genomic Diversity, Cornell University, 175 Biotechnology Building, Ithaca, NY, USA
| | - Robert Bukowski
- Bioinformatics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY, USA
| | - Qi Sun
- Bioinformatics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY, USA
| | - Shibin Gao
- Maize Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, China
- Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture, Chengdu, Sichuan, China
| | - Edward S Buckler
- Institute for Genomic Diversity, Cornell University, 175 Biotechnology Building, Ithaca, NY, USA
- USDA-ARS, R. W. Holley Center, Cornell University, Ithaca, NY, USA
| | - Fei Lu
- Institute for Genomic Diversity, Cornell University, 175 Biotechnology Building, Ithaca, NY, USA.
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.
- CAS-JIC Centre of Excellence for Plant and Microbial Science (CEPAMS), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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Blanc J, Kremling KAG, Buckler E, Josephs EB. Local adaptation contributes to gene expression divergence in maize. G3 (Bethesda) 2021; 11:6114460. [PMID: 33604670 PMCID: PMC8022924 DOI: 10.1093/g3journal/jkab004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/20/2020] [Indexed: 11/14/2022]
Abstract
Gene expression links genotypes to phenotypes, so identifying genes whose expression is shaped by selection will be important for understanding the traits and processes underlying local adaptation. However, detecting local adaptation for gene expression will require distinguishing between divergence due to selection and divergence due to genetic drift. Here, we adapt a QST−FST framework to detect local adaptation for transcriptome-wide gene expression levels in a population of diverse maize genotypes. We compare the number and types of selected genes across a wide range of maize populations and tissues, as well as selection on cold-response genes, drought-response genes, and coexpression clusters. We identify a number of genes whose expression levels are consistent with local adaptation and show that genes involved in stress response show enrichment for selection. Due to its history of intense selective breeding and domestication, maize evolution has long been of interest to researchers, and our study provides insight into the genes and processes important for in local adaptation of maize.
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Affiliation(s)
- Jennifer Blanc
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Karl A G Kremling
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA.,Inari Agriculture, Cambridge, MA 02139, USA
| | - Edward Buckler
- Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA.,Institute for Genomic Diversity, Cornell University, Ithaca, NY 14853, USA.,United States Department of Agriculture-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY 14853, USA
| | - Emily B Josephs
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.,Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI 48824, USA
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Li B, Kremling KAG, Wu P, Bukowski R, Romay MC, Xie E, Buckler ES, Chen M. Coregulation of ribosomal RNA with hundreds of genes contributes to phenotypic variation. Genome Res 2018; 28:1555-1565. [PMID: 30166407 PMCID: PMC6169892 DOI: 10.1101/gr.229716.117] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 08/29/2018] [Indexed: 12/16/2022]
Abstract
Ribosomal repeats occupy 5% of a plant genome, yet there has been little study of their diversity in the modern age of genomics. Ribosomal copy number and expression variation present an opportunity to tap a novel source of diversity. In the present study, we estimated the ribosomal DNA (rDNA) copy number and ribosomal RNA (rRNA) expression for a population of maize inbred lines and investigated the potential role of rDNA and rRNA dosage in regulating global gene expression. Extensive variation was found in both ribosomal DNA copy number and ribosomal RNA expression among maize inbred lines. However, rRNA abundance was not consistent with the copy number of the rDNA. We have not found that the rDNA gene dosage has a regulatory role in gene expression; however, thousands of genes are identified to be coregulated with rRNA expression, including genes participating in ribosome biogenesis and other functionally relevant pathways. We further investigated the potential roles of copy number and the expression level of rDNA on agronomic traits and found that both correlated with flowering time but through different regulatory mechanisms. This comprehensive analysis suggested that rRNA expression variation is a valuable source of functional diversity that affects gene expression variation and field-based phenotypic changes.
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Affiliation(s)
- Bo Li
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China 100101
- Institute for Genomic Diversity, Cornell University, Ithaca, New York 14853, USA
| | - Karl A G Kremling
- School of Integrative Plant Sciences, Section of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Penghao Wu
- Institute for Genomic Diversity, Cornell University, Ithaca, New York 14853, USA
- College of Agronomy, Xinjiang Agriculture University, Urumqi, China 830052
| | - Robert Bukowski
- Bioinformatics Facility, Institute of Biotechnology, Cornell University, Ithaca, New York 14853, USA
| | - Maria C Romay
- Institute for Genomic Diversity, Cornell University, Ithaca, New York 14853, USA
| | - En Xie
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China 100101
| | - Edward S Buckler
- Institute for Genomic Diversity, Cornell University, Ithaca, New York 14853, USA
- School of Integrative Plant Sciences, Section of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853, USA
- US Department of Agriculture-Agricultural Research Service (USDA-ARS), Ithaca, New York 14853, USA
| | - Mingsheng Chen
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China 100101
- University of Chinese Academy of Sciences, Beijing, China 100049
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Kremling KAG, Chen SY, Su MH, Lepak NK, Romay MC, Swarts KL, Lu F, Lorant A, Bradbury PJ, Buckler ES. Dysregulation of expression correlates with rare-allele burden and fitness loss in maize. Nature 2018. [PMID: 29539638 DOI: 10.1038/nature25966] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Here we report a multi-tissue gene expression resource that represents the genotypic and phenotypic diversity of modern inbred maize, and includes transcriptomes in an average of 255 lines in seven tissues. We mapped expression quantitative trait loci and characterized the contribution of rare genetic variants to extremes in gene expression. Some of the new mutations that arise in the maize genome can be deleterious; although selection acts to keep deleterious variants rare, their complete removal is impeded by genetic linkage to favourable loci and by finite population size. Modern maize breeders have systematically reduced the effects of this constant mutational pressure through artificial selection and self-fertilization, which have exposed rare recessive variants in elite inbred lines. However, the ongoing effect of these rare alleles on modern inbred maize is unknown. By analysing this gene expression resource and exploiting the extreme diversity and rapid linkage disequilibrium decay of maize, we characterize the effect of rare alleles and evolutionary history on the regulation of expression. Rare alleles are associated with the dysregulation of expression, and we correlate this dysregulation to seed-weight fitness. We find enrichment of ancestral rare variants among expression quantitative trait loci mapped in modern inbred lines, which suggests that historic bottlenecks have shaped regulation. Our results suggest that one path for further genetic improvement in agricultural species lies in purging the rare deleterious variants that have been associated with crop fitness.
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Affiliation(s)
- Karl A G Kremling
- Section of Plant Breeding and Genetics, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA
| | - Shu-Yun Chen
- Institute for Genomic Diversity, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA.,Institute of Plant and Microbial Biology, Academia Sinica 128, Sec 2nd, Academia road, Taipei, 11529, Taiwan
| | - Mei-Hsiu Su
- Institute for Genomic Diversity, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA
| | - Nicholas K Lepak
- USDA-ARS, R. W. Holley Center, Cornell University, Ithaca, New York 14853, USA
| | - M Cinta Romay
- Institute for Genomic Diversity, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA
| | - Kelly L Swarts
- Section of Plant Breeding and Genetics, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA.,Research Group for Ancient Genomics and Evolution, Department of Molecular Biology, Max Planck Institute for Developmental Biology, Spemannstr. 35, 72076 Tübingen, Germany
| | - Fei Lu
- Institute for Genomic Diversity, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA.,The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Anne Lorant
- Department of Plant Sciences, University of California Davis, Davis, California 95616, USA
| | - Peter J Bradbury
- USDA-ARS, R. W. Holley Center, Cornell University, Ithaca, New York 14853, USA
| | - Edward S Buckler
- Section of Plant Breeding and Genetics, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA.,Institute for Genomic Diversity, 175 Biotechnology Building, Cornell University, Ithaca, New York 14853, USA.,USDA-ARS, R. W. Holley Center, Cornell University, Ithaca, New York 14853, USA
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DeRidder BP, Shybut ME, Dyle MC, Kremling KAG, Shapiro MB. Changes at the 3'-untranslated region stabilize Rubisco activase transcript levels during heat stress in Arabidopsis. Planta 2012; 236:463-76. [PMID: 22411508 DOI: 10.1007/s00425-012-1623-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 02/26/2012] [Indexed: 05/24/2023]
Abstract
Inhibition of photosynthesis by heat stress is accompanied by functional impairment of Rubisco's chaperone, activase (RCA), resulting in deactivation of Rubisco. Since activase is extremely sensitive to thermal denaturation, changes in expression of RCA at the transcript or protein level could provide a mechanism for acclimation of photosynthesis to prolonged heat stress. Using quantitative real-time PCR (qPCR) we show steady-state RCA transcript levels in Arabidopsis thaliana are stabilized during prolonged exposure to moderate heat (35 °C). A survey of RCA transcripts indicates heat stress did not alter the relative abundance of transcripts encoding α and β-isoforms of activase that are produced by alternative splicing of the pre-mRNA. Instead, mRNA stabilization in heat-stressed plants coincided with a significant reduction in the average length of activase 3'-untranslated regions, and was associated with enrichment of an uncharacterized activase mRNA splice variant, AtRCAβ2. Transcript-specific qPCR revealed AtRCAβ2 mRNA was more stable than AtRCAα and AtRCAβ mRNA in heat-stressed plants. Using an inducible transgenic system, we found that RCA transcripts lacking their native 3'-untranslated region were significantly more stable than their full-length counterparts in vivo. Using this system, stability of the RCA protein was examined over 24 h in vivo, in the absence of RCA transcription. At both optimal and elevated temperatures, RCA protein levels remained stable in plants lacking RCA mRNA, but increased when RCA mRNA was present, particularly in heat-stressed plants. This study reveals a possible mechanism, involving post-transcriptional regulation of an important photosynthesis regulatory gene, for acclimation of photosynthesis to heat stress.
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Affiliation(s)
- Benjamin P DeRidder
- Department of Biology, Grinnell College, 1116 8th Avenue, Grinnell, IA 50112, USA.
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