scholarly journals Eleven biosynthetic genes explain the majority of natural variation for carotenoid levels in maize grain

2020 ◽  
Author(s):  
Christine H. Diepenbrock ◽  
Daniel C. Ilut ◽  
Maria Magallanes-Lundback ◽  
Catherine B. Kandianis ◽  
Alexander E. Lipka ◽  
...  
Keyword(s):  
Natural Variation ◽  
Genome Wide Association Study ◽  
Vitamin A Deficiency ◽  
Sub Saharan Africa ◽  
Phenotypic Variance ◽  
Multiple Traits ◽  
Molecular Control ◽  
Allelic Effect ◽  
Mapping Panel ◽  
Maize Grain

ABSTRACTVitamin A deficiency remains prevalent in parts of Asia, Latin America and sub-Saharan Africa where maize is a food staple. Extensive natural variation exists for carotenoids in maize grain; to understand its genetic basis, we conducted a joint linkage and genome-wide association study in the U.S. maize nested association mapping panel. Eleven of the 44 detected quantitative trait loci (QTL) were resolved to individual genes. Six of these were expression QTL (eQTL), showing strong correlations between RNA-seq expression abundances and QTL allelic effect estimates across six stages of grain development. These six eQTL also had the largest percent phenotypic variance explained, and in major part comprised the three to five loci capturing the bulk of genetic variation for each trait. Most of these eQTL had highly correlated QTL allelic effect estimates across multiple traits, suggesting that pleiotropy within this pathway is largely regulated at the expression level. Significant pairwise epistatic interactions were also detected. These findings provide the most comprehensive genome-level understanding of the genetic and molecular control of carotenoids in any plant system, and a roadmap to accelerate breeding for provitamin A and other priority carotenoid traits in maize grain that should be readily extensible to other cereals.

scholarly journals Genetic Basis of Maize Resistance to Multiple-Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization

2020 ◽  
Author(s):  
Arfang BADJI ◽  
Daniel Bomet KWEMOI ◽  
Lewis MACHIDA ◽  
Dennis OKII ◽  
Natasha MWILA ◽  
...  
Keyword(s):  
Insect Resistance ◽  
Defense Mechanisms ◽  
Genome Wide Association Study ◽  
Insect Pests ◽  
Physical Map ◽  
Nucleotide Polymorphisms ◽  
Multiple Traits ◽  
Significance Level ◽  
Mapping Panel ◽  
Genome Wide

Several herbivores feed on maize in field and storage setups making the development of multiple-insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to FAW whilst bulked grains were subjected to MW bioassay, genotyped with Diversity Array Technologies single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance level of 0.05 and 0.01, respectively, and located within or close to multiple-insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple-traits of which six were associated with resistance to both FAW and MW suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10-30kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of five of the six combined-resistance QTNs, thus, reinforcing the pleiotropy hypothesis. In addition, through In-silico co-functional network inferences, an additional 107 Network-based CGs (NbCGs), biologically connected to the 64 GbCGs, differentially expressed under biotic or abiotic stress were revealed within MIRGRs. The provided multiple-insect resistance physical map should contribute to the development of combined-insect resistance in maize.

scholarly journals Simultaneous Dissection of Grain Carotenoid Levels and Kernel Color in Biparental Maize Populations with Yellow-to-Orange Grain

2022 ◽  
Author(s):  
Mary-Francis LaPorte ◽  
Mishi Vachev ◽  
Matthew Fenn ◽  
Christine Diepenbrock
Keyword(s):  
Genome Wide Association Study ◽  
Vitamin A Deficiency ◽  
Provitamin A ◽  
Human Populations ◽  
Carotenoid Cleavage Dioxygenase ◽  
Total Carotenoids ◽  
Nested Association Mapping ◽  
Kernel Color ◽  
Mapping Panel ◽  
A Genome

ABSTRACT Maize enriched in provitamin A carotenoids could be key in combatting vitamin A deficiency in human populations relying on maize as a food staple. Consumer studies indicate that orange maize may be regarded as novel and preferred. This study identifies genes of relevance for grain carotenoid concentrations and kernel color, through simultaneous dissection of these traits in 10 families of the U.S. maize nested association mapping panel that have yellow to orange grain. Quantitative trait loci (QTL) were identified via joint-linkage analysis, with phenotypic variation explained for individual kernel color QTL ranging from 2.4 to 17.5%. These QTL were cross-analyzed with significant marker-trait associations in a genome-wide association study that utilized ∼27 million variants. Nine genes were identified: four encoding activities upstream of the core carotenoid pathway, one at the pathway branchpoint, three within the α- or β-pathway branches, and one encoding a carotenoid cleavage dioxygenase. Of these, three exhibited significant pleiotropy between kernel color and one or more carotenoid traits. Kernel color exhibited moderate positive correlations with β-branch and total carotenoids and negligible correlations with α-branch carotenoids. These findings can be leveraged to simultaneously achieve desirable kernel color phenotypes and increase concentrations of provitamin A and other priority carotenoids.

scholarly journals Genome-Wide Association Study of Natural Variation in Arabidopsis Exposed to Acid Mine Drainage Toxicity and Validation of Associated Genes with Reverse Genetics

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 191
Author(s):  
Bandana Ghimire ◽  
Thangasamy Saminathan ◽  
Abiodun Bodunrin ◽  
Venkata Lakshmi Abburi ◽  
Arjun Ojha Kshetry ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Association Study ◽  
Root Length ◽  
Natural Variation ◽  
Genome Wide Association Study ◽  
Mine Drainage ◽  
The United States ◽  
Genome Wide Association ◽  
Acid Mine ◽  
Genome Wide

Acid mine drainage (AMD) is a huge environmental problem in mountain-top mining regions worldwide, including the Appalachian Mountains in the United States. This study applied a genome-wide association study (GWAS) to uncover genomic loci in Arabidopsis associated with tolerance to AMD toxicity. We characterized five major root phenotypes—cumulative root length, average root diameter, root surface area, root volume, and primary root length—in 180 Arabidopsis accessions in response to AMD-supplemented growth medium. GWAS of natural variation in the panel revealed genes associated with tolerance to an acidic environment. Most of these genes were transcription factors, anion/cation transporters, metal transporters, and unknown proteins. Two T-DNA insertion mutants, At1g63005 (miR399b) and At2g05635 (DEAD helicase RAD3), showed enhanced acidity tolerance. Our GWAS and the reverse genetic approach revealed genes involved in conferring tolerance to coal AMD. Our results indicated that proton resistance in hydroponic conditions could be an important index to improve plant growth in acidic soil, at least in acid-sensitive plant species.

scholarly journals Methylome-wide analysis reveals epigenetic marks associated with resistance to tuberculosis in HIV-infected individuals from East Africa

2020 ◽  
Author(s):  
Catherine Stein ◽  
Penelope Bencheck ◽  
Jacquelaine Bartlett ◽  
Robert P Igo ◽  
Rafal S Sobota ◽  
...  
Keyword(s):  
Genome Wide Association Study ◽  
Sub Saharan Africa ◽  
Chromosome 1 ◽  
Chromosome 2 ◽  
Chromosome 5 ◽  
Epigenetic Marks ◽  
Genome Wide ◽  
A Genome ◽  
Immunodeficiency Virus ◽  
Sub Saharan

Background: Tuberculosis (TB) is the most deadly infectious disease globally and highly prevalent in the developing world, especially sub-Saharan Africa. Even though a third of humans are exposed to Myocbacterium tuberculosis (Mtb), most infected immunocompetent individuals do not develop active TB. In contrast, for individuals infected with both TB and the human immunodeficiency virus (HIV), the risk of active disease is 10% or more per year. Previously, we identified in a genome-wide association study a region on chromosome 5 that was associated with resistance to TB. This region included epigenetic marks that could influence gene regulation so we hypothesized that HIV-infected individuals exposed to Mtb, who remain disease free, carry epigenetic changes that strongly protect them from active TB. To test this hypothesis, we conducted a methylome-wide study in HIV-infected, TB-exposed cohorts from Uganda and Tanzania. Results: In 221 HIV-infected adults from Uganda and Tanzania, we identified 3 regions of interest that included markers that were differentially methylated between TB cases and LTBI controls, that also included methylation QTLs and associated SNPs: chromosome 1 (RNF220, p=4x10-5), chromosome 2 (between COPS8 and COL6A3 genes, p=2.7x10-5), and chromosome 5 (CEP72, p=1.3x10-5). These methylation results colocalized with associated SNPs, methylation QTLs, and methylation x SNP interaction effects. These markers were in regions with regulatory markers for cells involved in TB immunity and/or lung. Conclusion: Epigenetic regulation is a potential biologic factor underlying resistance to TB in immunocompromised individuals that can act in conjunction with genetic variants.

scholarly journals Natural variations in the P-type ATPase heavy metal transporter ZmCd1 controlling cadmium accumulation in maize grains

2021 ◽  
Author(s):  
Bin Tang ◽  
Meijie Luo ◽  
Yunxia Zhang ◽  
Huanle Guo ◽  
Jingna Li ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Molecular Markers ◽  
Genome Wide Association Study ◽  
Inbred Lines ◽  
Cd Accumulation ◽  
A Genome ◽  
Maize Varieties ◽  
Natural Variations ◽  
Maize Grain ◽  
P Type

SummaryCadmium (Cd) accumulation in maize grains is detrimental to human health. Developing maize varieties with low-Cd contents via marker-assisted selection is important for ensuring the production of maize grains safe for consumption. However, the key gene controlling maize grain Cd accumulation has not been cloned. In this study, we identified two major loci for maize grain Cd accumulation (qCd1 and qCd2) on chromosome 2 during a genome-wide association study (GWAS). The qCd1 locus was analyzed by bulked segregant RNA-seq and fine mapping with a biparental segregating population of Jing724 (low-Cd line) and Mo17 (high-Cd line). The ZmCd1 candidate gene in the qCd1 locus encodes a vacuolar membrane-localized heavy metal P-type ATPase transporter, ZmHMA3, which is orthologous to the tonoplast Cd transporter OsHMA3. Genomic DNA sequence and transcript analyses suggested that a transposon in intron 1 of ZmCd1 is responsible for the abnormal amino acid sequence in Mo17. An EMS mutant analysis and an allelism test confirmed ZmCd1 influences maize grain Cd accumulation. The natural variations in ZmCd1 were used to develop four PCR-based molecular markers, which revealed five ZmCd1 haplotypes in the GWAS population. The molecular markers were also used to predict the grain Cd contents in commonly cultivated maize germplasms in China. The predicted Cd contents for 36 inbred lines and 13 hybrids were consistent with the measured Cd contents. Furthermore, several low-Cd elite inbred lines and hybrids were identified, including Jing2416, MC01, Jingnonke728, and Jingke968. Therefore, the molecular markers developed in this study are applicable for molecular breeding and developing maize varieties with low grain Cd contents.

scholarly journals Genome-wide association study for yield and yield related traits under reproductive stage drought in a diverse indica-aus rice panel

2020 ◽  
Author(s):  
Aditi Bhandari ◽  
Nitika Sandhu ◽  
Jérôme Bartholome ◽  
Tuong-Vi Cao-Hamadoun ◽  
Nourollah Ahmadi ◽  
...  
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Genome Wide Association Study ◽  
Reproductive Stage ◽  
Phenotypic Variance ◽  
Rice Varieties ◽  
Drought Tolerant ◽  
Genome Wide ◽  
Close Proximity ◽  
Genomic Regions

Abstract Background Reproductive-stage drought stress is a major impediment to rice production globally. Conventional and marker-assisted breeding strategies for developing drought tolerant rice varieties are being optimized by mining and exploiting adaptive traits, genetic diversity; identifying the alleles and understanding their interactions with genetic backgrounds for contributing to drought tolerance. Field experiments were conducted in this study to identify marker-trait associations (MTAs) involved in response to yield under reproductive-stage drought. A diverse set of 280 indica-aus accessions was phenotyped for grain yield and nine yield-related traits under normal condition and under two managed drought environments. The accessions were genotyped with 215,250 single nucleotide polymorphism markers. Results The study identified a total of 220 significant MTAs and candidate gene analysis within 200kb window centred from GWAS identified SNP peaks detected these MTAs within/ in close proximity to 47 genes, 4 earlier reported major grain yield QTLs and 8 novel QTLs for 10 traits. The significant MTAs were majorly located on chromosomes 1, 2, 5, 6, 11 and 12 and the percent phenotypic variance captured for these traits ranged from 5 to 88%. The significant positive correlation of grain yield with yield-related traits, except flowering time, observed under different environments point towards their contribution in improving rice yield under drought. Seven promising accessions were identified for use in future genomics-assisted breeding program targeting grain yield improvement under drought. Conclusion These results provide a promising insight into the complex-genetic architecture of grain yield under reproductive-stage drought under different environments. Validation of major genomic regions reported in the study can be effectively used to develop drought tolerant varieties following marker-assisted selection as well as to identify genes and understanding the associated physiological mechanisms.

scholarly journals Identification and fine-mapping of a major QTL (qRtsc8-1) conferring resistance to maize tar spot complex and production markers validation in breeding lines

2021 ◽  
Author(s):  
Jiaojiao Ren ◽  
Penghao Wu ◽  
Gordon M. Huestis ◽  
Ao Zhang ◽  
Jingtao Qu ◽  
...  
Keyword(s):  
Latin American ◽  
Fine Mapping ◽  
Genome Wide Association Study ◽  
Selective Genotyping ◽  
Doubled Haploid Population ◽  
Phenotypic Variance ◽  
Breeding Lines ◽  
A Genome ◽  
Tar Spot ◽  
Major Qtl

Abstract Tar spot complex (TSC) is a major foliar disease of maize in many Central and Latin American countries and leads to severe yield loss. To dissect the genetic architecture of TSC resistance, a genome-wide association study (GWAS) panel and a bi-parental doubled haploid population were used for GWAS and selective genotyping analysis, respectively. A total of 115 SNPs in bin 8.03 were detected by GWAS and three QTL in bins 6.05, 6.07, and 8.03 were detected by selective genotyping. The major QTL qRtsc8-1 located in bin 8.03 was detected by both analyses, it explained 14.97% of the phenotypic variance. To fine-map qRtsc8-1, the recombinant-derived progeny test was implemented. Recombinations in each generation were backcrossed, and the backcross progenies were genotyped with Kompetitive Allele Specific PCR (KASP) markers and phenotyped for TSC resistance individually. The significant tests for comparing the TSC resistance between the two classes of progenies with and without resistant alleles were used for fine-mapping. In BC5 generation, qRtsc8-1 was fine mapped in an interval of ~721 kb flanked by markers of KASP81160138 and KASP81881276. In this interval, the candidate genes GRMZM2G063511 and GRMZM2G073884 were identified, which encode an integral membrane protein-like and a leucine-rich repeat receptor-like protein kinase, respectively. Both genes are involved in maize disease resistance responses. Two production markers KASP81160138 and KASP81160155 were verified in 471 breeding lines. This study provides valuable information for cloning the resistance gene, it will also facilitate the routine implementation of marker-assisted selection in the breeding pipeline for improving TSC resistance.

scholarly journals Dissection of the genetic basis of oil content in Chinese peanut cultivars through association mapping

2020 ◽  
Author(s):  
Nian Liu ◽  
Li Huang ◽  
Weigang Chen ◽  
Bei Wu ◽  
Manish K. Pandey ◽  
...  
Keyword(s):  
Association Mapping ◽  
Ssr Markers ◽  
Oil Content ◽  
Genetic Basis ◽  
Principal Component ◽  
Primary Sources ◽  
Phenotypic Variance ◽  
Mapping Panel ◽  
Stable Association ◽  
Faster Development

Abstract Background: Peanut is one of the primary sources for vegetable oil worldwide, and enhancing oil content is the main objective in several peanut breeding programs of the world. Tightly linked markers are required for faster development of high oil content peanut varieties through genomics-assisted breeding (GAB), and association mapping is one of the promising approaches for discovery of such associated markers. Results: An association mapping panel consisting of 292 peanut varieties extensively distributed in China was phenotyped for oil content and genotyped with 583 polymorphic SSR markers. These markers amplified 3663 alleles with an average of 6.28 alleles per locus. The structure, phylogenetic relationship, and principal component analysis (PCA) indicated two subgroups majorly differentiating based on geographic regions. Genome-wide association analysis identified 12 associated markers including one (AGGS1014_2) highly stable association controlling up to 9.94% phenotypic variance explained (PVE) across multiple environments. Interestingly, the frequency of the favorable alleles for 12 associated markers showed a geographic difference. Two associated markers (AGGS1014_2 and AHGS0798) with 6.90-9.94% PVE were verified to enhance oil content in an independent RIL population and also indicated selection during the breeding program. Conclusion: This study provided insights into the genetic basis of oil content in peanut and verified highly associated two SSR markers to facilitate marker-assisted selection for developing high-oil content breeding peanut varieties.

scholarly journals Simultaneous Dissection of Grain Carotenoid Levels and Kernel Color in Biparental Maize Populations with Yellow-to-Orange Grain

2021 ◽  
Author(s):  
Mary-Francis LaPorte ◽  
Mishi Vachev ◽  
Matthew Fenn ◽  
Christine Diepenbrock
Keyword(s):  
Genome Wide Association Study ◽  
Vitamin A Deficiency ◽  
Provitamin A ◽  
Human Populations ◽  
Carotenoid Cleavage Dioxygenase ◽  
Total Carotenoids ◽  
Nested Association Mapping ◽  
Kernel Color ◽  
A Genome ◽  
Variation Explained

ABSTRACTMaize enriched in provitamin A carotenoids could be key in combatting vitamin A deficiency in human populations relying on maize as a food staple. Consumer studies indicate that orange maize may be regarded as novel and preferred. This study identifies genes of relevance for grain carotenoid concentrations and kernel color, through simultaneous dissection of these traits in 10 families of the U.S. maize nested association mapping population that have yellow to orange grain. Quantitative trait loci (QTL) were identified via joint-linkage analysis, with phenotypic variation explained for individual kernel color QTL ranging from 2.4 to 17.5%. These QTL were cross-analyzed with significant marker-trait associations in a genome-wide association study that utilized ∼27 million variants. Nine genes were identified: four encoding activities upstream of the core carotenoid pathway, one at the pathway branchpoint, three within the α- or β-pathway branches, and one encoding a carotenoid cleavage dioxygenase. Of these, three exhibited significant pleiotropy between kernel color and one or more carotenoid traits. Kernel color exhibited moderate positive correlations with β-branch and total carotenoids and negligible correlations with α-branch carotenoids. These findings can be leveraged to simultaneously achieve desirable kernel color phenotypes and increase concentrations of provitamin A and other priority carotenoids.

scholarly journals Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 689
Author(s):  
A. Badji ◽  
D. B. Kwemoi ◽  
L. Machida ◽  
D. Okii ◽  
N. Mwila ◽  
...  
Keyword(s):  
Insect Resistance ◽  
Defense Mechanisms ◽  
Genome Wide Association Study ◽  
Insect Pests ◽  
Physical Map ◽  
Fall Armyworm ◽  
Nucleotide Polymorphisms ◽  
Multiple Traits ◽  
Maize Weevil ◽  
Genome Wide

Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology’s single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAW and MW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and differentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.

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