Genome Wide Association Study of Karnal Bunt Resistance in a Wheat Germplasm Collection from Afghanistan

Karnal bunt disease of wheat, caused by the fungus Neovossia indica, is one of the most important challenges to the grain industry as it affects the grain quality and also restricts the international movement of infected grain. It is a seed-, soil- and airborne disease with limited effect of chemical control. Currently, this disease is contained through the deployment of host resistance but further improvement is limited as only a few genotypes have been found to carry partial resistance. To identify genomic regions responsible for resistance in a set of 339 wheat accessions, genome-wide association study (GWAS) was undertaken using the DArTSeq® technology, in which 18 genomic regions for Karnal bunt resistance were identified, explaining 5–20% of the phenotypic variation. The identified quantitative trait loci (QTL) on chromosome 2BL showed consistently significant effects across all four experiments, whereas another QTL on 5BL was significant in three experiments. Additional QTLs were mapped on chromosomes 1DL, 2DL, 4AL, 5AS, 6BL, 6BS, 7BS and 7DL that have not been mapped previously, and on chromosomes 4B, 5AL, 5BL and 6BS, which have been reported in previous studies. Germplasm with less than 1% Karnal bunt infection have been identified and can be used for resistance breeding. The SNP markers linked to the genomic regions conferring resistance to Karnal bunt could be used to improve Karnal bunt resistance through marker-assisted selection.

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MULTI-TRAIT MODELS FOR GENOMIC REGIONS ASSOCIATED WITH MAL DE RÍO CUARTO AND BACTERIAL DISEASE IN MAIZE

Journal of Basic and Applied Genetics ◽

10.35407/bag.2021.32.01.03 ◽

2021 ◽

Vol 32 (Issue 1) ◽

pp. 25-33

Author(s):

M. Ruiz ◽

E.A. Rossi ◽

N.C. Bonamico ◽

M.G. Balzarini

Keyword(s):

Association Study ◽

Genome Wide Association Study ◽

Mixed Linear Model ◽

Snp Markers ◽

Genome Wide Association ◽

Bacterial Disease ◽

Maize Germplasm ◽

Genome Wide ◽

A Genome ◽

Genomic Regions

Maize (Zea Mays L.) production has been greatly benefited from the improvement of inbred lines in regard to the resistance to diseases. However, the absence of resistant genotypes to bacteriosis is remarkable. The aim of the study was to identify genomic regions for resistance to Mal de Río Cuarto (MRC) and to bacterial disease (BD) in a diverse maize germplasm evaluated in the Argentinian region where MRC virus is endemic. A maize diverse population was assessed for both diseases during the 2019-2020 crop season. Incidence and severity of MRC and BD were estimated for each line and a genome wide association study (GWAS) was conducted with 78,376 SNP markers. A multi-trait mixed linear model was used for simultaneous evaluation of resistance to MRC and BD in the scored lines. The germplasm showed high genetic variability for both MRC and BD resistance. No significant genetic correlation was observed between the response to both diseases. Promising genomic regions for resistance to MRC and BD were identified and will be confirmed in further trials. Key words: maize disease; genome wide association study; SNP; multi-trait model

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MULTI-TRAIT MODELS FOR GENOMIC REGIONS ASSOCIATED WITH MAL DE RÍO CUARTO AND BACTERIAL DISEASE IN MAIZE

Journal of Basic and Applied Genetics ◽

10.35407/bag.2020.32.01.03 ◽

2021 ◽

Vol 32 (Issue 1) ◽

pp. 25-33

Author(s):

M. Ruiz ◽

E.A. Ross ◽

N.C. Bonamico ◽

M.G. Balzarini

Keyword(s):

Association Study ◽

Genome Wide Association Study ◽

Mixed Linear Model ◽

Snp Markers ◽

Genome Wide Association ◽

Bacterial Disease ◽

Maize Germplasm ◽

Genome Wide ◽

A Genome ◽

Genomic Regions

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A Genome-Wide Association Study for Resistance to the Insect Pest Leptocybe invasa in Eucalyptus grandis Reveals Genomic Regions and Positional Candidate Defense Genes

Plant and Cell Physiology ◽

10.1093/pcp/pcaa057 ◽

2020 ◽

Vol 61 (7) ◽

pp. 1285-1296

Author(s):

Lorraine Mhoswa ◽

Marja M O’Neill ◽

Makobatjatji M Mphahlele ◽

Caryn N Oates ◽

Kitt G Payn ◽

...

Keyword(s):

Association Study ◽

Genome Wide Association Study ◽

Eucalyptus Grandis ◽

Nucleotide Binding ◽

Snp Markers ◽

Genome Wide Association ◽

Genome Wide ◽

A Genome ◽

Leptocybe Invasa ◽

Genomic Regions

Abstract The galling insect, Leptocybe invasa, causes significant losses in plantations of various Eucalyptus species and hybrids, threatening its economic viability. We applied a genome-wide association study (GWAS) to identify single-nucleotide polymorphism (SNP) markers associated with resistance to L. invasa. A total of 563 insect-challenged Eucalyptus grandis trees, from 61 half-sib families, were genotyped using the EUChip60K SNP chip, and we identified 15,445 informative SNP markers in the test population. Multi-locus mixed-model (MLMM) analysis identified 35 SNP markers putatively associated with resistance to L. invasa based on four discreet classes of insect damage scores: (0) not infested, (1) infested showing evidence of oviposition but no gall development, (2) infested with galls on leaves, midribs or petioles and (3) stunting and lethal gall formation. MLMM analysis identified three associated genomic regions on chromosomes 3, 7 and 8 jointly explaining 17.6% of the total phenotypic variation. SNP analysis of a validation population of 494 E. grandis trees confirmed seven SNP markers that were also detected in the initial association analysis. Based on transcriptome profiles of resistant and susceptible genotypes from an independent experiment, we identified several putative candidate genes in associated genomic loci including Nucleotide-binding ARC- domain (NB-ARC) and toll-interleukin-1-receptor-Nucleotide binding signal- Leucine rich repeat (TIR-NBS-LRR) genes. Our results suggest that Leptocybe resistance in E. grandis may be influenced by a few large-effect loci in combination with minor effect loci segregating in our test and validation populations.

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Genome Wide Association Study of Resistance to PstS2 and Warrior Races of Stripe (Yellow) Rust in Bread Wheat Landraces

10.1101/2020.02.09.940775 ◽

2020 ◽

Author(s):

Muhammad Massub Tehseen ◽

Fatma Aykut Tonk ◽

Muzaffer Tosun ◽

Ahmed Amri ◽

Carolina P. Sansaloni ◽

...

Keyword(s):

Association Study ◽

Resistance Genes ◽

Genome Wide Association Study ◽

Snp Markers ◽

Genome Wide Association ◽

Adult Plant ◽

Mapping Panel ◽

Genome Wide ◽

Genomic Regions ◽

Trait Associations

ABSTRACTStripe rust, caused by Puccinia striiformis Westend. f. sp. tritici is a major threat to wheat production worldwide. The breakdown in resistance of certain major genes and new emerging aggressive races of stripe rusts are causing serious concerns in all main wheat growing areas of the world. To search for new sources of resistance genes and associated QTL for effective utilization in future breeding programs an association mapping panel comprising of 600 bread wheat landraces collected from eight different countries conserved at ICARDA gene bank were evaluated for seedling and adult plant resistance against PstS2 and Warrior races of stripe rust at the Regional Cereal Rust Research Center (RCRRC), Izmir, Turkey during 2016, 2018 and 2019. A set of 25,169 informative SNP markers covering the whole genome were used to examine the population structure, linkage disequilibrium and marker-trait associations in the association mapping panel. The genome-wide association study (GWAS) was carried out using a Mixed Linear Model (MLM). We identified 47 SNP markers at 19 genomic regions with significant SNP-trait associations for both seedling and adult plant stage resistance, the threshold of significance for all SNP-trait associations was determined by the false discovery rate (q) ≤ 0.05. Three genomic regions (QYr.1D_APR, QYr.3A_seedling and QYr.7D_seedling) identified in this study are far away from any previously reported Yr gene or QTL hence, tagging novel genomic regions. The In-silico analysis of the novel QTL regions identified candidate resistance genes encoding proteins putative to plants disease resistance and defense mechanism.

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Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color

Science Advances ◽

10.1126/sciadv.abd1239 ◽

2021 ◽

Vol 7 (11) ◽

pp. eabd1239

Author(s):

Mark Simcoe ◽

Ana Valdes ◽

Fan Liu ◽

Nicholas A. Furlotte ◽

David M. Evans ◽

...

Keyword(s):

Association Study ◽

Genome Wide Association Study ◽

Color Variation ◽

Genome Wide Association ◽

Nucleotide Polymorphisms ◽

Melanin Pigmentation ◽

Eye Color ◽

Human Eye ◽

Genome Wide ◽

Genomic Regions

Human eye color is highly heritable, but its genetic architecture is not yet fully understood. We report the results of the largest genome-wide association study for eye color to date, involving up to 192,986 European participants from 10 populations. We identify 124 independent associations arising from 61 discrete genomic regions, including 50 previously unidentified. We find evidence for genes involved in melanin pigmentation, but we also find associations with genes involved in iris morphology and structure. Further analyses in 1636 Asian participants from two populations suggest that iris pigmentation variation in Asians is genetically similar to Europeans, albeit with smaller effect sizes. Our findings collectively explain 53.2% (95% confidence interval, 45.4 to 61.0%) of eye color variation using common single-nucleotide polymorphisms. Overall, our study outcomes demonstrate that the genetic complexity of human eye color considerably exceeds previous knowledge and expectations, highlighting eye color as a genetically highly complex human trait.

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Large-scale integration of meta-QTL and genome-wide association study discovers the genomic regions and candidate genes for yield and yield-related traits in bread wheat

Theoretical and Applied Genetics ◽

10.1007/s00122-021-03881-4 ◽

2021 ◽

Author(s):

Yang Yang ◽

Aduragbemi Amo ◽

Di Wei ◽

Yongmao Chai ◽

Jie Zheng ◽

...

Keyword(s):

Association Study ◽

Candidate Genes ◽

Bread Wheat ◽

Large Scale ◽

Genome Wide Association Study ◽

Genome Wide Association ◽

Genome Wide ◽

Large Scale Integration ◽

Scale Integration ◽

Genomic Regions

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Genome-Wide Association Study (GWAS) to Identify Salt-Tolerance QTLs Carrying Novel Candidate Genes in Rice During Early Vegetative Stage

Rice ◽

10.1186/s12284-020-00433-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Leila Nayyeripasand ◽

Ghasem Ali Garoosi ◽

Asadollah Ahmadikhah

Keyword(s):

Association Study ◽

Candidate Gene ◽

Candidate Genes ◽

Salinity Tolerance ◽

Genome Wide Association Study ◽

Dry Weight ◽

Genome Wide Association ◽

Vegetative Stage ◽

Genome Wide ◽

Genomic Regions

Abstract Background Rice is considered as a salt-sensitive plant, particularly at early vegetative stage, and its production is suffered from salinity due to expansion of salt affected land in areas under cultivation. Hence, significant increase of rice productivity on salinized lands is really necessary. Today genome-wide association study (GWAS) is a method of choice for fine mapping of QTLs involved in plant responses to abiotic stresses including salinity stress at early vegetative stage. In this study using > 33,000 SNP markers we identified rice genomic regions associated to early stage salinity tolerance. Eight salinity-related traits including shoot length (SL), root length (RL), root dry weight (RDW), root fresh weight (RFW), shoot fresh weight (SFW), shoot dry weight (SDW), relative water content (RWC) and TW, and 4 derived traits including SL-R, RL-R, RDW-R and RFW-R in a diverse panel of rice were evaluated under salinity (100 mM NaCl) and normal conditions in growth chamber. Genome-wide association study (GWAS) was applied based on MLM(+Q + K) model. Results Under stress conditions 151 trait-marker associations were identified that were scattered on 10 chromosomes of rice that arranged in 29 genomic regions. A genomic region on chromosome 1 (11.26 Mbp) was identified which co-located with a known QTL region SalTol1 for salinity tolerance at vegetative stage. A candidate gene (Os01g0304100) was identified in this region which encodes a cation chloride cotransporter. Furthermore, on this chromosome two other candidate genes, Os01g0624700 (24.95 Mbp) and Os01g0812000 (34.51 Mbp), were identified that encode a WRKY transcription factor (WRKY 12) and a transcriptional activator of gibberellin-dependent alpha-amylase expression (GAMyb), respectively. Also, a narrow interval on the same chromosome (40.79–42.98 Mbp) carries 12 candidate genes, some of them were not so far reported for salinity tolerance at seedling stage. Two of more interesting genes are Os01g0966000 and Os01g0963000, encoding a plasma membrane (PM) H+-ATPase and a peroxidase BP1 protein. A candidate gene was identified on chromosome 2 (Os02g0730300 at 30.4 Mbp) encoding a high affinity K+ transporter (HAK). On chromosome 6 a DnaJ-encoding gene and pseudouridine synthase gene were identified. Two novel genes on chromosome 8 including the ABI/VP1 transcription factor and retinoblastoma-related protein (RBR), and 3 novel genes on chromosome 11 including a Lox, F-box and Na+/H+ antiporter, were also identified. Conclusion Known or novel candidate genes in this research were identified that can be used for improvement of salinity tolerance in molecular breeding programmes of rice. Further study and identification of effective genes on salinity tolerance by the use of candidate gene-association analysis can help to precisely uncover the mechanisms of salinity tolerance at molecular level. A time dependent relationship between salt tolerance and expression level of candidate genes could be recognized.

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Genome-wide association analysis of resistance to Pseudoperonospora cubensis in citron watermelon

Plant Disease ◽

10.1094/pdis-08-21-1611-re ◽

2021 ◽

Author(s):

Dennis Katuuramu ◽

Sandra Branham ◽

Amnon Levi ◽

Patrick Wechter

Keyword(s):

Candidate Genes ◽

Genome Wide Association Study ◽

Citrullus Lanatus ◽

Phenotypic Variability ◽

Germplasm Collection ◽

Snp Markers ◽

Genome Wide Association ◽

Pseudoperonospora Cubensis ◽

Genome Wide ◽

A Genome

Cultivated sweet watermelon (Citrullus lanatus) is an important vegetable crop for millions of people around the world. There are limited sources of resistance to economically important diseases within C. lanatus, whereas Citrullus amarus has a reservoir of traits that can be exploited to improve C. lanatus for resistance to biotic and abiotic stresses. Cucurbit downy mildew (CDM), caused by Pseudoperonospora cubensis, is an emerging threat to watermelon production. We screened 122 C. amarus accessions for resistance to CDM over two tests (environments). The accessions were genotyped by whole-genome resequencing to generate 2,126,759 single nucleotide polymorphic (SNP) markers. A genome-wide association study was deployed to uncover marker-trait associations and identify candidate genes underlying resistance to CDM. Our results indicate the presence of wide phenotypic variability (1.1 - 57.8%) for leaf area infection, representing a 50.7-fold variation for CDM resistance across the C. amarus germplasm collection. Broad-sense heritability estimate was 0.55, implying the presence of moderate genetic effects for resistance to CDM. The peak SNP markers associated with resistance to P. cubensis were located on chromosomes Ca03, Ca05, Ca07, and Ca11. The significant SNP markers accounted for up to 30% of the phenotypic variation and were associated with promising candidate genes encoding disease resistance proteins, leucine-rich repeat receptor-like protein kinase, and WRKY transcription factor. This information will be useful in understanding the genetic architecture of the P. cubensis-Citrullus spp. patho-system as well as development of resources for genomics-assisted breeding for resistance to CDM in watermelon.

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