scholarly journals An Integrated Approach of QTL Mapping and Genome-Wide Association Analysis Identifies Candidate Genes for Phytophthora Blight Resistance in Sesame (Sesamum indicum L.)

2021 ◽  
Vol 12 ◽  
Author(s):  
Sovetgul Asekova ◽  
Eunyoung Oh ◽  
Krishnanand P. Kulkarni ◽  
Muhammad Irfan Siddique ◽  
Myoung Hee Lee ◽  
...  
Keyword(s):  
Qtl Mapping ◽  
Candidate Gene ◽  
Candidate Genes ◽  
Sesamum Indicum ◽  
Genome Wide Association ◽  
Phytophthora Blight ◽  
Chromosome 10 ◽  
Resistant Parent ◽  
Exon 2 ◽  
Genome Wide

Phytophthora blight (PB) caused by Phytophthora nicotianae is a highly destructive disease in sesame (Sesamum indicum L.). In this study, we used linkage mapping and genome-wide association study (GWAS) to identify quantitative trait loci (QTL) and candidate genes associated with PB resistance. The QTL mapping in 90 RILs of the Goenbaek × Osan cross using genotyping-by-sequencing detected significant QTLs for PB resistance on chromosome 10, explaining 12.79%–13.34% of phenotypic variation. Association of this locus to PB resistance was also revealed through bulked segregant analysis in second RIL population (Goenbaek × Milsung cross) comprising 188 RILs. The GWAS of 87 sesame accessions evaluated against three P. nicotianae isolates identified 29 SNPs on chromosome 10 significantly associated with PB resistance. These SNPs were located within a 0.79 Mb region, which co-located with the QTL intervals identified in RIL populations, and hence scanned for identifying candidate genes. This region contained several defense-related candidate R genes, five of which were selected for quantitative expression analysis. One of these genes, SIN_1019016 was found to show significantly higher expression in the resistant parent compared to that in the susceptible parents and selected RILs. Paired-end sequencing of the gene SIN_1019016 in parental cultivars revealed two synonymous SNPs between Goenbaek and Osan in exon 2 of coding DNA sequence. These results suggested SIN_1019016 as one of the candidate gene conferring PB resistance in sesame. The findings from this study will be useful in the marker-assisted selection as well as the functional analysis of PB resistance candidate gene(s) in sesame.

scholarly journals A Combinatorial Approach of Biparental QTL Mapping and Genome-Wide Association Analysis Identifies Candidate Genes for Phytophthora Blight Resistance in Sesame

2020 ◽  
Author(s):  
Asekova Sovetgul ◽  
Eunyoung Oh ◽  
Krishnanand P. Kulkarni ◽  
Myoung Hee Lee ◽  
Jung In Kim ◽  
...  
Keyword(s):  
Qtl Mapping ◽  
Candidate Genes ◽  
Genome Wide Association ◽  
Blight Resistance ◽  
Combinatorial Approach ◽  
Phytophthora Blight ◽  
Resistant Parent ◽  
Significant Qtls ◽  
Gwas Analysis ◽  
Genome Wide

SummaryPhytophthora blight, caused by pathogen Phytophthora nicotianae, is responsible for a huge reduction in sesame (Sesamum indicum L.) crop yields. In this study, we utilized a combinatorial approach involving biparental QTL mapping and genome-wide association (GWAS) analysis to identify genes associated with Phytophthora blight resistance in sesame. Evaluation of resistant of the parental varieties (Goenbaek, Osan and Milsung) and the RILs of both the populations in greenhouse conditions suggested the qualitative nature of the trait.. The genetic map comprised thirteen LGs covering a total map length of 887.49 cM with an average inter-marker distance of 4.69 cM. Significant QTLs explaining phenotypic variation in the range of 2.25% to 69.24% were identified on chromosomes 10 and 13 (Chr10 and Chr13). A resistance locus detected on Chr10 was found to be highly significant. The association of this locus to PBR was also identified through BSA and single marker analysis in Goenbaek × Milsung cross and through genome-wide association mapping of 87 sesame accessions. The GWAS analysis identified 44 SNP loci significantly associated with Phytophthora disease-resistant traits on Chr10. Further, the haplotype block analysis conducted in order to find whether the SNPs associated with resistance in this study showed that the SNPs are in high LD with the resistance QTL. We obtained a total of 68 candidate genes, which included a number of defense-related R genes. One of the genes, SIN_1019016 (At1g58390) showed high expression in the resistant parent. The results from this study would be highly useful in identifying genetic and molecular factors associated with Phytophthora blight resistance in sesame.

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

Rice ◽  
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.

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

2020 ◽  
Author(s):  
Leila Nayyeripasand ◽  
Ghasem Ali Garoosi ◽  
Asadollah Ahmadikhah
Keyword(s):  
Transcription Factor ◽  
Association Study ◽  
Candidate Gene ◽  
Candidate Genes ◽  
Salinity Tolerance ◽  
Genome Wide Association Study ◽  
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 SL, RL, RDW, RFW, SFW, SDW, RWC and TW in a diverse panel of rice consisted of 202 varieties 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. 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 The results for RDW and RFW were found more important than other traits, and known or novel candidate genes in this research can be used for improvement of salinity tolerance in molecular breeding programmes. 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.

scholarly journals Hypothesis-driven candidate genes for schizophrenia compared to genome-wide association results

2011 ◽  
Vol 42 (3) ◽  
pp. 607-616 ◽  
Author(s):  
A. L. Collins ◽  
Y. Kim ◽  
P. Sklar ◽  
M. C. O'Donovan ◽  
P. F. Sullivan ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Candidate Gene ◽  
Candidate Genes ◽  
Association Studies ◽  
Human Diseases ◽  
Genome Wide Association ◽  
Genome Wide Association Studies ◽  
Common Genetic Variation ◽  
Genome Wide ◽  
Candidate Gene Studies

BackgroundCandidate gene studies have been a key approach to the genetics of schizophrenia (SCZ). However, the results of these studies are confusing and no genes have been unequivocally implicated. The hypothesis-driven candidate gene literature can be appraised by comparison with the results of genome-wide association studies (GWAS).MethodWe describe the characteristics of hypothesis-driven candidate gene studies from the SZGene database, and use pathway analysis to compare hypothesis-driven candidate genes with GWAS results from the International Schizophrenia Consortium (ISC).ResultsSZGene contained 732 autosomal genes evaluated in 1374 studies. These genes had poor statistical power to detect genetic effects typical for human diseases, assessed only 3.7% of genes in the genome, and had low marker densities per gene. Most genes were assessed once or twice (76.9%), providing minimal ability to evaluate consensus across studies. The ISC studies had 89% power to detect a genetic effect typical for common human diseases and assessed 79% of known autosomal common genetic variation. Pathway analyses did not reveal enrichment of smaller ISCpvalues in hypothesis-driven candidate genes, nor did a comprehensive evaluation of meta-hypotheses driving candidate gene selection (SCZ as a disease of the synapse or neurodevelopment). The most studied hypothesis-driven candidate genes (COMT,DRD3,DRD2,HTR2A,NRG1,BDNF,DTNBP1andSLC6A4) had no notable ISC results.ConclusionsWe did not find support for the idea that the hypothesis-driven candidate genes studied in the literature are enriched for the common genetic variation involved in the etiology of SCZ. Larger samples are required to evaluate this conclusion definitively.

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