scholarly journals Genetic dissection of Striga hermonthica (Del.) Benth. resistance via genome-wide association and genomic prediction in tropical maize germplasm

2021 ◽  
Author(s):  
Manje Gowda ◽  
Dan Makumbi ◽  
Biswanath Das ◽  
Christine Nyaga ◽  
Titus Kosgei ◽  
...  
Keyword(s):  
Genomic Prediction ◽  
Genome Wide Association Study ◽  
Smallholder Farmers ◽  
Snp Markers ◽  
Sub Saharan Africa ◽  
Genome Wide Association ◽  
Striga Hermonthica ◽  
Tropical Maize ◽  
Genome Wide ◽  
Indicator Traits

Abstract Key message Genome-wide association revealed that resistance to Striga hermonthica is influenced by multiple genomic regions with moderate effects. It is possible to increase genetic gains from selection for Striga resistance using genomic prediction. Abstract Striga hermonthica (Del.) Benth., commonly known as the purple witchweed or giant witchweed, is a serious problem for maize-dependent smallholder farmers in sub-Saharan Africa. Breeding for Striga resistance in maize is complicated due to limited genetic variation, complexity of resistance and challenges with phenotyping. This study was conducted to (i) evaluate a set of diverse tropical maize lines for their responses to Striga under artificial infestation in three environments in Kenya; (ii) detect quantitative trait loci associated with Striga resistance through genome-wide association study (GWAS); and (iii) evaluate the effectiveness of genomic prediction (GP) of Striga-related traits. An association mapping panel of 380 inbred lines was evaluated in three environments under artificial Striga infestation in replicated trials and genotyped with 278,810 single-nucleotide polymorphism (SNP) markers. Genotypic and genotype x environment variations were significant for measured traits associated with Striga resistance. Heritability estimates were moderate (0.42) to high (0.92) for measured traits. GWAS revealed 57 SNPs significantly associated with Striga resistance indicator traits and grain yield (GY) under artificial Striga infestation with low to moderate effect. A set of 32 candidate genes physically near the significant SNPs with roles in plant defense against biotic stresses were identified. GP with different cross-validations revealed that prediction of performance of lines in new environments is better than prediction of performance of new lines for all traits. Predictions across environments revealed high accuracy for all the traits, while inclusion of GWAS-detected SNPs led to slight increase in the accuracy. The item-based collaborative filtering approach that incorporates related traits evaluated in different environments to predict GY and Striga-related traits outperformed GP for Striga resistance indicator traits. The results demonstrated the polygenic nature of resistance to S. hermonthica, and that implementation of GP in Striga resistance breeding could potentially aid in increasing genetic gain for this important trait.

scholarly journals Genome-wide association for heifer reproduction and calf performance traits in beef cattle

Genome ◽  
2015 ◽  
Vol 58 (12) ◽  
pp. 549-557 ◽  
Author(s):  
Everestus C. Akanno ◽  
Graham Plastow ◽  
Carolyn Fitzsimmons ◽  
Stephen P. Miller ◽  
Vern Baron ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Genome Wide Association Study ◽  
Average Daily Gain ◽  
Snp Markers ◽  
Genome Wide Association ◽  
Research Centre ◽  
Genome Wide ◽  
A Genome ◽  
Starting Point ◽  
And Performance

The aim of this study was to identify SNP markers that associate with variation in beef heifer reproduction and performance of their calves. A genome-wide association study was performed by means of the generalized quasi-likelihood score (GQLS) method using heifer genotypes from the BovineSNP50 BeadChip and estimated breeding values for pre-breeding body weight (PBW), pregnancy rate (PR), calving difficulty (CD), age at first calving (AFC), calf birth weight (BWT), calf weaning weight (WWT), and calf pre-weaning average daily gain (ADG). Data consisted of 785 replacement heifers from three Canadian research herds, namely Brandon Research Centre, Brandon, Manitoba, University of Alberta Roy Berg Kinsella Ranch, Kinsella, Alberta, and Lacombe Research Centre, Lacombe, Alberta. After applying a false discovery rate correction at a 5% significance level, a total of 4, 3, 3, 9, 6, 2, and 1 SNPs were significantly associated with PBW, PR, CD, AFC, BWT, WWT, and ADG, respectively. These SNPs were located on chromosomes 1, 5–7, 9, 13–16, 19–21, 24, 25, and 27–29. Chromosomes 1, 5, and 24 had SNPs with pleiotropic effects. New significant SNPs that impact functional traits were detected, many of which have not been previously reported. The results of this study support quantitative genetic studies related to the inheritance of these traits, and provides new knowledge regarding beef cattle quantitative trait loci effects. The identification of these SNPs provides a starting point to identify genes affecting heifer reproduction traits and performance of their calves (BWT, WWT, and ADG). They also contribute to a better understanding of the biology underlying these traits and will be potentially useful in marker- and genome-assisted selection and management.

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

Plant Disease ◽  
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.

scholarly journals Genome-wide association study and genomic selection for plant height, maturity, seed weight, and yield in soybean

2019 ◽  
Author(s):  
Waltram Ravelombola ◽  
Jun Qin ◽  
Ainong Shi ◽  
Fengmin Wang ◽  
Yan Feng ◽  
...  
Keyword(s):  
Association Study ◽  
Genomic Selection ◽  
Candidate Genes ◽  
Plant Height ◽  
Seed Weight ◽  
Genome Wide Association Study ◽  
Agronomic Traits ◽  
Snp Markers ◽  
Genome Wide Association ◽  
Genome Wide

Abstract Background Soybean [ Glycine max (L.) Merr.] is a legume of great interest worldwide. Enhancing genetic gain for agronomic traits via molecular approaches has been long considered as the main task for soybean breeders and geneticists. The objectives of this study were to evaluate maturity, plant height, seed weight, and yield in a diverse soybean accession panel, to conduct a genome-wide association study (GWAS) for these traits and identify SNP markers associated with the four traits, and to assess genomic selection (GS) accuracy. Results A total of 250 soybean accessions were evaluated for maturity, plant height, seed weight, and yield over three years. This panel was genotyped with a total of 10,259 high quality SNPs postulated from genotyping by sequencing (GBS). GWAS was performed using a Bayesian Information and Linkage Disequilibrium Iteratively Nested Keyway (BLINK) model, and GS was evaluated using a ridge regression best linear unbiased predictor (rrBLUP) model. The results revealed that a total of 20, 31, 37, 31, and 23 SNPs were significantly associated with the average 3-year data for maturity, plant height, seed weight, and yield, respectively; some significant SNPs were mapped into previously described loci ( E2 , E4 , and Dt1 ) affecting maturity and plant height in soybean and a new locus mapped on chromosome 20 was significantly associated with plant height; Glyma.10g228900 , Glyma.19g200800 , Glyma.09g196700 , and Glyma.09g038300 were candidate genes found in the vicinity of the top or the second best SNP for maturity, plant height, seed weight, and yield, respectively; a 11.5-Mb region of chromosome 10 was associated with both seed weight and yield; and GS accuracy was trait-, year-, and population structure-dependent. Conclusions The SNP markers identified from this study for plant height, maturity, seed weight and yield can be used to improve the four agronomic traits through marker-assisted selection (MAS) and GS in soybean breeding programs. After validation, the candidate genes can be transferred to new cultivars using SNP markers through MAS. The high GS accuracy has confirmed that the four agronomic traits can be selected in molecular breeding through GS.

Linkage mapping and genome-wide association reveal candidate genes conferring thermotolerance of seed-set in maize

2019 ◽  
Vol 70 (18) ◽  
pp. 4849-4864 ◽  
Author(s):  
Jingyang Gao ◽  
Songfeng Wang ◽  
Zijian Zhou ◽  
Shiwei Wang ◽  
Chaopei Dong ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Linkage Mapping ◽  
Genome Wide Association Study ◽  
Seed Set ◽  
Crop Yields ◽  
Expression Profiles ◽  
Snp Markers ◽  
Genome Wide Association ◽  
Genome Wide ◽  
A Genome

AbstractIt is predicted that high-temperature stress will increasingly affect crop yields worldwide as a result of climate change. In order to determine the genetic basis of thermotolerance of seed-set in maize under field conditions, we performed mapping of quantitative trait loci (QTLs) in a recombinant inbred line (RIL) population using a collection of 8329 specifically developed high-density single-nucleotide polymorphism (SNP) markers, combined with a genome-wide association study (GWAS) of 261 diverse maize lines using 259 973 SNPs. In total, four QTLs and 17 genes associated with 42 SNPs related to thermotolerance of seed-set were identified. Among them, four candidate genes were found in both linkage mapping and GWAS. Thermotolerance of seed-set was increased significantly in near-isogenic lines (NILs) that incorporated the four candidate genes in a susceptible parent background. The expression profiles of two of the four genes showed that they were induced by high temperatures in the maize tassel in a tolerant parent background. Our results indicate that thermotolerance of maize seed-set is regulated by multiple genes each of which has minor effects, with calcium signaling playing a central role. The genes identified may be exploited in breeding programs to improve seed-set and yield of maize under heat stress.

scholarly journals Genome-Wide Association Study and QTL Mapping Reveal Genomic Loci Associated with Fusarium Ear Rot Resistance in Tropical Maize Germplasm

2016 ◽  
Vol 6 (12) ◽  
pp. 3803-3815 ◽  
Author(s):  
Jiafa Chen ◽  
Rosemary Shrestha ◽  
Junqiang Ding ◽  
Hongjian Zheng ◽  
Chunhua Mu ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Association Study ◽  
Candidate Genes ◽  
Genome Wide Association Study ◽  
Physical Map ◽  
Genome Wide Association ◽  
Fusarium Ear Rot ◽  
Ear Rot ◽  
Tropical Maize ◽  
Genome Wide

Abstract Fusarium ear rot (FER) incited by Fusarium verticillioides is a major disease of maize that reduces grain quality globally. Host resistance is the most suitable strategy for managing the disease. We report the results of genome-wide association study (GWAS) to detect alleles associated with increased resistance to FER in a set of 818 tropical maize inbred lines evaluated in three environments. Association tests performed using 43,424 single-nucleotide polymorphic (SNPs) markers identified 45 SNPs and 15 haplotypes that were significantly associated with FER resistance. Each associated SNP locus had relatively small additive effects on disease resistance and accounted for 1–4% of trait variation. These SNPs and haplotypes were located within or adjacent to 38 candidate genes, 21 of which were candidate genes associated with plant tolerance to stresses, including disease resistance. Linkage mapping in four biparental populations to validate GWAS results identified 15 quantitative trait loci (QTL) associated with F. verticillioides resistance. Integration of GWAS and QTL to the maize physical map showed eight colocated loci on chromosomes 2, 3, 4, 5, 9, and 10. QTL on chromosomes 2 and 9 are new. These results reveal that FER resistance is a complex trait that is conditioned by multiple genes with minor effects. The value of selection on identified markers for improving FER resistance is limited; rather, selection to combine small effect resistance alleles combined with genomic selection for polygenic background for both the target and general adaptation traits might be fruitful for increasing FER resistance in maize.

Genome-wide association study and genomic prediction for resistance against Streptococcus agalactiae in hybrid red tilapia (Oreochromis spp.)

Aquaculture ◽  
2020 ◽  
Vol 525 ◽  
pp. 735297 ◽  
Author(s):  
Sila Sukhavachana ◽  
Pumipat Tongyoo ◽  
Cecile Massault ◽  
Nichanun McMillan ◽  
Amorn Leungnaruemitchai ◽  
...  
Keyword(s):  
Association Study ◽  
Streptococcus Agalactiae ◽  
Genomic Prediction ◽  
Genome Wide Association Study ◽  
Genome Wide Association ◽  
Red Tilapia ◽  
Genome Wide

scholarly journals European landrace diversity for common bean biofortification: a genome-wide association study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Leonardo Caproni ◽  
Lorenzo Raggi ◽  
Elise F. Talsma ◽  
Peter Wenzl ◽  
Valeria Negri
Keyword(s):  
Common Bean ◽  
Genome Wide Association Study ◽  
Preliminary Evidence ◽  
Snp Markers ◽  
Genome Wide Association ◽  
Future Research ◽  
Balanced Diet ◽  
Genome Wide ◽  
Seed Content ◽  
A Genome

AbstractMineral deficiencies represent a global challenge that needs to be urgently addressed. An adequate intake of iron and zinc results in a balanced diet that reduces chances of impairment of many metabolic processes that can lead to clinical consequences. In plants, bioavailability of such nutrients is reduced by presence of compounds such as phytic acid, that can chelate minerals and reduce their absorption. Biofortification of common bean (Phaseolus vulgaris L.) represents an important strategy to reduce mineral deficiencies, especially in areas of the world where this crop plays a key role in the diet. In this study, a panel of diversity encompassing 192 homozygous genotypes, was screened for iron, zinc and phytate seed content. Results indicate a broad variation of these traits and allowed the identification of accessions reasonably carrying favourable trait combinations. A significant association between zinc seed content and some molecular SNP markers co-located on the common bean Pv01 chromosome was detected by means of genome-wide association analysis. The gene Phvul001G233500, encoding for an E3 ubiquitin-protein ligase, is proposed to explain detected associations. This result represents a preliminary evidence that can foster future research aiming at understanding the genetic mechanisms behind zinc accumulation in beans.

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