Factors Influencing Genomic Prediction Accuracies of Tropical Maize Resistance to Fall Armyworm and Weevils

Genomic selection (GS) can accelerate variety release by shortening the variety development phase when factors that influence prediction accuracies (PA) of genomic prediction (GP) models such as training set (TS) size and relationship with the breeding set (BS) are optimized beforehand. In this study, PAs for the resistance to fall armyworm (FAW) and maize weevil (MW) in a diverse tropical maize panel composed of 341 double haploid and inbred lines were estimated using 16 parametric, semi-parametric, and nonparametric algorithms with a 10-fold and 5 repetitions cross-validation strategy. For MW resistance, 126 lines that had both genotypic and phenotypic data were used as a TS (37% of the panel) and the remaining lines, with only genotypic data, as a BS. Regarding FAW damage resistance, two TS determination strategies, namely: random-based TS (RBTS) with increasing sizes (37, 63, 75, and 85%) and pedigree-based TS (PBTS) were used. For both MW and FAW resistance datasets with an RBTS of 37%, PAs achieved with phenotypic best linear unbiased predictors were at least as twice as higher than those realized with best linear unbiased estimators. The PAs achieved with BLUPs for MW resistance traits varied from 0.66 to 0.82. The PAs with BLUPs for FAW resistance datasets ranged from 0.694 to 0.714 for RBTS of 37%, and 0.843 to 0.844 for RBTS of 85%. The PAs with BLUPs for FAW resistance with PBTS were generally high varying from 0.83 to 0.86, except for the third dataset which had the largest TS (86.22% of the panel) with PAs ranging from 0.11 to 0.75. GP models showed generally similar predictive abilities for each trait while the TS designation was determinant. There was a highly positive correlation (R=0.92***) between TS size and PAs for the RBTS approach while, for the PBTS, these parameters were highly negatively correlated (R=-0.44***), indicating the importance of the relationship between the TS and the BS with the smallest TS (31%) achieving the highest PAs (0.86). This study paves the way towards the use of GS for maize resistance to insect pests in sub-Saharan Africa.

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Genomic Prediction of Tropical Maize Resistance to Fall Armyworm and Weevils: Genomic Selection Should Focus on Effective Training Set Determination

10.20944/preprints202007.0336.v1 ◽

2020 ◽

Author(s):

Arfang Badji ◽

Lewis Machida ◽

Daniel Bomet Kwemoi ◽

Frank Kumi ◽

Dennis Okii ◽

...

Keyword(s):

Genomic Selection ◽

Genomic Prediction ◽

Insect Pests ◽

Fall Armyworm ◽

Sub Saharan Africa ◽

Tropical Maize ◽

Training Set ◽

Maize Weevil ◽

Maize Resistance ◽

Sub Saharan

Genomic selection (GS) can accelerate variety release by shortening variety development phase when factors that influence prediction accuracies (PA) of genomic prediction (GP) models such as training set (TS) size and relationship with the breeding set (BS) are optimized beforehand. In this study, PAs for the resistance to fall armyworm (FAW) and maize weevil (MW) in a diverse tropical maize panel composed of 341 double haploid and inbred lines were estimated. Both phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) were predicted using 17 parametric, semi-parametric, and nonparametric algorithms with a 10-fold and 5 repetitions cross-validation strategy. n. For both MW and FAW resistance datasets with an RBTS of 37%, PAs achieved with BLUPs were at least as twice as higher than those realized with BLUEs. The PAs achieved with BLUPs for MW resistance traits: grain weight loss (GWL), adult progeny emergence (AP), and number of affected kernels (AK) varied from 0.66 to 0.82. The PAs were also high for FAW resistance RBTS datasets, varying from 0.694 to 0.714 (for RBTS of 37%) to 0.843 to 0.844 (for RBTS of 85%). The PAs for FAW resistance with PBTS were generally high varying from 0.83 to 0.86, except for one dataset that had PAs ranging from 0.11 to 0.75. GP models showed generally similar predictive abilities for each trait while the TS designation was determinant. There was a highly positive correlation (R=0.92***) between TS size and PAs for the RBTS approach while, for the PBTS, these parameters were highly negatively correlated (R=-0.44***), indicating the importance of the degree of kinship between the TS and the BS with the smallest TS (31%) achieving the highest PAs (0.86). This study paves the way towards the use of GS for maize resistance to insect pests in sub-Saharan Africa.

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Factors Influencing Genomic Prediction Accuracies of Tropical Maize Resistance to Fall Armyworm and Weevils

Plants ◽

10.3390/plants10010029 ◽

2020 ◽

Vol 10 (1) ◽

pp. 29

Author(s):

Arfang Badji ◽

Lewis Machida ◽

Daniel Bomet Kwemoi ◽

Frank Kumi ◽

Dennis Okii ◽

...

Keyword(s):

Genomic Prediction ◽

Insect Pests ◽

Fall Armyworm ◽

Sub Saharan Africa ◽

Tropical Maize ◽

Maize Weevil ◽

Individual Traits ◽

Maize Resistance ◽

Sub Saharan ◽

Training Sets

Genomic selection (GS) can accelerate variety improvement when training set (TS) size and its relationship with the breeding set (BS) are optimized for prediction accuracies (PAs) of genomic prediction (GP) models. Sixteen GP algorithms were run on phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) of resistance to both fall armyworm (FAW) and maize weevil (MW) in a tropical maize panel. For MW resistance, 37% of the panel was the TS, and the BS was the remainder, whilst for FAW, random-based training sets (RBTS) and pedigree-based training sets (PBTSs) were designed. PAs achieved with BLUPs varied from 0.66 to 0.82 for MW-resistance traits, and for FAW resistance, 0.694 to 0.714 for RBTS of 37%, and 0.843 to 0.844 for RBTS of 85%, and these were at least two-fold those from BLUEs. For PBTS, FAW resistance PAs were generally higher than those for RBTS, except for one dataset. GP models generally showed similar PAs across individual traits whilst the TS designation was determinant, since a positive correlation (R = 0.92***) between TS size and PAs was observed for RBTS, and for the PBTS, it was negative (R = 0.44**). This study pioneered the use of GS for maize resistance to insect pests in sub-Saharan Africa.

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Factors Influencing Genomic Prediction Accuracies of Tropical Maize Resistance to Fall Armyworm and Weevils

10.20944/preprints202007.0336.v3 ◽

2020 ◽

Author(s):

Arfang Badji ◽

Lewis Machida ◽

Daniel Bomet Kwemoi ◽

Frank Kumi ◽

Dennis Okii ◽

...

Keyword(s):

Genomic Prediction ◽

Insect Pests ◽

Fall Armyworm ◽

Sub Saharan Africa ◽

Tropical Maize ◽

Maize Weevil ◽

Individual Traits ◽

Maize Resistance ◽

Sub Saharan ◽

Training Sets

Genomic selection (GS) can accelerate variety improvement when training set (TS) size, and its relationship with the breeding set (BS) are optimized for prediction accuracies (PA) of genomic prediction (GP) models. Sixteen GP algorithms were run on phenotypic best linear unbiased predictors (BLUPs) and estimators (BLUEs) of resistance to both fall armyworm (FAW) and maize weevil (MW) in a tropical maize panel. For MW resistance, 37% of the panel was the TS, and BS was the remainder whilst for FAW, random-based training sets (RBTS) and pedigree-based training sets (PBTS) were designed. PAs achieved with BLUPs varied from 0.66 to 0.82 for MW resistance traits, and, for FAW resistance, 0.694 to 0.714 for RBTS of 37%, and 0.843 to 0.844 for RBTS of 85%, and, these were at least two-fold those from BLUEs. For PBTS, FAW resistance PAs were generally higher than those for RBTS, except for one dataset. GP models generally showed similar PAs across individual traits whilst the TS designation was determinant since a positive correlation (R=0.92***) between TS size and PAs was observed for RBTS and, for the PBTS, it was negative (R=0.44**). This study pioneers the use of GS for maize resistance to insect pests in sub-Saharan Africa.

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

Genes ◽

10.3390/genes11060689 ◽

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

10.20944/preprints202005.0337.v2 ◽

2020 ◽

Author(s):

Arfang Badji ◽

Daniel Bomet Kwemoi ◽

Lewis Machida ◽

Dennis Okii ◽

Natasha Mwila ◽

...

Keyword(s):

Insect Resistance ◽

Genome Wide Association Study ◽

Insect Pests ◽

Physical Map ◽

Fall Armyworm ◽

Nucleotide Polymorphisms ◽

Multiple Traits ◽

Maize Weevil ◽

Significance Level ◽

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 (fall armyworm) whilst bulked grains were subjected to MW (maize weevil) 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.

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Beat the stress: breeding for climate resilience in maize for the tropical rainfed environments

Theoretical and Applied Genetics ◽

10.1007/s00122-021-03773-7 ◽

2021 ◽

Cited By ~ 2

Author(s):

Boddupalli M. Prasanna ◽

Jill E. Cairns ◽

P. H. Zaidi ◽

Yoseph Beyene ◽

Dan Makumbi ◽

...

Keyword(s):

Insect Pests ◽

Critical Role ◽

Sub Saharan Africa ◽

Tropical Maize ◽

Maize Breeding ◽

Genetic Gains ◽

Maize Cultivars ◽

Climate Resilience ◽

Maize Varieties ◽

The Tropics

Abstract Key message Intensive public sector breeding efforts and public-private partnerships have led to the increase in genetic gains, and deployment of elite climate-resilient maize cultivars for the stress-prone environments in the tropics. Abstract Maize (Zea mays L.) plays a critical role in ensuring food and nutritional security, and livelihoods of millions of resource-constrained smallholders. However, maize yields in the tropical rainfed environments are now increasingly vulnerable to various climate-induced stresses, especially drought, heat, waterlogging, salinity, cold, diseases, and insect pests, which often come in combinations to severely impact maize crops. The International Maize and Wheat Improvement Center (CIMMYT), in partnership with several public and private sector institutions, has been intensively engaged over the last four decades in breeding elite tropical maize germplasm with tolerance to key abiotic and biotic stresses, using an extensive managed stress screening network and on-farm testing system. This has led to the successful development and deployment of an array of elite stress-tolerant maize cultivars across sub-Saharan Africa, Asia, and Latin America. Further increasing genetic gains in the tropical maize breeding programs demands judicious integration of doubled haploidy, high-throughput and precise phenotyping, genomics-assisted breeding, breeding data management, and more effective decision support tools. Multi-institutional efforts, especially public–private alliances, are key to ensure that the improved maize varieties effectively reach the climate-vulnerable farming communities in the tropics, including accelerated replacement of old/obsolete varieties.

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

Theoretical and Applied Genetics ◽

10.1007/s00122-020-03744-4 ◽

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.

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The Spread of Fall Armyworm (faw) Spodotera Frugiperda

Outlooks on Pest Management ◽

10.1564/v29_oct_07 ◽

2018 ◽

Vol 29 (5) ◽

pp. 213-214 ◽

Cited By ~ 3

Author(s):

Graham Matthews

Keyword(s):

Fall Armyworm ◽

Sub Saharan Africa ◽

Sub Saharan ◽

Army Worm

The author introduces the next three articles on the invasion of Fall Army Worm into Sub-Saharan Africa and Asia describing how the pest spreads, the damage it causes and approaches to its control.

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Genomic Prediction Using Alternative Strategies of Weighted Single-Step Genomic BLUP for Yearling Weight and Carcass Traits in Hanwoo Beef Cattle

Genes ◽

10.3390/genes12020266 ◽

2021 ◽

Vol 12 (2) ◽

pp. 266

Author(s):

Hossein Mehrban ◽

Masoumeh Naserkheil ◽

Deuk Hwan Lee ◽

Chungil Cho ◽

Taejeong Choi ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Beef Cattle ◽

Genomic Prediction ◽

Quantitative Trait ◽

Carcass Traits ◽

Best Linear Unbiased Prediction ◽

Single Step ◽

Linear Unbiased Prediction ◽

Single Nucleotide ◽

Best Linear Unbiased

The weighted single-step genomic best linear unbiased prediction (GBLUP) method has been proposed to exploit information from genotyped and non-genotyped relatives, allowing the use of weights for single-nucleotide polymorphism in the construction of the genomic relationship matrix. The purpose of this study was to investigate the accuracy of genetic prediction using the following single-trait best linear unbiased prediction methods in Hanwoo beef cattle: pedigree-based (PBLUP), un-weighted (ssGBLUP), and weighted (WssGBLUP) single-step genomic methods. We also assessed the impact of alternative single and window weighting methods according to their effects on the traits of interest. The data was comprised of 15,796 phenotypic records for yearling weight (YW) and 5622 records for carcass traits (backfat thickness: BFT, carcass weight: CW, eye muscle area: EMA, and marbling score: MS). Also, the genotypic data included 6616 animals for YW and 5134 for carcass traits on the 43,950 single-nucleotide polymorphisms. The ssGBLUP showed significant improvement in genomic prediction accuracy for carcass traits (71%) and yearling weight (99%) compared to the pedigree-based method. The window weighting procedures performed better than single SNP weighting for CW (11%), EMA (11%), MS (3%), and YW (6%), whereas no gain in accuracy was observed for BFT. Besides, the improvement in accuracy between window WssGBLUP and the un-weighted method was low for BFT and MS, while for CW, EMA, and YW resulted in a gain of 22%, 15%, and 20%, respectively, which indicates the presence of relevant quantitative trait loci for these traits. These findings indicate that WssGBLUP is an appropriate method for traits with a large quantitative trait loci effect.

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Genomic prediction models trained with historical records enable populating the German ex situ genebank bio-digital resource center of barley (Hordeum sp.) with information on resistances to soilborne barley mosaic viruses

Theoretical and Applied Genetics ◽

10.1007/s00122-021-03815-0 ◽

2021 ◽

Author(s):

Maria Y. Gonzalez ◽

Yusheng Zhao ◽

Yong Jiang ◽

Nils Stein ◽

Antje Habekuss ◽

...

Keyword(s):

Genetic Resources ◽

Mosaic Virus ◽

Genomic Prediction ◽

Prediction Models ◽

Ex Situ ◽

Yellow Mosaic Virus ◽

Plant Responses ◽

Resource Center ◽

Digital Resource ◽

Best Linear Unbiased

AbstractKey messageGenomic prediction with special weight of major genes is a valuable tool to populate bio-digital resource centers.AbstractPhenotypic information of crop genetic resources is a prerequisite for an informed selection that aims to broaden the genetic base of the elite breeding pools. We investigated the potential of genomic prediction based on historical screening data of plant responses against theBarley yellow mosaic virusesfor populating the bio-digital resource center of barley. Our study includes dense marker data for 3838 accessions of winter barley, and historical screening data of 1751 accessions forBarley yellow mosaic virus(BaYMV) and of 1771 accessions forBarley mild mosaic virus(BaMMV). Linear mixed models were fitted by considering combinations for the effects of genotypes, years, and locations. The best linear unbiased estimations displayed a broad spectrum of plant responses against BaYMV and BaMMV. Prediction abilities, computed as correlations between predictions and observed phenotypes of accessions, were low for the marker-assisted selection approach amounting to 0.42. In contrast, prediction abilities of genomic best linear unbiased predictions were high, with values of 0.62 for BaYMV and 0.64 for BaMMV. Prediction abilities of genomic prediction were improved by up to ~ 5% using W-BLUP, in which more weight is given to markers with significant major effects found by association mapping. Our results outline the utility of historical screening data and W-BLUP model to predict the performance of the non-phenotyped individuals in genebank collections. The presented strategy can be considered as part of the different approaches used in genebank genomics to valorize genetic resources for their usage in disease resistance breeding and research.

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