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Mwangangi IM, Büchi L, Haefele SM, Rodenburg J. Macronutrient application rescues performance of tolerant sorghum genotypes when infected by the parasitic plant striga. ANNALS OF BOTANY 2024; 134:59-70. [PMID: 38428944 PMCID: PMC11161562 DOI: 10.1093/aob/mcae031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 02/28/2024] [Indexed: 03/03/2024]
Abstract
BACKGROUND AND AIMS Infection by the hemi-parasitic plant Striga hermonthica causes severe host plant damage and seed production losses. Increased availability of essential plant nutrients reduces infection. Whether, how and to what extent it also reduces striga-induced host plant damage has not been well studied. METHODS The effects of improved macro- and micronutrient supply on host plant performance under striga-free and infected conditions were investigated in glasshouse pot assays. One striga-sensitive and two striga-tolerant genotypes were compared. Plants growing in impoverished soils were supplied with (1) 25 % of optimal macro- and micronutrient quantities, (2) 25 % macro- and 100 % micronutrients, (3) 100 % macro- and 25 % micronutrients, or (4) 100 % macro- and micronutrients. KEY RESULTS Photosynthesis rates of striga-infected plants of the sensitive genotype increased with improved nutrition (from 12.2 to 22.1 μmol m-2 s-1) but remained below striga-free levels (34.9-38.8 μmol m-2 s-1). For the tolerant genotypes, increased macronutrient supply offset striga-induced photosynthesis losses. Striga-induced relative grain losses of 100 % for the sensitive genotype were reduced to 74 % by increased macronutrients. Grain losses of 80 % in the tolerant Ochuti genotype, incurred at low nutrient supply, were reduced to 5 % by improved nutrient supply. CONCLUSIONS Increasing macronutrient supply reduces the impact of striga on host plants but can only restore losses when applied to genotypes with a tolerant background.
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Affiliation(s)
- Immaculate M Mwangangi
- Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
| | - Lucie Büchi
- Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
| | - Stephan M Haefele
- Sustainable Soils and Crops Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK
| | - Jonne Rodenburg
- Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
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Rouamba A, Shimelis H, Drabo I, Mrema E, Ojiewo CO, Mwadzingeni L, Rathore A. Genome-wide association analyses of agronomic traits and Striga hermonthica resistance in pearl millet. Sci Rep 2023; 13:17152. [PMID: 37821558 PMCID: PMC10567810 DOI: 10.1038/s41598-023-44046-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023] Open
Abstract
Pearl millet (Pennisetum glaucum [L.] R. Br.) is a nutrient-dense, relatively drought-tolerant cereal crop cultivated in dry regions worldwide. The crop is under-researched, and its grain yield is low (< 0.8 tons ha-1) and stagnant in the major production regions, including Burkina Faso. The low productivity of pearl millet is mainly attributable to a lack of improved varieties, Striga hermonthica [Sh] infestation, downy mildew infection, and recurrent heat and drought stress. Developing high-yielding and Striga-resistant pearl millet varieties that satisfy the farmers' and market needs requires the identification of yield-promoting genes linked to economic traits to facilitate marker-assisted selection and gene pyramiding. The objective of this study was to undertake genome-wide association analyses of agronomic traits and Sh resistance among 150 pearl millet genotypes to identify genetic markers for marker-assisted breeding and trait introgression. The pearl millet genotypes were phenotyped in Sh hotspot fields and screen house conditions. Twenty-nine million single nucleotide polymorphisms (SNPs) initially generated from 345 pearl millet genotypes were filtered, and 256 K SNPs were selected and used in the present study. Phenotypic data were collected on days to flowering, plant height, number of tillers, panicle length, panicle weight, thousand-grain weight, grain weight, number of emerged Striga and area under the Striga number progress curve (ASNPC). Agronomic and Sh parameters were subjected to combined analysis of variance, while genome-wide association analysis was performed on phenotypic and SNPs data. Significant differences (P < 0.001) were detected among the assessed pearl millet genotypes for Sh parameters and agronomic traits. Further, there were significant genotype by Sh interaction for the number of Sh and ASNPC. Twenty-eight SNPs were significantly associated with a low number of emerged Sh located on chromosomes 1, 2, 3, 4, 6, and 7. Four SNPs were associated with days-to-50%-flowering on chromosomes 3, 5, 6, and 7, while five were associated with panicle length on chromosomes 2, 3, and 4. Seven SNPs were linked to thousand-grain weight on chromosomes 2, 3, and 6. The putative SNP markers associated with a low number of emerged Sh and agronomic traits in the assessed genotypes are valuable genomic resources for accelerated breeding and variety deployment of pearl millet with Sh resistance and farmer- and market-preferred agronomic traits.
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Affiliation(s)
- Armel Rouamba
- African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
- Institute of Environment and Agricultural Research, 01 BP 476, Ouagadougou, Burkina Faso.
| | - Hussein Shimelis
- African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
| | - Inoussa Drabo
- Institute of Environment and Agricultural Research, 01 BP 476, Ouagadougou, Burkina Faso
| | - Emmanuel Mrema
- African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
- Tanzania Agriculture Research Institute, Tumbi Center, P.O. Box 306, Tabora, Tanzania
| | - Christopher Ochieng Ojiewo
- International Maize and Wheat Improvement Center, CIMMYT - ICRAF, House, United Nations Avenue, Gigiri, Nairobi, Kenya
| | - Learnmore Mwadzingeni
- African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
- Seed Co Limited, 1 Shamwari Road, Stapleford, P.O. Box WGT 64 Westage, Harare, Zimbabwe
| | - Abhishek Rathore
- Excellence in Breeding Platform (EiB), International Maize and Wheat Improvement Center, CIMMYT, Hyderabad, Telangana, India
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Jhu MY, Kawa D, Brady SM. The genetic basis of plants' battle against witchweeds: linking immune responses to distinct resistance mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4903-4909. [PMID: 37702012 PMCID: PMC10498022 DOI: 10.1093/jxb/erad305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
This article comments on:
Mutinda S, Mobegi FM, Hale B, Dayou O, Ateka E, Wijeratne A, Wicke S, Bellis ES, Runo S. 2023. Resolving intergenotypic Striga resistance in sorghum. Journal of Experimental Botany 74, 5294–5306.
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Affiliation(s)
- Min-Yao Jhu
- Crop Science Centre, Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Dorota Kawa
- Department of Plant Biology and Genome Center, University of California, Davis, CA, USA
- Plant Stress Resilience, Department of Biology, Utrecht University, The Netherlands
- Plant Environment Signaling, Department of Biology, Utrecht University, The Netherlands
| | - Siobhán M Brady
- Department of Plant Biology and Genome Center, University of California, Davis, CA, USA
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Dossa EN, Shimelis H, Mrema E, Shayanowako ATI, Laing M. Genetic resources and breeding of maize for Striga resistance: a review. FRONTIERS IN PLANT SCIENCE 2023; 14:1163785. [PMID: 37235028 PMCID: PMC10206272 DOI: 10.3389/fpls.2023.1163785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 04/07/2023] [Indexed: 05/28/2023]
Abstract
The potential yield of maize (Zea mays L.) and other major crops is curtailed by several biotic, abiotic, and socio-economic constraints. Parasitic weeds, Striga spp., are major constraints to cereal and legume crop production in sub-Saharan Africa (SSA). Yield losses reaching 100% are reported in maize under severe Striga infestation. Breeding for Striga resistance has been shown to be the most economical, feasible, and sustainable approach for resource-poor farmers and for being environmentally friendly. Knowledge of the genetic and genomic resources and components of Striga resistance is vital to guide genetic analysis and precision breeding of maize varieties with desirable product profiles under Striga infestation. This review aims to present the genetic and genomic resources, research progress, and opportunities in the genetic analysis of Striga resistance and yield components in maize for breeding. The paper outlines the vital genetic resources of maize for Striga resistance, including landraces, wild relatives, mutants, and synthetic varieties, followed by breeding technologies and genomic resources. Integrating conventional breeding, mutation breeding, and genomic-assisted breeding [i.e., marker-assisted selection, quantitative trait loci (QTL) analysis, next-generation sequencing, and genome editing] will enhance genetic gains in Striga resistance breeding programs. This review may guide new variety designs for Striga-resistance and desirable product profiles in maize.
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Affiliation(s)
- Emeline Nanou Dossa
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - Hussein Shimelis
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - Emmanuel Mrema
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
- Tanzania Agricultural Research Institute, Tumbi Center, Tabora, Tanzania
| | | | - Mark Laing
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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Khaipho-Burch M, Ferebee T, Giri A, Ramstein G, Monier B, Yi E, Romay MC, Buckler ES. Elucidating the patterns of pleiotropy and its biological relevance in maize. PLoS Genet 2023; 19:e1010664. [PMID: 36943844 PMCID: PMC10030035 DOI: 10.1371/journal.pgen.1010664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 02/09/2023] [Indexed: 03/23/2023] Open
Abstract
Pleiotropy-when a single gene controls two or more seemingly unrelated traits-has been shown to impact genes with effects on flowering time, leaf architecture, and inflorescence morphology in maize. However, the genome-wide impact of biological pleiotropy across all maize phenotypes is largely unknown. Here, we investigate the extent to which biological pleiotropy impacts phenotypes within maize using GWAS summary statistics reanalyzed from previously published metabolite, field, and expression phenotypes across the Nested Association Mapping population and Goodman Association Panel. Through phenotypic saturation of 120,597 traits, we obtain over 480 million significant quantitative trait nucleotides. We estimate that only 1.56-32.3% of intervals show some degree of pleiotropy. We then assess the relationship between pleiotropy and various biological features such as gene expression, chromatin accessibility, sequence conservation, and enrichment for gene ontology terms. We find very little relationship between pleiotropy and these variables when compared to permuted pleiotropy. We hypothesize that biological pleiotropy of common alleles is not widespread in maize and is highly impacted by nuisance terms such as population structure and linkage disequilibrium. Natural selection on large standing natural variation in maize populations may target wide and large effect variants, leaving the prevalence of detectable pleiotropy relatively low.
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Affiliation(s)
| | - Taylor Ferebee
- Department of Computational Biology, Cornell University, Ithaca, New York
| | - Anju Giri
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
| | - Guillaume Ramstein
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
- Center for Quantitative Genetics and Genomics, Aarhus University, Aarhus, Denmark
| | - Brandon Monier
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
| | - Emily Yi
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
| | - M Cinta Romay
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
| | - Edward S Buckler
- Section of Plant Breeding and Genetics, Cornell University, Ithaca, New York
- Institute for Genomic Diversity, Cornell University, Ithaca, New York
- USDA-ARS, Ithaca, New York, United States of America
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Harnessing plant resistance against Striga spp. parasitism in major cereal crops for enhanced crop production and food security in Sub-Saharan Africa: a review. Food Secur 2023. [DOI: 10.1007/s12571-023-01345-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
AbstractGiven their long-lasting seed viability, 15–20-year lifespan and their high seed production levels, a significant impact of parasitic plant Striga spp. on African food production is inevitable. Over the last decades, climate change has increasingly favoured the adaptability, spread and virulence of major Striga species, S. hermonthica and S. asiatica, across arable land in Sub-Saharan Africa (SSA). These parasitic weeds are causing important yield losses on several staple food crops and endangering food and nutritional security in many SSA countries. Losses caused by Striga spp. are amplified by low soil fertility and recurrent droughts. The impact of Striga parasitism has been characterized through different phenotypic and genotypic traits assessment of their host plants. Among all control strategies, host-plant resistance remains the most pro-poor, easy-to-adopt, sustainable and eco-friendly control strategy against Striga parasitism. This review highlights the impact of Striga parasitism on food security in SSA and reports recent results related to the genetic basis of different agronomic, pheno-physiological and biochemical traits associated with the resistance to Striga in major African cereal food crops.
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Okunlola G, Badu-Apraku B, Ariyo O, Agre P, Offernedo Q, Ayo-Vaughan M. Genome-wide association studies of Striga resistance in extra-early maturing quality protein maize inbred lines. G3 (BETHESDA, MD.) 2023; 13:jkac237. [PMID: 36073937 PMCID: PMC9911053 DOI: 10.1093/g3journal/jkac237] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 09/03/2022] [Indexed: 11/14/2022]
Abstract
Identification of genes associated with Striga resistance is invaluable for accelerating genetic gains in breeding for Striga resistance in maize. We conducted a genome-wide association study to identify genomic regions associated with grain yield and other agronomic traits under artificial Striga field infestation. One hundred and forty-one extra-early quality protein maize inbred lines were phenotyped for key agronomic traits. The inbred lines were also genotyped using 49,185 DArTseq markers from which 8,143 were retained for population structure analysis and genome wide-association study. Cluster analysis and population structure revealed the presence of 3 well-defined genetic groups. Using the mixed linear model, 22 SNP markers were identified to be significantly associated with grain yield, Striga damage at 10 weeks after planting, number of emerged Striga plants at 8 and 10 weeks after planting and ear aspect. The identified SNP markers would be useful for breeders for marker-assisted selection to accelerate the genetic enhancement of maize for Striga resistance in sub-Saharan Africa after validation.
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Affiliation(s)
- Gbemisola Okunlola
- Maize Improvement Programme, International Institute of Tropical Agriculture, IITA, Oyo Road, Ibadan 200001, Oyo ,5320, Nigeria
- Department of Plant Breeding and Seed Technology, Federal University of Agriculture, Abeokuta 110124, Ogun, 2240, Nigeria
| | - Baffour Badu-Apraku
- Maize Improvement Programme, International Institute of Tropical Agriculture, IITA, Oyo Road, Ibadan 200001, Oyo ,5320, Nigeria
| | - Omolayo Ariyo
- Department of Plant Breeding and Seed Technology, Federal University of Agriculture, Abeokuta 110124, Ogun, 2240, Nigeria
| | - Paterne Agre
- Maize Improvement Programme, International Institute of Tropical Agriculture, IITA, Oyo Road, Ibadan 200001, Oyo ,5320, Nigeria
| | - Queen Offernedo
- Maize Improvement Programme, International Institute of Tropical Agriculture, IITA, Oyo Road, Ibadan 200001, Oyo ,5320, Nigeria
| | - Moninuola Ayo-Vaughan
- Department of Plant Breeding and Seed Technology, Federal University of Agriculture, Abeokuta 110124, Ogun, 2240, Nigeria
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Badu-Apraku B, Adewale S, Paterne A, Offornedo Q, Gedil M. Mapping quantitative trait loci and predicting candidate genes for Striga resistance in maize using resistance donor line derived from Zea diploperennis. Front Genet 2023; 14:1012460. [PMID: 36713079 PMCID: PMC9877281 DOI: 10.3389/fgene.2023.1012460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/02/2023] [Indexed: 01/13/2023] Open
Abstract
The parasitic weed, Striga is a major biological constraint to cereal production in sub-Saharan Africa (SSA) and threatens food and nutrition security. Two hundred and twenty-three (223) F2:3 mapping population involving individuals derived from TZdEI 352 x TZEI 916 were phenotyped for four Striga-adaptive traits and genotyped using the Diversity Arrays Technology (DArT) to determine the genomic regions responsible for Striga resistance in maize. After removing distorted SNP markers, a genetic linkage map was constructed using 1,918 DArTseq markers which covered 2092.1 cM. Using the inclusive composite interval mapping method in IciMapping, twenty-three QTLs influencing Striga resistance traits were identified across four Striga-infested environments with five stable QTLs (qGY4, qSC2.1, qSC2.2, qSC5, and qSC6) detected in more than one environment. The variations explained by the QTLs ranged from 4.1% (qSD2.3) to 14.4% (qSC7.1). Six QTLs each with significant additive × environment interactions were also identified for grain yield and Striga damage. Gene annotation revealed candidate genes underlying the QTLs, including the gene models GRMZM2G077002 and GRMZM2G404973 which encode the GATA transcription factors, GRMZM2G178998 and GRMZM2G134073 encoding the NAC transcription factors, GRMZM2G053868 and GRMZM2G157068 which encode the nitrate transporter protein and GRMZM2G371033 encoding the SBP-transcription factor. These candidate genes play crucial roles in plant growth and developmental processes and defense functions. This study provides further insights into the genetic mechanisms of resistance to Striga parasitism in maize. The QTL detected in more than one environment would be useful for further fine-mapping and marker-assisted selection for the development of Striga resistant and high-yielding maize cultivars.
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Calderón-González Á, Pérez-Vich B, Pouilly N, Boniface MC, Louarn J, Velasco L, Muños S. Association mapping for broomrape resistance in sunflower. FRONTIERS IN PLANT SCIENCE 2023; 13:1056231. [PMID: 36714707 PMCID: PMC9875907 DOI: 10.3389/fpls.2022.1056231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 12/14/2022] [Indexed: 06/18/2023]
Abstract
INTRODUCTION Sunflower breeding for resistance to the parasitic plant sunflower broomrape (Orobanche cumana Wallr.) requires the identification of novel resistance genes. In this research, we conducted a genome-wide association study (GWAS) to identify QTLs associated with broomrape resistance. METHODS The marker-trait associations were examined across a germplasm set composed of 104 sunflower accessions. They were genotyped with a 600k AXIOM® genome-wide array and evaluated for resistance to three populations of the parasite with varying levels of virulence (races EFR, FGV, and GTK) in two environments. RESULTS AND DISCUSSION The analysis of the genetic structure of the germplasm set revealed the presence of two main groups. The application of optimized treatments based on the general linear model (GLM) and the mixed linear model (MLM) allowed the detection of 14 SNP markers significantly associated with broomrape resistance. The highest number of marker-trait associations were identified on chromosome 3, clustered in two different genomic regions of this chromosome. Other associations were identified on chromosomes 5, 10, 13, and 16. Candidate genes for the main genomic regions associated with broomrape resistance were studied and discussed. Particularly, two significant SNPs on chromosome 3 associated with races EFR and FGV were found at two tightly linked SWEET sugar transporter genes. The results of this study have confirmed the role of some QTL on resistance to sunflower broomrape and have revealed new ones that may play an important role in the development of durable resistance to this parasitic weed in sunflower.
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Affiliation(s)
- Álvaro Calderón-González
- Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (IAS-CSIC), Córdoba, Spain
| | - Begoña Pérez-Vich
- Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (IAS-CSIC), Córdoba, Spain
| | - Nicolas Pouilly
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Marie-Claude Boniface
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Johann Louarn
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
| | - Leonardo Velasco
- Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (IAS-CSIC), Córdoba, Spain
| | - Stéphane Muños
- Laboratoire des Interactions Plantes Microbes-Environnement (LIPME), Université de Toulouse, CNRS, INRAE, Castanet-Tolosan, France
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Maazou ARS, Gedil M, Adetimirin VO, Mengesha W, Meseka S, Ilesanmi O, Agre PA, Menkir A. Optimizing use of U.S. Ex-PVP inbred lines for enhancing agronomic performance of tropical Striga resistant maize inbred lines. BMC PLANT BIOLOGY 2022; 22:286. [PMID: 35681124 PMCID: PMC9185936 DOI: 10.1186/s12870-022-03662-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/23/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Temperate maize inbred lines with expired Plant Variety Protection Act certificates (Ex-PVP) are potential sources of desirable alleles for tropical germplasm improvement. Up to now, the usefulness of the Ex-PVP inbred lines as a potential source of novel beneficial alleles for Striga hermonthica resistance breeding to enhance genetic gain in tropical maize has not been reported. RESULTS This study was thus conducted to characterize the combining ability of 24 Ex-PVP inbred lines in crosses with two tropical Striga resistant inbred testers under Striga-infested and non-infested conditions and across three locations for 2 years. Many testcrosses between Ex-PVP inbred lines and the first tester (T1) produced competitive or significantly higher grain yields compared to the hybrid between the two resistant testers under Striga infested and non-infested conditions and across multiple test locations. Also, most of the testcrosses with positive heterosis for grain yield and negative heterosis for Striga damage and emerged Striga count involved T1 as a tester. Our study identified six Ex-PVP inbred lines with positive GCA effects for grain yield under Striga infested and non-infested conditions and across multiple test locations. Amongst these, inbred lines HB8229-1 and WIL900-1 also displayed negative GCA effects for emerged Striga count and Striga damage rating. The inbred line HB8229-1 showed positive SCA effects for grain yield with T2, whereas WIL900-1 had positive SCA effects for grain yield with T1. Over 70% of the Ex-PVP inbred lines were consistently assigned to specific heterotic groups using yield-based classifying methods (mean grain yield and SCA effects). CONCLUSIONS These results could facilitate systematic introgression of the Ex-PVP inbred lines into the existing Striga resistant heterotic groups in IITA. The Ex-PVP inbred lines with positive GCA effects and producing high grain yields in hybrid combinations could be useful parents for enhancing Striga resistance and agronomic performance of tropical maize hybrids.
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Affiliation(s)
- Abdoul-Raouf Sayadi Maazou
- Pan African University Life and Earth Sciences Institute (Including Health and Agriculture), University of Ibadan, Ibadan, 200284, Nigeria
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Melaku Gedil
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Victor O Adetimirin
- Department of Crop and Horticultural Sciences, University of Ibadan, Ibadan, 200284, Nigeria
| | - Wende Mengesha
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Silvestro Meseka
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Oluyinka Ilesanmi
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Paterne A Agre
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria
| | - Abebe Menkir
- International Institute of Tropical Agriculture (IITA), PMB 5320, Ibadan, 200001, Nigeria.
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