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Mukaro R, Chaingeni D, Sneller C, Cairns JE, Musundire L, Prasanna BM, Mavankeni BO, Das B, Mulanya M, Chivasa W, Mhike X, Ndhlela T, Matongera N, Matova PM, Muungani D, Mutimaamba C, Wegary D, Zaman-Allah M, Magorokosho C, Chingwara V, Kutywayo D. Genetic trends in the Zimbabwe's national maize breeding program over two decades. FRONTIERS IN PLANT SCIENCE 2024; 15:1391926. [PMID: 38988630 PMCID: PMC11234322 DOI: 10.3389/fpls.2024.1391926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 05/16/2024] [Indexed: 07/12/2024]
Abstract
Monitoring genetic gains within breeding programs is a critical component for continuous improvement. While several national breeding programs in Africa have assessed genetic gain using era studies, this study is the first to use two decades of historical data to estimate genetic trends within a national breeding program. The objective of this study was to assess genetic trends within the final two stages of Zimbabwe's Department of Research & Specialist Services maize breeding pipeline between 2002 and 2021. Data from 107 intermediate and 162 advanced variety trials, comprising of 716 and 398 entries, respectively, was analyzed. Trials were conducted under optimal, managed drought stress, low nitrogen stress, low pH, random stress, and disease pressure (maize streak virus (MSV), grey leaf spot (GLS), and turcicum leaf blight under artificial inoculation. There were positive and significant genetic gains for grain yield across management conditions (28-35 kg ha-1 yr-1), under high-yield potential environments (17-61 kg ha-1 yr-1), and under low-yield potential environments (0-16 kg ha-1 yr-1). No significant changes were observed in plant and ear height over the study period. Stalk and root lodging, as well as susceptibility to MSV and GLS, significantly decreased over the study period. New breeding technologies need to be incorporated into the program to further increase the rate of genetic gain in the maize breeding programs and to effectively meet future needs.
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Affiliation(s)
- Ronica Mukaro
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
| | - Davison Chaingeni
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
| | - Clay Sneller
- Department of Horticulture and Crop Science, The Ohio State University College of Food, Agriculture and Environmental Science, Columbus, OH, United States
| | - Jill E Cairns
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Lennin Musundire
- Accelerated Breeding Initiative (ABI)-Transform, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Boddupalli M Prasanna
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Busiso Olga Mavankeni
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
| | - Biswanath Das
- Accelerated Breeding Initiative (ABI)-Transform, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Mable Mulanya
- Integrated Breeding Platform (IBP), International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Walter Chivasa
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Xavier Mhike
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Thokozile Ndhlela
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Nakai Matongera
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Scientific and Industrial Research and Development Center (SIRDC), Harare, Zimbabwe
| | - Prince Muchapondwa Matova
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Scientific and Industrial Research and Development Center (SIRDC), Harare, Zimbabwe
| | - Dean Muungani
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Mukushi Seeds (Pvt) Ltd, Harare, Zimbabwe
| | - Charles Mutimaamba
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
- Research for Development (R4D), International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | - Dagne Wegary
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Mainassara Zaman-Allah
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Cosmos Magorokosho
- Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Harare, Zimbabwe
| | - Victor Chingwara
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
| | - Dumisani Kutywayo
- Crop Breeding Institute, Department of Research & Specialist Services, Harare, Zimbabwe
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Dieng I, Gardunia B, Covarrubias-Pazaran G, Gemenet DC, Trognitz B, Ofodile S, Fowobaje K, Ntukidem S, Shah T, Imoro S, Tripathi L, Mushoriwa H, Mbabazi R, Salvo S, Derera J. Q&A: Methods for estimating genetic gain in sub-Saharan Africa and achieving improved gains. THE PLANT GENOME 2024; 17:e20471. [PMID: 38923724 DOI: 10.1002/tpg2.20471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 06/28/2024]
Abstract
Regular measurement of realized genetic gain allows plant breeders to assess and review the effectiveness of their strategies, allocate resources efficiently, and make informed decisions throughout the breeding process. Realized genetic gain estimation requires separating genetic trends from nongenetic trends using the linear mixed model (LMM) on historical multi-environment trial data. The LMM, accounting for the year effect, experimental designs, and heterogeneous residual variances, estimates best linear unbiased estimators of genotypes and regresses them on their years of origin. An illustrative example of estimating realized genetic gain was provided by analyzing historical data on fresh cassava (Manihot esculenta Crantz) yield in West Africa (https://github.com/Biometrics-IITA/Estimating-Realized-Genetic-Gain). This approach can serve as a model applicable to other crops and regions. Modernization of breeding programs is necessary to maximize the rate of genetic gain. This can be achieved by adopting genomics to enable faster breeding, accurate selection, and improved traits through genomic selection and gene editing. Tracking operational costs, establishing robust, digitalized data management and analytics systems, and developing effective varietal selection processes based on customer insights are also crucial for success. Capacity building and collaboration of breeding programs and institutions also play a significant role in accelerating genetic gains.
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Affiliation(s)
- Ibnou Dieng
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | | | | | - Dorcus C Gemenet
- EiB-CIMMYT c/o ICRAF House United Nations Avenue, Nairobi, Kenya
| | | | - Sam Ofodile
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | - Kayode Fowobaje
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | - Solomon Ntukidem
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | - Trushar Shah
- IITA c/o International Livestock Research Institute (ILRI), Nairobi, Kenya
| | - Simon Imoro
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | - Leena Tripathi
- IITA c/o International Livestock Research Institute (ILRI), Nairobi, Kenya
| | - Hapson Mushoriwa
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
| | | | | | - John Derera
- International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria
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Tarekegne A, Wegary D, Cairns JE, Zaman-Allah M, Beyene Y, Negera D, Teklewold A, Tesfaye K, Jumbo MB, Das B, Nhamucho EJ, Simpasa K, Kaonga KKE, Mashingaidze K, Thokozile N, Mhike X, Prasanna BM. Genetic gains in early maturing maize hybrids developed by the International Maize and Wheat Improvement Center in Southern Africa during 2000-2018. FRONTIERS IN PLANT SCIENCE 2024; 14:1321308. [PMID: 38293626 PMCID: PMC10825029 DOI: 10.3389/fpls.2023.1321308] [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: 10/13/2023] [Accepted: 12/07/2023] [Indexed: 02/01/2024]
Abstract
Genetic gain estimation in a breeding program provides an opportunity to monitor breeding efficiency and genetic progress over a specific period. The present study was conducted to (i) assess the genetic gains in grain yield of the early maturing maize hybrids developed by the International Maize and Wheat Improvement Center (CIMMYT) Southern African breeding program during the period 2000-2018 and (ii) identify key agronomic traits contributing to the yield gains under various management conditions. Seventy-two early maturing hybrids developed by CIMMYT and three commercial checks were assessed under stress and non-stress conditions across 68 environments in seven eastern and southern African countries through the regional on-station trials. Genetic gain was estimated as the slope of the regression of grain yield and other traits against the year of first testing of the hybrid in the regional trial. The results showed highly significant (p< 0.01) annual grain yield gains of 118, 63, 46, and 61 kg ha-1 year-1 under optimum, low N, managed drought, and random stress conditions, respectively. The gains in grain yield realized in this study under both stress and non-stress conditions were associated with improvements in certain agronomic traits and resistance to major maize diseases. The findings of this study clearly demonstrate the significant progress made in developing productive and multiple stress-tolerant maize hybrids together with other desirable agronomic attributes in CIMMYT's hybrid breeding program.
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Affiliation(s)
- Amsal Tarekegne
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Dagne Wegary
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Jill E. Cairns
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Mainassara Zaman-Allah
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Yoseph Beyene
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Demewoz Negera
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Addis Ababa, Ethiopia
| | - Adefris Teklewold
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Addis Ababa, Ethiopia
| | - Kindie Tesfaye
- Sustianable Agrifood Systems Program, International Maize and Wheat Improvement Centre (CIMMYT), Addis Ababa, Ethiopia
| | - MacDonald B. Jumbo
- Crop Improvement Program, International Crops Research Institute for Semi-Arid Tropics, Bamako, Mali
| | - Biswanath Das
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
| | - Egas J. Nhamucho
- Instituto de Investigação Agrária de Moçambique (IIAM), Chokwe, Mozambique
| | | | | | | | - Ndhlela Thokozile
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Xavier Mhike
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Harare, Zimbabwe
| | - Boddupalli M. Prasanna
- Global Maize Program, International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya
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Messina CD, Gho C, Hammer GL, Tang T, Cooper M. Two decades of harnessing standing genetic variation for physiological traits to improve drought tolerance in maize. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4847-4861. [PMID: 37354091 PMCID: PMC10474595 DOI: 10.1093/jxb/erad231] [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] [Received: 03/06/2023] [Accepted: 06/15/2023] [Indexed: 06/26/2023]
Abstract
We review approaches to maize breeding for improved drought tolerance during flowering and grain filling in the central and western US corn belt and place our findings in the context of results from public breeding. Here we show that after two decades of dedicated breeding efforts, the rate of crop improvement under drought increased from 6.2 g m-2 year-1 to 7.5 g m-2 year-1, closing the genetic gain gap with respect to the 8.6 g m-2 year-1 observed under water-sufficient conditions. The improvement relative to the long-term genetic gain was possible by harnessing favourable alleles for physiological traits available in the reference population of genotypes. Experimentation in managed stress environments that maximized the genetic correlation with target environments was key for breeders to identify and select for these alleles. We also show that the embedding of physiological understanding within genomic selection methods via crop growth models can hasten genetic gain under drought. We estimate a prediction accuracy differential (Δr) above current prediction approaches of ~30% (Δr=0.11, r=0.38), which increases with increasing complexity of the trait environment system as estimated by Shannon information theory. We propose this framework to inform breeding strategies for drought stress across geographies and crops.
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Affiliation(s)
- Carlos D Messina
- Horticultural Sciences Department, University of Florida, Gainesville, FL, USA
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Carla Gho
- School of Agriculture & Food Sciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Graeme L Hammer
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, Brisbane, Qld 4072, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Tom Tang
- Corteva Agrisciences, Johnston, IA, USA
| | - Mark Cooper
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, Brisbane, Qld 4072, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Qld 4072, Australia
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