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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Corn Host Plant Resistance Research » Research » Publications at this Location » Publication #306319
Title: Molecular breeding for developing drought tolerant and disease resistant maize in sub Saharan Africa

Author
item SEMAGN, KASSA - International Maize & Wheat Improvement Center (CIMMYT)
item BEYENE, YOSEPH - International Maize & Wheat Improvement Center (CIMMYT)
item BABU, RAMAN - International Maize & Wheat Improvement Center (CIMMYT)
item NAIR, SUDHA - International Maize & Wheat Improvement Center (CIMMYT)
item OLSEN, MICHAEL - International Maize & Wheat Improvement Center (CIMMYT)
item MAGOROKOSHO, COSMOS - International Maize & Wheat Improvement Center (CIMMYT)
item MAKUMBI, DAN - International Maize & Wheat Improvement Center (CIMMYT)
item TAREKEGNE, AMSAL - International Maize & Wheat Improvement Center (CIMMYT)
item MUGO, STEPHEN - International Maize & Wheat Improvement Center (CIMMYT)
item Warburton, Marilyn
item PRASANNA, B. - International Maize & Wheat Improvement Center (CIMMYT)

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2014
Publication Date: 2/20/2015
Citation: Semagn, K., Beyene, Y., Babu, R., Nair, S., Gowda, M., Das, B., Tarekegne, A.Olsen, M., Mugo,S., Mahuku, G.,Worku, M., Warburton, M.L., Olsen, M., Prasanna, B.M. 2015. Quantitative trait loci mapping and molecular breeding for developing stress resilient maize for sub-Saharan Africa. Crop Science. 55:1449-1459. doi:10.2135/cropsci2014.09.0646.

Interpretive Summary: The International Maize and Wheat Improvement Center (CIMMYT), in collaboration with public and private partners, is working on developing and disseminating drought tolerant maize for sub Saharan Africa (SSA) using pedigree selection and molecular breeding. In this paper, we provide an overview of the main results in quality control (QC) analysis and genetic and breeding methodologies using molecular markers. QC analysis was used to ensure that all named varieties and breeding lines were pure and correctly labeled. Unfortunately, varieties of the same name tested from different sources were neither pure nor correctly labeled, and the importance of molecular markers was demonstrated for helping keep order. Genetic mapping for drought tolerance and for grain yield has identified many chromosomal regions with genes contributing to increase yield under drought and yield in general. Initial trials indicate that these genetic regions and the molecular markers developed in them will increase breeding efficiency for these traits compared to breeding without molecular markers. A gene for resistance to maize streak virus (MSV) was also identified, validated, and is now being used to improve this trait in CIMMYT germplasm.

Technical Abstract: The International Maize and Wheat Improvement Center (CIMMYT), in collaboration with public and private partners, is working on developing and disseminating drought tolerant maize for sub Saharan Africa (SSA) using pedigree selection and molecular breeding. In this paper, we provide an overview of the main results in quality control (QC) analysis, QTL and fine mapping, marker-assisted recurrent selection (MARS), and genomic selection (GS). QC analysis was used to monitor differences among separately maintained samples of the same line, heterogeneity within lines, and parent-offspring tests. We found surprisingly high proportion of mismatch among different seed sources of the same line, higher than expected heterogeneity within each line and high proportion of failure in parent-offspring tests among several biparental populations. Across 18 biparental populations, meta-analyses reduced the number of QTL for grain yield and anthesis-silking interval from 183 to 68, with each meta QTL (mQTL) explaining from 1.2 to 13.1% of the total phenotypic variance. Four small to moderate effect mQTL associated with grain yield under both WS and WW environments were detected up to 6 backgrounds. A major QTL for maize streak virus (MSV) resistance on chromosome 1, which improves resistance on average by 25%, has been fine mapped, validated in several bi-parental populations, and implemented into pilot breeding programs using breeder-ready markers developed for the QTL. Hybrids derived from Cycle 3 of both the MARS and GS schemes produced higher grain yield than hybrids derived from the initial parents, via pedigree selection, and commercial checks, without significant change in anthesis date or plant height. The overall gains per year for MARS were 0.046 Mg ha-1 under WS and 0.093 Mg ha-1 under WW environments, which is approximately 2-3 fold higher than the gains achieved via the pedigree selection (0.015 and 0.050 Mg ha-1 under WS and WW environments, respectively). For GS, the gain per year under WS was 0.052 Mg ha-1, which is over three times higher than the pedigree selection (0.016 Mg ha-1). Overall both MARS and GS outperformed pedigree breeding in most populations but few populations showed either negligible or a reduction in grain yield as compared with the Cycle 0 populations.