Identification of QTLs conferring resistance to downy mildews of maize in Asia

George, M L C and Prasanna, B M P and Rathore, R S and Setty, T A S and Kasim, F and Azrai, M and Vasal, S and Balla, O and Hautea, D and Canama, A and Regalado, E and Vargas, M and Khairallah, M and Jeffers, D and Hoisington, D A (2003) Identification of QTLs conferring resistance to downy mildews of maize in Asia. TAG Theoretical and Applied Genetics, 107 (3). pp. 544-551. ISSN 1432-2242

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Downy mildew is one of the most destructive diseases of maize in subtropical and tropical regions in Asia. As a prerequisite for improving downy mildew resistance in maize, we analyzed quantitative trait loci (QTLs) involved in resistance to the important downy mildew pathogens – Peronosclerospora sorghi (sorghum downy mildew) and P. heteropogoni (Rajasthan downy mildew) in India, P. maydis (Java downy mildew) in Indonesia, P. zeae in Thailand and P. philippinensis in the Philippines – using a recombinant inbred line population derived from a cross between Ki3 (downy mildew resistant) and CML139 (susceptible). Resistance was evaluated as percentage disease incidence in replicated field trials at five downy mildew 'hotspots' in the four countries. Heritability estimates of individual environments ranged from 0.58 to 0.75 with an across environment heritability of 0.50. Composite interval mapping was applied for QTL detection using a previously constructed restriction fragment length polymorphism linkage map. The investigation resulted in the identification of six genomic regions on chromosomes 1, 2, 6, 7 and 10 involved in the resistance to the downy mildews under study, explaining, in total, 26–57% of the phenotypic variance for disease response. Most QTL alleles conferring resistance to the downy mildews were from Ki3. All QTLs showed significant QTL × environment interactions, suggesting that the expression of the QTL may be environment-dependent. A strong QTL on chromosome 6 was stable across environments, significantly affecting disease resistance at the five locations in four Asian countries. Simple-sequence repeat markers tightly linked to this QTL were identified for potential use in marker-assisted selection.

Item Type: Article
Uncontrolled Keywords: Downy mildews - Maize - Quantitative trait loci - Disease resistance - Molecular markers
Subjects: Others > Genetics and Genomics
Others > Maize
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 16 Mar 2012 12:00
Last Modified: 16 Mar 2012 12:00
Official URL:
Acknowledgement: . A. Hoisington is presently with ICRISAT (Patancheru)
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