Genetic mapping of maize streak virus resistance from the Mascarene source. II. Resistance in line CIRAD390 and stability across germplasm

Pernet, A and Hoisington, D A and et al, . (1999) Genetic mapping of maize streak virus resistance from the Mascarene source. II. Resistance in line CIRAD390 and stability across germplasm. TAG Theoretical and Applied Genetics, 99 (3-4). pp. 540-553. ISSN 1432-2242

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Abstract

The streak disease has a major effect on maize in sub-Saharan Africa. Various genetic factors for resistance to the virus have been identified and mapped in several populations; these factors derive from different sources of resistance. We have focused on the Réunion island source and have recently identified several factors in the D211 line. A second very resistant line, CIRAD390, was crossed to the same susceptible parent, B73. The linkage map comprised 124 RFLP markers, of which 79 were common with the D211×B73 map. A row-column design was used to evaluate the resistance to maize streak virus (MSV) of 191 F2:3 families under artificial infestation at two locations: Harare (Zimbabwe) and in Réunion island. Weekly ratings of resistance were taken and disease incidence and severity calculated. QTL analyses were conducted for each scoring date and for the integration over time of the disease scores, of incidence, and of severity. Heritability estimates (71–98%) were as high as for the D211×B73 population. Eight QTLs were detected on chromosomes 1, 2, 3, 5 (two QTLs), 6, 8, and 10. The chr1-QTL explained the highest proportion of phenotypic variation, about 45%. The QTLs on chromosomes 1, 2, and 10 were located in the same chromosomal bin as QTLs for MSV resistance in the D211×B73 population. In a simultaneous fit, QTLs explained together 43–67% of the phenotypic variation. The QTLs on chromosomes 3, 5, and 6 appeared to be specific for one or the other component of the resistance. For the chr3-QTL, resistance was contributed by the susceptible parent. There were significant QTL × environment interactions for some of the variables studied, but QTLs were stable in the two environments. They also appeared to be stable over time. Global gene action ranged from partial dominance to overdominance, except for disease severity. Some additional putative QTLs were also detected. The major QTL on chromosome 1 seemed to be common to the other sources of resistance, namely Tzi4, a tolerant line from IITA, and CML202 from CIMMYT. However, the distribution of the other QTLs within the genome revealed differences in Réunion germplasm and across these other resistance sources. This diversity is of great importance when considering the durability of the resistance.

Item Type:	Article
Divisions:	UNSPECIFIED
CRP:	UNSPECIFIED
Uncontrolled Keywords:	Quantitative trait loci, Resistance mechanism, MSV, Composite interval mapping, Tropical maize
Subjects:	Others > Maize
Depositing User:	Mr Siva Shankar
Date Deposited:	15 Mar 2012 07:44
Last Modified:	15 Mar 2012 07:45
URI:	http://oar.icrisat.org/id/eprint/5722
Official URL:	http://dx.doi.org/10.1007/s001220051267
Projects:	EU contract T5–3CT920150
Funders:	French Government
Acknowledgement:	[D. A. Hoisington is presently with ICRISAT (Patancheru)]---This work involved a lot of teams throughout the world. We thank D. Beck, J. Betrán, and M. Willcox from the Maize Program at CIMMYT-Mexico, for their helpful assistance in producing the material, B. Reynaud for providing the insects in Réunion. We also thank very much E. Pérez, G. Palacios, and A. Bouet for their technical assistance in the laboratory. S. Mawere, T. Gumunyui, R.-P. Hoareau, and M. Grondin are gratefully acknowledged for their help in the field work. We also thank C. Lanaud for the welcome in AGETROP lab, L. Grivet and L. Bigarré for helpful discussions. This work could not have been done without a graduate student fellowship provided by the French government. It was part of the EU contract T5–3CT920150.
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