A gene for resistance to the maize streak virus in the African CIMMYT maize inbred line CML202

• Published in: Molecular breeding 1998-04, Vol.4 (2), p.147-154
• Main Authors: Welz, H.G. (Hohenheim Univ., Stuttgart (Germany). Inst. of Plant Breeding, Seed Science and Population Genetics), Schechert, A, Pernet, A, Pixley, K.V, Geiger, H.H
• Format: Article
• Language: English
• Subjects: AFRICA AL SUR DEL SAHARA; AFRICA SOUTH OF SAHARA; AFRIQUE AU SUD DU SAHARA; Agricultural research; Agronomy; CARTE GENETIQUE; Chromosomes; Corn; DISEASE RESISTANCE; Field tests; Frequency distribution; GEMINIVIRUS DEL ESTRIADO DEL MAIZ; GEMINIVIRUS STRIURE DU MAIS; Gene mapping; GENETIC MAPS; Genotypes; Heritability; Heterosis; Hoppers; INBRED LINES; Inbreeding; LIGNEE CONSANGUINE; LINEAS CONSANGUINEAS; LOCI; LOCUS; MAIZE STREAK GEMINIVIRUS; MAPAS GENETICOS; Mapping; Molecular biology; Plant biology; Plant viruses; Quantitative trait loci; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; VARIEDADES; VARIETE; VARIETIES; Viruses; Wheat; ZEA MAYS
• ISSN: 1380-3743; 1572-9788
• DOI: 10.1023/A:1009602620244

Resistance to maize streak virus (MSV) is an essential trait of improved maize varieties in sub-Saharan Africa. We mapped quantitative trait loci (QTL) for resistance to MSV in a population of 196 F2:3 lines derived from a cross between the maize inbred lines CML202 (resistant) from CIMMYT-Zimbabwe and Lo951 (susceptible) from Italy. Field tests were planted at two locations in Zimbabwe, inoculated with viruliferous leaf hoppers (Cicadulina mbila), and scored twice (21 and 83 days after infesting, DAI) on a 1–5 scale. The mean final streak intensity (score 2) of the parent lines was 2.2 (CML202) and 4.8 (Lo951). Genotype × location interaction was large for score 1 but negligible for score 2. Consequently, the heritability was higher for score 2 (0.93) than for score 1 (0.62). By composite interval mapping across locations, using a linkage map with 110 RFLP loci, four significant (LOD ≥3.0) QTL were identified for score 1 on chromosomes (C) 1, 2, 3, and 4, respectively. All four were contributed by CML202. For score 2, only the QTL on C 1 was significant (LOD =37), explaining 59% of the phenotypic and 64% of the genotypic variance. The QTL's partially dominant gene action was consistent with the nearly intermediate resistance of the F1 generation (relative heterosis for resistance 12%). The presence of one major QTL is consistent with the bimodal frequency distribution of the mapping population showing a clear 3:1 segregation. This gene seems to be allelic or identical to Msv1, a major resistance gene which was previously identified in the same genomic region in Tzi4, an inbred line from IITA. Inbred CML202 had lower final disease ratings than Tzi4. The greater resistance of CML202 may be due to allelic differences at the msv1 locus or due to the minor QTL on C 2, 3, and 4 which were not detected in Tzi4.z y Trigo (International Maize and Wheat Improvement Center); IITA, International Institute of Tropical Agriculture; IRAT, Institute de Recherches Agronomiques Tropicales et des Cultures Vivrières; KARI, Kenya Agricultural Research Institute; MSV, maize streak virus; QTL, quantitative trait locus/loci