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Title: Mapping QTL Contributing to SCMV Resistance in Tropical Maize

Author
item DE SOUZA, I - EMBRAPA
item SCHUELTER, A - UNIVERSITY OF PARANAENSE
item GUIMARIES, C - EMBRAPA
item SCHUSTER, I - COODETEC
item DE OLIVEIRA, E - EMBRAPA
item Redinbaugh, Margaret

Submitted to: Hereditas
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2008
Publication Date: 7/26/2008
Citation: De Souza, I., Schuelter, A.R., Guimaries, C., Schuster, I., De Oliveira, E., Redinbaugh, M.G. 2008. Mapping QTL Contributing to SCMV Resistance in Tropical Maize. Hereditas. 145(4):167-173.

Interpretive Summary: Sugarcane mosaic virus (SCMV) is causing increasing disease problems in the corn crop in Brazil. Tropical corn lines with strong resistance to SCMV have been identified and characterized. In this study, genes or 'quantitative trait loci' (QTL) for SCMV resistance were identified in progeny of a cross between the SCMV-resistant line L520 and the SCMV-susceptible line L19. Two major QTL that came from the resistant parent L520 were found on chromosome 3. These QTL were identified under field conditions in two different years and in two different generations of progeny. Two minor QTL for SCMV resistance were found on chromosome 6. These QTL were detected only in one year each, and came from the susceptible parent L19. In most other SCMV-resistant lines, the strongest QTL for resistance have been found on chromosome 6, with weaker QTL on chromosome 3. Thus, SCMV resistance in L520 may be useful to breeders developing hybrids for regions where SCMV is a problem, and will be of interest to researchers investigating disease resistance and mechanisms associated with SCMV resistance. This work documents resistance to Sugarcane mosaic virus (SCMV) in tropical corn lines. The locations of genes associated with resistance were identified, and this will facilitate incorporation of resistance to the disease caused by SCMV in corn hybrids used by producers. The primary users of this information will be geneticists and breeders working to develop disease resistant crops.

Technical Abstract: Sugarcane mosaic virus (SCMV) has been increasing in importance as a maize disease in Brazil. In this study, were mapped and characterized quantitative trait loci (QTL) associated to resistance to SCMV in a maize population consisting of 150 F2:3 families from the cross between two tropical maize inbred lines, L520 (resistant) and L19 (susceptible). F2 individuals were genotyped with microsatellite (SSR) markers, and the derived F2:3 families were evaluated for their response to artificial inoculation with SCMV under field conditions at Sete Lagoas, MG, Brazil, in 2001 and 2005. Composite interval mapping was used for QTL detection with a linkage map based on 19 SSR markers. Four QTLs for SCMV resistance were identified with two major QTLs (Scm2a and Scm2b) clustered on chromosome 3, bin 3.04, and two minor QTLs (Scm1a and Scm1b) on chromosome 6, bin 6.01 and 6.00 respectively. The two QTLs on Chromosome 3 were consistently detected in both years. However, for the QTLs on chromosome 6 the Scm1b was detected on 2001 and Scm1a on 2005. Both regions explained together 60.14% and 52.46 % of the phenotypic variation for SCMV resistance in the years 2001 and 2005, respectively. The two major QTLs on chromosome 3, were confirmed to confer resistance in the F2:3 families of cross (L520 x L19), and were derived from the resistant parent, L520. The two QTLs (Scm1a and Scm1b) on chromosome 6, with minor effects, were contributed by the susceptible parent, L19, and they interact with the environment. IMPACT STATEMENT: This work documents resistance to Sugarcane mosaic virus (SCMV) in tropical corn lines. The locations of genes associated with resistance were identified, and this will facilitate incorporation of resistance to the disease caused by SCMV in corn hybrids used by producers. The primary users of this information will be geneticists and breeders working to develop disease resistant crops.