Microsatellite markers linked to QTL for resistance to Mal de Río Cuarto disease in Zea mays L.

Abstract

‘Mal de Río Cuarto’ (MRC) disease, caused by a member of the family Reoviridae belonging to the genus Fijivirus, is considered to be the most damaging viral disease of maize (Zea mays L.) in Argentina. Resistance to MRC disease is a quantitative trait with moderate heritability ranging from 0·44 to 0·56. The objective of this study was to identify simple sequence repeats (SSR) loci linked to quantitative trait loci (QTL) contributing to MRC disease resistance. Two hundred and twenty-seven F3 derived-lines from a cross between a susceptible inbred line, Mo17, and a partially resistant inbred line, BLS14, were evaluated across four Río Cuarto environments. A disease severity index (DSI) based on disease grades was calculated and used to rate F3 derived-lines for their resistance to MRC disease. A subset of parental F2 plants belonging to susceptible and resistant F3 derived-lines from field assessments was assayed for 180 SSR primer pairs to map resistance genes. Fifty-six maize SSR were employed for the testing of linkage among DNA markers and the mapping of QTL through composite interval mapping. Resistance to MRC disease was affected by two QTL on chromosomes 1 and 8 which showed overdominance and dominant gene action, respectively. A simultaneous fit with these QTL in the joint analyses explained 36·2% of the phenotypic variance. In spite of the fact that relative efficiency of marker-assisted selection (MAS) in comparison to phenotypic selection was close to 1, the mapped QTL could improve the efficiency of efforts in breeding for resistance to MRC disease.

Identification of significant single nucleotide polymorphisms for resistance to maize rough dwarf disease in elite maize (Zea mays L.) inbred lines

“…Among these associated SNPs, several were located in or near regions where QTLs for MRDD resistances have been mapped by linkage analysis. For (Bonamico et al 2010;Bonamico et al 2012;Di Renzo et al 2004). The SNPs of PZE-102123986 and PZE-102124518 in bin 2.06 were located near the region as QTLs for maize fine streak virus (MFSV) and maize mosaic virus (MMV) resistance in a previous study (Zambrano et al 2014).…”

Control of Virus Diseases in Maize

“…Natural infection, evaluated in disease nurseries or "hot spots" where the disease was naturally endemic or prevalent, was among the early approaches used (Findley et al, 1976). This method continues to be effective for identifying virus-resistant germplasm and characterizing resistance genes and QTLs in maize (Cao et al, 2013;Di Renzo et al, 2004, Ming et al, 1997. However, this approach does not ensure gain under selection, because of unequal disease pressure from season to season and the high risk of escapes.…”

“…Reducing weedy virus reservoirs can also help reduce disease. MRCV resistance has been fairly recently identified and mapped (Di Renzo et al, 2004;Martin et al, 2010), and it is not known whether resistant hybrids and cultivars are widely available.…”

“…However, protocols that integrate disease incidence with a measure of symptom severity are frequently used (Brewbaker, 1981;Louie, 1986;Scott & Rosenkranz, 1981). Severity index ratings and area under the disease progress curve are also effective (Di Renzo et al, 2004;Madden, Hughes, & Van Den Bosch, 2007;Shi et al, 2012).…”

“…Msv1, a gene that confers resistance to MSV, and QTLs that confer resistance to MRCV and MMV are found clustered on the short arm of chromosome 1 (Bonamico et al, 2012;Di Renzo et al, 2004;Kyetere et al, 1999;Welz et al, 1998;Zambrano, Jones, Brenner, et al, 2014). Msv1 and the MRCV-resistance QTLs account for almost 60% and 30% of the phenotypic variation, respectively.…”