Identification and fine-mapping of a major QTL conferring resistance against head smut in maize

Abstract

Head smut is one of the most devastating diseases in maize, causing severe yield loss worldwide. Here we report identification and fine-mapping of a major quantitative trait locus (QTL) conferring resistance to head smut. Two inbred lines 'Ji1037' (donor parent, highly resistant) and 'Huangzao4' (recurrent parent, highly susceptible) were crossed and then backcrossed to 'Huangzao4' to generate BC populations. Four putative resistance QTLs were detected in the BC(1) population, in which the major one, designated as qHSR1, was mapped on bin 2.09. The anchored ESTs, IDPs, RGAs, BAC and BAC-end sequences in bin 2.09 were exploited to develop markers to saturate the qHSR1 region. The recombinants in the qHSR1 region were obtained by screening the BC(2) population and then backcrossed again to 'Huangzao4' to produce 59 BC(2:3) families or selfed to generate nine BC(2)F(2) families. Individuals from each BC(2:3) or BC(2)F(2) family were evaluated for their resistances to head smut and genotypes at qHSR1. Analysis of genotypes between the resistant and susceptible groups within the same family allows deduction of phenotype of its parental BC(2) recombinant. Based on the 68 BC(2) recombinants, the major resistance QTL, qHSR1, was delimited into an interval of approximately 2 Mb, flanked by the newly developed markers SSR148152 and STS661. A large-scale survey of BC(2:3) and BC(2)F(2) progeny indicated that qHSR1 could exert its genetic effect by reducing the disease incidence by approximately 25%.

Characterization and molecular mapping of RsrR, a resistant gene to maize head smut

“…Several research groups detected single MHS-resistant gene or major QTL in the locus bin 2.09 on chromosome 2 (Shi et al 2005;Chen et al 2008;Shi et al 2009). Some scientists detected MHS-resistant gene on chromosome 1 (Shi et al 2005;Lu and Brewbaker 1999).…”

“…Shi et al (2009) developed a sequence characterized amplified region (SCAR) marker S130, which was highly associated with the MHS-resistant gene and located at chromosome bin 2.09. Chen et al (2008) mapped the MHS-resistant gene at the position bin 2.09 and delimited into an interval of *2 Mb, the MHS-resistant gene was flanked by markers SSR148152 and STS661.…”

Qualitative and Quantitative Trait Polymorphisms in Maize

“…Several resistance QTLs against head smut have been detected on almost all maize chromosomes Li et al 2008;Chen et al 2008). A major QTL on bin 2.09 has been detected in two independent mapping populations, explaining 43.7 and 30% of the total phenotypic variation, respectively (Chen et al 2008;Li et al 2008). The major QTL (qHSR1) was fine mapped into a region of 2 Mb.…”

“…The major QTL (qHSR1) was fine mapped into a region of 2 Mb. The genetic effect of qHSR1 has been validated in large backcross populations, indicating that qHSR1 could reduce the disease incidence by 25% (Chen et al 2008). Molecular markers within the qHSR1 region have been used to improve maize resistance to head smut (Zhao et al 2012).…”

Variation characteristics of the nitrate reductase gene of key inbred maize lines and derived lines in China

“…In recent years, quantitative trait loci for some important maize traits were detected using simple sequence repeat (SSR) and/or amplified fragment length polymorphism. These traits include grain protein concentration (Li et al, 2009), photoperiod sensitivity (Wang et al, 2008), head smut (Chen et al, 2008), flowering time (Szalma et al, 2007), callus initiation and totipotency (Krakowsky et al, 2006), gibberella ear rot (Ali et al, 2005), plant height (Yan et al, 2003), and so on, and many key genes related to some important traits were also cloned and identified. At the same time, genetic diversity and heterotic groups of maize inbred lines were studied extensively (Taramino and Tingey, 1996;Xu et al, 2004;Menkir et al, 2005;Legesse et al, 2007).…”