Mapping and characterization of quantitative trait loci affecting resistance against second-generation European corn borer in maize with the aid of RFLPs

Abstract

The European corn borer (Ostrinia nubilalis Hübner) is an important pest in the global production of maize (Zea mays L.). In this study, we mapped and characterized quantitative trait loci (QTLs) significantly affecting resistance against second-generation European corn borer (2ECB) and plant height with the aid of RFLP markers. A total of 300 F3 lines derived from cross B73 (susceptible) x B52 (resistant) were assayed for their parental F2 genotype at 87 RFLP loci. Field data on plant height and resistance against 2ECB were collected for the 300 F3 lines, the parents and the F2 generation at two sites, Ames and Ankeny, IA, USA. Resistance was assessed by measuring the damage of stalk tissue (tunnel length) caused by severe artificial infestation with 2ECB larvae. Genotypic variances among F3 lines were highly significant for tunnel length and plant height, but genotype by location interactions were significantly different from zero only for plant height. Heritabilities were intermediate (0.63) for tunnel length but high (0,87) for plant height. The genotypic correlation between the two traits was 0.29. The method of interval mapping was used for localization of QTLs and estimation of their genetic effects. In the combined analysis across locations, genomic regions significantly affecting resistance against 2ECB were found on chromosome arms IS, IL, 2S, 2L, 3L, 7L and IOL, Genomic regions on IS, 3L and 9L significantly affected plant height. Results were largely consistent across locations. Different types of gene action were found for the putative QTLs for both traits. For tunnel length a total of 38 per cent of the phenotypic variance was explained by simultaneous mapping of the seven putative QTLs. The three putative QTLs for plant height explained 63 per cent of the phenotypic variance. On 3L, evidence was found for an interaction of genes conferring resistance to 2ECB and plant height. Significant digenic epistasis was detected for one pair of marker loci.

QTL mapping of Sclerotinia midstalk-rot resistance in sunflower

“…Line CM625 was chosen as parent, because it had shown high susceptibility to S. sclerotiorum in artificial leaf infections (V. Hahn, unpublished data). However, as reported for other resistance traits (Scho¨n et al 1993;Bohn et al 2000), the susceptible parent P S also carried resistance alleles. For leaf lesion, significant transgression towards higher resistance of F 3 families was observed, suggesting that the susceptible parent CM625 contributed favorable alleles for resistance.…”

Comparative genetic analysis of quantitative traits in sunflower (Helianthus annuus L.) 1. QTL involved in resistance to Sclerotinia sclerotiorum and Diaporthe helianthi

“…During the past two decades, DNA molecular markers have been successfully used to map loci controlling quantitative trait variations. Depending on the hostparasite interaction considered, from two (Landry et al 1992) to seven (Schön et al 1993) QTL were identified, contributing to quantitative variations in disease resistance. Analyses of QTL associated with resistance to extension of the S. sclerotiorum mycelium on sunflower capitula and leaves, using molecular markers, have already been made by Mestries et al (1998).…”

Genetic analysis of quantitative trait loci with inbred and hybrid progeny of maize

“…This has been observed for morphological traits in tomato (Paterson et al, 1991) and for response to the disease gray leaf spot (caused by Cercospora zeaemaydis Tehon & Daniels) in maize . In contrast, maize studies have shown relatively consistent QTL detection across diverse environments for grain yield , morphological traits , and second generation European com borer resistance (Schon et al, 1993). These differences in consistency may be attributable to the biology of the traits, progeny and environment sampling variation, and QTL detection methods and threshold levels .…”

“…second generation European com borer resistance (Schon et al, 1993), and northern com leaf blight {Setosphaeria turcica) resistance (Freymark et al, 1993;Dingerdissen et al. 1996).…”

“…Few QTL were consistently detected across environments for morphological traits in tomato (Paterson et al, 1991), for response to the disease gray leaf spot {Cercospora zeae-maydis Tehon & Daniels) in maize , for plant height and lodging in soybean , and agronomic traits in rice (Lu et al, 1997). in contrast, studies in maize have shown relatively consistent detection of QTL across diverse environments for grain yield , morphological traits , second generation European com borer resistance (Schon et al, 1993). and northern corn leaf blight {Setosphaeria turcica) resistance (Freymark et al, 1993;Dingerdissen et al.…”