RFLP MAPPING IN MAIZE - QUANTITATIVE TRAIT LOCI AFFECTING TESTCROSS PERFORMANCE OF ELITE EUROPEAN FLINT LINES

The dissection of quantitative traits into their underlying Mendelian factors has become possible with the aid of molecular markers. In this study, we mapped and characterized quantitative trait loci (QTL) affe cting testcross performance of maize (Zea mays L.) and discussed the c onsistency of these QTL across environments and testers. Two homozygou s flint inbred lines were crossed to produce 380 F2 individuals which were genotyped at 89 restriction fragment length polymorphisin (RFLP) marker loci. By selfing the F2 plants 380 F3 lines were produced and s ubsequently crossed to two diverse dent inbred testers (T1 and T2). Ea ch series of testcrosses (TC) was evaluated in field trials with two r eplications in four environments. Three traits were analyzed: protein content, kernel weight, and plant height. Genotypic and genotype-by-en vironment interaction variances were highly significant for all traits in both TC series and heritabilities ranged between 0.71 and 0.85. Ge notypic correlations between the two TC series were 0.80 (protein cont ent), 0.88 (kernel weight), and 0.84 (plant height). The method of int erval mapping was used for characterization of QTL. Protein content wa s significantly affected by four QTL in TC with Tl explaining 32% of t he phenotypic variance, (sigma(p)2) and five QTL in TC with T2 explain ing 42% of sigma(p)2. For kernel weight, eight putative QTL were found in TC with T1 and six were found for T2, explaining about 60% of sigm a(p)2. Seven QTL explained 52% and four 60% of sigma(p)2 for plant hei ght. Results from QTL mapping agreed well across environments. Highly consistent results across testers were obtained for kernel weight and plant height but not for protein content. No significant evidence for epistasis among QTL was found.