Characterization of heterotic quantitative trait loci in maize by evaluation of near-isogenic lines and their crosses at two competition levels |
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Authors: | Email author" target="_blank">Elisabetta?FrascaroliEmail author Maria?Angela?Canè Mario?Enrico?Pè Giorgio?Pea Pierangelo?Landi |
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Institution: | 1.Department of Agroenvironmental Sciences and Technologies,University of Bologna,Bologna,Italy;2.Sant’Anna School of Advanced Studies,Pisa,Italy |
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Abstract: | In a previous study on a maize (Zea mays L.) population of recombinant inbreds derived from B73 × H99, we identified several quantitative trait loci (QTL) for agronomic
traits with high dominance-additive ratio. Then, for four of these QTL, we developed families of near-isogenic lines (NILs)
homozygous either for the QTL allele from B73 (BB) or from H99 (HH); for two of these QTL, the NILs’ families were produced
in two different genetic backgrounds. The present study was conducted to: (1) characterize these QTL for agronomic traits
and (2) verify whether their effects were influenced by the genetic background, inbreeding level and plant density (PD). The
six NILs’ families were tested across 3 years and in three experiments at different inbreeding levels as NILs per se and their
reciprocal crosses (Experiment 1), NILs crossed to related inbreds B73 and H99 (Experiment 2) and NILs crossed to four unrelated
inbreds (Experiment 3). Experiment 2 was conducted at two PDs (4.5 and 9.0 plants m−2). Results of Experiments 1 and 2 confirmed previous findings as to QTL effects, with dominance–additive ratio superior to
1 for several traits; as a tendency, dominance effects were more pronounced in Experiment 1. The QTL effects were also confirmed
in Experiment 3. The interactions involving QTL effects, families and PD were generally negligible, suggesting a certain stability
of the QTL. Results emphasize the importance of dominance effects for these QTL, suggesting that they might deserve further
studies, using the NILs’ families and their crosses as base materials. |
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