Abstract:

A double haploid rice population from IR64/Azucena was used to dissect the quantitative inheritance of flag leaf length. The QTL mapping method based on mixed linear model approaches was employed for detecting QTLs with additive and epistatic effects as well as their QE interaction effects in 4 years. The results revealed that altogether 18 QTLs for leaf length were detected on 11 chromosomes, and all of them were involved in epistasis. 3 QTLs were involved in epistasis but without detectable additive effects, such loci might play the role of modifying agents that tend to activate other loci or modify the action of other loci. The same locus could get involved in interactions with more than one other locus, as might indicat the possibility of multi-QTL associations in the formation of complex traits. QTL and epistasis could have both genetic main effects that expressed stably in every environment and QE interaction effects. Some QTLs had QE effects under multi-environments but without genetic main effect, as might suggest expression of this kind of QTLs could be modified by environmental factors easily. And also some QTLs had only genetic main effect, so would not easily be affected by environment. Epistasis had wider range of epistasis × environment effects than that of main effects, might indicate that some digenic interactions were more easily subjected to environmental influence. Compared with indirect mapping method with QE effects but without epistatic effects, more QTLs were detected in the present study, but no major QTL was found. The QE effects were treated as random effects, so the sum of QE effects would be zero in theory, and multi environments were suitable for estimating genetic main effects better.

Key words: Quantitative trait locus (QTL), Epistatic effects, QTL by environment interaction effects, Flag leaf length of rice