Epistasis and complementary gene action adequately account for the genetic bases of transgressive segregation of kilo-grain weight in rice

Abstract

Transgressive segregation is a common phenomenon in plant species. In this study, transgressive segregation for kilo-grain weight (KGW) was observed in a recombinant inbred line (RIL) population derived from the cross between an indica variety, Teqing, and a wide compatible japonica variety, 02428, in three environments. A genetic linkage map with 154 single sequence repeat markers (SSR) was developed. Effects on KGW of quantitative trait loci (QTLs), digenetic epistasis, and their environmental interaction (QE) were determined using a mixed linear model approach. 13 QTLs with additive effects and 8 digenetic interactions involving 16 loci were identified. Eight QTLs were involved in interactions. Two QTLs and one epistasis showed QE. 30.0 and 14.0% of variation was explained by the additive effects and epistasis, respectively, which were much greater than the 4.4% of variation explained by QE. According to the model used, predicted KGW values of extreme phenotypes in the RIL population were very close to their observed values. This indicated that complementary action of additive QTLs and epistasis can adequately account for the important genetic bases of transgressive segregation for KGW in the rice RIL population.

Two quantitative trait loci for grain yield and plant height on chromosome 3 are tightly linked in coupling phase in rice

“…The RIL population comprised 177 lines derived by single-seed descent from a cross between a highyielding indica variety, Teqing (TQ), and a widely compatible japonica variety, 02428 (Mao et al 2011). The major plant height QTL, qPh3, was identified in the interval between RM130a and Wph8 on chromosome 3 in the RIL population.…”

Hybridization in Plants: Old Ideas, New Techniques

“…Many QTL studies of transgressive traits find support for complementary gene action, epistasis, or both (deVicente and Tanksley, 1993;Hagiwara et al, 2006;Mao et al, 2011). For an example in Helianthus spp., see Box 2.…”

“…Drift or stabilizing selection increases the likelihood of fixing antagonistic alleles for a polygenic trait, whereas directional selection will tend to fix alleles with effects in the same direction. Observations of transgressive segregation for agriculturally important traits in domestic plants (Hagiwara et al, 2006;Mao et al, 2011) further complicate this hypothesis, because crops tend to be under strong directional selection yet demonstrate extensive transgressive segregation. Finally, hybrids between inbred plants are much more likely to show transgressive trait values than hybrids between outbred populations (Rieseberg et al, 1999).…”

QTL Analysis for Drought Tolerance in Wheat: Present Status and Future Possibilities

“…Epistasis has been shown to contribute substantially to the genetic variation for a number of complex traits (e.g., adaptation to drought, heat, and salinity) in crops including wheat and other cereals [62][63][64]. Therefore, the identification of epistatic QTLs is essential for the development of efficient marker-assisted selection (MAS) schemes for complex traits such as drought tolerance, aimed at improving breeding efficiency [65].…”