Identification of Quantitative Trait Loci Influencing Wood Property Traits in Loblolly Pine (Pinus taeda L.). III. QTL Verification and Candidate Gene Mapping

Abstract

A long-term series of experiments to map QTL influencing wood property traits in loblolly pine has been completed. These experiments were designed to identify and subsequently verify QTL in multiple genetic backgrounds, environments, and growing seasons. Verification of QTL is necessary to substantiate a biological basis for observed marker-trait associations, to provide precise estimates of the magnitude of QTL effects, and to predict QTL expression at a given age or in a particular environment. Verification was based on the repeated detection of QTL among populations, as well as among multiple growing seasons for each population. Temporal stability of QTL was moderate, with approximately half being detected in multiple seasons. Fewer QTL were common to different populations, but the results are nonetheless encouraging for restricted applications of marker-assisted selection. QTL from larger populations accounted for less phenotypic variation than QTL detected in smaller populations, emphasizing the need for experiments employing much larger families. Additionally, 18 candidate genes related to lignin biosynthesis and cell wall structure were mapped genetically. Several candidate genes colocated with wood property QTL; however, these relationships must be verified in future experiments.

Genetic Dissection of Growth and Eco-Physiological Traits Associated with Altitudinal Adaptation in Sakhalin Fir (Abies sachalinensis) Based on QTL Mapping

“…The linkage maps were saturated, with a 10 cM interval between nearest markers. The average distance between nearest markers detected in this study (approximately 4 cM; Table 3) was also comparable with that in previous studies [46,48,50,52]. The maximum marker gap distance in this study (approximately 20 cM) was also similar to that in a previous study [51].…”

“…This result corroborates that of a previous study on Sakhalin fir, in which several QTLs with small or moderate effects (PVE: 3.8-7.4%) were detected for H17 and D16 at the early stage. QTLs with small or moderate effects on growth traits have also been detected in other conifers [46][47][48][49].…”

“…Long generation times and the outbred mating system of conifers were used to construct a suitable mapping population. Because several pedigrees are available for important traits, including height growth and wood properties, in a tree breeding program, secondgeneration populations were used for QTL mapping [46][47][48][49]. However, F 1 pedigrees have been used for QTL mapping of eco-physiological studies in the evolutionary biology of conifers [50,51].…”

Mapping yield-associated QTL in globe artichoke

“…Of the 100 QTL detected overall, 73 were identifiable in both growing seasons. The effect of a QTL has been shown to vary over time in perennial plants with changing biotic and abiotic factors (Brown et al 2003). C. cardunculus is also a perennial plant, but our results seem to suggest that it is in some way adaptable to yearly variations in climate.…”

Genotype-by-environment interaction and genetic dissection of heartwood color in Cryptomeria japonica based on multiple common gardens and quantitative trait loci mapping

“…On the other hand, genomic selection would be effective in improvement programs under wide range of environmental conditions. These necessitates further studies with different genomic approaches such as association mapping studies [ 4 , 46 , 47 ] to validate the findings of this study and to capture wider genetic variations because the present study was limited to segregated populations derived from local cultivars.…”