QTL analysis of leaf morphological characters in a Quercus robur full‐sib family (Q. robur × Q. robur ssp. slavonica)

Abstract

The distinction between white oak species (section Quercus sensu stricto) is largely based on leaf morphological characters. There is, however, considerable within-species variation and no single species-diagnostic character, possibly due to phenotypic plasticity and/or underlying genetic variation. The aim of the present study was to identify quantitative trait loci (QTL) underlying the high within-species variation for leaf morphological characters in an F(1) full-sib family derived from a cross between Q. robur and Q. robur ssp. slavonica. In accordance with an earlier QTL mapping study in an intraspecific Q. robur full-sib family, polygenic inheritance was detected for leaf morphological characters that are used to discriminate between the species Quercus robur and Q. petraea. QTLs were distributed over ten linkage groups, showed a moderate effect in terms of phenotypic variance explained (PVE) in the mapping pedigree (3.6-9.6%), but accounted for a considerable amount of the parental differences. Co-localisation of QTLs on the same linkage group in different genetic backgrounds was found for the number and percentage of intercalary veins (NV, PV) on linkage group 3 and for NV on linkage group 5, revealing a high congruence in the relative QTL positions. The generally low correspondence of the other QTLs in the different mapping pedigrees may be an effect of the genetic background and of the environment. In conclusion, leaf morphological characters were found to be under polygenic control, and a comparison to earlier published results led to the identification of two QTLs that were stable across different genetic backgrounds.

Quantitative trait locus analysis of leaf morphological characters, yield-related traits, and secondary metabolite contents in Eucommia ulmoides

“…Furthermore, the clustering of QTLs controlling height and basal diameter has been observed in the same mapping population of E. ulmoides (Li et al, 2014c). In most cases, no clear patterns among phenotypic correlations have been found to coincide with the co-locating QTLs (Tsarouhas et al, 2002;Gailing, 2008;Freeman et al, 2009;Thumma et al, 2010;Li et al, 2014c). In the present study, we found that 16 QTLs were unique to specific traits (Figure 2).…”

“…The same observations were made for the number of leaves and the total dry weight. The instability of QTLs over years has been reported for leaf traits in other tree species (Scalfi et al, 2004;Gailing, 2008;Gailing et al, 2013). Fanizza et al (2005) hypothesized that QTL instability over time may be due to the presence of different genes or the differential expression of these genes due to changes in genotypic sensitivity to annual variations in the climatic conditions.…”

“…Previous QTL studies on main crops have frequently detected regions of the genome that contain clusters of QTLs for highly correlative traits (Zeng et al, 2009;Avia et al, 2013;Bian et al, 2013). Clusters of QTLs were also observed for growth traits and various leaf traits in poplar (Bradshaw and Stettler, 1995;Wu et al, 1997), for wood properties and growth traits in the genus Eucalyptus (Verhaegen et al, 1997;Freeman et al, 2009;Thumma et al, 2010), for growth traits in Salix (Tsarouhas et al, 2002;Ronnberg-Wastljung et al, 2005), for leaf morphological characters in European beech (Scalfi et al, 2004) and oak (Gailing, 2008;Gailing et al, 2013), and for chemical compositions in peach (Eduardo et al, 2013) and oil palm (Montoya et al, 2013). Furthermore, the clustering of QTLs controlling height and basal diameter has been observed in the same mapping population of E. ulmoides (Li et al, 2014c).…”

Interspecific gene flow and maintenance of species integrity in oaks

“…Thus, polygenic inheritance was found for most analyzed traits with high interspecifi c differentiation (Saintagne et al 2004, Scotti-Saintagne et al 2004a, Scotti-Saintagne et al 2004b, Parelle et al 2007, Gailing 2008, Gailing et al 2008. A major QTL was only detected for water use effi ciency in a Q. robur full-sib family explaining more that 20% of the phenotypic variation (Brendel et al 2008).…”

Strategies to Identify Adaptive Genes in Hybridizing Trees like Oaks and Poplars

“…Curtu et al, 2007;. QTL for species-discriminating leaf traits have been characterized in intraspecific Q. robur crosses and, similar to outlier loci, were distributed across most of the 12 oak linkage groups (Gailing, 2008;Gailing et al, 2013;Saintagne et al, 2004;Scotti-Saintagne et al, 2004a). Interestingly, one interspecific outlier locus, QrZAG96, colocated with a QTL for leaf morphological variation (petiole ratio and lobe-width ratio) on linkage group 10 in a Q. robur x Q. robur full-sib family (Saintagne et al, 2004).…”