Establishment of a quasi-field trial in Abies nordmanniana—test of a new approach to forest tree breeding

Abstract

This study used DNA markers to establish a quasi-field trial within a production Christmas tree stand produced from seed collected in an open-pollinated clonal seed orchard (CSO). A total of 660 offspring from the CSO, which comprised 99 clones of Abies nordmanniana, were genotyped with 12 microsatellites. Parentage was assigned successfully to 93% and 98% of the progeny at 95% and 80% confidence, respectively. The assignment rate declined only to 90% when the number of markers was reduced to 10. The distribution of parentage to the offspring among the CSO clones was highly skewed. The most successful clone was assigned as parent in 7% of the cases, and only 92 of the 119 potential parental genotypes were assigned as parents. The obtained pedigree was used to estimate breeding values for the CSO clones for five characters relevant for Christmas tree breeding. For high-heritability traits, such as flushing, accurate breeding values could be estimated for a considerable proportion of the clones. To estimate breeding values for low-heritability traits, such as Christmas tree quality score, more genotyped offspring will be required. The largest drawback of the method is the highly skewed distribution of parentage among the parents in the seed orchards, making it difficult to calculate breeding values for all clones. The approach seems well suited for tree breeding that puts more emphasis on pure selection of parental genotypes and less on estimating quantitative genetic parameters.

Genetic worth and diversity across 18 years in a Nordmann fir clonal seed orchard

“…Studies performed to date in conifer CSOs have established that there can be a large variation in fertility between the constituent clones, often following the 20-80 rule (Anonymous 1976), i.e. that 20% of the clones produce 80% of the gametes, a pattern also reported for Nordmann fir (Hansen and McKinney 2010). It is also well known among managers of seed orchards that there can be a large year-to-year variation in fertility, a fact which has been scientifically documented for a large number of species since the 1960s.…”

“…Based on the same seed orchard as in our study, Hansen and Nielsen (2010) demonstrated, by use of microsatellite markers, that visual evaluation of male strobili numbers had a good correlation (r=0.87) to the resulting paternity-based on the seed year 1992-and also that the assumption of true half-sibs after open pollination is correct. Furthermore, studies show that the selfing rate is low, and pollen contamination from outside sources is of either no or minor importance in Danish Nordmann fir orchards (Hansen and Kjaer 2006;Hansen and McKinney 2010;Hansen and Nielsen 2010). Moreover, female strobili are easy to identify visually, and are situated upright in the upper part of the crown.…”

“…Visual evaluation methods have earlier been suggested by Kjaer and Wellendorf (1998) and Nikkanen and Ruotsalainen (2000), as well as by Stoehr et al (2004). Although costly, marker-based parentage analysis (El-Kassaby et al 2010;Hansen and Mckinney 2010;Hansen and Nielsen 2010;Funda et al 2011) would be a relevant tool for seed crops with a high expected value, e.g. due to a large quantity of seed or high economic value.…”

“…Moriguchi et al 2004;Slavov et al 2005;Hansen and Kjaer 2006;Hansen 2008;Funda et al 2008). Recently, whole parental analyses on bulk seed crops from CSOs have been performed (Hansen and McKinney 2010;El-Kassaby et al 2010).…”

Increasing Breeding without Breeding (BwB) Efficiency: Full- vs. Partial-Pedigree Reconstruction in Lodgepole Pine

“…However, it should be stated that the work of Lambeth, et al [14] was inspring as it demonstrated the power of pedigree reconstruction in determining the male parents of crosses produced through polycross mating design (pollen consisted of a mixture from several male parents, thus parernity is unknown and the resulting families were considered half-sibs) and thus converted a set of half-sib to a full-sib families. Pedigree reconstruction as an aid to breeding has gained momentum and several retrospective studies on Eucalyptus urophylla [35], Pinus pinster [36], Abies nordmanniana [37] and Picea rubens [38] have been documented.…”