Results on quantitative trait loci for flushing date in oaks can be transferred to different segregating progenies.

Flushing date (bud burst) is one of the most important traits for the adaptation to different environments and climates in the temperate zone. Because of their wide geographic distribution, Quercus robur L. and Q. petraea (Matt.) Liebl. are suitable as model plants to study the genetic basis of bud burst. QTLs (Quantitative Trait Loci) with comparatively large effects have been mapped in a former study in a Q. robur x Q. robur full-sib family (French cross). In the present study, we performed a Bulked Segregant Analysis (BSA) in the F (1) progeny comprising 144 seedlings derived from a cross between a single Q. robur tree as common seed parent and five different pollen donors both from Q. robur and Q. petraea (Q. robur x Q. spp., Diekholzen crosses). In addition, markers linked to two bud burst QTLs with comparably strong effect in the above-mentioned full-sib family (French cross) were tested for their association with bud burst in the Q. robur x Q. spp. (Diekholzen) progeny. Using three microsatellite markers as anchor points, we could map QTLs on linkage group 7 and on linkage group 2, together explaining 16.2 % of the total phenotypic variance (PVE) in 1999 and 38.1 % in 2003. Out of 10 markers that segregated in both mapping progenies, four markers including the two microsatellite markers, showed a significant effect on bud burst in both materials. At microsatellite loci ssrQpZAG1/5 (linkage group 7) and ssrQpZAG119 (linkage group 2) alleles associated with early (allele 166 bp in ssrQpZAG1/5) and late bud burst (allele 57 bp in ssrQpZAG119) in the Q. robur x Q. robur full-sib family (French cross) showed a highly significant association with the same polarity of the effect in the Q. robur x Q. spp. (Diekholzen) progeny. The usefulness of these markers for marker-assisted selection in full-sib and half-sib families is discussed.

Inheritance of allozymes and hybridization in two European Tilia species.

Inheritance analysis of seven enzyme systems in hexaploid Tilia cordata Mill. was performed utilizing single trees and their open-pollinated progenies. Genetic analyses of 12 polymorphic gene loci showed that T. cordata had disomic inheritance despite being an allopolyploid. T. platyphyllos Scop. was also used in the investigations although no genetic inheritance analysis was carried out. In comparison with T. cordata, zymograms of 10 spontaneous T. cordata x T. platyphyllos hybrids showed markedly different banding patterns with species-specific alleles at 13 of the 14 described gene loci. Hence, differentiation between both species and their naturally occurring hybrid (T. x europaea) is easily feasible with allozyme studies.

Restriction fragment length polymorphisms of a chloroplast photosystem II gene from poplar and their use for species identification.

In a total DNA library from the poplar clone Beaupré (Populus trichocarpa x P. deltoides) one DNA clone was found to identify restriction site polymorphisms in different poplar species. This clone represents a cpDNA gene that shows close homology to a photosystem II gene of pea and spinach coding for the D2 protein and the 44 kDa reaction centre. In Southern blot analysis this probe identified interspecific restriction site variation among the different poplar species; intraspecific variation was not detectable. As the chloroplast genome is maternally inherited in poplars this cpDNA probe was used for identification of P. nigra or P. deltoides as the seed parents of F1 hybrid trees in natural stands of western Germany.

Transferrin polymorphism and genetic differentiation in Cervus elaphus L. (European red deer) populations.

A study of transferrin in 11 different European populations of Cervus elaphus as well as in one Cervus elephus x Cervus nippon hybrid population has revealed a polymorphism of this protein. Genetic analysis suggests that it is controlled by one gene locus with three codominant alleles. The allele frequencies allow a clear discrimination not only between the hybrid population and pure red deer but also between different Continental red deer populations. Comparison of the genotypic structures with the Hardy-Weinberg structure shows no significant deviation. Genetic variation within and differentiation between populations is evaluated for the transferrin gene locus using different measures. Average heterozygosities have been calculated for five populations including the results of previous studies on 14 other protein systems. Some management implications of the present results are discussed.

Reproductive systems in conifer seed orchards : 2. Reproductive selection monitored at an LAP gene locus in Pinus sylvestris L.

In a Scots pine seed orchard the genetic structures at an enzyme gene locus active in pine seeds were compared among the parental clones and the allorchard seeds produced over a period of three years. The genotypes of the seeds were identified as ordered pairs consisting of the female and male contribution. The sexual reproductive function monitored at the studied locus differed significantly between the two sexes. This fact proves the necessity of taking sexual asymmetry into account in studies of reproductive selection. This is done by comparing the observed genotypic structures among the offspring with the corresponding multiplicative structure expected under random gametic fusion. Additionally, accounting for partial self-fertilization increased the conformity between the observed and the hypothesized model structures. The differences in female and male gametic contributions to the offspring were used to estimate female and male relative fitness components. Significant deviations between the allelic and/or genotypic structures of orchard clones and their seed, and between seed lots collected in different years, may reduce the efficiency of realizing breeding gains in seed orchards.

Genetic distance between populations : Part 3: Wahlund's principle as related to genetic distance and an application.

An excess proportion of homozygous carriers of a gene arises on bulking of reproductively isolated subpopulations. This surplus of homozygotes in the mixture, measured relative to the panmictic proportion, is caused by variation of its frequencies in the respective subpopulations. It is shown that the result known as Wahlund's principle can be expressed as a simple function of genic distances among the subpopulations. If used with caution it can be employed to recognize mixtures of seed lots. The effect of bulking can be readily discriminated from that of inbreeding. It may also be distinguished from the effect of assortative mating by analysing such distances at several gene loci. Various effects of selection may disturb inference on whether a given lot is a mixture. Hence application should be confined to the dormant seed. Isozyme loci are most suitable for such checks since complete dominance occurs only rarely. Some advantages peculiar to conifer seed are discussed.

Some factors in the distribution of European pine sawfly egg clusters in an experimental plantation of hard pines.

1. During three successive years the frequencies of oviposition by Neodiprion sertifer (Hymenoptera: Diprionidae) were observed in 546 pines (provenances of various hard pine species, hybrids between such species, and some white pines). The insects were able to discriminate between 30 host genotypes since in this preference test average oviposition frequency varied between genotypes. 2. Oviposition frequencies had to be inferred to from groups of feeding larvae. 3. Besides genotype, four other groups of variables had an effect on the number of larval colonies: position of a tre in the plantation (in terms of rows and columns), its dimensions, the dimensions of its neighbors, and the number o colonies in the neighbors. 4. Apparently different crown portions were preferred oviposition sites in the various genotypes. 5. Water potentials of a sample of host trees during the hatching period showed no relations to susceptibility.