Interspecific hybridization and inbreeding effect in seed from a Eucalyptus grandis x E. urophylla clonal orchard in Brazil

Campinhos, Eduardo Nogueira; Peters-Robinson, Ingrid; Bertolucci, Fernando L.; Alfenas, Acelino C.

doi:10.1590/s1415-47571998000300014

Cited by 18 publications

(11 citation statements)

References 13 publications

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“…A significant proportion of the analyzed offspring, approximately 29%, was sired by pollen parents located outside of the orchard. Campinhos et al (1998) estimated a lower contamination rate of 14% in the same orchard based on isozyme markers, possibly due to limited informative polymorphism that would allow correct parental discrimination or simply due to a sampling effect. Outside pollinator trees did not contribute significantly to the generation of superior offspring individuals (Table 5), although one cannot preclude the possibility of some occasional superior trees deriving from pollen outside the orchard.…”

Section: Discussionmentioning

confidence: 99%

Retrospective selection of elite parent trees using paternity testing with microsatellite markers: an alternative short term breeding tactic for Eucalyptus

Grattapaglia

Ribeiro

Rezende³

2004

Theor Appl Genet

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The conventional way to drive modifications in old forest tree seed orchards is to establish progeny trials involving each parent tree and then evaluate its contribution to the performance of the progeny by estimating its general and specific combining ability (GCA and SCA). In this work, we successfully applied an alternative parent selection tactic based on paternity testing of superior offspring derived from a hybrid seed orchard established with a single Eucalyptus grandis seed parents and six E. urophylla pollen parents. A battery of 14 microsatellite markers was used to carry out parentage tests of 256 progeny individuals including two independent samples of selected trees and one control unselected sample, all derived from 6-year-old forest stands in eastern Brazil. Paternity determination was carried out for all progeny individuals by a sequential paternity exclusion procedure. Exclusion was declared only when the obligatory paternal allele in the progeny tree was not present in the alleged parent tree for at least four independent markers to avoid false exclusions due to mutation or null alleles. After maternity checks to identify seed mixtures and selfed individuals, the paternity tests revealed that approximately 29% of the offspring was sired by pollen parents outside the orchard. No selfed progeny were found in the selected samples. Three pollen parents were found to have sired essentially all of the offspring in the samples of selected and non-selected progeny individuals. One of these three parents sired significantly more selected progeny than unselected ones ( P< or =0.0002 in a Fisher exact test). Based on these results, low-reproductive-successful parents were culled from the orchard, and management procedures were adopted to minimize external pollen contamination. A significant difference ( P<0.01) in mean annual increment was observed between forest stands produced with seed from the orchard before and after selection of parents and revitalization of the orchard. An average realized gain of 24.3% in volume growth was obtained from the selection of parents as measured in forest stands at age 2-4 years. The marker-assisted tree-breeding tactic presented herein efficiently identified top parents in a seed orchard and resulted in an improved seed variety. It should be applicable for rapidly improving the output quality of seed orchards, especially when an emergency demand for improved seed is faced by the breeder.

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Section: Discussionmentioning

confidence: 99%

Retrospective selection of elite parent trees using paternity testing with microsatellite markers: an alternative short term breeding tactic for Eucalyptus

Grattapaglia

Ribeiro

Rezende³

2004

Theor Appl Genet

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“…Two seed lots showed complete outcrossing with no self-pollination events observed. Campinhos et al (1998) reported variation in individual outcrossing rates (t m =0.33-0.99) that was entirely due to environmental influences, as the individual trees were genetically identical clones of E. grandis. A previous study of E. grandis in natural populations showed a larger variation in outcrossing rates, with t m ranging from 0.34 to 1.48 for individual trees (Burgess et al 1996).…”

Section: Outcrossing Ratesmentioning

confidence: 99%

Pollen flow in Eucalyptus grandis determined by paternity analysis using microsatellite markers

Jones

Shepherd

Henry

et al. 2007

Tree Genetics & Genomes

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Gene flow by pollen dispersal from forestry plantations containing introduced species, provenances or selected elite breeding material may impact on local native forest by changing the genetic diversity, introducing new genes or gene combinations, or causing the extinction of rare genotypes in adjacent native forest areas. Patterns of pollen flow can be used to assess the risk of genetic pollution of native forest areas from nearby plantations. Pollen flow in an artificial population of Eucalyptus grandis was estimated using molecular markers and paternity analysis. Microsatellite genotyping was used to identify pollen parents of progeny arrays from six mother trees. Of 329 progeny analysed, 178 (54%) were assigned to pollen parents within the population. Pollen parents located within the population were between 0-192 m from the respective mother trees, with an average pollination distance of 57.96 m. Pollination of mother trees was outcrossed, not by nearest neighbours, and displayed a preference for inter-provenance matings within the population. Progeny that could not be assigned pollen parents within the population (46%) were assumed to have resulted from pollen immigration from external sources. These pollen flow parameters provide useful information about the dynamics of pollen movement within E. grandis populations and may be used in risk assessment of gene flow from plantations to adjacent areas of native forest.

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“…Similarly, RAO et al (2008) found relatively high levels of contamination in an E. globulus seed orchard in Victoria (Australia) (17.6 %) from neighbouring E. globulus plantations, presumably because of the small size of the seed orchard and low levels of flowering. Two isozyme based studies of mixed clonal orchards of E. grandis and E. urophylla in Brazil reported contamination rates into these orchards of 14.2 % (with a 400 m buffer of native tropical forest; CAMPINHOS et al, 1998) and 2.8 % respectively (with an 800 m buffer of native tropical forest; JUNG-HANS et al, 1998). The estimates of contamination are likely to be conservative as contamination was assumed only when allozymes not found amongst the clones in the orchard were identified in the progeny and cryptic gene flow is likely to be higher than with microsatellite markers (BYRNE, 2007).…”

Section: Resultsmentioning

confidence: 99%

Microsatellite Based Paternity Analysis in a Clonal Eucalyptus nitens Seed Orchard

2010

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Microsatellite markers were used to determine paternity in 473 open-pollinated progenies from a clonal Eucalyptus nitens seed orchard of 50 trees from 12 different genotypes. The outcrossing rate in this orchard was high, averaging 0.85 (weighted by capsule crop) but variable between trees (ranging from 0.6-1.0). Paternal contribution of each genotype to the open-pollinated seed crop was predicted by the size of the flower crop of each genotype (r = 0.76), but not the number of ramets. While the detectable contamination in this orchard is relatively low (4.5%), it is atypical when compared to other published estimates in eucalypt seed orchards suggesting that with suitable buffering low levels of contamination can be achieved.

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Interspecific hybridization and inbreeding effect in seed from a Eucalyptus grandis x E. urophylla clonal orchard in Brazil

Cited by 18 publications

References 13 publications

Retrospective selection of elite parent trees using paternity testing with microsatellite markers: an alternative short term breeding tactic for Eucalyptus

Retrospective selection of elite parent trees using paternity testing with microsatellite markers: an alternative short term breeding tactic for Eucalyptus

Pollen flow in Eucalyptus grandis determined by paternity analysis using microsatellite markers

Microsatellite Based Paternity Analysis in a Clonal Eucalyptus nitens Seed Orchard

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