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  • Author: M.L.T. Moraes x
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Estimating coancestry within open-pollinated progenies of a dioecious species: the case study of Myracrodruon urundeuva

Abstract

Understanding the coancestry coefficient within openpollinated progenies has long been an area of interest because of the implications of coancestry on estimates of additive genetic variation, variance effective size and the number of seed trees required for seed collection for ex situ conservation, tree breeding and environmental restoration. This study compares three methods to calculate the coancestry coefficient within open-pollinated progenies of the dioecious tree species, Myracrodruon urundeuva, using six microsatellite loci. The methods compared were: i) correlated mating model (CMM) (RITLAND, 1989); ii) TWOGENER method (SMOUSE et al., 2001) to estimate the differentiation among pollen pools (TGM); and iii) HARDY et al.’s 2004 method using the estimate of coancestry from LOISELLE et al. (1995) (HLM) and from RITLAND (1996) (HRM). The data analysis was based on four data sets: two populations were composed of 12 progenies, two of 24 progenies, and all progenies consisted of 15 plants. The coancestry estimated using CMM ranged among populations from 0.145 to 0.158, using TGM it ranged from 0.153 to 0.181, using HLM from 0.153 to 0.162, and HRM from 0.144 to 0.147. To investigate the bias of the estimates of true relatedness within progenies we simulated two half-sib and two full-sib populations. The most accurate method found in the study was CMM because the estimated values presented no bias for true half- or full-sib progenies and these values were very similar to those expected (0.125 and 0.25, respectively). These results have significant implications for breeding and conservation programs because coancestry-within-progenies is a key parameter in assessing the variance effective size.

Open access
Individual, fruit, and annual variation in correlated mating in a Genipa americana population

Abstract

In this paper, we use six microsatellite loci to examine a spatially isolated population of Genipa americana in relation to mating system variation at the level of individual and among and within fruits, over two reproductive events. For our analysis, we sampled hierarchically among and within fruits open-pollinated seeds collected from 13 seed trees during the reproductive event in 2010 and 12 seed trees in 2011. The rate of mating among relatives (1-ts) was significantly greater than zero and different between the investigated reproductive events, indicating that some seeds are inbred. The estimate of fixation index (Fo) was significantly higher than zero for seeds from both reproductive events (2010: Fo = 0.258; 2011: Fo = 0.294), confirming that seeds present inbreeding, probably originated from mating among full-sibs. The multilocus paternity correlation within fruits (rp(w)) and among fruits (rp(a)) varied among seed trees and reproductive events. The rp(w) was significantly higher than rp(a) in both reproductive events, suggesting that it is more likely to find full-sibs within fruits (2010: 36.4%; 2011: 72.4%), than among fruits (2010: 18.9%; 2011: 12.8%). Due to the presence of inbreeding, mating among relatives and correlated mating, the within families coancestry coefficient (Θ) was higher and the variance effective size (Ne) lower than expected in open-pollinated families from panmictic populations (Θ = 0.125, Ne = 4). In practical terms for conservation programs, our results show the need to collect seeds from at least 60 seed trees to retain progeny arrays with a total effective size of 150.

Open access
Validation of microsatellite loci for Balfourodendron riedelianum through analysis of Mendelian inheritance, genetic linkage, and genotypic linkage disequilibrium

Abstract

Balfourodendron riedelianum is a tropical tree endemic to the Atlantic Forest biome that is currently endangered due to forest fragmentation and extensive exploitation. Three populations of the species are conserved ex situ in a provenance and progeny test at the Luiz Antônio Experimental Station, São Paulo State, Brazil. To verify if seven microsatellite loci developed for the species can be used as genetic markers in analyses focused on conservation and sustainable use strategies, leaf tissue samples were collected from the three provenances and from 17 seed trees in one provenance. We analyzed Mendelian inheritance and genetic linkage for the 17 seed trees and genotypic linkage disequilibrium for individuals from the three provenances. For six of the seven loci analyzed, all 17 seed trees showed heterozygosity. The inheritance and genetic linkage analyses were performed using respective locus, while the genotypic linkage disequilibrium analysis was performed for the seven loci. After Bonferroni correction, none of the 75 tests showed deviation from Mendelian segregation and genetic linkage, nor did we detect genotypic linkage disequilibrium. The results suggest that six of the seven loci can be used for population genetics studies on B. riedelianum.

Open access
Genetic variation in silvicultural traits and carbon stock content in a provenance-progeny test of Genipa americana L. (Rubiaceae)

Abstract

The aim of this study was to determine the genetic variation of growth traits, wood basic density, dry mass of crown, leaf, and stem, and carbon stock within and between two Genipa ameri­cana L. provenances. The provenance and progeny test was installed in the Teaching, Research and Extension Farm, located in Selvíria, Mato Grosso do Sul, Brazil. The test was established using a randomized block design with two provenances and 36 progenies, a spacing of 3 x 2 m, four replicates, and six plants per plot. At 11 years of age, height and diameter at breast height (DBH) were measured. To estimate wood basic density, biomass, and carbon stock, 45 plants were thinned. Growth traits for crown, leaf, and stem, as well as wood basic specific gravity showed significant differences. Both provenances pre­sent high carbon storage, demonstrating the potential of this species to be included in carbon credit programs that help to minimize the effects of global warming. In general, heritability values were low, suggesting limited genetic control of the eva­luated traits. However, the traits presented a high coefficient of genetic variation, indicating adequate sampling among popu­lations; these results are promising for ex situ conservation and for future breeding programs.

Open access
Genotype x Environment interaction, stability, and adaptability in progenies of Eucalyptus urophylla S.T. BLAKE using the AMMI model

Abstract

One of the determinant factors in the success of breeding pro­grams that aim to select genotypes for different geographical regions is understanding the interaction between genotypes and environments (GxE). The objectives of this study were to evaluate GxE interaction, stability, and adaptability, and deter­mine the need for environmental stratification of open pollina­ted progenies of Eucalyptus urophylla. Five progeny tests were established in study areas with different environmental condi­tions in southeast and mid-west Brazil. We used a complete randomized block experimental design with 138 to 167 proge­nies, and variations in the numbers of replicates and plants per plot. The trait measured was diameter at breast height (DBH) at two years of age and the AMMI method was used to determine patterns of GxE interaction. Significant effects were detected for genotypes, environments, and for GxE interaction. The effect of environment was responsible for the greatest propor­tion of the phenotypic variation, followed by the effect of genotypes and GxE interaction. Some progenies with greater productivity and stability were identified, although stability is not associated with productivity. The stratification of the selec­tion in three specific environments is necessary due to the occurrence of a complex GxE interaction.

Open access
Maintenance of genetic diversity in Eucalyptus urophylla S. T. Blake populations with restriction of the number of trees per family

Abstract

Our aim was to verify the effect on gain and genetic diversity through the restriction of the number of trees per family in selection, in order to compose an elite population of Eucalyp­tus urophylla in two trials under distinct management levels. We studied 166 open-pollinated families of E. urophylla in Anhembi, Sao Paulo State, Brazil under commercial practices, and the same families in Selvíria, Mato Grosso do Sul State, Bra­zil under lower management level (mainly no mineral fertiliza­tion). Mortality, height and diameter at breast height (DBH) were measured. DBH was analyzed by the REML/BLUP to select the best 25 trees, with four levels of tree restriction per family (no restriction; 1; 2 and 3 per family). We evaluated heritability; genetic gain and effective size of number of total and private alleles; observed and expected heterozygosity; coancestry and fixation index. A large difference in survival (48 and 83 %) and productivity (MAI of 26 and 44 m3ha-1y-1) was observed bet­ween trials due to the different levels of management applied. The highest restriction in number of individuals per family caused a small decrease in gain, corresponding to 7 % in the more productive trial and 3 % in the less productive one. Observed and expected heterozygosity, coancestry and fixati­on index were not significantly (lower than 5 %) affected by the restriction in both sites. The restriction of one tree per family allowed different alleles to be kept in the selected population and higher effective population size in order to insure variation for the next generations.

Open access
Adaptability, stability, productivity and genetic parameters in slash pine second-generation families in early age

Abstract

The study was conducted to estimate the stability, adaptability, productivity and genetic parameters in Slash pine second-generation half-sib families, considering phenotypic traits in early age. Forty-four families from a first generation seed orchard in Colombo-PR, Brazil, were used in this study. Two progenies tests were established in a randomized complete block design. The first test was implemented in March 2009 in Ribeirão Branco, São Paulo state, containing 40 blocks, one tree per plot, 44 treatments (progenies) and 6 controls. Another test was implemented in Ponta Grossa, Paraná state, using the same experimental design and number of plants per plot, and with 24 treatments, 32 blocks. The growth traits evaluated were total height, diameter at breast height (dbh) and wood volume, within five years. The form traits evaluated were stem form, branch thickness, branch angle, number of branches, fork and fox tail five years after planting. Deviance analysis and estimates of stability, adaptability, productivity and genetic parameters were performed using the methods of best linear unbiased predictor (BLUP) and residual maximum likelihood (REML). There was significant variation among progenies for growth and form traits. Considerable genetic variation was detected mainly for wood volume. High coefficients of genetic variation and heritability showed low environmental influence on phenotypic variation, which is important for the prediction of genetic gain by selection. Crosses between different progenies individuals groups will be prioritized for obtaining heterotics genotypes and increase the probability of obtaining high specific combining ability.

Open access
Pollen contamination and nonrandom mating in a Eucalyptus camaldulensis Dehnh seedling seed orchard

Abstract

Eucalyptus camaldulensis has potential for timber, energy, pulp and cellulose production in Brazil due to its ability to adapt to a variety of environmental conditions. The use of improved seeds, selected for economic growth traits, is necessary to increase productivity of commercial stands. Seed seedlings orchards (SSO) are one option for improved seed production. However, pollen contamination from unimproved populations, as well as non-random mating in the SSO, can decrease the predicted genetic gains in selected populations. Thus, we investigate the mating system, pollen flow and dispersal patterns in an E. camaldulensis SSO and progeny test (PT), established with seedlings collected in the SSO, using seven microsatellite loci. All trees in the SSO were mapped, sampled, and genotyped. For the PT, we sampled, genotyped, and measured the total height of seedlings from 25 families. We detected 10 % inbreeding in the PT, resulting mainly from selfing. Furthermore, we found a correlated mating rate of 18.5 % in the SSO, indicating that within the PT there are some full-sibs. Using paternity analysis, we found 14.7 % pollen contamination and a pattern of pollen dispersal between near neighbor trees in the SSO. We found 9.5 % of inbreeding depression for seedlings height. Due to pollen contamination and nonrandom mating in the SSO, the actual genetic gains for growth traits in the PT are probably lower than the predicted genetic gains. We discuss some management strategies in the SSO that can be used to increase genetic gains in commercial reforestation established using seeds collected from the SSO

Open access
Clonal selection of Eucalyptus grandis x Eucalyptus globulus for productivity, adaptability, and stability, using SNP markers

Abstract

In Uruguay, reforestations with Eucalyptus sp. is of fundamental importance to supply paper, pulp, and wood production. This study investigates genetic, productivity, stability, and adaptability parameters in the selection of Eucalypts grandis x Eucalyptus globulus full-sib hybrid clones. The study was conducted in a clonal test, repeated in two different soils types, in Rio Negro State, Uruguay. The population was characterized phenotypically for diameter at breast height (dbh) and genotyped for SNP markers (EuCHIP60K chip). Mean dbh was similar between sites and the genotype–environment interaction was simple. We found high genotype correlation in clone performance between environments (0.708), indicating the possibility of selecting the same clones for both study locations. Mean heritability between clones (0.724), coefficient of individual genetic variation (10.9 %), and relative variation (0.916), suggest the possibility of gains (estimated at 3.1 % for both sites together) by selecting clones with higher growth rates. A total of 15,196 SNPs were used to confirm parentage and test a genomic selection model for dbh. The predictive capacity was negative (-0.15) given the small population size (78 individuals). The most adaptable material among the tested study sites presented higher values for SNP heterozygosity. Thus, using molecular markers to identify clones responsive to environmental changes can act as a powerful tool in Eucalyptus breeding programs. The hybrid population showed greater adaptability than E. globulus for this region.

Open access
Genetic control of silvicultural traits in Balfourodendron riedelianum (ENGL.) ENGL.

Abstract

The Atlantic Forest has very high levels of biodiversity and is considered one of the most important and threatened biomes in the world. Balfourodendron riedelianum is one of the forest’s characteristic tree species that is currently under considered endangered due to timber extraction and forest fragmentation. With the goal of generating information that may contribute to the genetic conservation of B. riedelianum, genetic parameters are estimated for quantitative traits important for silviculture in a provenance and progeny test located in the Experimental Station of Luiz Antônio, São Paulo State, Brazil. The test was established in 1986 and consists of three provenances, from which open-pollinated seeds from 19 seed trees were collected. The following traits were evaluated at 32 years of age: diameter at breast height (DBH), total height (H), stem height (SH), stem straightness (SS), and forking (FOR). The estimates were carried out using the REML/BLUP method. Significant genetic variation among progenies was detected for all traits (except SH) and between provenances for DBH. The coefficient of individual genetic variation (CV gi) ranged from 2.5 to 9.5 %. The mean heritability among progeny (hf2) was substantial for DBH (0.44) and FOR (0.36), enabling the selection of families with the highest DBH and lowest FOR for population improvement. Genotypic and phenotypic correlations among traits were also found. We conclude that there is genetic variability in the population that can be exploited in future breeding programs and for the genetic conservation of the species.

Open access