N. Negishi, K. Nanto, K. Hayashi, S. Onogi and A. Kawaoka
Eucalyptus globulus is the main hardwood species grown in pulpwood plantations in temperate regions of the world. We have cloned six genes influencing wood quality including the LIM domain transcription factor (LIM), 4-coumarate-CoA ligase (4CL), coniferaldehyde 5-hydroxylase (CAld5H) and the three catalytic units of cellulose synthase (CesA), from E. globulus. The transcript abundances of LIM in basal stems of ten independent E. globulus lines showed similar patterns to those of 4CL. We investigated the correlation between gene transcript abundances and wood qualities such as Klason lignin (KL) content, syringaldehyde/vanillin (S/V) ratio and holocellulose (HC) content. Expression of the LIM and 4CL were positively correlated with KL content. A highly significant positive correlation was observed between CAld5H expression and S/V ratio. Furthermore, a ratio of the sum of the transcript abundances of three CesA1, CesA2 and CesA3 to 4CL showed a positive correlation with a ratio of HC/KL content that positively correlated with the chemically extracted fiber content in this woody plant.
Sri Rahayu, Nor Aini Ab. Shukor, Lee Su See and Ghizan Saleh
Falcataria moluccana (batai) is one of the valuable multipurpose tree species for forest plantations, particularly in Malaysia and Indonesia. Gall rust disease caused by Uromycladium tepperianum (Sacc.) is one of the most destructive diseases in Batai plantations. The disease causes severe damage at all developmental stages of the plant from the nursery stage to mature trees in the field and includes the development of chocolate brown, cauliflower-like or whip-like galls on the stem, branch, petiole, shoot and pod. Different seed sources may respond differently to gall rust fungus. Thus, the responses of F. moluccana seedlings from 6 selected seed sources to gall rust disease caused by U. tepperianum, were evaluated, at the Brumas Estate, Malaysia, in terms of gall rust disease severity, mortality, and disease infection rate of the seedlings. Based on disease severity, infection rate and cumulative mortality due to gall rust disease, the wamena was found to be the best seed source in relation to gall rust disease resistance.
Terrance Z. Ye, K. J. S. Jayawickrama and J. B. St. Clair
Realized gains for coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) were evaluated using data collected from 15-year-old trees from five field trials planted in large block plots in the northern Oregon Cascades. Three populations with different genetic levels (elite - high predicted gain; intermediate - moderate predicted gain; and unimproved - wild seedlot) were compared at two planting spacings (1.8 × 1.8 m and 3.6 × 3.6 m). The realized gains at age 15 averaged over both the elite and intermediate progeny were 17.2% for stand volume per hectare, 3.5% for mean height, and 4.3% for diameter, compared to predicted genetic gains of 16.0% for volume, 5.4% for height, and 6.4% for diameter. Realized and predicted gains correlated well at the family level, with an average correlation coefficient close to 0.80. The improved populations also had higher survival rate and lower stem sinuosity than the unimproved population. Strong genetic level × planting spacing interaction effects were revealed for the growth traits at age 15 using mixed model analyses. Realized gains for stand per-hectare volume and mean growth rate were at least twice as large in the elite population as in the intermediate population at the close spacing. By contrast, both populations performed similarly at the wide spacing. This indicates that the selected genetic materials responded differently to the changes of competitive environment, and realized gain trials should closely mimic operational plantations in order to provide valid estimates of realized gains. Realized gains in per-hectare volume varied greatly among test sites. No significant genetic level x site interactions were found for any traits.
Elizabeth M. Gillet, Martin Ziehe and Hans-Rolf Gregorius
Viability selection can be detected directly in an environment when the genotypes of the individuals at one ontogenetic stage (e.g. seeds) and the genotypes of the survivors at a later stage are both known, but genotypes at the earlier stage often cannot be determined. In this case, differential viability selection between environments can be detected as differences in the distributions of genetic types among survivors growing in different environments, provided that the survivors stem from random samples of seeds from the same base population (e.g. seed lot). Since common FST-outlier methods for detecting selected gene loci use only allele frequencies, selection that affects the higher hierarchical levels of genetic integration (single- or multi-locus genotypes) without changing allele frequencies is not noticed. A new method for detecting differential viability selection at any level of genetic integration enables discovery of elementary mechanisms of selection that older methods miss. It is based on two measures of compositional differentiation between environments. δSD measures qualita-tive differences between distributions of genetic types at any given integration level without regarding differences in their constituent alleles, while ΔSD measures quantitative differences between the same distributions by additionally considering the genic differences. The difference between these measures expresses the degree to which the patterns of gene association in the genotypes differ between environments. The P-values of all measures are estimated by permutation analysis under the assumption that survivors were randomly assigned to environments. Significance indicates the occurrence of differential viability selection at the loci. As a case study, a field study of viability in juvenile beech (Fagus sylvatica L.) for twelve enzyme loci is reanalyzed. It turns out that the significant differential selection for genotypes detected at three loci can be attributed to three combinations of selective effects: on alleles only (SKDH-A), mostly alleles but also association patterns (LAP-A); interaction of effects on alleles and association patterns that are non-significant when viewed separately (AAT-B).
L. Zhang, N. Huanqiong, Washington J. Gapare, S. K. Dillon, X. Li and H. X. Wu
Genetic diversity within radiata pine first generation of open-pollinated selections (OPS) from the native resource stands was compared with that observed in native populations to monitor potential changes in genetic diversity during domestication. Genetic diversity was estimated using 58 single nucleotide polymorphisms (SNPs) from 8 expressed genes. Nucleotide diversity maintained in first generation of selections (OPS) (mean π = 0.0036; mean θw = 0.0058) was similar to that found within the native population material (mean π = 0.0043; mean for θw = 0.0065). Likewise, mean values for expected heterozygosity (HE) within and between native population material and OPS were similar (mean = 0.27 ± 0.04) and not significantly different (P = 0.068). Also, the overall distribution of allele frequency classes was not significantly different between native population material and OPS. These results point to no evidence of loss of diversity in OPS due to artificial selection. One possible reason is that the domestication of the OPS is at a very early stage. Another may be that artificial selection in the OPS was based on tree growth and form, not wood properties. The genes selected in this study are mostly involved in cell wall formation, thus genetic diversity of these genes should remain stable between natural population and OPS, unless there was a significant sampling bias in the OPS. Although the SNP information suggests similarities among mainland populations, results from quantitative genetic studies found large provenance differences for growth-, morphological-, stem-form traits, and disease resistance. Determining the threshold at which genetic diversity levels will be significantly reduced during selection should help breeders to make informed decisions regarding the intensity of selection in managed breeding populations as well as gene resource populations.
M. A. Ortiz-Bibian, A. Blanco-García, R. A. Lindig-Cisneros, M. Gómez-Romero, D. Castellanos-Acuña, Y. Herrerías-Diego, N. M. Sánchez-Vargas and C. Sáenz-Romero
Conservation of Abies religiosa (sacred fir) within the Monarch Butterfly Biosphere Reserve (MBBR) in Mexico requires adaptive management to cope with expected climatic change, in order to have healthy trees for Danaus plexippus overwintering sites in the future. Open pollinated seeds from fifteen A. religiosa populations were collected along an elevational gradient (2850-3550 masl; one sampled population every 50 m of elevational difference). Seedlings were evaluated in a common garden test over a period of 30 months. We found significant differences (P < 0.03) among populations in total elongation, final height, date of growth cessation, foliage, stem and total dry weight, as well as frost damage. These differences were strongly associated with the Mean Temperature of the Coldest Month (MTCM; r2 = 0.6222, P = 0.0005). Seedlings originating from lower elevation populations grew more but suffered more frost damage than those from higher elevations. Populations differentiate genetically when they are separated by 364 m in elevation. Such differentiation was used to delineate three elevational/climatic zones for seed collection, with limits defined at: 2650 masl or 9.7 °C of MTCM; 3000 masl or 8.5 °C; 3350 masl or 7.3 °C; and 3700 masl or 6.1 °C. Zonification for seedling deployment aiming to match a suitable climate in year 2030 (after projections using an ensemble of 18 General Circulation Models and a Representative Concentration Pathway 6.0 watts/ m2), would have the same MTCM zone limits, but shifted 350 m upwards in elevation. This shift would exceed the highest elevations within the MBBR, necessitating the establishment of A. religiosa stands outside the MBBR, to serve as potential future overwintering sites.
Regeneration obligations in British Columbia for high-elevation coastal sites requires a secure seed supply of quality seed in coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Consequently, a seed orchard is under development to supply seed after genetic testing and selection. For this purpose, 55 coastal Douglas-fir families were field-tested for 11 years on two contrasting high-elevation sites to examine differential growth performance and tolerance to cold conditions. Although heritabilities for growth on both sites were moderate at age 11, the higher elevation colder site had substantially slower growth and over 90% of the trees exhibited some form of cold damage to foliage, branches and stems; however, variation in this damage was not significant at the family level. Combined site analysis revealed a highly significant genotype by environment (GxE) component in height that could not be removed or reduced by using site-specific error variances or spatial analysis (i.e., GxE was primarily due to rank changes of families across the two sites). This was also reflected by a drop in heritability estimates obtained from the combined site analyses. In the presence of this type of GxE, independent culling, considering height a separate trait on each site, was employed to identify parents that were at a threshold breeding value of 5% or greater in growth superiority on both sites. Average breeding values for the selected parents, based on a combined site analysis, were around 5% above the trial mean for height at age 11. The use of independent culling, for situations where accurate genetic parameters are difficult to obtain, should be considered a practical alternative to more complex and error prone methods of selection.
Naoko Miyamoto, Kazuya Iizuka, Jin’ya Nasu and Hiroo Yamada
Characteristic evaluation for forest tree genetic resources No.1 (This title is a tentative translation from the original Japanese by the author of this paper)
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A. H. Wiese, J. A. Zalesny, D. M. Donner and R. S. Zalesny
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RIEMENSCHNEIDER, D. E. and E. O. BAUER (1997): Quantitative
Two progeny trials of native provenances of Pinus radiata, representing the 1978 seed collection, were assessed for wood density and standing tree acoustic velocity. One trial, planted in 1980 in southern New South Wales, Australia contains all five provenances. The second trial, planted in the same region in 1982 contains only the island provenances. Results for extracted wood density, assessed from pith to bark in 5 ring segments, and standing tree acoustic velocity, measured at age 24 or 26 years, are reported. Large differences between the mainland and island provenance were apparent for wood density and stiffness. The mainland provenances were very similar for density and followed the “normal” pattern of change with a gradual increase from the pith, followed by a plateauing around age 20. Neither of the island provenances followed this pattern of change in density: Cedros had stable density across the 4 inner most segments and Guadalupe had stable density for the inner two segments followed by a linear increase. Juvenile density was higher in both the island provenances than the mainland provenances. The island provenances differed from each other for standing tree acoustic velocity, with velocity being higher in Guadalupe provenance. Heritabilities for wood density and acoustic velocity (average 0.37) were higher than those for tree growth and form. Across the stem radius, heritability of density was variable with some segments having zero heritabilities in some provenances, particularly Cambria, Cedros and Guadalupe. Heritability for acoustic velocity was highest for Cambria and the island provenances. Within the mainland provenances, little difference was found between populations for either wood density or acoustic velocity. Density and standing tree acoustic velocity were negatively genetically correlated with tree diameter. Differences in provenance means were greater for acoustic velocity than for density in the outermost segment. Provenance rankings also differed, with the rankings for acoustic velocity being similar to those for density in the 2nd segment from the bark. The genetic correlations between density and velocity reached a maximum for 3rd segment. These results indicate that outerwood density is not the sole driver of acoustic velocity, and that the sound wave is perhaps not travelling through the outer most wood, but is penetrating some distance into the tree.