Washington J. Gapare

Phylogeography of Quercus variabilis Based on Chloroplast DNA Sequence in East Asia: Multiple Glacial Refugia and Mainland-Migrated Island Populations

The biogeographical relationships between far-separated populations, in particular, those in the mainland and islands, remain unclear for widespread species in eastern Asia where the current distribution of plants was greatly influenced by the Quaternary climate. Deciduous Oriental oak (Quercus variabilis) is one of the most widely distributed species in eastern Asia. In this study, leaf material of 528 Q. variabilis trees from 50 populations across the whole distribution (Mainland China, Korea Peninsular as well as Japan, Zhoushan and Taiwan Islands) was collected, and three cpDNA intergenic spacer fragments were sequenced using universal primers. A total of 26 haplotypes were detected, and it showed a weak phylogeographical structure in eastern Asia populations at species level, however, in the central-eastern region of Mainland China, the populations had more haplotypes than those in other regions, with a significant phylogeographical structure (N ST = 0.751> G ST = 0.690, P<0.05). Q. variabilis displayed high interpopulation and low intrapopulation genetic diversity across the distribution range. Both unimodal mismatch distribution and significant negative Fu’s FS indicated a demographic expansion of Q. variabilis populations in East Asia. A fossil calibrated phylogenetic tree showed a rapid speciation during Pleistocene, with a population augment occurred in Middle Pleistocene. Both diversity patterns and ecological niche modelling indicated there could be multiple glacial refugia and possible bottleneck or founder effects occurred in the southern Japan. We dated major spatial expansion of Q. variabilis population in eastern Asia to the last glacial cycle(s), a period with sea-level fluctuations and land bridges in East China Sea as possible dispersal corridors. This study showed that geographical heterogeneity combined with climate and sea-level changes have shaped the genetic structure of this wide-ranging tree species in East Asia.

Genetic correlations among juvenile wood quality and growth traits and implications for selection strategy in Pinus radiata D. Don

Abstract• Juvenile wood quality in Pinus radiata is affected by factors such as low density, stiffness, and high microfibril angle, spiral grain, and shrinkage. Adverse genetic correlations between growth and wood quality traits remain as one of the main constraints in radiata pine advanced generation selection breeding program.• Juvenile wood property data for this study were available from two progeny tests aged 7 and 6 y. We estimated the genetic correlations between stiffness, density, microfibril angle, spiral grain, shrinkage in the juvenile core and DBH growth in radiata pine, and) to evaluated various selection scenarios to deal with multiple objective traits.• Negative genetic correlations were found for modulus of elasticity (MoE) and density with microfibril angle, spiral grain, shrinkage, and DBH. We observed low to moderate unfavourable genetic correlations between all wood quality traits and DBH growth.• These low to moderate genetic correlations suggest that there may be some genotypes which have high DBH growth performance while also having high wood stiffness and density, and that the adverse correlation between DBH and MoE may not entirely prohibit the improvement of both traits. Results indicate that, in the short term, the optimal strategy is index selection using economic weights for breeding objective traits (MAI and stiffness) in radiata pine.• In the long-term, simultaneously purging of the adverse genetic correlation and optimizing index selection may be the best selection strategy in multiple-trait selection breeding programs with adverse genetic correlations.Résumé• La qualité du bois juvénile chez Pinus radiata est affectée par des facteurs tels que la faible densité, la rigidité, et un angle de microfibrille grand, la fibre torse, et les fentes de retrait. Les mauvaises corrélations génétiques entre la croissance et les caractéristiques de la qualité du bois restent l’une des principaux obstacles à un programme poussé d’amélioration de Pinus radiata. Les données sur les propriétés du bois juvénile pour cette étude étaient disponibles à partir de deux tests de descendance âgés de 7 ans et 6 ans. Nous avons estimé les corrélations génétiques entre la rigidité, la densité, l’angle des microfibrilles, la fibre torse, les fentes de retrait dans le cœur juvénile et la croissance en diamètre à hauteur de poitrine (DBH) de Pinus radiata, et pour évaluer différents scénarios de sélection pour faire face à de multiples caractéristiques objectives.• Des corrélations génétiques négatives ont été trouvées pour le module d’élasticité (MoE) et la densité avec l’angle des microfibrilles, la fibre torse, les fentes de retrait, et la croissance en diamètre à hauteur de poitrine (DBH). Nous avons observé des corrélations génétiques défavorablement faibles à modérées entre toutes les caractéristiques de la qualité du bois et la croissance en diamètre à hauteur de poitrine (DBH).• Ces corrélations génétiques faibles à modérées suggèrent que peut être certains génotypes, ont une croissance importante en diamètre à hauteur de poitrine (DBH) tout en ayant une rigidité et une densité du bois élevée, et que les corrélations défavorables entre DBH et MoE peuvent ne pas interdire entièrement l’amélioration de ces deux caractéristiques. Les résultats indiquent que, dans le court terme, la stratégie optimale est l’index de sélection en utilisant le poids économique pour un objectif d’amélioration des caractéristiques (AMI et rigidité) chez Pinus radiata.• À long terme, à la fois la purge de la corrélation génétique défavorable et l’optimisation de l’index de sélection peut être la meilleure stratégie de sélection multicaractère dans les programmes sélection amélioration ayant des corrélations génétiques défavorables.

Genetic Parameters and Genotype by Environment Interaction in Radiata Pine for Growth and Wood Quality Traits in Australia

Abstract The phenotypic response of genotypes across different environments can be quantified by estimating the genotype by environment interaction (GxE). In a practical sense, GxE means that the relative performance of genotypes does not remain constant under all test conditions. Genetic parameters and genotype by environment interactions for wood density, growth, branching characteristics and stem straightness were investigated in eight radiata pine progeny trials derived from a second generation breeding population in Australia. Five trials were on the mainland, while three trials were in Tasmania. Generally, ĥ2 for density > branch angle > stem straightness > tree diameter > branch size; and significant ĥ2 was observed for all traits and at all trials with only two exceptions. Genetic correlations were estimated among the five traits, and a large negative genetic correlation observed between wood density and tree diameter indicated that a selection strategy should be developed in dealing with this adverse genetic correlation in advanced generations of breeding for radiata pine. Interactions for density, branch angle, and stem straightness were small within the two regions. Overall, branch angle had the least GxE, followed by density and stem straightness. Growth traits (tree diameter and branch size) tended to be the most interactive with substantial GxE present. Genotype by regional interactions (Mainland versus Tasmania) revealed that density and branch angle had the least interactions (ȓB = 0.98 and ȓB = 0.95, respectively). Branch size and tree diameter had the highest interactions among the two regions (ȓB = 0.55 and ȓB = 0.63, respectively). Within Tasmania, only branch size and tree diameter had a sizable interaction within the three sites. In contrast, there was little interaction for tree diameter among the Mainland trials. Branch size in the Mainland trials had a similar size of interaction as in Tasmania. Further research is recommended in identifying the cause of GxE for tree diameter and branch size in radiata pine across the entire radiata pine estate in Australia.

Genetic parameters and provenance variation of Pinus radiata D. Don. ‘Eldridge collection’ in Australia 1: growth and form traits

Growth and form traits data were obtained from eight provenance trials of radiata pine (Pinus radiata D. Don) planted across the radiata pine plantation estate in southeast Australia. The genetic pool included 466 open-pollinated families collected from Año Nuevo, Monterey and Cambria provenances on the Californian mainland coast in the USA and from Guadalupe and Cedros islands off the coast of Baja California in Mexico. Early survival of all provenances was around 90%, except for Cedros (<60%). Monterey and Año Nuevo were the best performers at almost all sites. However, good growth performance of Cambria and good stem straightness of Guadalupe on some sites are important results, because the genetic base of the present Australian plantations evidently originated from only Monterey and Año Nuevo. The average estimated single-site heritability for diameter at breast height was 0.22 and 0.32 at juvenile and mature ages, respectively. Heritability estimates for stem straightness and branching ranged from 0.23 to 0.55. Genetic correlation estimates between diameter at breast height (DBH) at juvenile and rotation ages were all >0.80. Estimates of between-site genetic and provenance correlations for DBH were often low, indicating high genotype by environment interaction across trials, consistent with previous Australian studies. However, there was minimal G × E among trials on high-altitude high-rainfall sites and among trials on low-altitude, low-rainfall sites.

Inheritance of spiral grain in the juvenile core of Pinus radiata

Spiral grain is the angular arrangement of fibres in a tangential plane with reference to the pith or vertical tree axis. Spiral grain angles exceeding 5° can cause wood to twist, which may result in a considerable amount of waste and degrade. We assessed spiral grain at breast height in two related progeny tests of radiata pine (Pinus radiata D. Don) aged 8 and 9 years established at two different sites in Australia. Radial trends for grain angle at the two sites were similar. Mean spiral grain (MSG) across the two trials was 4.3° with a standard deviation of 1.5° and a range of 0.8–10°. Estimates of individual tree heritabilities on a single-site basis for individual rings and MSG suggested that spiral grain is lowly to highly inherited (h2 = 0.11 ± 0.08 to 0.66 ± 0.21 for individual rings and 0.44 ± 0.12 for MSG). Additive genotypic correlations between individual rings grain angle and MSG were generally high, above 0.71, suggesting a favourable expected correlated response of mean grain angle in the j...

Influence of cambial age and climate on ring width and wood density in Pinus radiata families

Abstract• ContextThe correlation between tree ring width and density and short-term climate fluctuations may be a useful tool for predicting response of wood formation process to long-term climate change.• AimsThis study examined these correlations for different radiata pine genotypes and aimed at detecting potential genotype by climate interactions.• MethodsFour data sets comprising ring width and density of half- and full-sib radiata pine families were used. Correlations with climate variables were examined, after the extraction of the effect of cambial age.• ResultsCambial age explained the highest proportion of the ring to ring variation in all variables. Calendar year and year by family interaction explained a smaller but significant proportion of the variation. Rainfall had a positive correlation with ring width and, depending on test site, either a negative or positive correlation with ring density. Correlations between temperature during growing season and ring density were generally negative.• ConclusionClimate variables that influence ring width and wood density can be identified from ring profiles, after removing the cambial age effect. Families can be selected that consistently show desirable response to climate features expected to become prevalent as a result of climate change.

Genetic parameters and provenance variation of Pinus radiata D. Don. 'Eldridge collection' in Australia 2: wood properties

Provenance variation and genetic parameters for wood properties of mature radiata pine (Pinus radiata D. Don) were studied by sampling three provenance/progeny trials in southeast Australia. Among the mainland provenances, Monterey and Año Nuevo had higher density and modulus of elasticity (at one site) than Cambria. Basic density and predicted modulus of elasticity (MoE) for the island provenances, Guadalupe and Cedros, were ∼20% higher at Billapaloola compared to mainland provenances grown at Green Hills and Salicki, differences that may or may not be linked to site differences. Heritability estimates of density, predicted MoE and microfibril angle were significant and

Risks Affecting Breeding Objectives for radiata pine in Australia

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