Search

Russet formation in apple (Malus domestica Borkh.) is a superficial skin disorder that detracts from fruit appearance and is likely controlled by many small-effect quantitative trait loci (QTLs). Genomewide prediction has been reported to be an effective breeding approach when targeting highly quantitative traits in apple. Our objective was to investigate the utility of genomewide prediction for russet formation within an apple breeding program. Germplasm included 1,009 unselected offspring from 13 full-sib families derived from 14 breeding parents. 'Honeycrisp' and 'Minneiska', two breeding parents prone to moderate levels of russet, were highly represented. High-quality single nucleotide polymorphism data (947 SNPs) and three years of shoulder and lenticel russet formation data were leveraged in this study. Moderate predictive abilities (r = 0.28−0.35) were observed across training-testing set scenarios and models. In this germplasm, the inclusion of previously detected QTLs as fixed effects in the model did not have significant effects on predictive abilities. Postdiction (retrospective) analyses demonstrated that genomewide predictions and phenotypic observations agreed for 54% of advanced selections. Genomewide prediction is a promising approach when targeting russet formation, a trait that cannot be phenotypically observed in offspring in apple breeding programs until they are past their juvenile phase.

Casuarina equisetifolia, the most commonly grown species of Casuarina in India, is mainly used for pulpwood, scaffolding, poles, fuelwood and stakes for banana crop. It is most suited for agrarian ecosystems due to many favourable characteristics like desirable stem form and fast growth. It is one among the non-leguminous nitrogen fixing tree species also. In India, tremendous variations are documented for tree species in different states. Wide variations were observed when 23 international provenances of C. equisetifolia infused from CSIRO, Australia were subjected to multi-location field testing. Among the three primary characters which contribute directly towards volume growth, diameter at breast height showed higher degree of variation than total height in all the provenances. Volume index recorded the maximum genotypic coefficient of variation followed by frustum volume in all the provenances at 3 years of age. Tree height registered the lowest value for GCV and PCV. Among the various characters studied, frustum volume recorded the maximum heritability (0.24) followed by diameter at breast height, basal diameter and volume index (0.20). The lowest value was for tree height (0.05). Mahalanobis’ D2 statistics followed by Tocher’s clustering method grouped the 23 provenances of C. equisetifolia into 9 clusters with cluster strength varying from one (clusters 8 and 9) to eight (cluster 4). Clusters 4,5,7 and 9 registered higher mean values for frustum volume and volume index. Based on the genetic variability studies, it is concluded that provenances 18141 Kenya, 18378 QLD, 18298 Thailand, 18344 Malaysia, Mixed Seedlot India, 18586 China and 18355 Benin could be the potential candidates for future breeding programmes.

The GRAS (GAI\RGA\SCL) gene family encodes plant-specific transcription factors that play crucial roles in plant growth and development, stress tolerance, and hormone network regulation. Plant dwarfing symptom is mainly regulated by DELLA proteins of the GRAS gene subfamily. In this study, the association between the GRAS gene family and Paulownia witches' broom (PaWB) was investigated. A total of 79 PfGRAS genes were identified using bioinformatics methods and categorized into 11 groups based on amino acid sequences. Tandem duplication and fragment duplication were found to be the main modes of amplification of the PfGRAS gene family. Gene structure analysis showed that more than 72.1% of the PfGRASs had no introns. The genes PfGRAS12/18/58 also contained unique DELLA structural domains; only PfGRAS12, which showed significant response to PaWB phytoplasma infection in stems, showed significant tissue specificity and responded to gibberellin (GA3) in PaWB-infected plants. We found that the internodes were significantly elongated under 100 µmol·L−1 GA3 treatment for 30 days. The subcellular localization analysis indicated that PfGRAS12 is located in the nucleus and cell membrane. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays confirmed that PfGRAS12 interacted with PfJAZ3 in the nucleus. Our results will lay a foundation for further research on the functions of the PfGRAS gene family and for genetic improvement and breeding of PaWB-resistant trees. [ABSTRACT FROM AUTHOR]

Light is one of the most important environmental factors for plant growth. In the production process of tung oil tree cultivation, due to the inappropriate growth of shading conditions, the lower branches are often dry and dead, which seriously affects the yield of tung oil trees. However, little is known about the key factors of light-induced tree photomorphogenesis. In this study, a total of 22 VfBBX family members were identified to provide a reference for candidate genes in tung tree seedlings. All members of the VfBBX family have different numbers of highly conserved B-box domains or CCT domains. Phylogenetic evolution clustered the VfBBX genes into four categories, and the highest density of members was on chromosome 6. Interspecific collinearity analysis suggested that there were six pairs of duplicate genes in VfBBX members, but the expression levels of all family members in different growth and development stages of the tung tree were significantly divergent. After different degrees of shading treatment and physiological data determination of tung tree seedlings, the differential expression level and chlorophyll synthesis genes correlation analysis revealed that VfBBX9 was a typical candidate nuclear localization transcription factor that was significantly differentially expressed in light response. This study systematically identified the VfBBX gene family and provided a reference for studying its molecular function, enhanced the theoretical basis for tung tree breeding, and identified excellent varieties. [ABSTRACT FROM AUTHOR]

Background: Early selection in tree breeding could be achieved by addressing the longevity of tree improvement activities. Genetic parameter changes and age–age correlations are essential for determining the optimal timing of early selection. Practical tracking of genetic parameters of Pinus koraiensis, a major timber species with economic and ecological value, has become feasible as its progeny testing has entered the mid-term age in Korea. However, research on the age−age correlation of P. koraiensis as progeny trials approach rotation age is limited. This study aimed to investigate genetic parameter trends and age−age correlations in P. koraiensis progeny. P. koraiensis progeny were assessed at two sites using a linear mixed-effects model with two-dimensional spatial autoregressive structure. Height, diameter, and volume growth were measured in 11 assessments over 40 years. Results: Genetic parameters, such as height and diameter, showed different patterns of change. The heritability ranged for the three growth traits in 0.083–0.710, 0.288–0.781, and 0.299–0.755 across the sites and age. Height heritability and its coefficient of variance decreased, whereas the diameter and volume estimates remained relatively constant. Correlations with Age 40 for phenotypic, genetic, and rank of breeding values ranged between 0.16 and 0.92, 0.594 and 0.988, and 0.412 and 0.965, respectively. These correlations generally increased as the age approached Age 40, with particularly high levels observed at Age 26 and Age 30. Conclusion: The observed genetic trends in P. koraiensis progeny testing offer valuable insights for early and precise selection. Notably, selecting superior genotypes at Ages 26–30 is supported by discernible genetic gains and robust correlations. Future research should integrate unbalanced data for selecting mother trees or families and conduct a comprehensive economic analysis of early selection to validate its practical benefits. [ABSTRACT FROM AUTHOR]

Genotype-environment interaction is pervasive in forest genetics. Delineation of spatial breeding zones (BZs) is fundamental for accommodating genotype-environment interaction. Here we developed a BZ classification pipeline for the forest tree Eucalyptus globulus in 2 Australian regions based on phenotypic, genomic, and pedigree data, as well on a detailed environmental characterization ("envirotyping") and spatial mapping of BZs. First, the factor analytic method was used to model additive genetic variance and site–site genetic correlations (rB) in stem volume across 48 trials of 126,467 full-sib progeny from 2 separate breeding programs. Thirty-three trials were envirotyped using 145 environmental variables (EVs), involving soil and landscape (71), climate (73), and management (1) EVs. Next, sparse partial least squares-discriminant analysis was used to identify EVs that were required to predict classification of sites into 5 non-exclusive BZ classes based on rB. Finally, these BZs were spatially mapped across the West Australian and "Green Triangle" commercial estates by enviromic prediction using EVs for 80 locations and 15 sets of observed climate data to represent temporal variation. The factor analytic model explained 85.9% of estimated additive variance. Our environmental classification system produced within-zone mean rB between 0.76 and 0.84, which improves upon the existing values of 0.62 for Western Australia and 0.67 for Green Triangle as regional BZs. The delineation of 5 BZ classes provides a powerful framework for increasing genetic gain by matching genotypes to current and predicted future environments. [ABSTRACT FROM AUTHOR]

Key message: Superior F1 mulberry genotypes with high leaf yield, quality, and moderate to high stability were identified for optimal and sub-optimal input conditions. Mulberry (Morus spp.) is a highly heterozygous, perennial tree widely grown for its foliage to feed monophagous silkworms (Bombyx mori L.) and fruits for human consumption across the globe. The present study evaluated twenty-one F1 mulberry genotypes for the selection of superior ones based on leaf yield, yield attributes, leaf quality, and stability over two years under optimal and sub-optimal input (irrigation and fertilizer) conditions. Based on pooled data analysis over four crop seasons, it was found that six mulberry genotypes, D16, D21, D22, D23, D28, and D67, had leaf yields (663–840 g/plant) statistically similar to or better than the Vishala check (663 g/plant) under optimal conditions. Similarly, under sub-optimal conditions, seven genotypes, D16, D21, D22, D23, D24, D28 and D34, showed significantly higher leaf yields (418–596 g/plant) than Vishala (415 g/plant). The δ13C (a surrogate trait of water-use efficiency) of five mulberry genotypes, D16, D21, D24, D28, and D34, varied from – 28.21 to – 28.98 and was similar to the AGB8 check (– 28.87). Total soluble sugar, protein, chlorophyll content, and the silkworm moulting percentage and single larval weight for the seven genotypes D16, D21, D22, D23, D24, D28, and D34 were statistically similar to or better than Vishala under both optimal and sub-optimal conditions. The additive main effects and the multiplicative interaction-based simultaneous selection index showed that these seven genotypes had moderate to high stability and high leaf-yielding ability over the seasons under both optimal and sub-optimal conditions. DNA fingerprint profiles of these selected genotypes have been developed for their molecular identification. Under this context, these seven genotypes might be further tested under advanced evaluation trials to identify the best one regarding leaf yield and quality under optimal and sub-optimal conditions. [ABSTRACT FROM AUTHOR]

Selecting individuals in breeding programs for pulp production, the physical and chemical wood traits must be considered in the genotype selection. In this study, trees from hybrid progeny tests of Corymbia torelliana x Corymbia citriodora (CTOxCCT) and progenies of Eucalyptus dunnii (EDU) were investigated. Sawdust of genetically selected standing trees was collected, classified and prepared for near infrared (NIR) spectra readings. The chemical properties of the selected trees were determined through kraft pulping. Predictive models for each property were developed based on the reference data and NIR spectra. Two approaches for models were developed. The first approach, models were fitted with 25 samples of CTOxCCT, and in the second approach, models were fitted using 61 samples (25 of CTOxCCT and 36 of EDU). The estimated R²cv values were 0.60 and 0.73 for basic chip density, 0.37 and 0.65 for extractive contents, 0.56 and 0.53 for total lignin contents, 0.63 and 0.66 for S/G ratio, and 0.52 and 0.77 for screened pulp yield for the first and second approaches, respectively. All developed models have potential for ranking trees in breeding programs. NIR spectroscopy can potentially be applied as a high-throughput field phenotyping tool where thousands of varieties need to be evaluated. [ABSTRACT FROM AUTHOR]

Families of 38 month-old Calycophyllum spruceanum planted at three locations in the Peruvian Amazon were analyzed for breeding purpose. Significant differences were detected among families, sites and combined sites for the traits trunk diameter (D), height (H), number of nodes (NN), number of branches (NB) and survival rate (SUR), except for NN at site 2 and SUR at site 3 and combined sites. The correlation of the genotype-environment interaction was simple for D, H, NN, and SUR (0.77-0.89). Heritability was generally highest for D, H, NN, and NB (0.12-0.7), and the genotypic coefficient of variation ranged from 8.6-27.4%. Genetic correlations between these traits within and among sites ranged from 0.35-1.0. The selection of 75 trees from different families, within blocks and locations, suggested the possibility of genetic gains (6.1-29.8%) for D, H, NN, and NB, and that the remaining effective population size can be exploited in future selection cycles. [ABSTRACT FROM AUTHOR]

Forest tree breeding is new and more difficult, time-consuming, and expensive than crop breeding. Forest trees breed every 20–40 years. Genomic and molecular biology advances have revolutionized plant breeding based on phenotypes. Molecular markers make genotype selection possible. Marker-assisted breeding can speed up breeding, however, it is not effective for selecting complicated features in forest trees. The genomic estimated breeding value of an individual can be determined using this unique genomic selection method, which studies all impacts of quantitative trait loci using a large number of genetic markers across the genome. This method should improve forest trees better than conventional breeding. This article reviews genomic selection's current advancements in forest tree improvement and discusses genotyping and phenotyping methods. We also evaluate genomic prediction algorithms and stress the importance of cost–benefit analysis before genomic selection. This technique of forest breeding can be improved by boosting species diversity, favorable traits, and epigenetic variation. [ABSTRACT FROM AUTHOR]

Wood density is an intricate trait that encapsulates water transport, growth, and productivity. It is probably the most used parameter to deduce wood quality. In this study, the wood density of 81 European provenances of Norway spruce tested in three provenance trials from the Romanian Carpathians was analysed and compared at 49 years after planting. We also analysed the correlations between wood density and the provenances' geographic coordinates, as well as other traits, such as diameter at breast height, total height, and survival rate. For the genetic variance analysis of the wood density in each provenance trial and across sites, linear mixed models were used. Significant differences between the Norway spruce provenances regarding wood density were found only in the Dorna Candrenilor trial, where the mean wood density per provenance had values ranging from 0.311 ± 0.030 g/cm³ to 0.356 ± 0.019 g/cm³. No significant correlations between wood density and the provenances' geographic coordinates were found. Negative correlations were found between wood density and the other traits analysed. Provenances with good performances in provenance trials could be used in assisted migration. [ABSTRACT FROM AUTHOR]

This study developed three transgenic mulberry lines containing heterologous phosphoenol pyruvate carboxylase gene of Flaveria trinervia through Agrobacterium tumefaciens-mediated genetic transformation using cotyledon and hypocotyl explants of mulberry cv. G4. These transgenic lines had 1–1.56-fold expression of the phosphoenol pyruvate carboxylase gene of Flaveria trinervia, regulated by a constitutive promoter. The phosphoenol pyruvate carboxylase activity in transgenic mulberry lines enhanced upto 1.91 to 2.66-fold compared to wild-type plants. Transgenic mulberry lines exhibited significantly higher photosynthetic rate, improved instantaneous water use efficiency, stomatal conductance, transpiration rate, relative water, and proline content than the WT plants under 60% field capacity. Leaf discs assay of transgenic lines revealed less chlorophyll degradation and electrolyte leakage than those in wild-type plants under 25% polyethylene glycol (molecular weight > 6000) and 200 mM NaCl. In this study, for the first time, transgenic mulberry lines expressing the phosphoenol pyruvate carboxylase gene of Flaveria trinervia were developed, which showed improved photosynthesis rate with tolerance to drought and salinity stresses. These transgenic mulberry lines developed in this study could be further tested in a confined field trial to evaluate their leaf yield, yield attributes, leaf quality, and physiological parameters under irrigated and sub-optimal irrigation/drought stress conditions. These transgenic lines could be used as pre-breeding resources in mulberry breeding programs in the future.Key message: Transgenic mulberry lines were developed by introducing the PEPC gene of Flaveria trinervia through Agrobacterium-mediated genetic transformation, and the transgenic lines showed improved gas exchange parameters, tolerance to abiotic stresses. [ABSTRACT FROM AUTHOR]

In the southern Kalahari Desert, cooperatively breeding Southern Pied Babblers Turdoides bicolor frequently build their nests and forage in camelthorn trees Vachellia erioloba, a keystone species in the region, and blackthorn trees Senegalia mellifera, a widespread early successional shrub. Using Ivlev's electivity indices (Ei), we show that Southern Pied Babblers preferentially nest in camelthorn trees and preferentially forage in or under camelthorn and blackthorn trees. Southern Pied Babblers primarily forage on the ground; however, they will make use of arboreal resources when these are available. We observed the birds spending the highest proportion of foraging time off the ground during October, when breeding is also most common, compared with all other months within the austral summer breeding season. They are most likely to be observed foraging in camelthorn trees earlier in the breeding season and blackthorn trees later in the breeding season. We demonstrate that Southern Pied Babblers have a strong relationship with camelthorn trees, in which they prefer to both nest and forage. We highlight the importance of protecting camelthorn trees, a keystone species in the region, as part of the conservation and management of endemic Kalahari fauna such as the Southern Pied Babbler. In addition to contributing to the literature on keystone species, our observations raise questions about the ways in which avian reproduction in the arid zone could be decoupled from rainfall via the phenology of deep‐rooted tree species. [ABSTRACT FROM AUTHOR]

Salix psammophila is an important tree species adapted to sand-fixing afforestation in arid areas, and its different plant type characteristics can have different ecological functions. To identify the genes affecting the plant type of S. psammophila, this study used RT-qPCR and RNA-seq technology to establish a method for screening the candidate genes of the S. psammophila plant type based on the correlation coefficient of the crown–height ratio. We then screened out the gene combination that can best control the expression of the S. psammophila plant type. The results show the following: (1) The expression levels of the FHY1 and TAC2 genes were positively correlated with the crown–height ratio, whereas those of the ATX1, RFK1, PYL1, ABF2, SPA2, TB1, ZFP4, and LAZY1b genes were negatively correlated with the crown–height ratio. (2) The ATX1 + FHY1 gene combination had the greatest influence on the plant type traits of S. psammophila, and the correlation between the gene combination and the crown–height ratio reached 0.74. (3) The double- gene combination screening method improved the screening efficiency and accuracy, as well as the sensitivity and specificity, indicating certain universality. This strategy can be used for the determination of other plants or other traits, providing a theoretical basis for the directional breeding of forest trees. [ABSTRACT FROM AUTHOR]

In the Baltics, warming is expected to burden the growth of Norway spruce Picea abies, with weather anomalies/extremes having strong triggering effects, which can be mitigated by tree breeding. Within the region, breeding programmes have been aiming for productivity, yet being conservative, their sustainability depends on the adaptability of native genotypes, which is unclear. The adaptability of genotypes can be assessed through local adaptations and phenotypic plasticity, with the sensitivity of increment depicting the conformity of genotypes and environments. To assess the adaptability of native populations to anticipated climates, local genetic adaptation and phenotypic plasticity of the weather sensitivity of the radial increment were assessed by the methods of time series analysis and quantitative genetics based on three clonal trials (low-density single-tree plot plantations of grafted clones of native plus trees) representing the local climatic gradient in Latvia. The growth of trees was sensitive to the moisture availability in summer and the thermal regime in winter, yet coinciding anomalies in both were associated with abrupt changes in tree ring width. These environmental effects differed among the clones, indicating genetic controls over the sensitivity of increment, which, however, decreased under a warmer climate, suggesting a limited adaptability of local populations to warming. Still, the weather-growth relationships showed moderate phenotypic plasticity, suggesting some mid-term adaptability. Accordingly, supplementation of breeding populations via assisted gene transfer with the genotypes that are adapted to warmer and drier climates appears crucial. [ABSTRACT FROM AUTHOR]

The single nucleotide polymorphism (SNP) chip provides a convenient platform for accelerating breeding progress and promoting basic research in the field of crop science. Given the long and inefficient traditional breeding of the rubber tree, it is urgent to develop an SNP chip to promote changes in breeding patterns. Here, we developed and validated a liquid SNP chip named 'HbGBTS80K'. The SNPs were selected from wholegenome resequencing data containing 335 diverse rubber tree accessions. After quality control of 69 additional accessions, the final SNP chip included 80,080 SNPs evenly distributed across 18 chromosomes. Population genetic diversity analysis showed that the HbGBTS80K was effective in distinguishing rubber accessions into four groups, which was highly consistent with previous findings based on resequencing data. Genomewide association study (GWAS) on the reported genotypic data of the number of laticifer rings (NLR) could also detect the major gene HbPSK5 in the HbGBTS80K platform. In summary, the HbGBTS80K liquid SNP chip is a valuable tool that will facilitate functional studies and molecular breeding of the rubber tree. [ABSTRACT FROM AUTHOR]

Background: Light-harvesting chlorophyll a/b binding proteins (Lhcb) play crucial roles in plant growth, development, and the response to abiotic stress in higher plants. Previous studies have reported that Lhcb genes were involved in the phytochrome regulation and responded to different light and temperature conditions in Poaceae (such as maize). However, the evolution and functions of Lhcb genes remains poorly characterized in important Rosaceae species. Results: In this investigation, we conducted a genome-wide analysis and identified a total of 212 Lhcb genes across nine Rosaceae species. Specifically, we found 23 Lhcb genes in Fragaria vesca, 20 in Prunus armeniaca, 33 in Malus domestica 'Gala', 21 in Prunus persica, 33 in Rosa chinensis, 29 in Pyrus bretschneideri, 18 in Rubus occidentalis, 20 in Prunus mume, and 15 in Prunus salicina. Phylogenetic analysis revealed that the Lhcb gene family could be classified into seven major subfamilies, with members of each subfamily sharing similar conserved motifs. And, the functions of each subfamily was predicted based on the previous reports from other species. The Lhcb proteins were highly conserved within their respective subfamilies, suggesting similar functions. Interestingly, we observed similar peaks in Ks values (0.1–0.2) for Lhcb genes in apple and pear, indicating a recent whole genome duplication event (about 30 to 45 million years ago). Additionally, a few Lhcb genes underwent tandem duplication and were located across all chromosomes of nine species of Rosaceae. Furthermore, the analysis of the cis-acting elements in the 2000 bp promoter region upstream of the pear Lhcb gene revealed four main categories: light response correlation, stress response correlation, hormone response correlation, and plant growth. Quantitative expression analysis demonstrated that Lhcb genes exhibited tissue-specific expression patterns and responded differently to low-temperature stress in Rosaceae species. Conclusions: These findings shed light on the evolution and phylogeny of Lhcb genes in Rosaceae and highlight the critical role of Lhcb in pear's response to low temperatures. The results obtained provide valuable insights for further investigations into the functions of Lhcb genes in Rosaceae, and these functional genes will be used for further fruit tree breeding and improvement to cope with the current climate changes. [ABSTRACT FROM AUTHOR]

CRISPR (short for "Clustered Regularly Interspaced Short Palindromic Repeats") is a technology that research scientists use to selectively modify the DNA of living organisms. CRISPR was adapted for use in the laboratory from the naturally occurring genome-editing systems found in bacteria. In this work, we reviewed the methods used to introduce CRISPR/Cas-mediated genome editing into fruit species, as well as the impacts of the application of this technology to activate and knock out target genes in different fruit tree species, including on tree development, yield, fruit quality, and tolerance to biotic and abiotic stresses. The application of this gene-editing technology could allow the development of new generations of fruit crops with improved traits by targeting different genetic segments or even could facilitate the introduction of traits into elite cultivars without changing other traits. However, currently, the scarcity of efficient regeneration and transformation protocols in some species, the fact that many of those procedures are genotype-dependent, and the convenience of segregating the transgenic parts of the CRISPR system represent the main handicaps limiting the potential of genetic editing techniques for fruit trees. Finally, the latest news on the legislation and regulations about the use of plants modified using CRISPR/Cas systems has been also discussed. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis Franch. is an economically and ecologically important pine endemic to southwest China. A large number of low-quality and low-efficiency individuals have appeared in P. yunnanensis forests due to climate change, environmental stress, and human overexploitation. There is a lack of comprehensive information about the genetic diversity, population structure and a core germplasm collection establishment with individuals taken across its natural range. Understanding the important information will be invaluable for germplasm efficient conservation and utilization. A total of 287 individuals from 10 populations across its range were analyzed using 17 polymorphic microsatellite markers. The research revealed P. yunnanensis was a typical outcrossing plant (Fis = − 0.1), maintaining moderately high genetic diversity (He = 0.540). The continuous distribution and wind-dispersal traits of two-sacs pollen and winged seeds may have promoted gene flow (Nm = 12.71) and lessened genetic differentiation between populations (Fst = 0.023). There was a lack of significant isolation by distance (P = 0.07). Geographical and ecological isolation following the uplift of the southeastern margin of the Tibetan Plateau may have contributed to the formation of three discrete groups (K = 3). A core collection of 72 individuals (25% of the whole collection) was established, of which genetic diversity parameters showed no-significance from the whole collection. In situ conservation of the three populations (XC, CY, and XP) showing distinct genetic diversity was recommended, and ex situ conservation for individuals with private alleles. The core collection was recommended as a possible germplasm resource for tree breeding and improvement. [ABSTRACT FROM AUTHOR]

Forest trees are beleaguered by the ever-increasing onslaught of invasive pests and pathogens, with some species in danger of functional extinction. Recent successes in developing resistant populations using traditional tree breeding assures that some of the affected species will persist in future forests. However, the sheer number of threatened species requires increases in breeding efficiency. The time is right to consider how the use of genomic resources might aid breeding efforts in the next 20 years. Any operational benefit of genomic resources will be minimal without closer collaboration between tree breeders, forest managers, and genomic researchers. We reflect here on what attributes were responsible for the success of traditional resistance breeding programs and whether advances in genomics can realistically accelerate breeding. We conclude that the use of genomics to directly advance resistance breeding efforts in the next 20 years will be limited. Major obstacles will include factors such as the undomesticated nature of most tree species, the quantitative genetic nature of resistance in many species, and the lack of adequate funding to accelerate and more fully develop genomic resources. Despite these limitations, genomic tools have potential to help increase our understanding of the nature of resistance, and the genetic variability in the host, which can aid in the deployment of resistant populations and may assist in marker-assisted selection, particularly for major gene resistance. [ABSTRACT FROM AUTHOR]

AbstractThe breeding program for Acacia mangium has entered advanced-generation breeding cycles through adopting a recurrent selection system and a sub-lining breeding population. Genetic variation changes along the successive generations could affect its genetic stability on wide ranges of sites. The aim of this study is to observe genetic stability in third-generation progeny trials of A. mangium established at three different sites in Indonesia. Analysis was conducted, including single-site and multi-sites analyses for height, diameter, and stem forking that were grouped into two sets of analysis based on the genetic background of the trial: SET01 for the single sub-line and SET02 for the composite sub-lines. Index selection for multiple-traits was then used to identify the family changing ranks for multiple-traits and genetic gain prediction. The results showed that the recurrent selection system adopted in the breeding strategy for single-site analysis could maintain sufficient genetic variance of A. mangium in the third-generation progeny trial. Family heritability was moderate to high for almost all traits. However, a strong genetic-environment interaction (G × E) exists in multi-sites analysis for the single sub-line population (SET01), indicating a less sufficient genetic variation and a low Type B genetic correlation in anticipating a wider range of environment. On the contrary, compositing selected family from several sub-lines (SET02) could diminish the strength of G × E and increase Type B correlation. Selection and genetic gain prediction could be more effective in multi-sites analysis for SET02, but it was less effective for SET01. The results imply that adopting a recurrent selection system in advanced-generation breeding of A. mangium should consider structuring the breeding population. It could be practiced by compositing selected superior families from several sub-lines into one breeding population to maintain high genetic stability, while increasing genetic diversity and productivity.

In view of the short blooming period of pear tree crossbreeding and the complexity of pollination process, a method that can improve the efficiency of crossbreeding of pear trees was provided. Meanwhile, this method can also be applied to the study of pollen xenia effect, pollination tree selection and pure pollen collection in pear tree cultivation. [ABSTRACT FROM AUTHOR]

Introduction: Shorea macrophylla is a commercially important tropical tree species grown for timber and oil. It is amenable to plantation forestry due to its fast initial growth. Genomic selection (GS) has been used in tree breeding studies to shorten long breeding cycles but has not previously been applied to S. macrophylla. Methods: To build genomic prediction models for GS, leaves and growth trait data were collected from a half-sib progeny population of S. macrophylla in Sari Bumi Kusuma forest concession, central Kalimantan, Indonesia. 18037 SNP markers were identified in two ddRAD-seq libraries. Genomic prediction models based on these SNPs were then generated for diameter at breast height and total height in the 7th year from planting (D7 and H7). Results and discussion: These traits were chosen because of their relatively high narrow-sense genomic heritability and because seven years was considered long enough to assess initial growth. Genomic prediction models were built using 6 methods and their derivatives with the full set of identified SNPs and subsets of 48, 96, and 192 SNPs selected based on the results of a genome-wide association study (GWAS). The GBLUP and RKHS methods gave the highest predictive ability for D7 and H7 with the sets of selected SNPs and showed that D7 has an additive genetic architecture while H7 has an epistatic genetic architecture. LightGBM and CNN1D also achieved high predictive abilities for D7 with 48 and 96 selected SNPs, and for H7 with 96 and 192 selected SNPs, showing that gradient boosting decision trees and deep learning can be useful in genomic prediction. Predictive abilities were higher in H7 when smaller number of SNP subsets selected by GWAS p-value was used, However, D7 showed the contrary tendency, which might have originated from the difference in genetic architecture between primary and secondary growth of the species. This study suggests that GS with GWAS-based SNP selection can be used in breeding for non-cultivated tree species to improve initial growth and reduce genotyping costs for next-generation seedlings. [ABSTRACT FROM AUTHOR]

Introduction: Genomic selection (GS) experiments in forest trees have largely reported estimates of predictive abilities from cross-validation among individuals in the same breeding generation. In such conditions, no effects of recombination, selection, drift, and environmental changes are accounted for. Here, we assessed the effectively realized predictive ability (RPA) for volume growth at harvest age by GS across generations in an operational reciprocal recurrent selection (RRS) program of hybrid Eucalyptus. Methods: Genomic best linear unbiased prediction with additive (GBLUP_G), additive plus dominance (GBLUP_G+D), and additive single-step (HBLUP) models were trained with different combinations of growth data of hybrids and pure species individuals (N = 17,462) of the G1 generation, 1,944 of which were genotyped with ~16,000 SNPs from SNP arrays. The hybrid G2 progeny trial (HPT267) was the GS target, with 1,400 selection candidates, 197 of which were genotyped still at the seedling stage, and genomically predicted for their breeding and genotypic values at the operational harvest age (6 years). Seedlings were then grown to harvest and measured, and their pedigree-based breeding and genotypic values were compared to their originally predicted genomic counterparts. Results: Genomic RPAs ≥0.80 were obtained as the genetic relatedness between G1 and G2 increased, especially when the direct parents of selection candidates were used in training. GBLUP_G+D reached RPAs ≥0.70 only when hybrid or pure species data of G1 were included in training. HBLUP was only marginally better than GBLUP. Correlations ≥0.80 were obtained between pedigree and genomic individual ranks. Rank coincidence of the top 2.5% selections was the highest for GBLUP_G (45% to 60%) compared to GBLUP_G+D. To advance the pure species RRS populations, GS models were best when trained on pure species than hybrid data, and HBLUP yielded ~20% higher predictive abilities than GBLUP, but was not better than ABLUP for ungenotyped trees. Discussion: We demonstrate that genomic data effectively enable accurate ranking of eucalypt hybrid seedlings for their yet-to-be observed volume growth at harvest age. Our results support a two-stage GS approach involving family selection by average genomic breeding value, followed by within-top-families individual GS, significantly increasing selection intensity, optimizing genotyping costs, and accelerating RRS breeding. [ABSTRACT FROM AUTHOR]

Background: Global climate change poses a grave threat to biodiversity and underscores the importance of identifying the genes and corresponding environmental factors involved in the adaptation of tree species for the purposes of conservation and forestry. This holds particularly true for spruce species, given their pivotal role as key constituents of the montane, boreal, and sub-alpine forests in the Northern Hemisphere. Results: Here, we used transcriptomes, species occurrence records, and environmental data to investigate the spatial genetic distribution of and the climate-associated genetic variation in Picea crassifolia. Our comprehensive analysis employing ADMIXTURE, principal component analysis (PCA) and phylogenetic methodologies showed that the species has a complex population structure with obvious differentiation among populations in different regions. Concurrently, our investigations into isolation by distance (IBD), isolation by environment (IBE), and niche differentiation among populations collectively suggests that local adaptations are driven by environmental heterogeneity. By integrating population genomics and environmental data using redundancy analysis (RDA), we identified a set of climate-associated single-nucleotide polymorphisms (SNPs) and showed that environmental isolation had a more significant impact than geographic isolation in promoting genetic differentiation. We also found that the candidate genes associated with altitude, temperature seasonality (Bio4) and precipitation in the wettest month (Bio13) may be useful for forest tree breeding. Conclusions: Our findings deepen our understanding of how species respond to climate change and highlight the importance of integrating genomic and environmental data in untangling local adaptations. [ABSTRACT FROM AUTHOR]

Gonipterus sp. n. 2 (Coleoptera, Curculionidae) is an invasive, commercially important weevil that causes large‐scale defoliation of Eucalyptus trees. The weevil specifically feeds on young leaves and new shoots, thus reducing tree growth. The weevil displays a very strong preference for certain Eucalyptus genotypes, however, this behaviour and the chemistry underlying it is poorly understood, thereby complicating the selection of resistant trees. To elucidate the feeding preference of Gonipterus sp. n. 2, we assessed the relative levels of susceptibility of 62 Eucalyptus genotypes from 23 species using a laboratory choice assay. This revealed large intraspecific variation in susceptibility to weevil feeding, which for certain species, exceeded the interspecific variation. A semiquantitative metabolite profile analysis on 13 genotypes revealed strong correlations of 10 metabolites to feeding damage. The behavioural effects of the identified compounds were assessed through an in vitro feeding preference assay using artificial diets as well as under field conditions. This revealed three phagostimulants (1,8‐cineole, oxalic acid and sucrose) and two feeding deterrent compounds (shikimic acid and palmitic acid) for Gonipterus sp. n. 2. These chemical markers can be applied to tree breeding programmes for the selection of resistant genotypes to reduce damage caused by Gonipterus weevils. Summary statement: Laboratory choice assays on 62 Eucalyptus genotypes from 23 species, detailed metabolic profiling, in vitro feeding assays and independent field trials revealed three phagostimulants and two feeding deterrent compounds for Gonipterus sp. n. 2. [ABSTRACT FROM AUTHOR]

An immediate concern of commercial tree plantation is the depleting water resource and drastic change in climatic conditions, which adversely affect the biomass productivity. Maximizing productivity from the available water and nutrient resources is presently the focus of most tree breeding and plantation programs. In Eucalyptus species variations in response to water deprived conditions are reported between species, among provenances and between clones. In the present study, 126 clones derived from the breeding program of Eucalyptus camaldulensis James. and Eucalyptus tereticornis sm. were screened for their response to progressive dehydration stress under controlled environmental conditions and morpho-physiological changes were recorded. Specific Leaf Area (SLA) and Relative Water Content (RWC) were found to be effective dehydration stress indices in both the species. Drought Susceptibility Index (DSI) which measures the decrease in yield of a genotype under drought conditions with respect to mean reduction of all genotypes studied, is a major selection criteria and quantitative indicator in selecting varieties for dehydration tolerance. DSI was recorded for each measured traits and SLA–DSI and RWC–DSI clustered the clones based on their tolerance/ susceptibility to dehydration stress. Additionally, ten prospective clones were selected as dehydration tolerant genotypes and are probable candidates for future multi-environment evaluation under arid and semi-arid conditions for deployment in plantation and breeding programs. [ABSTRACT FROM AUTHOR]

The increasing demand for climate-adapted seeds and planting material poses a challenge due to the limited availability, particularly for tree species such as oaks. National parks, known for their large-standing diversity and a wide range of habitats, can serve as valuable sources for identifying trees suitable for both the initiation of tree breeding and conservation strategies. This study aimed to identify valuable forest genetic resources of the Thayatal National Park in Austria by selecting potentially drought-tolerant phenotypes. For this purpose, we selected 404 mature trees of Quercus petraea (Matt.) Liebl. from eight populations growing on medium to dry sites in eight populations. Further, we characterized them for autochthony, genetic structure, genetic diversity using genetic markers (plastid- and nuclear-SSRs) and estimated their age. Finally, we applied wood core analysis to estimate tree response to historical drought events to identify the possible drought-tolerant phenotypes. The age of the trees ranged from 29 to 245 years (as of the year 2023). All Q. petraea trees were inhabiting a plastid haplotype 17a, autochthonous for this area. Nevertheless, the genetic structure estimated by ten nuSSRs revealed a pronounced structure in the dataset, largely caused by young trees exhibiting lower genetic diversity. A total of 85 elite potentially drought-tolerant trees were finally selected based on their morphological response (resistance, recovery ability, resilience, and relative resilience) to three historical drought events (1992–1994, 1947, 1917). The intrinsic water use efficiency and its difference (iWUE and DWiWUE), estimated by isotope analysis of δ13C of latewood in wet (1987) and dry (1994) years, did not correlate with any of the drought response traits (Rt, Rc, Rs, rRs). We discuss the further use of the selected oak trees for the establishment of seed stands and orchards to enhance seed production and the integration of other omics approaches, such as large-scale high-throughput plant phenotyping (HTPP) and transcriptomics, for in-depth analyses of drought tolerance of selected phenotypes. [ABSTRACT FROM AUTHOR]

The utilization of genotyping has gained significant popularity in tree improvement programs, aiding in enhancing the precision of breeding values, removing pedigree errors, the assessment of genetic diversity, and evaluating pollen contamination. Our study explores the impact of utilizing 5308 SNP markers to genotype seed orchard parents (166), progeny in progeny trials (667), and seedlot orchard seedlings (780), to simultaneously enhance variance components, breeding values, genetic diversity estimates, and pollen flow in the Region I white spruce (Picea glauca) breeding program in central Alberta (Canada). We compared different individual tree mixed models, including pedigree-based (ABLUP), genomic-based (GBLUP), and single-step pedigree-genomic-based (ssGBLUP) models, to estimate variance components and predict breeding values for the height and diameter at breast height traits. The highest heritability estimates were achieved using the ssGBLUP approach, resulting in improved breeding value accuracy compared to the ABLUP and GBLUP models for the studied growth traits. In the six orchard seedlots tested, the genetic diversity of the seedlings remained stable, characterized by an average of approximately 2.00 alleles per SNP, a Shannon Index of approximately 0.44, and an expected and observed heterozygosity of approximately 0.29. The pedigree reconstruction of seed orchard seedlings successfully identified consistent parental contributions and equal genotype contributions in different years. Pollen contamination levels varied between 11% and 70% using SNP markers and 8% to 81% using pollen traps, with traps both over- and under-estimating contamination. Overall, integrating genomic information from parents and offspring empowers forest geneticists and breeders in the Region I white spruce breeding program to correct errors, conduct backward and forward selections with greater precision, gain a deeper understanding of the orchard's genetic structure, select superior seedlots, and accurately estimate the genetic worth of each orchard lot, which can ultimately result in increased and more precise estimates of genetic gain in the studied growth traits. [ABSTRACT FROM AUTHOR]

Key message: The range-wide level of genetic variation of Scots pine (Pinus sylvestris L.) is geographically structured. High admixture and low genetic structure of populations in Central Europe and Fennoscandia suggest past recolonization from multiple sources and the influence of human-mediated gene transfer. Gene pools of marginal and isolated stands require active conservation. Some areas of Scots pine distribution need further genetic studies. Context: Scots pine (Pinus sylvestris L.) seems to be a species of low conservation priority because it has a very wide Eurasian distribution and plays a leading role in many forest tree breeding programs. Nevertheless, considering its economic value, long breeding history, range fragmentation, and increased mortality, which is also projected in the future, it requires a more detailed description of its genetic resources. Aims: Our goal was to compare patterns of genetic variation found in biparentally inherited nuclear DNA with previous research carried out with mitochondrial and chloroplast DNA due to their different modes of transmission. Methods: We analyzed the genetic variation and relationships of 60 populations across the distribution of Scots pine in Eurasia (1262 individuals) using a set of nuclear DNA markers. Results: We confirmed the high genetic variation and low genetic differentiation of Scots pine spanning large geographical areas. Nevertheless, there was a clear division between European and Asian gene pools. The genetic variation of Asian populations was lower than in Europe. Spain, Turkey, and the Apennines constituted separate gene pools, the latter showing the lowest values of all genetic variation parameters. The analyses showed that most populations experienced genetic bottlenecks in the distant past. Ongoing admixture was found in Fennoscandia. Conclusions: Our results suggest a much simpler recolonization history of the Asian than European part of the Scots pine distribution, with migration from limited sources and possible founder effects. Eastern European stands seem to have descended from the Urals refugium. It appears that Central Europe and Fennoscandia share at least one glacial refugium in the Balkans and migrants from higher latitudes, as well as from south-eastern regions. The low genetic structure between Central Europe and Fennoscandia, along with their high genetic admixture, may result at least partially from past human activities related to the transfer of germplasm in the nineteenth and early twentieth centuries. In light of ongoing climate changes and projected range shifts of Scots pine, conservation strategies are especially needed for marginal and isolated stands of this species. Genetic research should also be complemented in parts of the species distribution that have thus far been poorly studied. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the genetic diversity among 36 wild strawberry tree (Arbutus unedo L.) genotypes belonging to different altitude and geographical origins, using 16 ISSR (Inter Simple Sequence Repeats) markers. Results revealed that ISSR primers produced a total of 344 bands, of which 94.1% were polymorphic, indicating a high level of genetic variation among the studied populations. The mean values of polymorphism information content (PIC), efective multiplex ratio (EMR), resolving power (Rp) and marker index (MI) were 0.34, 19.13, 23.46 and 6.45, respectively. The total gene diversity (Ht), gene diversity within populations (Hs) and total genetic differentiation coefficient among the populations (Gst) values were 0.33, 0.15 and 0.50, respectively. The genetic distance between all pairwise combinations of the genotypes ranged from 0.113 to 0.512. The cluster analysis revealed three main groups and which are subdivided into eight subgroups and a two independant branches. Therefore, the grouping of strawberry tree genotypes was independent of their geographical origins and altitude with exception for the genotypes belonging to Bin El-ouidane and Laanoucer populations. The results showed that ISSR markers are suitable tools for the evaluation of genetic diversity among strawberry tree genotypes. The data of this work will be useful for strawberry tree breeding programs and conservation strategies. [ABSTRACT FROM AUTHOR]

We investigate and characterize the morphophysiological changes related to germination and the initial growth and development of seedlings of wild and cultivated genotypes of the genus Hevea spp. in finding to add value to new clones. Seeds from six genotypes (H. brasiliensis (Willd. Ex A. Juss) Müll. Arg, H. guianensis Aubl., H. spruceana (Benth.) Müll. Arg., RRIM 600, Fx 3844, and IAN 873) were sterilized, and their imbibition curve, germination parameters, and initial seedling growth were characterized. In parallel, the morphology of the germination and post-germination stages was monitored from seeds germinated in washed sand. Morphological differences in the seeds/embryos, different strategies in the imbibition process, emergence, and initial seedling growth were observed. The species H. guianensis and H. spruceana showed the greatest differences in size, shape, and color of the seeds/embryos and initial seedling growth. The characteristics of the seed coat patterns, the seedling imbibition, growth, and development processes can serve as morphophysiological markers for genotype identification and selection. This is the first morphophysiological study of seeds and seedlings of wild and cultivated genotypes of species of the genus Hevea. We conclude that there is considerable phenotypic variability among species of the Hevea genus regarding seed and seedling morphophysiology, which can be explored in the rubber tree breeding programs. [ABSTRACT FROM AUTHOR]

Eucalyptus pellita is currently the predominant tree species deployed for tree plantation establishment in many parts of Borneo, particularly in the state of Sabah, Malaysia. This study evaluates the occurrence of end-splitting in four-year old plantation grown E. pellita in Sabah as affected by site and growth attributes. An existing progeny tree breeding trial, involving seeds originated from Papua New Guinea, China, Vietnam, Australia and Sabah with 101 individual families, was used to carry out the split assessment. The trial trees were planted on two contrasting sites which differed significantly in soil type, soil texture, soil physical conditions, effective rooting depth and drainage capacity. Logs from the second thinning were cut into 2.2 m long sections. The end splits were evaluated by using a designated split scoring system. Plastic s-hooks, a wax emulsion end sealer and a bitumen end sealer were used as remediation measure and were compared against a control of no remedial application. The study showed that significant variation exists in log end-splitting, comparing the two sites, in combination with significant variation in tree growth. The variation in log end-splitting is attributed to the variation in tree growth as a response to the different growing conditions. Application of plastic s-hooks reduced split occurrence and severity significantly (49.62%), while the wax and bitumen end sealers had no effect on reduction of growth strain related splits. The findings suggested that end-splitting is caused by complex genetic-environment/site-growth interactions. It is vital to better understand factors involved in log end-splitting to optimise E. pellita plantation management. [ABSTRACT FROM AUTHOR]

SUMMARY: Olive tree (Olea europaea L. subsp. europaea var. europaea) is one of the most important species of the Mediterranean region and one of the most ancient species domesticated. The availability of whole genome assemblies and annotations of olive tree cultivars and oleaster (O. europaea subsp. europaea var. sylvestris) has contributed to a better understanding of genetic and genomic differences between olive tree cultivars. However, compared to other plant species there is still a lack of genomic resources for olive tree populations that span the entire Mediterranean region. In the present study we developed the most complete genomic variation map and the most comprehensive catalog/resource of molecular variation to date for 89 olive tree genotypes originating from the entire Mediterranean basin, revealing the genetic diversity of this commercially significant crop tree and explaining the divergence/similarity among different variants. Additionally, the monumental ancient tree 'Throuba Naxos' was studied to characterize the potential origin or routes of olive tree domestication. Several candidate genes known to be associated with key agronomic traits, including olive oil quality and fruit yield, were uncovered by a selective sweep scan to be under selection pressure on all olive tree chromosomes. To further exploit the genomic and phenotypic resources obtained from the current work, genome‐wide association analyses were performed for 23 morphological and two agronomic traits. Significant associations were detected for eight traits that provide valuable candidates for fruit tree breeding and for deeper understanding of olive tree biology. Significance Statement: The most comprehensive genomic variation map to date has been developed for olive trees (Olea europaea L. subsp. europaea var. europaea) originating from the entire Mediterranean basin, providing insights into the complex olive tree domestication and biology, and through a selective sweep scan and genome‐wide association approaches candidate genes controlling important agronomic traits in olive tree have been identified. [ABSTRACT FROM AUTHOR]

Tamil Nadu, in southern India, has the second-largest number of neem trees in the country. The oil from the seeds has high economic significance for cottage industries in the region. This paper examines 28 Candidate Plus Trees (CPTs) selected from six agroclimatic zones in Tamil Nadu which exhibit exceptional traits such as superior growth and other desirable characteristics. We aimed to understand seed morphology variations and physicochemical properties in the oil across different regions. Significant differences were observed for morphometric traits. Fruit production correlated negatively with rainfall. 100-seed kernel weight and seed length correlated with oil percentage. Rainfall influenced seed breadth and pericarp weight. Clustering using morphological characters did not group genotypes from the same region; while soil type could distinguish them. Correlation helped us determine the prominent features which influence the traits of interest, which can be useful for breeding programs, cultivation practices, and the development of neem-based products in Tamil Nadu and beyond. [ABSTRACT FROM AUTHOR]

Advances in DNA sequencing technologies allow the sequencing of whole genomes of thousands of individuals and provide several million single nucleotide polymorphisms (SNPs) per individual. These data combined with precise and high-throughput phenotyping enable genome-wide association studies (GWAS) and the identification of SNPs underlying traits with complex genetic architectures. The identified causal SNPs and estimated allelic effects could then be used for advanced marker-assisted selection (MAS) in breeding programs. But could such MAS compete with the broadly used genomic selection (GS)? This question is of particular interest for the lengthy tree breeding strategies. Here, with our new software "SNPscan breeder," we simulated a simple tree breeding program and compared the impact of different selection criteria on genetic gain and inbreeding. Further, we assessed different genetic architectures and different levels of kinship among individuals of the breeding population. Interestingly, apart from progeny testing, GS using gBLUP performed best under almost all simulated scenarios. MAS based on GWAS results outperformed GS only if the allelic effects were estimated in large populations (ca. 10,000 individuals) of unrelated individuals. Notably, GWAS using 3,000 extreme phenotypes performed as good as the use of 10,000 phenotypes. GS increased inbreeding and thus reduced genetic diversity more strongly compared to progeny testing and GWAS-based selection. We discuss the practical implications for tree breeding programs. In conclusion, our analyses further support the potential of GS for forest tree breeding and improvement, although MAS may gain relevance with decreasing sequencing costs in the future. [ABSTRACT FROM AUTHOR]

Key message: Forest tree breeding must undergo significant revisions to adapt to the evolving challenges posed by climate change. Addressing the shifts in environmental conditions requires a comprehensive multidisciplinary approach that includes theoretical work and practical application. Specifically, there is a need to focus on developing new breeding strategies that are theoretically sound and practically feasible, considering the economic constraints of actual tree breeding programs. We present a novel concept utilizing genetic evaluation of multiple traits in forest stands of successive ages across wide ecological ranges. Incorporating genomics allows for detailed genetic evaluation, making use of high-density SNP markers and sophisticated algorithms like GBLUP for genetic parameter estimates. High-throughput phenotyping is conducted using drone-borne lidar technology to capture tree height and survival data across various forest stands. Assisted migration is considered to strategically position genotypes across predicted environmental climatic gradients, thereby accommodating the dynamic nature of ecological shifts. Mathematical optimization acts as an essential component for logistics, guiding the spatial allocation and timely substitution of genotypes to ensure a continually adaptive breeding program. The concept replaces distinct breeding cycles with continuous evaluation and selection, enhancing the rate of genetic response over time. [ABSTRACT FROM AUTHOR]

With the growth of urban areas, the fragments and trees present in this environment have become fundamental to the conservation of biodiversity, as they provide food and nesting sites. The availability of breeding sites in hollows in an area is a determining factor in the reproductive success of several species that require this resource. This study aims to evaluate the dynamics of use of dead palm tree trunks as nests by Ara ararauna, the blue-and-yellow macaw, over seven breeding seasons in the urban perimeter of Campo Grande, Mato Grosso do Sul. Data were collected between 2011 and 2017. One hundred and forty-six natural nests were recorded, mainly in house yards (55.5%) and public areas (32.9%). The nests were built on dead palm trees of five tree species: macauba palm (Acrocomia aculeata), moriche palm (Mauritia flexuosa), fishtail palm (Caryota urens), imperial palm (Roystonea oleracea), and babassu palm (Attalea speciosa). Forty-six natural nests were lost, which corresponded to 31.5% of the nests recorded. Just over half of these nests were removed by the residents (58.7%), while the remaining fell naturally (41.3%). Considering the importance of the vegetation present in residential yards and public areas, particularly palm trees for breeding and feeding of A. ararauna, it is important to conserve them and encourage the planting of native palm trees in the city. [ABSTRACT FROM AUTHOR]

Breeding long-lived trees is challenging, but it has been shown that genomic information can be used to improve efficiency. In this study, genomic prediction (GP) was tested on selected individuals of a two-generation breeding population of Cryptomeria japonica, the most common plantation tree in Japan. In the 1980s, the second-generation plus trees (101 clones) were selected from about 8500 individuals obtained by cross-mating the first-generation plus trees (47 clones). RAD-seq based on 8664 SNPs was used to perform GP for three important traits in this population: tree height, wood stiffness, and male flower quantity. The association between traits and genotypes was modeled using five Bayesian models whose predictive accuracy was evaluated by cross-validation, revealing that the best model differed for each trait (BRR for tree height, BayesA for wood stiffness, and BayesB for male flower quantity). GP was 1.2–16.0 times more accurate than traditional pedigree-based methods, attributed to its ability to model Mendelian sampling. However, an analysis of the effects of intergenerational kinship showed that parent–offspring relationships reduce the predictive accuracy of GP for traits strongly affected by selection pressure. Overall, these results show that GP could significantly expedite tree breeding when supported by a deep understanding of the targeted population's genetic background. [ABSTRACT FROM AUTHOR]

Parrots are among the most diverse and widely distributed groups of birds and one of the most threatened bird orders mainly due to habitat loss and illegal poaching. Most parrots are obligate cavity nesters, so the logging of mature trees and the transformation of natural cliffs represent important threats to their conservation. Here, we report novel observations of Neotropical parrots nesting in previously unrecorded substrates. We show the first documented case of the cliff‐nesting burrowing parrots trying to breed at ground level in an abandoned burrowing owl cavity. Additionally, we provide the first documented observations of this species attempting to nest in building cavities in three urbanized areas of Argentina. Moreover, we report data from four countries of 148 pairs of eight species typically breeding in tree cavity using palm tree bracts as nest sites. Behavioral plasticity in nest sites may allow parrots to maximize their nesting success by exploiting alternative breeding substrates. Moreover, these novelties could contribute to cope with habitat loss and further transformation. However, further research is needed to assess the consequences of these nesting innovations in terms of individual fitness and population dynamics as well as potential factors promoting their appearance. [ABSTRACT FROM AUTHOR]

Breeding perennial tree crops often requires prediction of mature performance from juvenile data. To assess the utility of juvenile screens to predict salinity tolerance of mature pistachio trees, we compared performance of 3-month ungrafted seedlings and 4-year-old grafted rootstocks under salinity stress. The QTL allele associated with higher salt exclusion from seedling leaves conferred lower growth in saline field conditions, suggesting that mapping QTL in seedlings may be easier than discerning the optimal allele for field performance. [ABSTRACT FROM AUTHOR]

Human commensal species take advantage of anthropogenic conditions that are less likely to be challenged by the selective pressures of natural environments. Their morphological and physiological phenotypes can therefore dissociate from habitat characteristics. Understanding how these species adjust their morphological and physiological traits across latitudinal gradients is fundamental to uncovering the eco‐physiological strategies underlying coping mechanisms. Here, we studied morphological traits in breeding Eurasian tree sparrows (ETSs; Passer montanus) among low‐latitude (Yunnan and Hunan) and middle‐latitude (Hebei) localities in China. We then compared body mass; lengths of bill, tarsometatarsus, wing, total body, and tail feather; and baseline and capture stress‐induced levels of plasma corticosterone (CORT) and the metabolites including glucose (Glu), total triglyceride (TG), free fatty acid (FFA), total protein, and uric acid (UA). None of the measured morphological parameters varied with latitude except in the Hunan population, which demonstrated longer bills than those in other populations. Stress‐induced CORT levels significantly exceeded baseline levels and decreased with increasing latitude, but total integrated CORT levels did not vary with latitude. Capture stress‐induced significantly increased Glu levels and decreased TG levels, independent of site. However, the Hunan population had significantly higher baseline CORT, baseline and stress‐induced FFA levels, but lower UA levels, which differed from other populations. Our results suggest that rather than morphological adjustments, physiological adjustments are mainly involved in coping mechanisms for middle‐latitude adaptation in ETSs. It is worth investigating whether other avian species also exhibit such dissociation from external morphological designs while depending on physiological adjustments. [ABSTRACT FROM AUTHOR]

Eucalyptus tereticornis exhibits adaptation to a wide range of soils and environments, making it suitable for various protective and productive purposes throughout the territory of Uruguay. Due to the absence of a locally improved seed source, INIA began a tree breeding program in 2007 using genetic material from two sources: the natural distribution area of the species and local plantations. The performance of the genetic pool was evaluated at different sites over a nine-year growth period. The objectives of this study were to estimate genetic parameters (heritability, genetic correlations, and genotype-by-environment interaction) for growth and stem form traits and to estimate the genetic gains achievable through selection at different ages, in order to guide the breeding strategy for E. tereticornis. The genotype-environment interaction for volume and survival exhibited moderate to low levels, with Type B genetic correlations ranging from 0.68 to 0.82. The combined analysis of the trials revealed that heritability increased with the age of measurement for all traits, with values ranging from low to moderate for growth variables (0.04 - 0.23) and stem form (stem straightness and forking) showing low values (0.05 - 0.12). Genetic correlations between growth traits at different ages and volume at 9 years were positive and high (0.32 - 0.99), while the correlations between stem form (stem straightness and forking) and volume were low to moderate (0.30 - 0.56). The results obtained suggest that it is possible establish a single breeding unit and that through early selection, genetic gains can be maximized, evaluation costs reduced, and improved seed obtained in a shorter timeframe. [ABSTRACT FROM AUTHOR]

Dangers confronting forest ecosystems are many and the strength of these biological systems is deteriorating, thus substantially affecting tree physiology, phenology, and growth. The establishment of genetically engineered trees into degraded woodlands, which would be adaptive to changing climate, could help in subsiding ecological threats and bring new prospects. This should not be resisted due to the apprehension of transgene dispersal in forests. Consequently, it is important to have a deep insight into the genetic structure and phenotypic limits of the reproductive capability of tree stands/population(s) to endure tolerance and survival. Importantly, for a better understanding of genes and their functional mechanisms, gene editing (GeEd) technology is an excellent molecular tool to unravel adaptation progressions. Therefore, GeEd could be harnessed for resolving the allelic interactions for the creation of gene diversity, and transgene dispersal may be alleviated among the population or species in different bioclimatic zones around the globe. This review highlights the potential of the CRISPR/Cas tools in genomic, transcriptomic, and epigenomic-based assorted and programmable alterations of genes in trees that might be able to fix the trait-specific gene function. Also, we have discussed the application of diverse forms of GeEd to genetically improve several traits, such as wood density, phytochemical constituents, biotic and abiotic stress tolerance, and photosynthetic efficiency in trees. We believe that the technology encourages fundamental research in the forestry sector besides addressing key aspects, which might fasten tree breeding and germplasm improvement programs worldwide. [ABSTRACT FROM AUTHOR]

The present investigation was carried out in three districts of South Eastern Rajasthan; Jhalawar, Kota and Baran to select the phenotypically superior trees (CPTs) of Azadirachta indica and to study the variation of the phenotypic characters among provenances. Thirty CPTs each were selected for study from each of the three districts and the parameters tree height, crown diameter, bark thickness, Girth, clear bole height, Ratio of clear bole height and tree height were recorded and subjected to descriptive statistical analysis. The data analyzed for the CPTs selected reveals that both the Kota and Baran region have highest value for tree height, crown diameter, bark thickness, Girth, clear bole height, Ratio of clear bole height and tree height. The trees selected from Kota region is also having highest value of both crown diameter and second highest value of leaf area after Jhalawar region and the trees selected from Jhalawar region has the highest value for both Girth and bark thickness among other provenances. The data of this experiment can also be used as a base line data for using in further tree breeding and tree improvement programme of Azadirachta indica. [ABSTRACT FROM AUTHOR]

Forest plantations play an important role in maintaining a supply of high-quality timber from managed forest. With an expected increase in the prevalence of drought in some forested areas, climate change increases concerns about future seedling growth. A promising approach to promote the suitability of plantation seedlings to current and future climate would be to use variation in growth and wood traits of trees under drought as selection criteria in tree breeding programs, especially at a young stage when they are most vulnerable to drought. We evaluated the genetic control of the growth and wood density response of white spruce clonal seedlings submitted to various drought conditions in a greenhouse experiment. By varying the watering treatment of 600 two year-old seedlings from 25 clones, we simulated three levels of drought-induced stress during two growing seasons. Apical and radial growth decreased markedly as the intensity of drought increased, whereas wood density tended to increase. We also developed a woody biomass index composed of wood density and ring area, which was observed to decrease slightly with increasing drought. There was important variation in all traits among clones and heritability tended to decrease with the intensity and duration of drought-induced stress, mainly for wood density and radial growth. However, the heritability of apical growth tended to increase under drought conditions. Our results show that the response of young white spruce clones to drought is highly variable, and together with the significant levels of heritability noted, the results indicate that multi-trait genetic selection for drought stress response at a young age could represent a promising approach to increase resilience to drought. [ABSTRACT FROM AUTHOR]

Eucalyptus is an economically important genus comprising more than 890 species in different subgenera and sections. Approximately twenty species of subgenus Symphyomyrtus account for 95% of the world's planted eucalypts. Discrimination of closely related eucalypt taxa is challenging, consistent with their recent phylogenetic divergence and occasional hybridization in nature. Admixture, misclassification or mislabeling of Eucalyptus germplasm resources maintained as exotics have been suggested, although no reports are available. Moreover, hybrids with increased productivity and traits complementarity are planted worldwide, but little is known about their actual genomic ancestry. In this study we examined a set of 440 trees of 16 different Eucalyptus species and 44 interspecific hybrids of multi-species origin conserved in germplasm banks in Brazil. We used genome-wide SNP data to evaluate the agreement between the alleged phylogenetic classification of species and provenances as registered in their historical records, and their observed genetic clustering derived from SNP data. Genetic structure analyses correctly assigned each of the 16 species to a different cluster although the PCA positioning of E. longirostrata was inconsistent with its current taxonomy. Admixture was present for closely related species' materials derived from local germplasm banks, indicating unintended hybridization following germplasm introduction. Provenances could be discriminated for some species, indicating that SNP-based discrimination was directly proportional to geographical distance, consistent with an isolation-by-distance model. SNP-based genomic ancestry analysis showed that the majority of the hybrids displayed realized genomic composition deviating from the expected ones based on their pedigree records, consistent with admixture in their parents and pervasive genome-wide directional selection toward the fast-growing E. grandis genome. SNP data in support of tree breeding provide precise germplasm identity verification, and allow breeders to objectively recognize the actual ancestral origin of superior hybrids to more realistically guide the program toward the development of the desired genetic combinations. [ABSTRACT FROM AUTHOR]