Blueberry and cranberry pangenomes as a resource for future genetic studies and breeding efforts.

Domestication of cranberry and blueberry began in the United States in the early 1800s and 1900s, respectively, and in part owing to their flavors and health-promoting benefits are now cultivated and consumed worldwide. The industry continues to face a wide variety of production challenges (e.g. disease pressures), as well as a demand for higher-yielding cultivars with improved fruit quality characteristics. Unfortunately, molecular tools to help guide breeding efforts for these species have been relatively limited compared with those for other high-value crops. Here, we describe the construction and analysis of the first pangenome for both blueberry and cranberry. Our analysis of these pangenomes revealed both crops exhibit great genetic diversity, including the presence-absence variation of 48.4% genes in highbush blueberry and 47.0% genes in cranberry. Auxiliary genes, those not shared by all cultivars, are significantly enriched with molecular functions associated with disease resistance and the biosynthesis of specialized metabolites, including compounds previously associated with improving fruit quality traits. The discovery of thousands of genes, not present in the previous reference genomes for blueberry and cranberry, will serve as the basis of future research and as potential targets for future breeding efforts. The pangenome, as a multiple-sequence alignment, as well as individual annotated genomes, are publicly available for analysis on the Genome Database for Vaccinium-a curated and integrated web-based relational database. Lastly, the core-gene predictions from the pangenomes will serve useful to develop a community genotyping platform to guide future molecular breeding efforts across the family.

A multiplexed plant-animal SNP array for selective breeding and species conservation applications.

Reliable and high-throughput genotyping platforms are of immense importance for identifying and dissecting genomic regions controlling important phenotypes, supporting selection processes in breeding programs, and managing wild populations and germplasm collections. Amongst available genotyping tools, single nucleotide polymorphism arrays have been shown to be comparatively easy to use and generate highly accurate genotypic data. Single-species arrays are the most commonly used type so far; however, some multi-species arrays have been developed for closely related species that share single nucleotide polymorphism markers, exploiting inter-species cross-amplification. In this study, the suitability of a multiplexed plant-animal single nucleotide polymorphism array, including both closely and distantly related species, was explored. The performance of the single nucleotide polymorphism array across species for diverse applications, ranging from intra-species diversity assessments to parentage analysis, was assessed. Moreover, the value of genotyping pooled DNA of distantly related species on the single nucleotide polymorphism array as a technique to further reduce costs was evaluated. Single nucleotide polymorphism performance was generally high, and species-specific single nucleotide polymorphisms proved suitable for diverse applications. The multi-species single nucleotide polymorphism array approach reported here could be transferred to other species to achieve cost savings resulting from the increased throughput when several projects use the same array, and the pooling technique adds another highly promising advancement to additionally decrease genotyping costs by half.

Correlation Between Sagittal Balance and Mechanical Distal Junctional Failure in Degenerative Pathology of the Spine: A Retrospective Analysis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: This study aimed to investigate the failure of the caudal end of lumbar posterior fixation in terms of pre-operative and post-operative spinopelvic parameters, correction performed, demographic and clinical data. METHODS: The lumbar, thoraco-lumbar and lumbo-sacral posterior fixations performed with pedicle screws and rods in 2017-2019 were retrospectively analyzed. As 81% failures occurred within 4 years, an observational period of 4 years was chosen. The revision surgeries due to the failure in the caudal end were collected in the junctional group. Fixations which have not failed were gathered in the control group. The main spinopelvic parameters were measured for each patient on standing lateral radiographs with the software Surgimap. Demographic and clinical data were extracted for both groups. RESULTS: Among the 457 patients who met the inclusion criteria, the junctional group included 101 patients, who required a revision surgery. The control group collected 356 primary fixations. The two most common causes of revision surgeries were screws pullout (57 cases) and rod breakage (53 cases). SVA, PT, LL, PI-LL and TPA differed significantly between the two groups (P = .021 for LL, P < .0001 for all the others). The interaction between the two groups and the pre-operative and post-operative conditions was significant for PT, SS, LL, TK, PI-LL and TPA (P < .005). Sex and BMI did not affect the failure onset. CONCLUSIONS: Mechanical failure is more likely to occur in patients older than 40 years with a thoraco-lumbar fixation where PT, PI-LL and TPA were not properly restored.

Blueberry and cranberry pangenomes as a resource for future genetic studies and breeding efforts.

Domestication of cranberry and blueberry began in the United States in the early 1800s and 1900s, respectively, and in part owing to their flavors and health-promoting benefits are now cultivated and consumed worldwide. The industry continues to face a wide variety of production challenges (e.g. disease pressures) as well as a demand for higher-yielding cultivars with improved fruit quality characteristics. Unfortunately, molecular tools to help guide breeding efforts for these species have been relatively limited compared with those for other high-value crops. Here, we describe the construction and analysis of the first pangenome for both blueberry and cranberry. Our analysis of these pangenomes revealed both crops exhibit great genetic diversity, including the presence-absence variation of 48.4% genes in highbush blueberry and 47.0% genes in cranberry. Auxiliary genes, those not shared by all cultivars, are significantly enriched with molecular functions associated with disease resistance and the biosynthesis of specialized metabolites, including compounds previously associated with improving fruit quality traits. The discovery of thousands of genes, not present in the previous reference genomes for blueberry and cranberry, will serve as the basis of future research and as potential targets for future breeding efforts. The pangenome, as a multiple-sequence alignment, as well as individual annotated genomes, are publicly available for analysis on the Genome Database for Vaccinium - a curated and integrated web-based relational database. Lastly, the core-gene predictions from the pangenomes will serve useful to develop a community genotyping platform to guide future molecular breeding efforts across the family.

Vaccinium as a comparative system for understanding of complex flavonoid accumulation profiles and regulation in fruit.

The genus Vaccinium L. (Ericaceae) contains premium berryfruit crops, including blueberry, cranberry, bilberry, and lingonberry. Consumption of Vaccinium berries is strongly associated with various potential health benefits, many of which are attributed to the relatively high concentrations of flavonoids, including the anthocyanins that provide the attractive red and blue berry colors. Because these phytochemicals are increasingly appealing to consumers, they have become a crop breeding target. There has been substantial recent progress in Vaccinium genomics and genetics together with new functional data on the transcriptional regulation of flavonoids. This is helping to unravel the developmental control of flavonoids and identify genetic regions and genes that can be selected for to further improve Vaccinium crops and advance our understanding of flavonoid regulation and biosynthesis across a broader range of fruit crops. In this update we consider the recent progress in understanding flavonoid regulation in fruit crops, using Vaccinium as an example and highlighting the significant gains in both genomic tools and functional analysis.

Assessment of foraminal decompression following discoplasty using a combination of ex vivo testing and numerical tools.

Percutaneous Cement Discoplasty (PCD) is a minimally invasive surgical technique to treat degenerated intervertebral discs. When the disc is severely degenerated, the vacuum observed in place of the nucleus pulposus can be filled with bone cement to restore the disc height, open the foramen space, and relieve pain. This study aimed to evaluate the foramen geometry change due to PCD, in the loaded spine. Cadaveric spines (n = 25) were tested in flexion and extension while Digital Image Correlation (DIC) measured displacements and deformations. Tests were performed on simulated pre-operative condition (nucleotomy) and after PCD. Registering DIC images and the 3D specimen geometry from CT scans, a 3D model of the specimens aligned in the experimental pose was obtained for nucleotomy and PCD. Foramen space volume was geometrically measured for both conditions. The volume of cement injected was measured to explore correlation with the change of foramen space. PCD induced a significant overall foraminal decompression in both flexion (foramen space increased by 835 ± 1289 mm3, p = 0.001) and extension (1205 ± 1106 mm3, p < 0.001), confirming that the expected improvements of PCD show also during spine motion. Furthermore, in extension when the foramen is the most challenged, the impact of PCD on the foramen correlated with the injected cement volume.

The origins of the camper's chiasm asymmetry: a cadaveric study and clinical implications for flexor tendons surgery.

The Camper's chiasm (CC) originates from the decussation of tendon fibers of the flexor digitorum superficialis at the level of the proximal phalanx. Previous studies described several conformations of the CC, but none has studied the asymmetry pattern for each finger. We lack studies about the relationship between the vincula tendinum and the morphology of the CC. We aimed to study the precise pattern of asymmetry and the aforementioned relationship in a cadaveric study. We studied the fingers of 9 fresh frozen human hands (thumb excluded). We observed the distribution of the fibers and categorized each CC according to the Gonzalez classification. Finally, we recorded the inset point of the vincula longa superficiales (VLS) according to Schmidt. We found 7 symmetrical CCs, while the remaining 29 showed an asymmetrical pattern that matched with the site of insertion of the VLS. For the index and long fingers, we detected a dominance of the ulnar slip. For the ring and little finger, we found a higher radial dominance. The inset point of the VLS always coincided with the side of slip dominance, whereas in symmetrical CCs, the VLS was symmetrical as well. Since the vascular role of the vincula tendinum, we speculate that the asymmetry of the CC may be of vascular origin.

Biomechanical consequences of cement discoplasty: An in vitro study on thoraco-lumbar human spines.

With the ageing of the population, there is an increasing need for minimally invasive spine surgeries to relieve pain and improve quality of life. Percutaneous Cement Discoplasty is a minimally invasive technique to treat advanced disc degeneration, including vacuum phenomenon. The present study aimed to develop an in vitro model of percutaneous cement discoplasty to investigate its consequences on the spine biomechanics in comparison with the degenerated condition. Human spinal segments (n = 27) were tested at 50% body weight in flexion and extension. Posterior disc height, range of motion, segment stiffness, and strains were measured using Digital Image Correlation. The cement distribution was also studied on CT scans. As main result, percutaneous cement discoplasty restored the posterior disc height by 41% for flexion and 35% for extension. Range of motion was significantly reduced only in flexion by 27%, and stiffness increased accordingly. The injected cement volume was 4.56 ± 1.78 ml (mean ± SD). Some specimens (n = 7) exhibited cement perforation of one endplate. The thickness of the cement mass moderately correlated with the posterior disc height and range of motion with different trends for flexions vs. extension. Finally, extreme strains on the discs were reduced by percutaneous cement discoplasty, with modified patterns of the distribution. To conclude, this study supported clinical observations in term of recovered disc height close to the foramen, while percutaneous cement discoplasty helped stabilize the spine in flexion and did not increase the risk of tissue damage in the annulus.

High-density linkage map construction in an autotetraploid blueberry population and detection of quantitative trait loci for anthocyanin content.

Highbush blueberry (Vaccinium corymbosum, 2n = 4x = 48) is the most cultivated type of blueberry, both in New Zealand and overseas. Its perceived nutritional value is conferred by phytonutrients, particularly anthocyanins. Identifying the genetic mechanisms that control the biosynthesis of these metabolites would enable faster development of cultivars with improved fruit qualities. Here, we used recently released tools for genetic mapping in autotetraploids to build a high-density linkage map in highbush blueberry and to detect quantitative trait loci (QTLs) for fruit anthocyanin content. Genotyping was performed by target sequencing, with ∼18,000 single nucleotide polymorphism (SNP) markers being mapped into 12 phased linkage groups (LGs). Fruits were harvested when ripe for two seasons and analyzed with high-performance liquid chromatography-mass spectrometry (HPLC-MS): 25 different anthocyanin compounds were identified and quantified. Two major QTLs that were stable across years were discovered, one on LG2 and one on LG4, and the underlying candidate genes were identified. Interestingly, the presence of anthocyanins containing acylated sugars appeared to be under strong genetic control. Information gained in this study will enable the design of molecular markers for marker-assisted selection and will help build a better understanding of the genetic control of anthocyanin biosynthesis in this crop.

Evaluating new species for aquaculture: A genomic dissection of growth in the New Zealand silver trevally (Pseudocaranx georgianus).

Aquaculture is the fastest-growing food production sector worldwide, yet industry has been slow to implement genomic techniques as routine tools. Applying genomics to new breeding programmes can provide important information about pedigree structure and genetic diversity; key parameters for a successful long-term breeding programme. It can also provide insights on potential gains for commercially important, yet complex, quantitative traits such as growth rate. Here we investigated a population of 1100 captive-bred F1 silver trevally (Pseudocaranx georgianus), a promising new species for New Zealand aquaculture. We used whole-genome information, coupled with image-based phenotypic data collected over two years, to build the pedigree of the population, assess its genetic diversity, describe growth patterns of ten growth traits and estimate their genetic parameters. Successful parentage assignment of 664 F1 individuals showed that the pedigree consisted of a complex mixture of full- and half-sib individuals, with skewed reproductive success among parents, especially in females. Growth patterns showed seasonal fluctuations (average increase across all traits of 27.3% in summer and only 7% in winter) and strong inter-family differences. Heritability values for growth traits ranged from 0.27 to 0.76. Genetic and phenotypic correlations between traits were high and positive, ranging from 0.57 to 0.94 and 0.50 to 1.00 respectively. The implications of these findings are threefold: first, the best on-growing conditions are in warmer months, where highest growth peaks can be achieved; second, size- and family-based selection can be used as early selection criterion if pedigree structure and inbreeding risks are closely monitored; third, selection for body length results in concomitant increases in height and weight, traits of paramount importance for aquaculture. It is concluded that there is substantial potential for genetic improvement of economically important traits, suggesting that silver trevally is a promising species for selective breeding for enhanced growth.

Preservation of terminal branches of the palmar cutaneous branch of the median nerve in open carpal tunnel release.

PURPOSE: Post-operative pain in the palm and scar area is the most common complication after carpal tunnel release and injury to the terminal branches of the palmar cutaneous nerve is generally considered one of the causes for this complication. The Authors performed an intraoperative study preserving the terminal branches of the palmar cutaneous branch of the median nerve and verifying the frequency, location and direction of the branches that cross an interthenar incision. METHOD AND MATERIAL: Eighty-five consecutive patients (57 F - 28 M, mean age 66 y) underwent carpal tunnel release between February and June 2021. The cutaneous branches crossing the incision were identified and preserved by careful dissection. Subsequently they were counted and classified by their direction and distance from the proximal border of the transverse carpal ligament. RESULTS: Sensory branches were found in 40 % of cases (34/85) and their origin was observed at an average of 1.05 cm (0-1.8 cm) distal from the proximal border of the carpal tunnel. A total of 44 branches were observed of which 23 branches crossed the incision with a transverse course and 21 with an oblique, generally proximal-distal radio-ulnar course. The subcutaneous layer overlying the distal third of the transverse carpal ligament was found to be devoid of sensory branches, therefore it can be considered a relatively safe area. CONCLUSION: Isolation and protection of palmar sensory branches is important for improving carpal tunnel release results. This goal can be more easily achieved by locating the skin incision on the distal third of the transverse carpal ligament, where the sensory branches have a lower frequency, possibly associated with a second proximal incision (biportal technique) to better visualize the proximal portion of the ligament and antebrachial fascia.

Unraveling the complex genetic basis of growth in New Zealand silver trevally (Pseudocaranx georgianus).

Growth directly influences production rate and therefore is one of the most important and well-studied traits in animal breeding. However, understanding the genetic basis of growth has been hindered by its typically complex polygenic architecture. Here, we performed quantitative trait locus mapping and genome-wide association studies for 10 growth traits that were observed over 2 years in 1,100 F1 captive-bred trevally (Pseudocaranx georgianus). We constructed the first high-density linkage map for trevally, which included 19,861 single nucleotide polymorphism markers, and discovered 8 quantitative trait loci for height, length, and weight on linkage groups 3, 14, and 18. Using genome-wide association studies, we further identified 113 single nucleotide polymorphism-trait associations, uncovering 10 genetic hot spots involved in growth. Two of the markers found in the genome-wide association studies colocated with the quantitative trait loci previously mentioned, demonstrating that combining quantitative trait locus mapping and genome-wide association studies represents a powerful approach for the identification and validation of loci controlling complex traits. This is the first study of its kind for trevally. Our findings provide important insights into the genetic architecture of growth in this species and supply a basis for fine mapping quantitative trait loci, genomic selection, and further detailed functional analysis of the genes underlying growth in trevally.

Post-traumatic entrapment of the median nerve in the ulno-humeral joint: Diagnosis, treatment and literature review.

BACKGROUND: The incidence of median nerve injuries in pediatric elbow dislocations is approximately 3% and avulsion of the open medial epicondylar epiphysis in the pediatric population is one predisposing factor that may explain this age predilection. These lesions can be difficult to diagnose in the acute phase because symptoms tend to be mild or delayed, consequently their management can be challenging and functional outcome poorer. METHODS: We present the case of an unrecognized median nerve entrapment in a 16-year-old boy with posterior dislocation of the elbow and a medial epicondyle fracture, treated initially with close reduction and open stabilization with a cannulated screw. Assessment is supported by a review of similar reported cases available in literature. RESULTS: We discuss the diagnostic approach and the surgical options that can be used for this type of injury. CONCLUSIONS: High clinical suspicion of entrapment is imperative in presence of signs of damage to the median nerve in the pediatric patient immediately after the reduction of an elbow dislocation. If diagnosis of entrapment is made the therapeutic choice between neurolysis and nerve graft depends on the lesion severity. In the presence of a Fourrier's type 4 lesion, neurolysis should be avoided, while nerve resection and grafting are recommended.

Palmar fracture-dislocation of the trapezoid with median nerve contusion. Case report and literature review.

Complete dislocations of the trapezoid are very uncommon injuries. The authors present a case of open palmar trapezoid fracture-dislocation with significant displacement of the fracture, acute carpal tunnel syndrome and other concomitant carpometacarpal injuries. A review of the literature search for palmar trapezoid dislocations and treatments was performed.

Reconstruction of the Largest Pedigree Network for Pear Cultivars and Evaluation of the Genetic Diversity of the USDA-ARS National Pyrus Collection.

The USDA-ARS National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, maintains one of the world's largest and most diverse living Pyrus collection. A thorough genetic characterization of this germplasm will provide relevant information to optimize the conservation strategy of pear biodiversity, support the use of this germplasm in breeding, and increase our knowledge of Pyrus taxonomy, evolution, and domestication. In the last two decades simple sequence repeat (SSR) markers have been used at the NCGR for cultivar identification and small population structure analysis. However, the recent development of the Applied Biosystems Axiom Pear 70K Genotyping Array has allowed high-density single nucleotide polymorphism (SNP)-based genotyping of almost the entire collection. In this study, we have analyzed this rich dataset to discover new synonyms and mutants, identify putative labeling errors in the collection, reconstruct the largest pear cultivar pedigree and further elucidate the genetic diversity of Pyrus.

Quantitative phenotyping of shell suture strength in walnut (Juglans regia L.) enhances precision for detection of QTL and genome-wide association mapping.

Walnut shell suture strength directly impacts the ability to maintain shell integrity during harvest and processing, susceptibility to insect damage and other contamination, and the proportion of kernel halves recovered during cracking. Suture strength is therefore an important breeding objective. Here, two methods of phenotyping this trait were investigated: 1) traditional, qualitative and rather subjective scoring on an interval scale by human observers, and; 2) quantitative and continuous measurements captured by a texturometer. The aim of this work was to increase the accuracy of suture strength phenotyping and to then apply two mapping approaches, quantitative trait loci (QTL) mapping and genome wide association (GWAS) models, in order to dissect the genetic basis of the walnut suture trait. Using data collected on trees within the UC Davis Walnut Improvement Program (n = 464), the genetic correlation between the texturometer method and qualitatively scored method was high (0.826). Narrow sense heritability calculated using quantitative measurements was 0.82. A major QTL for suture strength was detected on LG05, explaining 34% of the phenotypic variation; additionally, two minor QTLs were identified on LG01 and LG11. All three QTLs were confirmed with GWAS on corresponding chromosomes. The findings reported in this study are relevant for application towards a molecular breeding program in walnut.

Dissecting Genetic Resistance to Fire Blight in Three Pear Populations.

Fire blight, caused by the bacterial pathogen Erwinia amylovora, is a persistent problem for pear (Pyrus spp.) growers in the United States. Growing resistant cultivars is one of the best options for managing fire blight. The cultivars Potomac and Old Home and the selection NJA2R59T69 display resistance to fire blight. As such, three mapping populations (El Dorado × Potomac, Old Home × Bartlett, and NJA2R59T69 × Bartlett) were developed to identify genomic regions associated with resistance to fire blight. Progeny were phenotyped during 2017 and 2018 by inoculating multiple actively growing shoots of field-grown seedling trees with E. amylovora isolate E153n via the cut-leaf method. Genotyping was conducted using the recently developed Axiom Pear 70 K Genotyping Array and chromosomal linkage groups were created for each population. An integrated two-way pseudo-testcross approach was used to map quantitative trait loci (QTLs). Resistance QTLs were identified on chromosome 2 for each population. The QTLs identified in the El Dorado × Potomac and Old Home × Bartlett populations are in the same region as QTLs that were previously identified in Harrow Sweet and Moonglow. The QTL in NJA2R59T69 mapped proximally to the previously identified QTLs and originated from an unknown Asian or occidental source. Future research will focus on further characterizing the resistance regions and developing tools for DNA-informed breeding.

Pseudo-chromosome-length genome assembly of a double haploid "Bartlett" pear (Pyrus communis L.).

BACKGROUND: We report an improved assembly and scaffolding of the European pear (Pyrus communis L.) genome (referred to as BartlettDHv2.0), obtained using a combination of Pacific Biosciences RSII long-read sequencing, Bionano optical mapping, chromatin interaction capture (Hi-C), and genetic mapping. The sample selected for sequencing is a double haploid derived from the same "Bartlett" reference pear that was previously sequenced. Sequencing of di-haploid plants makes assembly more tractable in highly heterozygous species such as P. communis. FINDINGS: A total of 496.9 Mb corresponding to 97% of the estimated genome size were assembled into 494 scaffolds. Hi-C data and a high-density genetic map allowed us to anchor and orient 87% of the sequence on the 17 pear chromosomes. Approximately 50% (247 Mb) of the genome consists of repetitive sequences. Gene annotation confirmed the presence of 37,445 protein-coding genes, which is 13% fewer than previously predicted. CONCLUSIONS: We showed that the use of a doubled-haploid plant is an effective solution to the problems presented by high levels of heterozygosity and duplication for the generation of high-quality genome assemblies. We present a high-quality chromosome-scale assembly of the European pear Pyrus communis and demostrate its high degree of synteny with the genomes of Malus x Domestica and Pyrus x bretschneideri.

Development of a highly efficient Axiom™ 70 K SNP array for Pyrus and evaluation for high-density mapping and germplasm characterization.

BACKGROUND: Both a source of diversity and the development of genomic tools, such as reference genomes and molecular markers, are equally important to enable faster progress in plant breeding. Pear (Pyrus spp.) lags far behind other fruit and nut crops in terms of employment of available genetic resources for new cultivar development. To address this gap, we designed a high-density, high-efficiency and robust single nucleotide polymorphism (SNP) array for pear, with the main objectives of conducting genetic diversity and genome-wide association studies. RESULTS: By applying a two-step design process, which consisted of the construction of a first 'draft' array for the screening of a small subset of samples, we were able to identify the most robust and informative SNPs to include in the Applied Biosystems™ Axiom™ Pear 70 K Genotyping Array, currently the densest SNP array for pear. Preliminary evaluation of this 70 K array in 1416 diverse pear accessions from the USDA National Clonal Germplasm Repository (NCGR) in Corvallis, OR identified 66,616 SNPs (93% of all the tiled SNPs) as high quality and polymorphic (PolyHighResolution). We further used the Axiom Pear 70 K Genotyping Array to construct high-density linkage maps in a bi-parental population, and to make a direct comparison with available genotyping-by-sequencing (GBS) data, which suggested that the SNP array is a more robust method of screening for SNPs than restriction enzyme reduced representation sequence-based genotyping. CONCLUSIONS: The Axiom Pear 70 K Genotyping Array, with its high efficiency in a widely diverse panel of Pyrus species and cultivars, represents a valuable resource for a multitude of molecular studies in pear. The characterization of the USDA-NCGR collection with this array will provide important information for pear geneticists and breeders, as well as for the optimization of conservation strategies for Pyrus.

Novel Insights into Tree Biology and Genome Evolution as Revealed Through Genomics.

Reference genome sequences are the key to the discovery of genes and gene families that determine traits of interest. Recent progress in sequencing technologies has enabled a rapid increase in genome sequencing of tree species, allowing the dissection of complex characters of economic importance, such as fruit and wood quality and resistance to biotic and abiotic stresses. Although the number of reference genome sequences for trees lags behind those for other plant species, it is not too early to gain insight into the unique features that distinguish trees from nontree plants. Our review of the published data suggests that, although many gene families are conserved among herbaceous and tree species, some gene families, such as those involved in resistance to biotic and abiotic stresses and in the synthesis and transport of sugars, are often expanded in tree genomes. As the genomes of more tree species are sequenced, comparative genomics will further elucidate the complexity of tree genomes and how this relates to traits unique to trees.