Quantitative Genetics and Genomics Converge to Accelerate Forest Tree Breeding

Forest tree breeding has been successful at delivering genetically improved material for multiple traits based on recurrent cycles of selection, mating, and testing. However, long breeding cycles, late flowering, variable juvenile-mature correlations, emerging pests and diseases, climate, and market changes, all pose formidable challenges. Genetic dissection approaches such as quantitative trait mapping and association genetics have been fruitless to effectively drive operational marker-assisted selection (MAS) in forest trees, largely because of the complex multifactorial inheritance of most, if not all traits of interest. The convergence of high-throughput genomics and quantitative genetics has established two new paradigms that are changing contemporary tree breeding dogmas. Genomic selection (GS) uses large number of genome-wide markers to predict complex phenotypes. It has the potential to accelerate breeding cycles, increase selection intensity and improve the accuracy of breeding values. Realized genomic relationships matrices, on the other hand, provide innovations in genetic parameters' estimation and breeding approaches by tracking the variation arising from random Mendelian segregation in pedigrees. In light of a recent flow of promising experimental results, here we briefly review the main concepts, analytical tools and remaining challenges that currently underlie the application of genomics data to tree breeding. With easy and cost-effective genotyping, we are now at the brink of extensive adoption of GS in tree breeding. Areas for future GS research include optimizing strategies for updating prediction models, adding validated functional genomics data to improve prediction accuracy, and integrating genomic and multi-environment data for forecasting the performance of genetic material in untested sites or under changing climate scenarios. The buildup of phenotypic and genome-wide data across large-scale breeding populations and advances in computational prediction of discrete genomic features should also provide opportunities to enhance the application of genomics to tree breeding

Decoupling of height growth and drought or pest resistance tradeoffs is revealed through multiple common-garden experiments of lodgepole pine

14 páginas.- 4 figuras.- 1 tabla.- 101 referencias.- Supplementary material is available online at Evolution (https://academic.oup.com/evolut/qpad004) . A correction has been published: Evolution, Volume 77, Issue 4, 1 April 2023, Page 1174, https://doi.org/10.1093/evolut/qpad030 Issue Section: Correction This is a correction to: Yang Liu, Nadir Erbilgin, Eduardo Pablo Cappa, Charles Chen, Blaise Ratcliffe, Xiaojing Wei, Jennifer G Klutsch, Aziz Ullah, Jaime Sebastian Azcona, Barb R Thomas, Yousry A El-Kassaby, Decoupling of height growth and drought or pest resistance tradeoffs is revealed through multiple common-garden experiments of lodgepole pine, Evolution, 2023; qpad004, https://doi.org/10.1093/evolut/qpad004 In the originally published version of this manuscript, the images for Figures 3 and 4 were erroneously transposed. The images are now in their correct position to align with their respective legends. The Funding section was erroneously removed, and its details situated at the end of the Acknowledgements section. Funding details are now situated within the replaced Funding section. The publisher would like to apologise for the errors introduced here. The errors have been corrected in the article online.The environment could alter growth and resistance tradeoffs in plants by affecting the ratio of resource allocation to various competing traits. Yet, how and why functional tradeoffs change over time and space is poorly understood particularly in long-lived conifer species. By establishing four common-garden test sites for five lodgepole pine populations in western Canada, combined with genomic sequencing, we revealed the decoupling pattern and genetic underpinnings of tradeoffs between height growth, drought resistance based on δ13C and dendrochronology, and metrics of pest resistance based on pest suitability ratings. Height and δ13C correlation displayed a gradient change in magnitude and/or direction along warm-to-cold test sites. All cold test sites across populations showed a positive height and δ13C relationship. However, we did not observe such a clinal correlation pattern between height or δ13C and pest suitability. Further, we found that the study populations exhibiting functional tradeoffs or synergies to various degrees in test sites were driven by non-adaptive evolutionary processes rather than adaptive evolution or plasticity. Finally, we found positive genetic relationships between height and drought or pest resistance metrics and probed five loci showing potential genetic tradeoffs between northernmost and the other populations. Our findings have implications for deciphering the ecological, evolutionary, and genetic bases of the decoupling of functional tradeoffs due to environmental change.This work was funded by Genome Canada, Genome Alberta through Alberta Economic Trade and evelopment, Genome British Columbia, the University of Alberta, the University of Calgary, the University of Cambridge, and the Australian Research Council Centre of Excellence for Plant Success in Nature and Agriculture (CE200100015).Peer reviewe

Enfrentando el cambio climático: análisis de las respuestas a la inundación en una familia de Populus deltoides W.Bartram ex Marshall

Uno de los mayores impactos del cambio climático a nivel mundial será la alteración en el patrón de las precipitaciones. Los posibles escenarios de cambio climático indican que habrá un aumento en la ocurrencia de precipitaciones extremas en ciertas áreas, ocasionando un aumento en la frecuencia de episodios de inundación. En Argentina la principal área de plantaciones de álamo se encuentra en el Delta del Río Paraná, donde los modelos de cambio climático predicen un aumento en la frecuencia de precipitaciones locales excesivas. Incluso cuando estos eventos de estrés no ocasionan la muerte de la planta, el álamo puede experimentar reducción del crecimiento y la productividad. Es por ello que resulta necesario obtener clones con un mejor rendimiento cuando se encuentran sometidos a estrés por inundación. El objetivo de este trabajo fue identificar caracteres fenotípicos que puedan ser útiles como herramienta de selección indirecta de clones tolerantes a dicho estrés. Se realizó un ensayo de inundación en invernáculo con una F1 de P. deltoides obtenida en el programa de mejoramiento de álamo del INTA, a partir del cruzamiento de los clones A106 x ST67. De acuerdo a los datos preliminares, la F1 muestra variabilidad en la tolerancia a la inundación evaluada como reducción del crecimiento, siendo algunos clones de la F1 más tolerantes y otros más sensibles que sus padres. No hubo diferencias clonales en la respuesta de la conductancia estomática y la formación de lenticelas hipertrofiadas y raíces adventicias. Sin embargo, se observó variabilidad de respuesta en el crecimiento en altura y biomasa y en la formación de nuevas hojas. Utilizando los resultados obtenidos en este experimento, se identificarán caracteres que puedan ser usados para la selección indirecta de individuos con tolerancia a la inundación, determinando la correlación genética de estos caracteres con la tolerancia a la inundación, y su heredabilidad bajo esta situación de estrés.Instituto de Fisiología Vegeta

Breeding without Breeding: Is a Complete Pedigree Necessary for Efficient Breeding?

Complete pedigree information is a prerequisite for modern breeding and the ranking of parents and offspring for selection and deployment decisions. DNA fingerprinting and pedigree reconstruction can substitute for artificial matings, by allowing parentage delineation of naturally produced offspring. Here, we report on the efficacy of a breeding concept called “Breeding without Breeding” (BwB) that circumvents artificial matings, focusing instead on a subset of randomly sampled, maternally known but paternally unknown offspring to delineate their paternal parentage. We then generate the information needed to rank those offspring and their paternal parents, using a combination of complete (full-sib: FS) and incomplete (half-sib: HS) analyses of the constructed pedigrees. Using a random sample of wind-pollinated offspring from 15 females (seed donors), growing in a 41-parent western larch population, BwB is evaluated and compared to two commonly used testing methods that rely on either incomplete (maternal half-sib, open-pollinated: OP) or complete (FS) pedigree designs. BwB produced results superior to those from the incomplete design and virtually identical to those from the complete pedigree methods. The combined use of complete and incomplete pedigree information permitted evaluating all parents, both maternal and paternal, as well as all offspring, a result that could not have been accomplished with either the OP or FS methods alone. We also discuss the optimum experimental setting, in terms of the proportion of fingerprinted offspring, the size of the assembled maternal and paternal half-sib families, the role of external gene flow, and selfing, as well as the number of parents that could be realistically tested with BwB

Atorvastatin Improves Survival in Septic Rats: Effect on Tissue Inflammatory Pathway and on Insulin Signaling

The aim of the present study was to investigate whether the survival-improving effect of atorvastatin in sepsis is accompanied by a reduction in tissue activation of inflammatory pathways and, in parallel, an improvement in tissue insulin signaling in rats. Diffuse sepsis was induced by cecal ligation and puncture surgery (CLP) in male Wistar rats. Serum glucose and inflammatory cytokines levels were assessed 24 h after CLP. The effect of atorvastatin on survival of septic animals was investigated in parallel with insulin signaling and its modulators in liver, muscle and adipose tissue. Atorvastatin improves survival in septic rats and this improvement is accompanied by a marked improvement in insulin sensitivity, characterized by an increase in glucose disappearance rate during the insulin tolerance test. Sepsis induced an increase in the expression/activation of TLR4 and its downstream signaling JNK and IKK/NF-κB activation, and blunted insulin-induced insulin signaling in liver, muscle and adipose tissue; atorvastatin reversed all these alterations in parallel with a decrease in circulating levels of TNF-α and IL-6. In summary, this study demonstrates that atorvastatin treatment increased survival, with a significant effect upon insulin sensitivity, improving insulin signaling in peripheral tissues of rats during peritoneal-induced sepsis. The effect of atorvastatin on the suppression of the TLR-dependent inflammatory pathway may play a central role in regulation of insulin signaling and survival in sepsis insult

Efficient genomics based 'end-to-end' selective tree breeding framework

<p>Since their initiation in the 1950s, worldwide selective tree breeding programs followed the recurrent selection scheme of repeated cycles of selection, breeding (mating), and testing phases and essentially remained unchanged to accelerate this process or address environmental contingences and concerns. Here, we introduce an "end-to-end" selective tree breeding framework that: 1) leverages strategically preselected GWAS-based sequence data capturing trait architecture information, 2) generates unprecedented resolution of genealogical relationships among tested individuals, and 3) leads to the elimination of the breeding phase through the utilization of readily available wind-pollinated (OP) families. Individuals' breeding values generated from multi-trait multi-site analysis were also used in an optimum contribution selection protocol to effectively manage genetic gain/co-ancestry trade-offs and traits' correlated response to selection. The proof-of-concept study involved a 40-year-old spruce OP testing population growing on three sites in British Columbia, Canada, clearly demonstrating our method's superiority in capturing most of the available genetic gains in a substantially reduced timeline relative to the traditional approach. The proposed framework is expected to increase the efficiency of existing selective breeding programs, accelerate the start of new programs for ecologically and environmentally important tree species, and address climate-change caused biotic and abiotic stress concerns more effectively.</p><p>Funding provided by: Natural Sciences and Engineering Research Council<br>Crossref Funder Registry ID: https://ror.org/01h531d29<br>Award Number: Discovery Grant</p><p>Funding provided by: Johnson's Family Forest Biotechnology Endowment*<br>Crossref Funder Registry ID: <br>Award Number: </p><p>See Readme file</p&gt

Impacts of population structure and analytical models in genome-wide association studies of complex traits in forest trees: a case study in Eucalyptus globulus.

The promise of association genetics to identify genes or genomic regions controlling complex traits has generated a flurry of interest. Such phenotype-genotype associations could be useful to accelerate tree breeding cycles, increase precision and selection intensity for late expressing, low heritability traits. However, the prospects of association genetics in highly heterozygous undomesticated forest trees can be severely impacted by the presence of cryptic population and pedigree structure. To investigate how to better account for this, we compared the GLM and five combinations of the Unified Mixed Model ( UMM ) on data of a low-density genome-wide association study for growth and wood property traits carried out in a Eucalyptus globulus population (n = 303) with 7,680 Diversity Array Technology (DArT) markers. Model comparisons were based on the degree of deviation from the uniform distribution and estimates of the mean square differences between the observed and expected p-values of all significant marker-trait associations detected. Our analysis revealed the presence of population and family structure. There was not a single best model for all traits. Striking differences in detection power and accuracy were observed among the different models especially when population structure was not accounted for. The UMM method was the best and produced superior results when compared to GLM for all traits. Following stringent correction for false discoveries, 18 marker-trait associations were detected, 16 for tree diameter growth and two for lignin monomer composition (S:G ratio), a key wood property trait. The two DArT markers associated with S:G ratio on chromosome 10, physically map within 1 Mbp of the ferulate 5-hydroxylase (F5H) gene, providing a putative independent validation of this marker-trait association. This study details the merit of collectively integrate population structure and relatedness in association analyses in undomesticated, highly heterozygous forest trees, and provides additional insights into the nature of complex quantitative traits in Eucalyptus

Mean squared differences (MSD) between observed and expected <i>p</i>-values for the six association genetics models applied in the study.

<p>The selected models are highlighted in bold (see text for models' and traits' abbreviations).</p

Significant DArT marker-trait associations for DBH and S∶G ratio retained for the six models.

<p>Shown are <i>p</i>-values after correction for multiple testing (FDR <i>p</i>-value≤0.05, <i>Q</i>-value) and estimates of percent phenotypic variance putatively explained (R²). Highlighted in bold, the best trait by model combinations reported based on the degree of deviation from the uniform distribution and estimates of the mean square differences (MSD) between the observed and expected <i>p</i>-values (see text for models' and traits' abbreviations).</p