Two new publications on drought resilience in white spruce

Drought response was investigated in a large cohort of white spruce multiclonal seedlings for multiple growth and wood anatomy traits, in part to better understand the effects on hydraulicity. The results indicate that genetic selection to improve resilience to drought at the juvenile stage would be possible, when the young trees are most susceptible to such stress after reforestation. Full publications available at the following links (1) (2).

Important progress in genomic prediction applied to spruces

A recent study published in Frontiers in Plant Science by the Research Chair team indicates that the accuracy of genomic prediction models for traits related to growth and wood quality can be increased by considering non-additive genetic effects and large datasets. The implications are important, including to better predict the value of new spruce families without having to phenotype them or wait to do so.

Analysis of spruce genomes reveals important evolutionary mechanisms related to adaptation

The genomes of new spruce species have just been deciphered. Notwithstanding their size seven times that of the human genome (thus among the largest genomes in the living world), the study confirmed that the largest part of their genomes is made up of repeated and non-coding DNA. As for the genes, most of them were grouped into large families, some of them being in expansion. Also, some genes were found to evolve faster than others at the level of the proteins they encode. They were found to be mainly involved in species differential adaptation to biotic and abiotic stresses, just like for expanding gene families. Therefore, this study sheds light on two important mechanisms of evolution of conifer genomes in response to the multiple environmental stresses that they face since their inception, millions of years ago. Link to the complete publication here.

Limits of climate change adaptation in forest trees

In the context of climate change, an article has just been published by the researchers of the Chair on the maladaptation of trees in the face of severe climatic stress caused by the growing climate instability. Spring 2021 was exceptionally warm and early under our northern latitudes, leading to an early shoot bud burst up to two weeks earlier than usual. However, at the end of May 2021, the Quebec province was hit by a major cold snap caused by the instability of the polar vortex, which resulted in severe frost damages to the annual growing shoots in young white spruce plantations, and the cancellation of the growth of 2021. The study of young comparative plantations of various seed sources indicated that there was no significant genetic variation in resistance to such severe late frosts. The researchers will follow growth recovery in 2022 to check if significant genetic variation exists and if it is related to previous tree vigor. Link to the complete publication here.

Trembling aspen, a widespread species genetically diverse and heterogeneous throughout its range

A vast collaborative study has just been published by researchers from the Chair on the distribution of genetic diversity throughout the entire range of this pioneer species, which covers most of the North American continent from Canada to Mexico. The distribution of genomic diversity, estimated using a large number of populations, appeared highly geographically structured. Signatures of genetic adaptation to regional climate were detected, especially for water stress. Other factors were also investigated, such as polyploidy and seed germination, for which significant regional differences were also observed. Link to the complete publication here.

Improving drought response through genomic selection

The Chair’s researchers have just published an article on the potential for improving the response to drought in white spruce, thanks to genomic selection. Based on the dendrochronological profiles of trees established on two experimental sites over the past twenty years, they were able to assess the genetic variability in the responses to two distinct droughts suffered by the trees obtained from controlled crosses. In particular, they discovered that the trees that responded best to water stress were those that displayed the best vigor throughout their life. The genomic selection models were as accurate as those developed using conventional approaches, making it possible to accelerate the selection of more resilient trees in the context of climate change, and in particular in relation to the intensification of stress due to droughts. Link to the complete publication here.

A new article on the genetic basis of drought adaptation in white spruce elected for the cover of the journal Molecular Ecology

In a recent work elected for the cover page of the August 2021 issue of the journal Molecular Ecology, Depardieu et al. combined the results of dendrochronology analyses of mature trees replicated in a common garden, genotype-phenotype associations and genotype-environment associations for thousands of candidate genes, as well as transcriptomics to study the genomic basis of drought resistance in white spruce. In total, they identify 285 genes likely involved in drought resistance including differentially expressed genes in seedlings submitted to water stress. This publication was also the subject of an editorial comment on pages 3893-95 of the same issue. Link to the complete publication.