Abstract Detail

The impact of climate change on plant physiology in natural and agricultural systems

Ribeiro, Rafael Candido [1], Lind, Brandon [1], Lu, Mengmeng [2], Singh, Pooja [2], Obreht Vidakovic, Dragana [1], Yeaman, Sam [2], Aitken, Sally [1].

Understanding the capacity of Douglas-Fir (Pseudotsuga menziesii) to adapt to drought.

Widespread conifers are known to be, in general, adapted to their local environments, with populations genetically differentiated for adaptive traits. With climate change, drought is likely to become a major driver of mortality and selection. However, little is known about the extent of population variation in drought tolerance of seedlings and the magnitude of local adaptation to drought in widespread conifers. Furthermore, the main climatic drivers of drought tolerance and the genes underpinning this trait are largely unknown. Here, we investigate these components to better understand the adaptive potential of Douglas-fir (Pseudotsuga menziesii) to future climatic conditions. We conducted a drought experiment with seedlings from 73 natural provenances spanning most of the species’ range and including both coastal (var. menziesii) and interior (var. glauca) varieties. Chlorophyll fluorescence, visual damage, and height were monitored over time on seedlings submitted to a drought-to-death treatment in summer. In a subsequent study, we conducted a case-control genome-wide association study with 20 of the same provenances (80 seedlings/provenance) to identify genetic variants associated with drought tolerance. Associations were tested between drought tolerance and allele counts for over 1.5 million SNPs in pooled extremes (10 cases and 10 controls per provenance). Strong phenotypic differences were observed between the two varieties. However, the signal of local adaptation to drought was weak within var. glauca and almost absent within var. menziesii, while within-provenance variation was large. Additionally, var. menziesii showed higher levels of plasticity than var. glauca. The variety, the scale of the studied region, and the climate variable used affect the slope and sign of relationships between climatic drivers and drought tolerance, suggesting a context-dependent relationship between drought tolerance and climate in Douglas-fir. For example, drought tolerance within western Washington was mainly driven by higher temperatures, meanwhile within the eastern most part of the range, low temperatures appear to be driving adaptation to drought. After corrections for false discovery rate, we successfully identified 359 drought-tolerance candidate genes (transcriptional contigs) for the var. menziesii and 468 for var. glauca, with an overlap of 8 genes between the two varieties. The next steps include predicting genomic vulnerability under climate change scenarios for those SNPs most strongly associated with drought tolerance and within the most relevant annotated candidate genes. The results of this study will inform Douglas-fir assisted gene flow strategies and breeding programs to better match genotypes and phenotypes with predicted future climates.

1 - University of British Columbia, Department of Forest and Conservation Sciences, Vancouver, BC, Canada
2 - University of Calgary, Department of Biological Sciences, Calgary, AB, Canada

Keywords:
Local adaptation
drought tolerance
GWAS
candidate genes
assisted gene flow
Phenotypic variation
adaptive traits.

Presentation Type: Colloquium Presentations
Number: C1005
Abstract ID:749
Candidate for Awards:Margaret Menzel Award,Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation