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Ecological genomics of variation in bud‐break phenology and mechanisms of response to climate warming in Populus trichocarpa
Author(s) -
McKown Athena D.,
Klápště Jaroslav,
Guy Robert D.,
ElKassaby Yousry A.,
Mansfield Shawn D.
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15273
Subject(s) - populus trichocarpa , biology , annual growth cycle of grapevines , phenology , genetic variation , population , local adaptation , ecology , botany , genetics , genome , gene , demography , shoot , sociology
Summary Spring bud‐break phenology is a critical adaptive feature common to temperate perennial woody plants. Understanding the molecular underpinnings of variation in bud‐break is important for elucidating adaptive evolution and predicting outcomes relating to climate change. Field and controlled growth chamber tests were used to assess population‐wide patterns in bud‐break from wild‐sourced black cottonwood ( Populus trichocarpa ) genotypes. We conducted a genome‐wide association study ( GWAS ) with single nucleotide polymorphisms ( SNP s) derived from whole genome sequencing to test for loci underlying variation in bud‐break. Bud‐break had a quadratic relationship with latitude, where southern‐ and northern‐most provenances generally broke bud earlier than those from central parts of the species’ range. Reduced winter chilling increased population‐wide variation in bud‐break, whereas greater chilling decreased variation. GWAS uncovered 16 loci associated with bud‐break. Phenotypic changes connected with allelic variation were replicated in an independent set of P . trichocarpa trees. Despite phenotypic similarities, genetic profiles between southern‐ and northern‐most genotypes were dissimilar based on our GWAS ‐identified SNP s. We propose that the GWAS ‐identified loci underpin the geographical pattern in P . trichocarpa and that variation in bud‐break reflects different selection for winter chilling and heat sum accumulation, both of which can be affected by climate warming.