Fig. 2.

A Experimental set-up of the first methylome study. We sampled 16 plants of Lombardy poplar grown in a common environment in Belgium. These plants included first-generation vegetative offspring (F₁) grown from ramets collected from four adult Lombardy poplars (F₀) located in Hungary, Italy, Spain, and the UK, respectively, and second-generation vegetative offspring (F₂). We took leaf samples in 2017 on March 31 and July 25, and in 2018 on June 12. We extracted DNA from one leaf per plant and performed whole-genome bisulfite sequencing (WGBS). We used clustering analysis to study the methylome stability across a growing season and across vegetative generations. We studied differentially methylated regions (DMRs) by grouping the WGBS data by the F₀-parent. B Experimental set-up of the second methylome study. We sampled 53 plants of Lombardy poplar grown in a common environment in Belgium. These plants included first-generation vegetative offspring (F₁) grown from ramets collected from 53 adult Lombardy poplars (F₀) located over Europe. We took leaf samples in March 2017 and we extracted DNA from one leaf per plant. We prepared 13 DNA pools from 2 to 9 F₁-plants originating from F₀ -Lombardy poplars growing in proximity. We performed WGBS and searched for DMRs by grouping the WGBS data based on the climate of the F₀-parent, using the average January temperature as a proxy for the parental climate, resulting in three groups. C Experimental set-up of the common environment experiment. We observed timing of bud set on 791 plants of Lombardy poplar grown in a common environment in Belgium using a seven-stage scoring. These plants included F₁-ramets collected from 67 adult Lombardy poplars (F₀) grown on 28 different locations in 13 different countries over Europe. We used a linear mixed effects analysis on the total bud set data spanning 4 years (2017–2020) to investigate the relationship between bud set phenology of the ramets in the common environment experiment (F₁) and the latitude of origin of the home site of the Lombardy poplar parent-of-origin (F₀). Icons made by Freepik from www.flaticon.com