Varying Levels of Genetic Control and Phenotypic Plasticity in Timing of Bud Burst, Flower Opening, Leaf Senescence and Leaf Fall in Two Common Gardens of Prunus padus L.&#x0D;

Kristine Vander Mijnsbrugge,Stefaan Moreels

doi:10.3390/f11101070

Abstract

Several phenological phases mark the seasonal growth pattern in temperate woody perennials. To gain further insight into the way these phases react on an altering growth environment, we tested whether vegetative and reproductive phenophases in a shrub species respond differentially among different genetic entities and between two different planting sites. We scored leaf bud burst, flower opening, leaf senescence and leaf fall on 267 ramets of Prunus padus L. belonging to 53 genotypes that were sampled in 9 local populations, and that were planted in 2 common gardens in the northern part of Belgium. The data were processed with cumulative logistic regression. The contribution of genetic and non-genetic components to the total variability varied between the four studied seasonal phenophases. The timing of flower opening displayed the smallest relative amount of intragenotypic variance (between ramets), suggesting a stronger genetic control and a lesser need at the individual plant level for plastic fine tuning to the micro-environment. In addition, whereas leaf bud burst showed the highest relative variance at the interpopulation level among all phenophases, probably at least partly attributable to local adaptation, flower opening displayed the highest intergenotypic variance, which may have been promoted more by assortative mating. Spring phenophases were strongly correlated (r = 0.89) as well as the autumnal phenophases (r = 0.72). Flower opening was not correlated with the autumnal phenophases. Timing of leaf bud burst and leaf senescence were negatively correlated, demonstrating that the length of the growing season enlarged or diminished among the studied genotypes. Although the two planting sites were only 24 km apart, all phenophases were advanced at the less exposed site, indicating a phenotypic plastic response. Together, our results suggest that in P. padus, flowering is less sensitive to environmental variation than leaf bud break and may show a lesser impact of a changing environment on this reproductive phenophase.

Highlights

Understanding how plants respond to environmental change will help predict the impact of climate change on plant populations
General linear mixed models were fit to the observational data to examine the timing of the phenophases leaf bud burst, flower opening, leaf senescence and leaf fall in the shrub P. padus in two common gardens (Table 3)
As the location variable was accounted for in the fixed part of the models, results of the variance partitioning were independent of the different growth environments at the two planting sites

Summary

Introduction

Understanding how plants respond to environmental change will help predict the impact of climate change on plant populations. This is especially true for woody species that are sessile and perennial organisms, have a long life-span, support diverse communities and give structure to a wide range of ecosystems on Earth [1]. An individual plant can maintain its fitness by altering its phenotype in response to a changing growth environment [2]. Trees experience considerable variation in growth conditions throughout their life [3,4]. The ability of tree species for phenotypic plastic responses and to adapt locally to altering environments is studied [5]. Plasticity will likely play an Forests 2020, 11, 1070; doi:10.3390/f11101070 www.mdpi.com/journal/forests

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