Temperature during Seed Maturation Influences Timing of Bud Burst in Seedlings and Saplings of Prunus padus

Abstract

Climate change increases global average temperatures worldwide. We tested whether temperature during seed maturation in a broadleaved woody perennial may influence the phenological performance of the seedlings. We performed two controlled crosses of Prunus padus L. in two subsequent years (2015 and 2016). Clonal mother shrubs were subjected to a cold and a warm condition during seed maturation. In the first year after germination, the seedlings from the warm seed maturation condition burst their buds earlier compared with the cold condition seedlings. In contrast, in the second and third years, these seedlings burst their buds later. A temporary maternal effect may have advanced bud burst for the warm condition seedlings in the first year, whereas a delay of bud burst in the following years may be caused by a transgenerational epigenetic memory, putatively expressing a stress reaction upon the suboptimal elevated temperature during seed maturation. A warm spring treatment in 2020 enlarged the difference in timing of bud burst between the cold and warm seed maturation conditions in offspring of both crosses, suggesting that the epigenetic memory is more strongly expressed in a warmer spring environment. The timing of the autumnal leaf senescence in the seedlings was not influenced by the temperature during seed maturation in all observation years, suggesting that autumnal senescence is less (epi)genetically determined compared with bud burst and more sensitive to ambient temperatures.