Environmentally induced transgenerational changes in seed longevity: maternal and genetic influence

Seed longevity, a fundamental plant trait for ex situ conservation and persistence in the soil of many species, varies across populations and generations that experience different climates. This study investigates the extent to which differences in seed longevity are due to genetic differences and/or modified by adaptive responses to environmental changes.

Seeds of two wild populations of Silene vulgaris from alpine (wA) and lowland (wL) locations and seeds originating from their cultivation in a lowland common garden for two generations (cA1, cL1, cA2 and cL2) were exposed to controlled ageing at 45 °C, 60 % relative humidity and regularly sampled for germination and relative mRNA quantification (SvHSP17.4 and SvNRPD12).

The parental plant growth environment affected the longevity of seeds with high plasticity. Seeds of wL were significantly longer lived than those of wA. However, when alpine plants were grown in the common garden, longevity doubled for the first generation of seeds produced (cA1). Conversely, longevity was similar in all lowland seed lots and did not increase in the second generation of seeds produced from alpine plants grown in the common garden (cA2). Analysis of parental effects on mRNA seed provisioning indicated that the accumulation of gene transcripts involved in tolerance to heat stress was highest in wL, cL1 and cL2, followed by cA1, cA2 and wA.

Seed longevity has a genetic basis, but may show strong adaptive responses, which are associated with differential accumulation of mRNA via parental effects. Adaptive adjustments of seed longevity due to transgenerational plasticity may play a fundamental role in the survival and persistence of the species in the face of future environmental challenges. The results suggest that regeneration location may have important implications for the conservation of alpine plants held in seed banks.