Parental environment nitrogen and phosphorus availability affects offspring traits of eight annual plant species

The rates in which nitrogen (N) and phosphorus (P) are entering natural plant communities have reached unprecedented levels, resulting in increasingly imbalanced N:P ratios potentially aggravating both plant invasions and plant extinctions. Plants may cope with changing environments via phenotypic plasticity, which may occur within one generation or between generations (transgenerational plasticity, TGP). Here, we investigated TGP in plant traits in response to variation in N and P availabilities, in eight annual plant species comprising endangered, nonendangered and invasive species. We hypothesized that adaptive effects would be evident when parental and offspring environments match. We also expected endangered species to exhibit the lowest, and invasive species the highest, adaptive TGP-potential. A parental generation was raised under N-limitation, balanced nutrient supply and P-limitation, from which an offspring generation was grown under either the same or another option of these nutrient conditions. Across all species, offspring plants of N-stressed parents showed thin roots, i.e. low average root diameter, which is advantageous under N-limitation when repeatedly exposed to N-limitation, and offspring of P-stressed parents showed highest levels of phosphomonoesterase activity (PME activity), associated with P-uptake, when repeatedly grown under P-limitation. Contrary to our expectation, endangered species with P-stressed parents performed better than nonendangered or invasive species especially when grown under P-limitation in the offspring generation, probably due to a higher PME activity and longer and thicker roots. Our results demonstrate that the parental nutrient environment can have profound effects on offspring fitness and trait expressions, especially when parental and offspring environments match. There, TGP in response to parental nutrient limitation pre-adapts the offspring generation, resulting in individuals exhibiting traits associated with higher nutrient uptake under nutrient deficient conditions. Overall, our findings indicate that TGP may play a significant role in the realised niches of plant species in general, and specifically in endangered species.