Abstract: Arbuscular mycorrhizal fungi (AMF) can help host plants adapt to low P environment by enhancing the root secretion of acid phosphatase (APase). Whether such plastic change can be transmitted across generations, however, remains unclear. In this study, we conducted two experiments to investigate the transgenerational effect of AMF on APase activity in a host plant Medicago truncatula. Under low P condition in experiment 1, AMF infection increased APase activity in root, and increased APase activity and available P content in rhizosphere soil. Under high P condition, there was no difference of APase activity between AMF and non-AMF plants. Under low P condition in experiment 2, the offsprings from parental plants with AMF had higher APase activity compared to those from parental plants without AMF. No difference of APase activity was found between the offsprings from both nonAMF and AMF parental plants grown in high P condition. Under high P condition in experiment 2, however, there was no significant difference of the root APase activity among the offsprings of different parental plants. The results suggest that there was an AMF transgenerational effect on root APase activity, which was determined by soil P condition encountered by the parental plants.

Key words: arbuscular mycorrhizal fungi, acid phosphatase, transgenerational effect, low phosphorus, phenotypic plasticity.