Background and Aims Enhanced availability of photosynthates increases nitrogen (N) mineralization and nitrification in the rhizosphere via rhizodeposition from plant roots. Under heterogeneous light conditions, photosynthates supplied by exposed ramets may promote N assimilation in the rhizosphere of shaded, connected ramets. This study was conducted to test this hypothesis.

The effects of rhizodeposition on soil C and N availabilities lead to substantial changes of microbial community composition and processes in the rhizosphere of plants. Under heterogeneous light, photosynthates can be translocated or shared between exposed and shaded ramets by clonal integration. Clonal integration may enhance the rhizodeposition of the shaded ramets, which further influences nutrient recycling in their rhizosphere. To test the hypothesis, we conducted a pot experiment by the stoloniferous herb Glechoma longituba subjected to heterogeneous light. Microbial biomass and community composition in the rhizosphere of shaded offspring ramets, assessed by phospholipid fatty acids (PLFAs) analysis, were markedly altered by clonal integration. Clonal integration positively affected C, N availabilities, invertase and urease activities, N mineralization (N_min) and nitrification rates (N_nitri) in the rhizosphere of shaded offspring ramets. However, an opposite pattern was also observed in phenoloxidase (POXase) and peroxidase (PODase) activities. Our results demonstrated that clonal integration facilitated N assimilation and uptake in the rhizosphere of shaded offspring ramets. The experiment provides insights into the mechanism of nutrient recycling mediated by clonal integration.

Environmentally induced transgenerational plasticity can increase success of progeny and thereby be adaptive if progeny experiences the similarly parental environment. The ecological and evolutionary significance of transgenerational plasticity in plant has been studied mainly in the context of sexual generations. A pot experiment using the stoloniferous herb Centella asiatica was conducted to investigate the effects of high/low light treatment experienced by parental ramets (F₀ generation) on morphological and physiological properties of offspring ramets (F₂ generation) as well as growth performance. Light environment experienced by parental ramets (F₀ generation) significantly influenced petiole length, specific petiole length, internode length of stolon, leaf area, specific leaf area (SLA), leaf nitrogen and chlorophyll contents, potential maximum net photosynthetic rate (P_max) in offspring ramets subjected to parental or non-parental environments even after they were detached from the parental ramets. Potential maximum net photosynthetic rate (P_max) of offspring ramets (F₂ generation) from parental ramets (F₀ generation) subjected to low light treatment was significantly greater than that of offspring ramets (F₂ generation) from parental ramets (F₀ generation) subjected to high light treatment. Potential maximum net photosynthetic rate (P_max) of offspring ramets (F₂ generation) subjected to parental light environment was greater than that of offspring ramets (F₂ generation) subjected to non-parental light environment. The greatest biomass accumulation and total stolon length were observed in offspring ramets (F₂ generation) subjected to low light treatment as parental ramets (F₀ generation) experienced. When parental ramets (F₀ generation) were subjected to low light treatment, biomass accumulation and total stolon length of offspring ramets (F₂ generation) experiencing parental light environment were significantly greater than those of offspring ramets (F₂ generation) experiencing non-parental light environment. Opposite pattern was observed in offspring ramets (F₂ generation) from parental ramets subjected to high light treatment. Our work provides evidence that transgenerational plasticity through both morphological and physiological flexibility was triggered across vegetative generations for stoloniferous herb C. asiatica subjected to high/low light treatment. The transgenerational plasticity can allow offspring ramets to present adaptive phenotype early without lag time in response to the current environment. Thus, it is very important for clonal plants in adapting temporally and spatially heterogeneous habitats.