Effects of fragmentation on the survival and growth of the invasive, clonal plant Alternanthera philoxeroides

AbstractResource sharing between the connected ramets of clonal plants through physiological integration can increase the tolerance of plants to environmental stress. However, the role of physiological integration in the translocation of heavy-metal pollutants between different habitats receives little attention, especially in the aquatic-terrestrial ecotones. An amphibious clonal plant Alternanthera philoxeroides was used to simulate plant expansion from unpolluted soil to a chromium (Cr)-polluted water environment. Basal older ramets growing in unpolluted soil were connected or disconnected with apical younger ramets of the same fragments in polluted environments at different Cr concentrations. Harvested basal ramets were also used for decomposition tests for the loss of residual mass and release of Cr to soil. With increasing Cr concentration there was reduction in biomass of the apical ramets, especially those separated from the basal parts. Cr was detected in the basal ramets with connection to apical parts. The decomposition of plant litter from the basal ramets connected with polluted apical parts might release retained Cr to unpolluted soil. The amount and chemical forms of Cr in the plant litter changed over time. It is concluded that Cr could be transferred from polluted aquatic to unpolluted terrestrial habitats through amphibious clonal plants.

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Trans-generational effects in the clonal invader Alternanthera philoxeroides

Journal of Plant Ecology ◽

10.1093/jpe/rtz043 ◽

2019 ◽

Vol 13 (1) ◽

pp. 122-129

Author(s):

Rubén Portela ◽

Bi-Cheng Dong ◽

Fei-Hai Yu ◽

Rodolfo Barreiro ◽

Sergio R Roiloa ◽

...

Keyword(s):

Dna Methylation ◽

Soil Nutrient ◽

Clonal Plant ◽

Common Garden ◽

Clonal Plants ◽

Alternanthera Philoxeroides ◽

Native Range ◽

Plant Invaders ◽

Generational Effects ◽

Plastic Responses

Abstract Aims Recent studies have revealed heritable phenotypic plasticity through vegetative generations. In this sense, changes in gene regulation induced by the environment, such as DNA methylation (i.e. epigenetic changes), can result in reversible plastic responses being transferred to the offspring generations. This trans-generational plasticity is expected to be especially relevant in clonal plants, since reduction of sexual reproduction can decrease the potential for adaptation through genetic variation. Many of the most aggressive plant invaders are clonal, and clonality has been suggested as key to explain plant invasiveness. Here we aim to determine whether trans-generational effects occur in the clonal invader Alternanthera philoxeroides, and whether such effects differ between populations from native and non-native ranges. Methods In a common garden experiment, parent plants of A. philoxeroides from populations collected in Brazil (native range) and Iberian Peninsula (non-native range) were grown in high and low soil nutrient conditions, and offspring plants were transplanted to control conditions with high nutrients. To test the potential role of DNA methylation on trans-generational plasticity, half of the parent plants were treated with the demethylating agent, 5-azacytidine. Important Findings Trans-generational effects were observed both in populations from the native and the non-native ranges. Interestingly, trans-generational effects occurred on growth variables (number of ramets, stem mass, root mass and total mass) in the population from the native range, but on biomass partitioning in the population from the non-native range. Trans-generational effects of the population from the native range may be explained by a ‘silver-spoon’ effect, whereas those of the population from the non-native range could be explained by epigenetic transmission due to DNA methylation. Our study highlights the importance of trans-generational effects on the growth of a clonal plant, which could help to understand the mechanisms underlying expansion success of many clonal plants.

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