Trophic Diversity in Duckweed: Mixotrophy, More Than the Sum of its Extremes

The duckweed family Lemnaceae, aquatic plants within the early-diverging monocot order Alismatales, are model organisms in plant biology. Owing to their exceptionally rapid growth rates, high protein content, notable capacity for starch accumulation, and demonstrated utility in phytoremediation, duckweeds are increasingly recognized as promising candidates for diverse biotechnological applications spanning environmental remediation, bioenergy production, and sustainable biomass generation. Mixotrophy-the capacity of autotrophic plants to utilize exogenous organic carbon-is increasingly recognized as widespread in aquatic ecosystems, yet it has been less studied in duckweeds compared to microalgae and cyanobacteria. Here, we compile evidence from physiological, structural, and environmental perspectives supporting mixotrophy and heterotrophy in duckweeds, a clonal, genomically tractable angiosperm with rapid vegetative growth and direct environmental exchange, offering advantages beyond microalgal models. We emphasize mechanisms that enable mixotrophy to achieve synergistic outcomes beyond the additive effects of autotrophy and heterotrophy. Additionally, we explore the ecological and biotechnological significance of these trophic strategies and propose that duckweeds represent a valuable model for understanding mixotrophy across aquatic plants and for linking microalgal findings with higher-plant physiology.