Enhanced Nitrogen Uptake and Early Flowering Mitigate Fitness Costs Associated With Glufosinate Resistance in Goosegrass ( Eleusine indica )

ABSTRACT

Herbicide resistance in weeds is frequently accompanied by fitness trade‐offs that compromise survival and reproductive success. In this study, we investigated a glufosinate‐resistant (R) population of Eleusine indica , in which the GS1‐1Ser59Gly mutation confers resistance to glufosinate, alongside a susceptible (S) population. Both R and S populations achieved 100% final germination under natural germination conditions, with no significant difference in germination rate. However, R plants displayed significantly earlier tillering and flowering in both monoculture and mixed growth conditions, approximately 15 days earlier than the S population, indicating accelerated reproductive timing. This precocity incurred a substantial fitness cost, manifested as a ~60% reduction in seed production per plant and reduced competitive suppression of rice growth. Transcriptomic analysis identified EiMADS56 , a key‐flowering regulatory gene, that was significantly upregulated (2.2‐ to 3.1‐fold) in the R population, and its over‐expression of EiMADS56 in Arabidopsis thaliana advanced flowering by approximately 7 days. Moreover, the R population demonstrated enhanced ammonium nitrogen (NH ₄ ⁺ ) uptake and transport efficiency, suggesting a mechanistic link between improved nitrogen utilization and early reproduction. These results suggest that the GS1‐1Ser59Gly mutation may drive fitness trade‐offs in glufosinate‐resistant E. indica via nitrogen uptake‐mediated reproductive acceleration, thereby providing preliminary insights for refining herbicide resistance management and ecological risk evaluation.