Trans-aconitic acid inhibits the growth and photosynthesis of Glycine max

Abstract Grasses producing trans -aconitic acid, a geometric isomer of cis -aconitic acid, are often used in Glycine max rotation systems. However, the effects of trans- aconitic acid on Glycine max are unknown. We conducted a hydroponic experiment to evaluate the effects of 2.5–10 mM trans- aconitic acid on Glycine max growth and photosynthesis. The results revealed that the enhanced H 2 O 2 production in the roots increased the membrane permeability and reduced the water uptake. These effects culminated with a reduced stomatal conductance (g s ), which seems to be the main cause for a decreased photosynthetic rate (A). Due to low g s , the limited CO 2 assimilation may have overexcited the photosystems, as indicated by the high production of H 2 O 2 in leaves. After 96 h of incubation, and due to H 2 O 2 -induced damage to photosystems, a probable non-stomatal limitation for photosynthesis contributed to reducing A. This is corroborated by the significant decrease in the quantum yield of electron flow through photosystem II in vivo (Φ PSII ) and the chlorophyll content. Taken together, the damage to the root system and photosynthetic apparatus caused by trans -aconitic acid significantly reduced the Glycine max plant growth.