Imazethapyr Enantioselectively Affects Growth And Flowering Time In Arabidopsis Thaliana

Plant growth and development are strongly affected by environmental pollutants, such as herbicides; widely used herbicides can remain in soil or aquatic systems for long periods of time. Herbicide pollutants have been reported to heavily affect global plant growth and pose a significant challenge to agriculture, imazethapyr (IM) is a widely used chiral herbicide.In this report, we investigated enantioselectivity between R- and S-IM in Arabidopsis thaliana on the effect of chlorophylls synthesis, photosynthesis process and flowering time.The results suggested that R-IM inhibited the transcript of chlM, which reduced the synthesis of chlorophylls. R-IM also showed strong inhibitory effect on the transcript of photosynthesis-related genes to affect CO2 fixation and linear electron transport. IM stress induced transcriptional up-regulation of NDH-H gene, a representative of NDH-complex. In contrast, the expression of PGR5 was down-regulation, which demonstrated that IM stress stimulated NDH-dependent route to enhance ATP synthesis, but not in FD-dependent route. On the field of inducing flowering, IM can enantioselectively promote flowering in Arabidopsis thaliana. We clarified the possible mechanism by which IM promotes flowering and found that the photoperiod pathway may play an important role in propagating the IM stress signal. IM enantiomers decreased the amplitude of core oscillators (CCA1 and LHY) and utilized the up-regulation of the GI-(CO)-FT pathway to induce AP1 over-expression enantioselectively; this treatment ultimately caused early flowering. Our findings provide new insight into the method by which plants control reproductive timing in response to herbicide stress. Flowering time is an important trait in crops and affects the life cycles of pollinator species. The persistence of herbicides in the biosphere will alter plant life cycles and diversity. This study also suggested that R-IM has stronger toxicity to flowering and photosynthesis process against plants growth through affecting chlorophylls synthesis than S-IM.