Elevated CO2 induces alteration in lignin accumulation in celery (Apium graveolens L.)

Carbon dioxide (CO2) is an important regulator of plant growth and development, and its proportion in the atmosphere continues to rise now. Lignin is one of the major secondary products in plants with vital biological functions. However, the relationship between CO2 level and xylogenesis in celery is still unknown. In order to investigate the effects of increasing CO2 concentration on lignin accumulation in celery, 'Jinnanshiqin' were exposed to two CO2 applications, 400 (e0) and 1000 μmol mol−1 (e1), respectively. Plant morphology and lignin distribution in celery plants treated with elevated CO2 did not change significantly. There was an upward trend on lignin content in celery leaves, and the transcript abundance of 12 genes involved in lignin metabolism has altered in response to elevated CO2. The effects of high level of CO2 on different tissues were different. Our works confirmed that CO2 may play an important role in lignin accumulation in celery leaves. The current study will offer new evidence to understand the regulation mechanism of lignin biosynthesis under elevated CO2 and provide a reference to improve celery quality by adjusting the growth environment.