Adaptation responses in C4 photosynthesis of sweet maize (Zea mays L.) exposed to nicosulfuron

• Published in: Ecotoxicology and environmental safety 2021-05, Vol.214, p.112096, Article 112096
• Main Authors: Wang, Jian, Gao, Hui, Guo, Zhenqing, Meng, Yanyu, Yang, Min, Li, Xiangling, Yang, Qing
• Format: Article
• Language: English
• Subjects: C4 photosynthetic enzymes; Chloroplast ultrastructure; Gene expression; Nicosulfuron; Sweet maize
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2021.112096

Nicosulfuron is an ingredient in photosynthesis-inhibiting herbicides and has been widely used in corn post-emergence weed control. In the current study, a pair of sister lines, HK301 (nicosulfuron-tolerence, NT) and HK320 (nicosulfuron-sensitive, NS), was used to study the effect of nicosulfuron in sweet maize seedlings on C4 photosynthetic enzymes and non-enzymatic substances, expression levels of key enzymes, and chloroplast structure. Nicosulfuron was sprayed at the four-leaf stage, and water was sprayed as a control. After nicosulfuron treatment, phosphoenolpyruvate carboxylase (PEPC), NADP-malic dehydrogenase (NADP-MDH), NADP-malic enzyme (NADP-ME), pyruvate orthophosphate dikinase (PPDK), and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activities of NT were significantly higher than those of NS. Compared to NT, malate, oxaloacetic acid, and pyruvic acid significantly decreased as exposure time increased in NS. Compared to NS, nicosulfuron treatment significantly increased the expression levels of PEPC, NADP-MDH, NADP-ME, PPDK, and Rubisco genes in NT. Under nicosulfuron treatment, chloroplast ultrastructure of NS, compared to that of NT, nicosulfuron induced swelling of the chloroplast volume and reduced starch granules in NS. In general, our results indicate that in different resistant sweet maize, C4 photosynthetic enzymes activity and key genes expression play a critical role in enhancing the adaptability of plants to nicosulfuron stress at a photosynthetic physiological level. •Nicosulfuron affects C4 photosynthetic pathway enzyme activity.•The activity of most C4 photosynthetic pathway enzyme was associated with the exposure time.•C4 pathway genes play an important role in maintaining the photosynthetic capacity of plants against nicosulfuron stress.