Identification of low grain cadmium accumulation genotypes and its physiological mechanism in maize (Zea mays L.)

Soil cadmium (Cd) contamination poses adverse impacts on crop yield and quality. Maize is a widely cultivated cereal throughout the world. In this study, field and hydroponic experiments were conducted to investigate the genotypic difference in Cd accumulation and tolerance in maize. There were significant genotypic differences in grain Cd concentrations among 95 genotypes. From these 95 genotypes, L42 which showed a higher grain Cd concentration and L63 which showed a lower grain Cd concentration was selected for further study. Under Cd stress, L63 showed much less reduction in plant growth than L42 compared with the control. Seedlings of L63 recorded higher Cd concentration in roots, but lower in shoots L42, indicating that the low grain Cd concentration in L63 is mainly due to the low rate of transportation of Cd from roots to shoots. Most Cd accumulated in epidermis and xylem vessels of L63, while the green fluorescent was found across almost the entire cross-section of root in L42. Obvious ultrastructural damage was observed in L42 under Cd stress, especially in mesophyll cells, while L63 was less affected. These findings could contribute to developing low Cd accumulation and high tolerance maize cultivars.

Automated summary

A study was conducted to investigate genotypic difference in Cd accumulation and tolerance in maize, with significant differences found among 95 genotypes. Among the selected genotypes, L63 showed less reduction in plant growth under Cd stress compared to L42. The low grain Cd concentration in L63 was attributed to a lower rate of transportation of Cd from roots to shoots, and L63 exhibited less ultrastructural damage under Cd stress compared to L42. These findings could aid in developing maize cultivars with low Cd accumulation and high tolerance.