Longitudinal variation in cadmium influx in intact first order lateral roots of sunflower (Helianthus annuus. L)
Résumé
Aims
Contamination of sunflower (Helianthus annuus L.) by cadmium (Cd) is a concern for food and feed safety as this species accumulates Cd to a greater extent than other crops. We examined the relationships between root architecture and Cd2+ uptake by roots.
Methods
We determined and mathematically modelled the longitudinal variation of Cd2+ influx in first order roots of sunflower grown in hydroponics by using short-term exposure to 109Cd-labelled solutions (0.8 to 500 nM). Thereafter, by taking into account the longitudinal variation of the influx, we simulated the uptake of Cd2+ for 24 h by cohorts of roots characterised by various architectural characteristics.
Results
Cd2+ influx at the root tip was on average 2.9 times that of the basal region close to the taproot. The simulations indicated that the total Cd2+ uptake by root cohorts mainly depends on 1/ the root diameter and the number of roots, 2/ the value of the Cd2+ influx at the basal region 3/ the stronger influx at the root tip.
Conclusion
Considering a higher Cd2+ influx at the root tip may be important to understand the relationship between root architecture and Cd2+ uptake by the root system.