Longitudinal variation in cadmium influx in intact first order lateral roots of sunflower (Helianthus annuus. L)
Laporte, Marie A. | Denaix, Laurence | Pagès, Loïc | Sterckeman, Thibault | Flénet, Francis | Dauguet, Sylvie | Nguyen, Christophe
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. © 2013 Springer Science+Business Media Dordrecht.
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