Impact of long-term cadmium exposure on mineral content of Solanum lycopersicum plants: Consequences on fruit production

Abstract

a b s t r a c t Edited by RA Street Keywords: Cadmium Mineral elements Solanum lycopersicum Seed FruitIn young tomato plants, modifications in mineral composition by short-term cadmium (Cd) treatments have been extensively examined. However, long-term Cd treatments have been fewly investigated, and little information about Cd-stress in fruiting plants is available. In the present work, we examined the changes in mineral nutrients of roots, stems, leaves, flowers, seeds and fruit pericarp of tomato plants submitted to a long-term Cd stress. After a 90-day culture period in hydroponic contaminated environment (0, 20 and 100 μM CdCl 2 ), fruit production was affected by increasing external Cd levels, with the absence of fruit set at 100 μM Cd. Meanwhile, Cd altered the plant mineral contents with an element-and organ-dependent response. At 20 μM, Cd triggered a significant increase in Ca content in roots, mature leaves, flowers and developing fruits. However, at 100 μM Cd, Ca content was reduced in shoots, and enhanced in roots. Cd stress reduced Zn and Cu contents in shoots and increased them in roots. High Cd level led to a significant decrease in K and Mg content in all plant organs. Furthermore, Fe concentration was reduced in roots, stems and leaves but increased in flowers, seeds and red ripe fruits. Our results suggest that tomato plants acclimatize during long-term exposure to 20 μM Cd, while 100 μM Cd results in drastic nutritional perturbations leading to fruit set abortion.

New insights about cadmium impacts on tomato: Plant acclimation, nutritional changes, fruit quality and yield

“…This mechanism may explain why fruits, during distinct development stages, contained a lower Cd concentration than flowers, as observed previously by Hédiji et al. (, ). From the ecological point of view, this mechanism may protect tomato progenies from the potential side‐effects of increased Cd accumulation in fruits and even seeds.…”

“…In contrast to the Cd accumulation in plants (Figure a), the concentration of several nutrients was decreased in tomato roots (Figures and ), indicating that Cd prevents their uptake. This antagonist effect, which was also reported in other tomato cultivars (Dong, Wu, & Zhang, ; Hédiji et al., ; López‐Millán, Sagardoy, Solanas, Abadía, & Abadía, ), is probably due to Cd‐induced alterations in the activity of plasma membrane transporters (Migocka & Klobus, ), as well as due to sharing of transporters between Cd and some nutrients (Korshunova, Eide, Clark, Guerinot, & Pakrasi, ; Thomine, Wang, Ward, Crawford, & Schroeder, ). The last assumption is especially consistent for Mn and Fe transporters that are enrolled in Cd absorption and translocation in several species (Sasaki, Yamaji, Yokosho, & Ma, ; Thomine et al., ; Wu et al., ), indicating that Cd uptake occurs at the expense of Mn and Fe absorption (Figure b,c), so decreasing their accumulation in fruits, especially in the peel of those from the fourth bunch (Figures d and b).…”

“…The current data concerning Cd accumulation in vegetative organs (Figure a) are not in line with previous works, which showed that roots always possess a higher Cd concentration than leaves (Alves et al., ; Hédiji et al., ; Kumar et al., ; López‐Millán et al., ; Monteiro et al., ). Four main hypotheses that do not exclude each other support this result: (1) The high transpiration rate of leaflets from the selected leaves (youngest and fully expanded leaves) provided the increased Cd accumulation, probably because they were one of the main organs for gas exchange at the end of the tomato biological cycle; (2) Changes in Cd distribution and remobilization during the end of reproductive stage provoked Cd accumulation in the leaflets; (3) The use of leaflets, rather than the complete tomato leaves, may overestimate Cd concentrations due to the exclusion of rachis that, as an extension of stems, may have a low Cd accumulation; and (4) A “dilution effect” on the root Cd concentrations might have occurred due to both an increased root development in adult plants and a reduced Cd uptake in soil‐cultivated plants, when compared to the hydroponic‐cultivated ones.…”

“…Once within the plant, Cd triggers oxidative stress, disturbs nutrient uptake and distribution, impairs photosynthesis, triggers chromosomal aberrations, and decreases yield (Bayçu, Gevrek‐Kürüm, et al., ; Bayçu, Rognes, et al., ; Carvalho et al., ; Gallego et al., ; Gratão, Polle, Lea, & Azevedo, ; Gratão et al., ; Hédiji et al., ; Sebastian & Prasad, ,). Multiple studies have shown great damages in cell systems due to the overproduction of reactive oxygen and nitrogen species (the so‐called ROS and RNS, respectively) as a consequence of plant exposure to heavy metals (Alves et al., ; Branco‐Neves et al., ; Cuypers et al., ; Fidalgo, Freitas, Ferreira, Pessoa, & Teixeira, ; Fidalgo et al., ; Gallego et al., ; Iannone, Groppa, & Benavides, ).…”

A comparison of technologies for remediation of heavy metal contaminated soils

“…Heavy metal(loid)s are even capable to induce toxic effects to living organisms including human beings at very low levels due to the absence of proper defense mechanism to mitigate the toxic effects of these metals and to remove them from the body. Consumption of heavy metal(loid)s contaminated vegetables can cause depletion of nutrients in the human body that causes many problems in humans, intrauterine growth retardation, disabilities with malnutrition, impaired psycho-social faculties, upper gastrointestinal cancer and immunological defenses (Hediji et al, 2015). Heavy metal(-loid)s can induce oxidative stress by overproduction of ROS, which can destroy cell's inherent defense system and can cause cell damage or death (Shahid et al, 2014a).…”