Comparing the effects of excess copper in the leaves ofBrassica juncea(L. Czern) andBrassica napus(L.) seedlings: Growth inhibition, oxidative stress and photosynthetic damage

Abstract

Hydroponic experiments were conducted to compare the effects of excess copper (Cu) on growth and photosynthesis in young Indian mustard (Brassica juncea) and oilseed rape (Brassica napus). We compared the effects of excess Cu on the two Brassica species at different physiological levels from antioxidant levels to photosynthetic activity. Nine-day-old plants were treated with Cu (10, 25 and 50 µM CuSO 4 ) for 7 and 14 days. Both species took up Cu from the external solution to a similar degree but showed slight root-to-shoot translocation. Furthermore, after seven days of treatment, excess Cu significantly decreased other microelement content, such as iron (Fe) and manganese (Mn), especially in the shoots of B. napus. As a consequence, the leaves of young Brassica napus plants showed decreased concentrations of photosynthetic pigments and more intense growth inhibition; however, accumulation of highly reactive oxygen species (hROS) were not detected. After 14 days of Cu exposure the reduction of Fe and Mn contents and shoot growth proved to be comparable in the two species. Moreover, a significant Cu-induced hROS accumulation was observed in both Brassica species. The diminution in pigment contents and photosynthetic efficiency were more pronounced in B. napus during prolonged Cu exposure. Based on all the parameters, B. juncea appears to be more resistant to excess Cu than B. napus, rendering it a species with higher potential for phytoremediation.Keywords: Brassica juncea -Brassica napus -copper -oxidative stress -phytoremediation -photosynthesis INTRODUCTIONAmong heavy metals, copper in trace amounts is essential for plant life but it becomes toxic at higher concentrations. In excess, this heavy metal seriously inhibits leaf expansion at the early growth stage and it causes changes in physiological processes such as transpiration, photosynthetic electron transport and biosynthesis of chlorophyll [30]. Indeed, photosynthesis is the most heavy metal-sensitive process [1] since * Corresponding author; e-mail address: fglgbr@gmail.com + These authors contributed equally to this work. 206Gábor FeiGl et al. Biologica Hungarica 66, 2015 excess Cu can, inter alia, affect photosynthetic electron transport on the reducing side of PSI at the level of ferredoxin. In addition, it can alter the PSII on the oxidising side by inhibiting the electron transport at P680 as well as by inactivating some PSII reaction centres [41]. A few studies indicate that excess Cu can impair the PSII electron transport on its reducing side by affecting the rate of electron transfer from tyrosine (Y Z ) to the oxidized primary donor P680 + [16]. ActaAt the molecular level, excess Cu is able to induce the formation of reactive oxygen species (ROS) via the Fenton or Haber-Weiss reactions which subsequently damage proteins, nucleic acids and lipids [14]. This effect of excess Cu was supported by the positive correlation between Cu-treatment and the production of hydroxyl radicals in Arabidopsis [9]. Besides, excess Cu can indirectly cause oxida...

Ecotoxicological and Interactive Effects of Copper and Chromium on Physiochemical, Ultrastructural, and Molecular Profiling in Brassica napus L.

“…Generally, B. napus plants grown under Cr treatment experienced higher oxidative stress, which is strongly correlated with the enhanced accumulation of ROS (H 2 O 2 , O 2 ∙− , and − OH) compared to the individual Cu treatment (Tables 2 and 3 ). Furthermore, ROS contents were also increased significantly when plants were exposed to individual Cu treatment (Tables 2 and 3 ), which is supported by previous studies conducted by Feigl et al [ 31 ] in which a significant ROS level was produced in both Brassica species treated with Cu. Besides this, ROS concentration increased further under combined treatment of Cu and Cr, which is also in line with the previous studies, where the combined treatment of Cr or Cu with other metals proved to be more toxic than their alone treatments [ 32 , 33 ].…”

Effects of water pollution on some physiological parameters and phytoremediation performance of watercress (Nasturtium officinale)

“…Previous studies have considered the pollution in plants as the reason for a decrease in plant metabolism activity and similarly necrosis and leaf chlorosis in plants (Ali et al, 2013;Feigl et al, 2015;John et al, 2012), which is consistent with the results of this study. Feigl et al (2015) states that in the plants copper as a result of preventing the photosystem activity or further avoiding in the photosynthesis level causes reduction in photosynthesis processes and decreases plant growth. Copper also with disabling the membrane enzymes such as ATPase damages the plasma membrane (Feigl et al, 2015).…”

The effect of excess copper on growth and physiology of important food crops: a review

“…In addition, maize and rice were more sensitive to Cu toxicity compared to peanut (Arachis hypogaea L.) and soybean, and plant concentrations exceeding 20 mg Cu kg −1 DW appeared to be toxic to maize and rice (Borkert et al 1998). However, comparable decrease in growth of Indian mustard and rapeseed plants was exposed to increasing Cu levels during 14 days (Feigl et al 2015). Excess Cu (100 μM) during 8 days reduced the weight of shoots and roots of maize to about 70 and 80 %, respectively, as compared to control (Dresler et al 2014).…”

“…Similarly, 100 μM Cu treatment reduced the total chlorophyll contents of maize leaves by 37.02 and 55.83 % in SC 122 and SC 10 cultivars, respectively, over control (Aly and Mohamed 2012). The leaves of young rapeseed and Indian mustard plants showed decreased concentrations of photosynthetic pigments when exposed to increasing Cu (10-50 μM) levels in the growth medium (Feigl et al 2015).…”

“…High Cu (150 μM CuSO 4 ) concentration reduced Zn uptake by the roots of rapeseed (Ivanova et al 2010). Recent research in hydroponic design indicated that concentrations of Fe and Mn reduced in 14-day-old Indian mustard and rapeseed plants when plants were exposed to increasing Cu levels (Feigl et al 2015). The Ca and Mg concentrations increased in wheat seedlings especially at 80 and 100 mM Cu in the nutrient solution which showed a synergistic effect of Cu on Ca and Mg in wheat (Azooz et al 2012).…”