Boron-mediated amelioration of copper-toxicity in sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] seedlings involved reduced damage to roots and improved nutrition and water status

Boron Reduced Copper Excess-Induced Oxidative Damage in Citrus sinensis by Modulating Reactive Oxygen Species and Methylglyoxal Formation and Their Detoxification Systems

“…On the basis of previous studies [ 7 , 8 ], we further investigated the effects of Cu and B treatments on 62 indexes in leaves (31 indexes) and roots (31 indexes). We found that at B2.5, B10, and B25, Cu350 altered 56 (28 leaf + 28 root), 24 (11 leaf + 13 root), and 10 (5 leaf + 5 root) indexes, respectively ( Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 and Table 1 ).…”

“…This was supported by the PCoA ( Figure 6 B,C) and PCA ( Figure S1A–C ), and the findings that B addition mitigated the effects of Al excess on ROS generation and removal in Poncirus trifoliata roots [ 35 ] and leaves [ 36 ], and the impacts of cadmium (Cd) excess on ROS production and removal in wheat roots and shoots [ 37 ]. A study from our laboratory showed that Cu levels in LCu350 and RCu350 decreased with elevating B supply [ 7 ]. This could explain why the changes of the 62 indexes caused by Cu350 decreased with increasing B supply.…”

“…A recent study from our research team demonstrated that boron (B) addition could counteract Cu exposure-induced reduction of growth via reducing root damage and Cu uptake and upgrading water and nutrition status in Citrus sinensis seedlings [ 7 ]. In another subsequent study, we investigated the effects of B addition on Cu-induced exudation of low molecular weight compounds (LMWCs; total free amino acids, total phenolics, total soluble sugars, malate, and citrate) by roots and their concentrations in leaves and roots, as well as related enzyme activities (gene expression levels) in leaves and roots of C. sinensis seedlings.…”

“…The study aimed to corroborate the hypothesis that B addition mitigated Cu excess-induced oxidative damage in leaves and roots by reducing Cu excess-induced formation and accumulation of ROS and MG and by counteracting the impairments of Cu excess on ROS (antioxidant enzymes, ASC-glutathione cycle, and thiol-based antioxidant system) and MG detoxification systems. This study was conducted on the basis of previous studies [ 7 , 8 ] and could complement the previous studies, since it might provide some novel information on the B-mediated internal detoxification mechanisms of Cu.…”

Physiological and Ultrastructural Responses to Excessive-Copper-Induced Toxicity in Two Differentially Copper Tolerant Citrus Species

“…Excessive Cu absorption by citrus roots resulted in oxidative stress, which inhibited root elongation and decreased the number of root branches [ 13 ]. Citrus leaves suffering from Cu toxicity are yellowish with lower chlorophyll content and photosynthetic rate [ 14 ]. Moreover, Cu phytotoxicity decreased the fruiting number of citrus species [ 15 ] and caused visible damage on the fruit surface, which reduced its profitability markedly.…”