Trade-off between cadmium tolerance and relative growth rate in 10 grass species

Plant species exhibit great differences in heavy metal accumulation and tolerance. In this study we compared interspecific differences in responses to Cadmium (Cd) stress among 10 C₃ grass species by growing hydroponically under the conditions of different Cd treatments (0, 5, 10 and 50 μM). Responses of plant shoot dry mass to Cd treatments (resistance) were separated into avoidance (the response of shoot Cd concentration to Cd treatments) and tolerance (the response of shoot dry mass to shoot Cd concentration). The relative growth rate (RGR) and leaf structural properties of plants were measured under optimum growth condition. There were large differences in resistance, avoidance and tolerance among the species. Avoidance and tolerance were attributed independently to total Cd resistance. Resistance and tolerance were correlated negatively with RGR, leaf water content (LW), specific leaf area (SLA), leaf elongation rate (LER), and leaf length (LL), but the leaf dry matter concentration (LMDC), and nuclear DNA content showed a positive correlation with resistance and tolerance. These results indicate a trade-off between growth rate and tolerance to Cd stress. Species with higher Ca/Mg ratios showed low avoidance (r = −0.943***), suggesting uptake inhibition by Ca²⁺ to develop avoidance against Cd stress.     

Influence of static magnetic field on cadmium toxicity: Study of oxidative stress and DNA damage in rat tissues

In the present study, we investigated the effect of co-exposure to static magnetic field (SMF) and cadmium (Cd) on the biochemical parameters, antioxidant enzymes activity and DNA damage in rat tissues. Animals were treated with cadmium (CdCl₂, 40 mg/L, per os) in drinking water during 4 weeks. Cd treatment induced an increase of plasma lactate dehydrogenase (LDH) and transaminases levels. Moreover, Cd treatment increased malondialdehyde (MDA) and 8-oxodGuo levels in rat tissues. However, the antioxidant enzymes activity such as the glutathione peroxidase (GPx), catalase (CAT) and the superoxide dismutase (SOD) were decreased in liver and kidney, while we noted a huge increase of hepatic and renal cadmium content. Interestingly, the combined effect of SMF (128mT, 1 h/day during 30 consecutive days) and Cd (40 mg/L, per os) decreased the GPx and CAT activities in liver compared to cadmium treated group. However, the association between SMF and Cd failed to alter transaminases, MDA and 8-oxodGuo concentration.

Cd treatment altered antioxidant enzymes and DNA in liver and kidney of rats. Moreover, SMF associated to Cd disrupt this antioxidant response in liver compared to Cd-treated rats.     

Expression of CT-wpr, screened by cDNA-AFLP approach, associated with hydroxysafflor yellow A in Carthamus tinctorius L.

Hydroxysafflor yellow A (HSYA) is the main active compound in petals of Carthamus tinctorius L. In this study, we used cDNA-amplified fragment length polymorphism (cDNA-AFLP), coupled with bulked segregant analysis (BSA), to screen differentially expressed genes in two cDNA pools, and obtained 2560 reproducible bands ranging from 1500 bp to 100 bp with 64 AFLP primer combinations. Two TDFs (TDF-4 and TDF-11) were identified with low recombination and successfully sequenced. The genetic distance of the linkage map from the HSya locus was 9.9 cM and 2.9 cM, respectively. The full-length cDNA sequence of TDF-11 gene, designated as CT-wpr (GenBank Accession No. GU227360) was cloned. Nucleotide sequence alignment revealed that CT-wpr shared 66% identity with Populus trichocarpa. Semi-quantitative RT-PCR analysis revealed that the mRNA of the two TDFs only expressed in the HSYA-absent line. Possible functions of CT-wpr are also discussed.