Cadmium (Cd) and arsenic (As) exist simultaneously in soil environment, which poses a serious threat to the safety of agricultural products and forage production. Four Perennial Ryegrass (Lolium perenne L.) cultivars with different accumulation characteristics (ʻNicaraguaʼ, ʻVenusʼ, ʻExcellentʼ and ʻMonroʼ) were selected as the material for pot experiment. The coupled responses of key components and related enzyme activities under combined stresses of Cd and As were investigated. key components contents include Non protein sulfhydryl (NPT), glutathione (GSH) and phytochelatins (PCs). The related enzyme includes (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), γ-glutamylcysteine synthetase (γ-ECS), glutathione synthetase (GSS), phytochelatin synthetases (PCSase) and arsenate reductase (AR). The results showed that Cd contents of perennial ryegrass were higher than those of As contents with TF_Cd/As < 1. Cd and As contents in roots were in the higher proportion than those in shoots. Compared to control, POD activities increased by 2.72 folds under 120 mg kg⁻¹ As treatment. The contents of PCs increased by 5.68 folds under 120 mg kg⁻¹ As treatment. Under combined Cd and As stress, the MDA contents and antioxidant enzyme activities of ʻVenusʼ were higher than those of ʻNicaraguaʼ. ʻNicaraguaʼ, a high accumulation cultivar. Under the combined stresses of Cd and As, the enzyme activities and the key components were significantly correlated (P < 0.05) with the contents of Cd and As. The tolerance to Cd and As was improved with increase in GSH and PCs contents and γ-ECS, GSS, PCSase and AR activities. In conclusion, the antioxidant enzyme system and key resistant substances of perennial ryegrass have important and antagonistic effects on Cd and As stresses.

Cadmium (Cd) pollution poses potential safety risks for Panax notoginseng cultivation, a medicinal plant in Yunnan. Under exogenous Cd stress, field experiments were conducted to understand the effects of lime (0, 750, 2250 and 3750 kg hm⁻²) applied and oxalic acid (0, 0.1 and 0.2 mol L⁻¹) leaves sprayed on Cd accumulation, antioxidant system and medicinal components of P. notoginseng. The results showed that Lime and foliar spray of oxalic acid were able to elevate Ca²⁺ and alleviate Cd²⁺ toxicity in P. notoginseng under Cd stress. The addition of lime and oxalic acid increased the activities of antioxidant enzymes and alters osmoregulator metabolism. The most significant increase in CAT activities increased by 2.77 folds. And the highest increase of SOD activities was 1.78 folds under the application of oxalic acid. While MDA content decreased by 58.38%. There were very significant correlation with soluble sugar, free amino acid, proline and soluble protein. Lime and oxalic acid were able to increase calcium ions (Ca²⁺), decrease Cd content and improve the stress resistance of P. notoginseng, while increasing the production of total saponins and flavonoids. Cd content were the lowest, 68.57% lower than controls, and met the standard value (Cd ≤ 0.5 mg kg⁻¹, GB/T 19086-2008). The proportion of SPN was 7.73%, which reached the highest level of all treatments, the flavonoids content increased significantly by 21.74%, which reached the medicinal standard value and optimal yield.

The objective of this study was to examine the atrazine biodegradation pathway and its genes of the bacteria Arthrobacter FM326, and to understand the degradation mechanism. Our laboratory has found that Arthrobacter FM326 is a highly efficient atrazine-degrading bacteria. A suspension of FM326 was grown in an inorganic salt medium containing atrazine, and during cultivation the content of atrazine and its degradation products were determined every 24 h to reveal the FM326 atrazine degradation pathway. The results revealed the expression of the degradation genes trzN, atzB and atzC during cultivation and that the atrazine content of the medium was decreased in the presence of FM326 when compared to the control group. During cultivation of FM326, hydroxyl atrazine levels increased at first then stabilized during the training process, before declining at 120 h. The cyanuric acid content increased at first and then decreased, and was significantly reduced in FM326 when compared to the control, while the ammonia nitrogen content increased gradually and was significantly increased when compared to the control. There was no significant change in the pH of the FM326 and control cultures. FM326, which expresses atrazine-degrading genes, could completely degrade atrazine into CO2 and NH3 and did not accumulate cyanuric acid in culture.

Panax notoginseng was used as material with exogenous Cd (0, 0.6, 3.0, 6.0, 9.0, 12 mg kg(-1), prepared with CdCl2) and lime (0, 0.75, 1.5 t ha(-2), prepared with Ca(OH) Z ) application to study the effect of cadmium stress on growth and saponins contents of P. notoginseng, the relative enzymes activities of saponins metabolism (SS, mevalonate kinase(MVK), P450, beta-amyrin synthase (beta-AS)) and protein expression used with iTRAQ proteome analysis technique to understand the response mechanism of P. notoginseng. The results showed the contents of soil available Cd and Cd contents in main mot decreased under lime application. The available contents of soil Cd decreased by 9.2%-38.1% with 1.5 t ha(-2) lime application under Cd treatments. The biomass, root length, root surface area and root volume increased with lime application under Cd stress. The activities and expression levels of MVK, P450 and beta-amyrin synthase decreased, resulting in decrease 8.6%-23.6% in saponins contents and ratio of Rg1 to Rb1. In general, the results indicate excessive application of lime would lead to a certain reduction in the content of saponin under Cd stress and inhibition of conversion of diol-saponins to triol-saponins with single-peak model to Ca/Cd ratio. It could be recommended that the ratio of Ca to Cd is less than 680 for reduction of cadmium content and maintaining saponin contents of main root of P. notoginseng for the production of high quality.