[Effects of propiconazole on physiological and biochemical properties of Panax notoginseng and dietary risk assessment].

To study the residue and dietary risk of propiconazole in Panax notoginseng and the effects on physiological and bioche-mical properties of P. notoginseng, we conducted foliar spraying of propiconazole on P. notoginseng in pot experiments. The physiolo-gical and biochemical properties studied included leaf damage, osmoregulatory substance content, antioxidant enzyme system, non-enzymatic system, and saponin content in the main root. The results showed that at the same application concentration, the residual amount of propiconazole in each part of P. notoginseng increased with the increase in the times of application and decreased with the extension of harvest interval. After one-time application of propiconazole according to the recommended dose(132 g·hm~(-2)) for P. ginseng, the half-life was 11.37-13.67 days. After 1-2 times of application in P. notoginseng, propiconazole had a low risk of dietary intake and safety threat to the population. The propiconazole treatment at the recommended concentration and above significantly increased the malondialdehyde(MDA) content, relative conductivity, and osmoregulatory substances and caused the accumulation of reactive oxygen species in P. notoginseng leaves. The propiconazole treatment at half(66 g·hm~(-2)) of the recommended dose for P. ginseng significantly increased the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in P. notoginseng leaves. The propiconazole treatment at 132 g·hm~(-2) above inhibited the activities of glutathione reductase(GR) and glutathione S-transferase(GST), thereby reducing glutathione(GSH) content. Proconazole treatment changed the proportion of 5 main saponins in the main root of P. notoginseng. The treatment with 66 g·hm~(-2) propiconazole promoted the accumulation of saponins, while that with 132 g·hm~(-2) and above propiconazole significantly inhibited the accumulation of saponins. In summary, using propiconazole at 132 g·hm~(-2) to prevent and treat P. notoginseng diseases will cause stress on P. notoginseng, while propiconazole treatment at 66 g·hm~(-2) will not cause stress on P. notoginseng but promote the accumulation of saponins. The effect of propiconazole on P. notoginseng diseases remains to be studied.

Rapid determination and dietary intake risk assessment of 249 pesticide residues in Panax notoginseng.

UPLC-MS/MS and GC-MS/MS were used to establish a method to simultaneously determine various pesticide residues in Panax notoginseng. Results showed that the limits of detection of 249 pesticides were all 5-10 µg/kg. The detection rate of pesticides in 121 P. notoginseng samples was 93.39%, and 19 pesticides were detected. According to the US Code of Federal Regulations, the Chinese Pharmacopoeia recommended algorithm, and the Japanese "positive list system", the pass rates of pesticide residues were 100%, 99.17%, and 89.26%, respectively. The chronic risk quotient (ADI%) and acute risk quotient (ARfD%) of P. notoginseng were 0.00-0.12% and 0.00-0.15%, respectively. In summary, the detection method established in this study can be used for routine analysis of various P. notoginseng pesticide residues. The pesticide residues in the main root samples of P. notoginseng were at a safe level and unlikely pose health risks to consumers.

Characterization of calcineurin from Cryptococcus humicola and the application of calcineurin in aluminum tolerance.

BACKGROUND: Calcineurin (CaN) is a Ca2+- and calmodulin (CaM)-dependent serine/threonine phosphatase. Previous studies have found that CaN is involved in the regulation of the stress responses. RESULTS: In this study, the growth of Cryptococcus humicola was inhibited by the CaN inhibitor tacrolimus (FK506) under aluminum (Al) stress. The expression of CNA encoding a catalytic subunit A (CNA) and its interaction with CaM were upregulated when the concentration of Al was increased. A CaM-binding domain and key amino acids responsible for interaction with CaM were identified. ∆CNAb with a deletion from S454 to A639 was detected to bind to CaM, while ∆CNAa with a deletion from R436 to A639 showed no binding to CaM. The binding affinities of CNA1 and CNA2, in which I439 or I443 were replaced by Ala, were decreased relative to wild-type CNA. The phosphatase activities of ∆CNAa, CNA1 and CNA2 were lower than the wild-type protein. These results suggest that the region between R436 and S454 is essential for the interaction with CaM and I439, I443 are key amino acids in this region. The ability of the CNA transgenic yeast to develop resistance to Al was significantly higher than that of control yeast. Residual Al in the CNA transgenic yeast culture media was significantly lower than the amount of Al originally added to the media or the residual Al remaining in the control yeast culture media. These findings suggest that CNA confers Al tolerance, and the mechanism of Al tolerance may involve absorption of active Al. CONCLUSIONS: Al stress up-regulated the expression of CNA. CaM-binding domain and key amino acids responsible for interaction with CaM were identified and both are required for phosphatase activities. CNA conferred yeast Al resistance indicating that the gene has a potential to improve Al-tolerance through gene engineering.