Effects of propiconazole on physiological and biochemical properties of Panax notoginseng and dietary risk assessment / 中国中药杂志

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.

Application of Tn5 Transposon Mutagenesis Technology in Molecular and Genetic Researches of Gram-negative Bacteria / 中国生物工程杂志

With development of wide-host-range vector systems,Tn5 transposon and its derivative vectors have been widely applied to genetic research of gram-negative bacteria.The applications of Tn5 transposon mutagenesis technology to genetic researches of bacteria were briefly discussed,including researches on biological control mechanisms of biocontrol bacteria,identification of bacterial essential genes,discovering virulence genes of bacterial pathogens,characterization of metabolism regulatory genes and genetic improvements of bacteria.

Genetic Engineering Progresses in Plant Resistance to Salt Stress / 中国生物工程杂志

Salinity is the main limitation factor for plant growth and crop production.Many approaches to enhance plant resistance to salinity by genetic engineering have been developed.Over-expressions of salt-tolerance related genes encoding proteins involved in signal transduction pathways,ion channels and compatible solutes synthesis for the stabilization of biological structures under salinity stress are the most often used strategies.The recent progresses in genetic engineering to improve salt tolerance in plants and the possible problems in researches was reviewed.