Effects Of Tumv Infection On Photosynthesis And Antioxidases And Cloning Of CP And HC-Pro Genes Of Tumv In Non-Heading Chinese Cabbage

In this research, the physiological effects of TuMV infection on photosynthesis and antioxidases of non-heading Chinese cabbage were investigated, and we have got the CP and HC-Pro geng of TuMV. The results are as follows:1. The study was to evaluate the effects of Turnip mosaic virus (TuMV) infection on photosynthetic and fluorescent characteristics of non-heading Chinese cabbage (’Aijiaohuang’ and ’Duanbaigeng’). As the result of infection, the chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2concentration (Ci) and transpiration (Tr) of leaves decreased in comparison with that of the healthy plants, but the smaller reduction were observed in ’Duanbaigeng’. No great differences in the photochemical efficiency of PS Ⅱ in the light (Fv’/Fm’) and the maximal photochemical efficiency of PS Ⅱ in the dark (Fv/Fm) were observed, but slight decrease compared with control plants. The actual photochemical efficiency of PS Ⅱ in the light (OPS Ⅱ), the linear whole-chain electron transport rate (ETR) and the photochemical quenching of chlorophyll fluorescence (qP) in ’Aijiaohuang’ reduced more obviously than that in ’Duanbaigeng’. The non-photochemical quenching of chlorophyll fluorescence (qN) was always higher in infected plants than control and it increased markedly in’Aijiaohuang’.2. The activity of POD was enhanced more highly in Duanbaigeng than in Aijiaohuang compared with control after inoculation, and always higher in Duanbaigeng. The activity of CAT was kept rising after inoculation and started to decline at9d in Duanbaigeng, but still higher than that in Aijiaohuang. Compared with Aijiaohuang, the CAT activity in Duanbaigeng changed more acutely and was higher, and the peak of enzymatic activity on the3th day and the9th day.3. A virus isolate NCB was collected from non-heading Chinese cabbage in Nanjing. CP and HC-Pro genes of isolate NCB were then amplified by RT-PCR. The size of these two genes were1kb and1.4kb as same as expected, respectively. The PCR products were cloned and their sequences were determined. CP gene of NCB was composed of864 nucleotides encoding a polypeptide of288amino acids; HC-Pro gene was composed of1374nucleotides encoding a polypeptide of458amino acids. CP gene of NCB has90%-99%nucleotide and96%-100%amino acid sequence identities with other reported TuMV isolates, while HC-Pro gene of NCB has80%-95%nucleotide and94%-99%amino acid sequence identities with other reported TuMV isolates. Comparisons of the nucleotide sequence identities of CP gene suggested that NCB were more closely related to TuMV isolates from Raphanus genus, but HC-Pro less related to the isolates from Raphanus genus.