Changes Of Endogenous Hormones And Cloning Of The Genes Relative To Resistance During The Interaction Of Non-Heading Chinese Cabbage And TuMV

The non-heading Chinese cabbage, one of the main vegetable varieties over the Mid-Lower Reaches of Yangtze River, plays a major role in vegetable supply, but its quality and agricultural yields tend to be reduced constantly by various plant diseases, especially the turnip mosaic virus. The farmers suffered a sizable economic loss because of plant diseases. When the plants were infected by the turnip mosaic virus, a series of cell pathological effects would be produced, which would cause the changes of endogenous hormones in plants. What's more, it was discovered that the eukaryotic translation initiation factor 4E was very important for virus infection and translation. This study revealed the dynamics of IAA, GA3, ABA and JA, and the expression changes of endogenous hormone related genes in response to Turnip mosaic virus (TuMV) infection on non-heading Chinese cabbage, cloned BceIF4E and BceIF(iso)4E genes from non-heading Chinese cabbage, and constructed RNAi expression vectors successfully, which did great helpful to understand the TuMV irulence mechanisms, and further to enhace host resistance to TuMV.1. ELISA and Real-time PCR experiments were conducted for investigating the dynamics of IAA, GA3, ABA and JA, and the expression changes of endogenous hormone related genes in response to Turnip mosaic virus (TuMV) infection on susceptible variety of non-heading Chinese cabbage (Aijiaohuang). The results showed that there was a positive correlation between the level of plant disease degree and the content of IAA in TuMV infected plants. Gene PAP1 encoding phytochrome-associated protein 1, played a negative regulation role on IAA synthesis. The content of GA3 and related protodermal factor gene PDF1 expression in TuMV infected plants were considerably lower than that in control. While the content of ABA in infected plants accumulated continuously with the increase of inoculation time, which was always higher than that in control. The severer the disease occurred, the lower the GA3 content was, and the higher the ABA content was. The content of JA and JA-inducible vegetative storage protein gene Vspl expression had two rises after inoculation, and the more serious symptoms the plants had, the lower the content of JA was. The ratios of IAA/ABA and GA3/ABA in infected plants were both significantly lower than that in control in response to TuMV infection, which indicated that TuMV infection disrupted the balance of endogenous hormones, and thus disturbed the normal growth and development of plants.2. The eukaryotic translation initiation factor 4E gene was cloned from non-heading Chinese cabbage, which was named as BceIF4E. The gene contained 851bp nucleotides encoding 234 amino acids. BceIF4E had different homology score of amino acid compared with the cloned eukaryotic translation 4E gened of other plants. Phylogenetic analysis revealed the gene had the closest relationship with Brassica rapa and Arabidopsis thaliana. It was forecasted that the protein encoded by the BceIF4E was in the cytoplasm using Target P server and WOLFPSORT software. The RNAi expression vector of BceIF4E gene was constructed by GatewayTM technology and pHellsgate 12 vector, which provided theoretical and technical support for studying the function of BceIF4E during the interaction between virus and non-heading Chinese cabbage.3. Using RT-PCR and RACE technique, the full-leng cDNA of eukaryotic translation initiation factor iso4E gene was cloned from the susceptible variety of non-heading Chinese cabbage'aijiaohuang', which was named as BceIF(iso)4E. Sequence analysis indicated that BceIF(iso)4E gene contained 721bp nucleotides encoding 200 amino acids. Amino acid sequence alignment and phylogenetic analysis indicated that the amino acid encoded by BceIF(iso)4E gene had different homology compared with the other eukaryotic translation iso4E genes of plants, and the amino-acid encoded by BceIF(iso)4E had the closest relationship with Brassica rapa and Arabidopsis thaliana. The analysis of SignalP 3.0 Serve software indicated that BceIF(iso)4E protein was not secretory protein, and it was forecasted that the protein located in the cytoplasm using Target P server and WOLFPSORT software. The RNAi expression vector of BceIF(iso)4E gene was constructed successfully by GatewayTM technology instead of the traditional construction method, which laid a solid foundation for studying the function of BceIF(iso)4E gene in the infection of non-heading Chiense cabbage by virus.