Inhibition Of Expression Of PdGLK On Resistance Of Populus Davidiana To Leaf Rust Study Of Influence

In this experiment,wild Populus davidiana Dode was used as material to obtain PdGLK inhibitory expression by Agrobacterium-mediated genetic method.The growth characters,leaf color parameters,chlorophyll content,chlorophyll fluorescence parameters and photosynthetic parameters of P.davidiana Dode inhibited by PdGLK were measured.The physiological and biochemical indexes,photosynthetic parameters and the content of cell wall degrading enzyme of P.davidiana Dode inhibited by PdGLK were also measured.The leaf color variation of P.davidiana Dode inhibited by PdGLK gene expression and the effect of PdGLK gene on leaf rust resistance were investigated.The results were as follows:(1)The genetic transformation of wild aspen was carried out by Agrobacterium mediated method and detected by PCR and qRT-PCR.The results showed that the relative expression of PdGLK gene was reduced by 60%compared with the wild P.davidiana Dode,and the PDGLK-inhibited transgenic aspen was obtained and propagated.(2)Seedling height,ground diameter,leaf color,net photosynthetic rate,chlorophyll fluorescence parameters,chlorophyll relative content and photosynthetic pigment content of wild type poplar inhibited by PdGLK were determined.The results showed that there was no significant difference in seedling height,the growth rate was the same at different growth stages,and they entered the rapid growth stage at the same period.Compared with wild type aspen,leaf brightness of inhibited expression was higher,chlorophyll content was significantly decreased,and L*and b*values were significantly increased.The L*value of inhibited expression and wild P.davidiana Dode reached the maximum on June 15th and May 15th.The mean L*value of inhibited expression P.davidiana Dode was 18.18%and 10.91%higher than that of wild P.davidiana Dode.b*values of inhibited and wild P.davidiana Dode reached the maximum on August 15th and July 30th.The mean b*values of inhibited P.davidiana Dode were 43.29%and 25.63%higher than that of wild P.davidiana Dode.Therefore,the expression of PdGLK gene affects the chlorophyll content of P.davidiana Dodewhich is inhibited by PdGLK expression.(3)We measured the net photosynthetic rate(Pn),intercellular carbon dioxide concentration(Ci),stomatal conductance(Gs)and transpiration rate(Tr)of inhibition expression and wild P.davidiana Dode which were affected by Melawpsora spp.It was found that their Pn and Ci decreased with the increase of inoculation time,but the values of wild P.davidiana Dode were higher.After inoculation,Tr showed a trend of first decreasing and then increasing,Gs showed a trend of first increasing and then decreasing.The results showed that Melampsora spp.affected photosynthesis and transpiration,and the effect on inhibitory expression of P.davidiana Dode was more significant.(4)The contents of soluble sugar,protein and biochemical indexes superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),phenylalanine ammonia-lyase(PAL)and malondialdehyde(MDA)in transgenic and Wild type of P.davidiana Dode infected by Melampsora spp.were determined.It was found that the contents of these indexes changed after infected by Melampsora spp.The activity of POD,CAT,PAL of wild P.davidiana Dode was higher than that of inhibited P.davidiana Dode.The activity of POD,CAT,PAL of wild P.davidiana Dode was higher than that of inhibited P.davidiana Dode after inoculated with Melampsora spp.The results showed that the resistance of wild P.davidiana Dode was higher than that of P.davidiana Dode inhibited by PdGLK.(5)Polygalacturonase(PG)and endoglucanase(β-1,4-glucanase)were detected.The activity of these enzymes in P.davidiana Dode inhibited by PdGLK was higher than that in the wild P.davidiana Dode.In fact,P.davidiana Dode inhibited by PdGLK were more susceptible to disease than the wild P.davidiana Dode.