Toxicity Difference Between Multinuclear And Binuclear Toxin Of Rhizoctonia Solani

Rice sheath blight is a global rice disease.Up to now,most rice varieties planted all over the world are susceptible.This disease can seriously affect rice yield and rice quality.In this paper,the polynuclear and binuclear strains of Rhizoctonia solani were used to extract the toxin from the tested strains.The pathogenicity of binuclear strain and polynuclear strain and their toxin and the difference of disease resistance of different rice varieties were compared.The ultrastructure of rice leaves infected with different toxins was observed by transmission electron microscope,and the resistance response of rice plants infected with different toxins and the difference of the expression of related genes were studied.It provides a theoretical basis for the prevention and control of rice sheath blight.The main results were as follows:1.Analysis on the pathogenicity of R.solani and the difference of resistance between different rice varietiesThree polynuclear strains(LND18,LND06 and LND21)and two binuclear strains(JLS10 and JLS07)were selected for crude toxin extraction.Pathogenicity and disease resistance of different strains,toxins and 25 rice varieties were tested.The results showed that the binucleated strains of R.solani were pathogenicity,and there were significant differences between the multicore strains and binuclear strains,and the amount of toxin produced by the polynuclear strains was higher than that of the binuclear strains.The pathogenicity of polynuclear strain was stronger than that of binuclear strain,and the pathogenicity of different strains was positively correlated with that of binuclear strain.There were significant differences in disease resistance among different rice varieties.After inoculating 25 rice varieties,1 was highly susceptible,8 were moderately susceptible and 16 were susceptible,and after inoculation of binuclear strains,5 showed sensibility and 20 showed moderate resistance.2.Analysis and Identification of toxin components of R.solaniThe extracted toxins were determined by column chromatography,GC-MS and HPLC.The results showed that the toxin components of R.solani and Rhizoctonia oryzae-sativae were both glucose and fructose,and the content of fructose was not significantly different between them.The content of glucose in the polynuclear strain of R.solani was higher than that in R.oryzae-sativae.3.Studies on the pathogenic mechanism of R.solani toxinThe inhibition of the toxin of polynucleated and binuclear strains of R.solani on the radicle of rice,the passivation of different compounds to the toxin of R.solani,the non-host specificity,The effects of polynucleated and binuclear toxins of R.solani on the cell membrane and ultrastructure of rice leaves were studied.The results showed that the inhibition effect of crude toxin on radicle germ was the best when the crude toxin was diluted 10 times.KMn O4 had the best passivation effect on the toxin of rice sheath blight fungus.After inoculating the toxin of rice sheath blight fungus polynucleated strain and binuclear strain,the typical disease spot appeared in plant leaves.The results showed that the toxin of R.solani was non-host specific toxin.Studies on the difference of Resistance response of Rice Rhizoctonia solani and its toxin hosts;the POD,PAL,APX,PPO,CAT,T-SOD,GSH-PX activity and the contents of ASAFR and H2O2 increased first and then decreased after inoculation of multicellular and binuclear strains and their toxins in Gangyuan No.8 and autumn respectively.Compared with the more disease-resistant rice variety,Gangyuan 8,the more susceptible rice variety,Akita,had a late response to the host resistance,and the host defense enzyme inoculated with the polynuclear strain and its toxin had a higher peak value,and the time of reaching the peak value was earlier than that of the disease-resistant rice variety,Gangyuan 8.Part reached peak value at 36 h,others reached peak value at 36 h,but the decline rate was faster after reaching peak value,the resistance response of host inoculated with binuclear strain and its toxin was late and reached peak value at 48 h.But after reaching the peak,the rate of the decrease of defense enzyme was slower,and maintained at the stable level which was slightly higher than that of the control.4.Changes in the expression of related genes after inoculation of R.solani toxinAfter inoculation with R.solani and its toxin,the expression of related genes was determined.The results showed that the expression of Os PR10 gene in Os SHM1 gene,Os GS2 gene,Os RBCS2 gene,Os PBZ1 gene and CHT gene was increased to peak value at 12 h.After inoculation of rice sheath blight toxin,the expression of Os SHM1 gene,Os GS2 gene,Os RBCS2 gene,Os PBZ1 gene,CHT gene and Os PR10 gene increased from 48 h to 36 h,and the peak value of POD gene increased to the peak value at 36 h.The gene expression of theinoculated polynuclear strain and its toxin was higher than that of the binuclear strain and its toxin.