Studies On Monitoring And Inheritance Of Resistance To Flumorph In Phytophthora Sojae In Anhui

Phytophthora root rot caused by Phytophthora sojae is a soil borne disease,which can cause wide distribution and extremely harm to the produce of soybean.It has enormous influence on the production of soybean,causing huge loss of agricultural production.Therefore,the disease prevention and control is becoming the key of soybean production in China.Fungicide control is still the main measure to prevente soybean disease.How to reasonably choose and use microbicides to prevent or delay the generation of resistance is particularly important.The study about P.sojae resistance monitoring and inheritance of flumorph is less,and no study was reported in Anhui area.This experiment mainly research flumorph resistance monitoring of P.sojae in Anhui province and further test the P.sojae resistance and its genetic stability of fluorine morpholine,meaning to clarify the inhibition mechanism of flumorph and inheritance law on P.sojae,providing experiment basis on the the rational use and governance resistance of flumorph in the produce on P.Sojae.The main results are as follows.The sensitivity of 43 P.sojae.isolates obtained from Anhui to flumorph was tested by the methods of mycelial growth inhibition.The results shows that the EC₅₀0 values of 43isolates ranged from 0.0758?g/mL to 0.1892?g/mL,and the mean EC₅₀0 value was0.1274?g/mL,less than 1?g/mL.It shows the population of P.sojae from Anhui has been still sensitive to flumorph.However,the sensitivity of the populations in different area is various.The sensitivity of the populations in Taihe to flumorph is the most sensitive,and the mean EC₅₀0 value was 0.0965?g/mL,but the sensitivity of the populations Sixian and Xiaoxian show high resistance of flumorph.The each area EC₅₀0 value was 0.1514?g/mL and 0.1502?g/mL.Flumorph-resistance mutant was obtained from the wide-type parent isolate by the drug taming method.The result showed the flumorph-resistance mutant resistance level could be up to 1023 times higher than the parents.The resistance level can inherited steadily both in asexual and sexual progenies.The study of the biological characters showed that:?1?the rate of hyphal growth of flumorph-resistant mutant was the same as wide-type parent;?2?the production and the sizes of sporangium didn't have much difference between the flumorph-resistant mutant and wide-type parent;?3?the row-spore-hole of flumorph-resistant mutant were the same as thoes of wide-type parent,but oospore production of flumorph-resistant mutant was less than the wide-type parent.Pathogenicity of flumorph-resistant mutant was the same as the wide-type parent.Through the establishent of drug-resistant mutant strain Fr Single zoospore G1 and G2 generation group and single egg spore of D1 and D2 generation group,we study the genetic characteristics of resistant mutant strain.The results showed that there were at least two types in the inheritance of flumorph resistance of P.sojae:?1?the resistant mutant strains of Fr lost its resistance to the flumorph in the successive generations,the character might be controlled by the genetic instability of mitochondrial genes in the cytoplasm;?2?the resistant mutant strains of Fr,its drug resistance in asexual and sexual reproduction is stable,but different from the offspring of the same mutant strain type single spore of fluorine morpholine resistance between individual differences.Through the growth rate of the mutant strain Fr ffspring and pathogenicity of the study found that mutant strain Fr asexual and sexual reproduction,in the growth rate and pathogenic characters cannot be stable genetic.