The Classification And Identification Of Kinds Of Parasitic Nematodes Of Corn And Sugarcane In Guangxi And The Reserch Of Corn Cyst Nematode Biology

Plant parasitic nematodes are one of the major plant pathogens,it is important work to learn the parasitic nematodes taxonomy of crops.In order to learn the parasitic nematodes of corn and sugarcane in Guangxi,from 68 counties/cities of Guangxi were surveyed in this study,139 and 71 soil samples from corn and sugarcane rhizosphere were collected,and nematodes were extracted by sieving-decanting method and were classified based on morphology.In addition,the nematode from the corn field in Xiaopingyang Town,Xinbin District,Laibin City is a new nematode on corn in China,and the nematode identification was performed by morphological features of cyst,second-stage juvenile morphology measurements,and molecular analyses;pathogenicity of the nematode was verified by infection and reproduction of the nematode on corn,and acid fuchsin-NaCIO method were used for infection and incubation characteristics research.The results are as follows:(1)32 and 24 families/genus parasitic nematodes were identified on corn and sugarcane respectively,and Pratylenchus and Dorylainida were the dominant nematode parasitic populations in corn;the sugarcane parasitic nematodes dominant populations were Tylenchorhynchus and Dorylainida.(2)The cyst nematode which host is corn,is lemon-shaped,with a prominent vulva cone,zigzag pattern on the cyst wall,and a vulval cone with two ambifenestrates.There is a slender vulval underbridge along obvious vulval slit.When see above ambifenestrate,there are four finger-like bullaes with randomly distributed a mass of bullaes under the underbridge;The morphological characteristics of second-stage juveniles include vermiform body and strong stylet which with obviously stylet knobs.The hyaline tail terminus is most part of tail and the shape of tail is terminus and short;the measurement values of the various morphological characteristics were within a variable range of reported of Heterodera zeae;The results of a single cyst amplification of the ribosomal internal transcribed spacer(rDNA-ITS)regions and 28S rDNA D2D3 PCR product sequences were 99%similar to those of previous populations from America and India;Pathogenic pot experiment indicated that the nematode population could infect in the corn roots and propagated a large number of new cysts;So the parasitic nematode was identified as Heterodera zeae,a new record species in China.(3)when corn seeds were sown in the nematode-infested soil,and the light/dark cycle was 12h/12h,and cultured at 30?.On the 6th day after sowing,second-stage juveniles were detected in the corn root,and the white females appeared on the 24th day after sowing.And the root leison nematodes were found to infect corn roots at the same time,and the peak of population appeared on the 24th day after sowing.The number is as high as 450 per plant root system,the nematodes need to be further study for the species taxonomy;(4)The hatching test results showed that the hatching rate of eggs within mature white females of Heterodera zeae has significant differences in different temperature treatments(p<0.05),the highest hatching rate occurred at 33?.The cumulative hatching rate was 21%on the 6th day after incubation,and the cumulative hatching rate was 51%on the 9th day which was significantly higher than that of other temperatures(p<0.05),On the 6th to 9th day,the average daily hatching of ten cysts was 71 J2;There was no egg hatching at 15? and 40? conditions,and the eggs do not hatch at 15? and 40?.The cumulative hatching rate is very low,2%at 20? and 35?,suitable hatching temperature of Heterodera zeae is range from 25 to 33?.