Screening Of Biocontrol Strains Against Wheat Cereal Cyst Nematode And Preliminary Studies On The Biocontrol Mechanism

Cereal cyst nematode (CCN) has been a serious disease in Huanghuai wheat production area in China and takes on a growing trend. It caused serious losses to wheat production. There aren't effective control methods to this disease at present in China. Using biocontrol microbes to reduce its damage was considered a potential and promising method. For this reason, this paper reported the results in the screening of biocontrol microbes against cereal cyst nematode of wheat and study on their control mechanism.10 fungal trains were isolated in selective medium (Martin Agar Medium) from wheat roots and CCN cysts, which were collected from the wheat filed which has been happened CCN in Henan province. The control effects of this fungi strains, with other 6 former screened fungi strains,were tested in pots (greenhouse) and in plots (field). F20, F08, F26, 09F11, and 08F04 were found that have an evident control effects to CCN, with more than 50% decreasing ratio of cysts.33 bacterial strains were isolated in selective media (Beef extract-peptone Medium) from wheat root and CCN, and were evaluated for their ability to inhibit nematodes in vitro, respectively. The 12 strains causing J2 mortality over 60% were were chosen for tested in pots (greenhouse) in which 3 strains biocontrol efficacy were over 79%. The 3 strains were tested in plots, 09B18 have an evident control effects to CCN, with 58.78% decreasing ratio of cysts.14 actinomycetes strains were isolated in selective media (Gause's Synthetic Agar Medium) from wheat root and CCN, and were evaluated for their ability to inhibit nematodes in vitro, respectively. The 3 strains (S01, S06 and S07) causing the decreased ratios of cyst over 60% in pots were chosen for tested in plots in which S07 and S08 were found that have an evident control effects to CCN, with 76.92% and 50.22% decreasing ratio of cysts, respectively.Preliminary studies on the biocontrol mechanism against wheat cereal cyst nematode, the results showed that F20, F08, F26, 08F04 and 09F11 strain had inhibition on egg-hatching, F08, 08F04 and 09F11 strains were parasitic on eggs and J2, the parasite rate to eggs were more than 50%, and parasite rate of fungus to juveniles were more than 30%. F08, F20, F26, 09F11, 09B18, S01 and S07 had ability to nematicidal activity to J2。These screened biocontrol strains were identified in morphological and molecular characterization(sequences analysis of the rDNA-ITS region). The results showed that five biocontrol fungi strains are Fusarium solani(F08), Penicillium oxalicum(F20), Stemphylium solani(F26), Beauveria bassiana(08F04) and Paecilomyces marquandii(09F11) respectively. The identification of biocontrol bacteria and actinomycetes strains was underway.