关键词: 溪流鱼类, 主成分分析, 鱼鳍, 临界游泳速度, 爆发游泳速度

Abstract: An antagonism strain XM5 which can strongly inhibit Fusarium graminearum was isolated from wheat leaves at jointing stage. The strain was identified as Bacillus atrophaeus by 16S-23S internal transcribed spacer (ITS) nucleotide sequences. To track the XM5 colonized in wheat plant, a dualantibioticmarker resistant to rifampicin and streptomycin was induced by gradually increasing the concentration of antibiotics in the medium for XM5. Meanwhile, the ITS sequence of XM5 was used as a DNA marker. A pair of specific primers L6SF and L6SR was adopted for PCR test. With the double labels of the dual antibiotic resistance and the specific PCR test, the amount of XM5 colonized in wheat plant was measured. The results showed that XM5 could colonize in wheat plant for a long time, but the amount of XM5 in seedlings decreased with time. To measure the biocontrol efficiency of XM5 to Fusarium head blight (FHB), the XM5 cell suspension and cultured broth (with cells) were sprayed on the heading wheat, respectively, and the amount of endophytic XM5 in wheat ear and the resistance efficiency against FHB were surveyed. In the two treatments, the amount of XM5 on the surface of wheat ear decreased with time, only less than 5% XM5 being survived 10 days later, but in the cell suspension treatment, the amount of colonized XM5 in wheat ear increased unceasingly from 5.2×10³ to 4.8×10⁴ cfu·head^-1, and the biological control efficiency to FHB reached 68.3% after 7 days.

Key words: stream fish, principal component analysis, burst swimming speed., fin, critical swimming speed