关键词: 进口粮食, 小麦, 链格孢菌, 磷脂脂肪酸PLFA分析, 多元线性回归

Abstract: Fungal diseases are usually found in wheat during port quarantine. In order to detect pathogenic microorganisms carried by imported grain more quickly and simply，the genetically stable phospholipid fatty acid（PLFA）in the microbial cell membrane was used as an important identification marker. Based on the observation of microbial LB culture and DNA sequencing analysis,it was determined that the strain isolated and purified from the diseased part of imported wheat was Alternari alternata,which was one of the main pathogens of crops. After PLFA analysis，the significant difference in response value was compared，and the biological sampling range for detecting this strain was 0.070—0.090 g. After correlation analysis and redundancy analysis，it was determined that the characteristic fatty acids of Alternaria alternata were 15∶0 iso，15∶0 anteiso，16∶1 w7c and 18∶2 w6，9c. By analyzing the correlation between the biological sampling amount and the PLFA response value，the models of Y1 =0.047 + 6.183 × 10-5 × C15：0 anteiso + 4.330 × 10-6 × C18：2w6，9c + 1.386 × 10-7 × C16：1w7c and Y2 = 0.036 +2.864 × 10-5 × C15：0 iso were established. Y1 is the biomass calculated by regression of 15：0 anteiso，18：2 w6，9c and 16：1 w7c；Y2 is the biomass calculated by 15：0 iso regression.This model can predict the amount of pathogenic microorganisms carried by wheat，and provides theoretical data and referencesfor establishing quality quarantine and testing standards for imported grains.

Key words: Imported grain, Wheat, Alternaria alternata, Phospholipid fatty acid（PLFA）analysis, Multiple linear regression