Abstract: 【Objective】 Fusarium pseudograminearum is the dominant pathogen causing wheat crown rot. The objective of this study is to reveal the genetic diversity of F. pseudograminearum populations collected from Henan and Hebei winter wheat regions using inter-simple sequence repeat (ISSR) technology. 【Method】 F. pseudograminearum populations containing 166 isolates collected from Henan and Hebei winter wheat regions were amplified using 17 ISSR primers. Genetic diversity parameters were calculated by POPGENE version l.32 software. According to the genetic similarity coefficient of different geographical populations, the group clustering analysis was conducted using NTSYSpc version 2.11 software. 【Result】Seventeen ISSR primers which could amplify more polymorphic loci were screened from 97 ISSR primers. The genetic diversity of 166 F. pseudograminearum isolates collected from Henan and Hebei winter wheat regions was analyzed with 17 primers. The amplification results showed that 234 fragments were amplified, and 218 fragments displayed polymorphic which accounted for 93.16% in the total amplified fragments. The average number of bands amplified per primer was 13.76 and the length of the amplified fragments ranged from 150 to 2 500 bp. The POPGENE analysis results showed that the number of polymorphic loci of 6 populations F. pseudograminearum ranged from 58 to 208 with an average of 124. The percentage of polymorphic loci ranged from 24.79% to 88.89% with an average of 52.92%. The effective number of alleles ranged from 1.1548 to 1.3293 with an average of 1.2584. At geographical population level, Nei’s gene diversity ranged from 0.0897 to 0.2069 with an average of 0.1548 and Shannon’s information index varied from 0.1337 to 0.3257 with an average of 0.2368, indicating that there was a genetic variation between geographic populations of F. pseudograminearum. The Shannon’s information index and Nei’s gene diversity of Northern Henan were highest indicating that the isolates of F. pseudograminearum collected from Northern Henan had the highest genetic diversity. The Shannon’s information index and Nei’s gene diversity of Southern Henan were lowest indicating that the isolates of F. pseudograminearum collected from Southern Henan had the lowest genetic diversity. By analysis of the genetic similarity coefficient, the F. pseudograminearum populations of Northern Henan and Eastern Henan were closest and populations of Southern Henan and Eastern Henan were the farthest. The coefficient of the population genetic differentiation (Gst) among geographical groups was 0.1571, while it reached 0.8429 within the populations indicating more divergent genetic diversity within the populations. The number of migrants per generation between 6 geographical populations was 2.6819, which indicated that genetic information exchange was frequent among the 6 populations. Total gene diversity (Ht) was 0.1837, gene diversity within populations (Hs) was 0.1548, and gene diversity between populations (Dst) was 0.0289, which indicated that the isolates collected from the same region showed a relatively close genetic relationship. The dendrogram based on ISSR markers revealed that 6 geographical populations were clustered into two groups at the threshold of a genetically similar coefficient of 0.966. The group Ⅰ included Northern Henan, Eastern Henan, Middle of Henan, Middle of Hebei, and Western Henan, while Southern Henan belongs to group II.  【Conclusion】The genetic variation of F. pseudograminearum collected from Henan and Hebei winter wheat regions was relevant to its geographic distribution. The genetic diversity of F. pseudograminearum among the populations was lower than that within populations. The gene flow of 6 populations of F. pseudograminearum causing crown rot was very frequent.

Key words: ISSR; Fusarium pseudograminearum, wheat crown rot, genetic diversity