关键词: 稻瘟病菌, PWL基因家族, 变异, 无毒基因

Abstract: 【Objective】Understanding the distribution and variation characteristics of PWL family in different rice blast strain populations is of great significance for studying the genetic diversity and specificity of different rice blast strain populations. 【Method】In this study, 8 pairs of specific primers were designed for the promoter region and CDS region of PWL gene family according to the avirulence (Avr) gene sequences published in NCBI. DNA was extracted from 397 Ｍonospora oryzae isolates collected from different regions of Heilongjiang and Hainan provinces in 2020, and the avirulence (Avr) gene were amplified by PCR and detected by agarose gel electrophoresis. Representative strains from different regions were selected from the detection results and the amplified fragments were sequenced. The sequencing results were compared with the base and amino acid sequences of the promoters and CDS regions of the corresponding avirulence (Avr) gene in NCBI.【Result】The results of PCR electrophoresis showed that PWL1 was not detected in all strains; specific fragments of PWL2, PWL3 and PWL4 were amplified in Heilongjiang and Hainan provinces, indicating that these three genes were distributed in the two provinces with different distribution frequencies and variation types. The distribution frequency of PWL2 was the highest in Heilongjiang Province and Hainan Province, with 98.14% and 100%, respectively. The distribution frequencies of PWL3 and PWL4 in the two provinces were significantly different, with 89.30% and 82.79% of the two genes in the Heilongjiang strain and 5.49% in the Hainan strain, respectively. Through the analysis of avirulence (Avr) gene combinations, the results showed that the combinations could be divided into five types, which were PWL2, PWL3, PWL2+PWL3, PWL2+PWL4, PWL2+PWL3+PWL4. Among them, the Heilongjiang strain contained all combination types, while the Hainan strain contained only two, indicating that the Heilongjiang strain was richer in avirulent genotypes than the Hainan strain. Sequencing of the PCR products of PWL gene family showed that the PWL gene family has abundant mutation sites in promoter region and CDS region, which can be divided into 9 types with point mutation and deletion as the main mutation types, and the mutation types of different strains from different populations are specific and consistent. Among them, PWL2 detected five types of variation PWL2- (1, 2, 3, 4, 5), and the base sequence changes lead to amino acid sequence missense mutations. Two variants were detected in PWL3 and PWL4, respectively, which were PWL3- (1, 2) and PWL4- (1, 2). Frameshift mutations occurred in both PWL3 and PWL4, which changed the following amino acids, leading to premature termination of translation.【Conclusion】The distribution and variation types of PWL gene family in different populations of blast strains showed regional differences, and the variation sites were abundant.

Key words: Magnaporthe oryzae,  , PWL , gene family,  , mutation,  , virulence gene