Analysis of smooth bromegrass populations based on GBS sequencing

Although smooth bromegrass is an important forage grass, there is still a lack of molecular analysis of the genetic relationship of germplasm resources. Based on genotyping by sequencing (GBS) sequencing technology, the genetic relationships and inheritance structures of 67 smooth bromegrass germplasm resources collected from different regions were analyzed. The results showed that the coefficient of variation analysis of 21 phenotypic traits of Bromus inermis showed that the variation range was large, and all were greater than 10%, with the variation range of 12.67%～54.17%. Based on phenotypic characteristics, 67 materials could be divided into four groups. Groups Ⅰ, Ⅱ, and Ⅲ are all single materials, respectively, that is, N06 (Xinjiang), M09 (Inner Mongolia), and QG07 (Gansu). Group Ⅳ contains 64 materials from various regions. Based on the phylogenetic evolution tree and Principal Component Analysis constructed by single nucleotide polymorphism (SNP) locus information, 67 smooth bromegrass germplasm resources were divided into four groups, that is, Group I, N08, belonging to the northern mountains of Xinjiang; Group Ⅱ consisting of four closely related germplasm from regions outside Xinjiang; Group Ⅲ composed of 39 materials that have relatively distant genetic relationships with other groups of germplasm; Group Ⅳ consisting of 22 Xinjiang regional germplasms. The two methods have similarities in the division of materials. According to the GBS sequencing sequence, it was found that the main type of SNP variation was transversion, and the transversion was higher than the transition. The transition accounted for 76.02%, while the transversion accounted for 23.98%. Based on the distribution of SNP in different materials, the smooth bromegrass materials were divided into two groups through population genetic structure analysis. Group I mainly came from Xinjiang, and Group Ⅱ included materials from all over the country. 67 materials had a population structure. The above results have laid a foundation for the identification and evaluation, association analysis, systematic classification, and variety selection of smooth bromegrass germplasm resources.