Genetic Diversity and Population Structure of Broomcorn Sorghum Investigated with Simple Sequence Repeat Markers Mengjiao Zhu 1 & Jun Chen 1 & Nana Yuyama 2 & Le Luo 3 & Xin Xiao 1 & Ya Lv 1 & Yishan Liu 1 & Hongwei Cai 1,2,4 Received: 26 November 2019 /Accepted: 18 December 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract In order to study the genetic diversity and population structure of broomcorn, a special type of sorghum for broom making, a total of 140 accessions of sorghum varieties including broomcorn (72), half-broomcorn (4), non-broomcorn (64) accessions were genotyped by using 45 simple sequence repeat (SSR) markers that are evenly distributed throughout the sorghum genome. These genotyping analyses demonstrated that the average values of N A (number of alleles per locus), PIC (polymorphism information content) and H e (genetic diversity/expected heterozygosity) of the broomcorn accessions were 9.09, 0.60 and 0.63, respectively, which were higher than that of the half-broomcorn accessions (N A , 2.64; PIC, 0.46; H e , 0.52) but lower than that of the non-broomcorn accessions (N A , 11.69; PIC, 0.73; H e , 0.75). These results implied that the genetic diversity of broomcorn is not as abundant as that of non- broomcorn, and the genetic diversity level of broomcorn is relatively rich. Moreover, the STRUCTURE analysis, phylogenetic analysis and principle coordinate analysis (PCoA) indicated that most of broomcorn collections from Ethiopia (Africa) and Turkey (West Asia) were clustered into one group whereas a majority of broomcorn accessions from East Asia (China, South Korea) were grouped into another group. Two broomcorn individuals from Africa (Sudan) belonged to another distinctive group. These results suggest that broomcorn possesses a wide genetic background and can be divided into three types of differentiation. The information of this study is useful for the understanding of domesticating history and broomcorn differentiations. Keywords Broomcorn . Genetic diversity . Population structure . Differentiation . Sorghum Introduction Sorghum [Sorghum bicolor (L.) Moench; 2n = 2x =20] is one of the most important cereals for food, forage, sugar and bio- fuel worldwide (Paterson et al. 2009). Sorghum inflorescence is a panicle with primary branches to grow in wholes upon nodes of the central axis (Doggett 1988). The panicle type of wild sorghum is a completely open loose type. After a series of continuous variation, it has developed into a highly evolved compact type in cultivated sorghum (Harlan and De Wet 1972). Therefore, sorghum possesses abundant panicle type such as lax type, oval type, broom type and mixed type (Harlan and De Wet 1972). As for the classification of sor- ghum, previous research has divided sorghum into nine clas- ses according to its inflorescence characters (Harlan and De Wet 1972). Generally, sorghum was divided into classes 1–7 according to the degree of loose and compact panicles; mean- while, half-broomcorn and broomcorn with tight rachis inter- node were separately classified into the 8th and 9th classes (Harlan and De Wet 1972). Sorghum originated from Africa (Sudan and Ethiopia) was a well-documented fact (Doggett 1988; Wendorf et al. 1992), however, there was no enough Communicated by: Ray Ming Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12042-019-09251-1) contains supplementary material, which is available to authorized users. * Hongwei Cai caihw@cau.edu.cn 1 Department of Plant Genetics, Breeding and Seed Science, Beijing Key Laboratory of Crop Genetic Improvement; Laboratory of Crop Heterosis and Utilization, MOE, China Agricultural University, Beijing 100193, China 2 Forage Crop Research Institute, Japan Grassland Agricultural and Forage Seed Association, 388-5 Higashiakada, Nasushiobara, Tochigi 329-2742, Japan 3 College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China 4 College of Grassland Science and Technology, China Agricultural University, No. 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People’ s Republic of China Tropical Plant Biology https://doi.org/10.1007/s12042-019-09251-1