title: Genetic diversity of male and female Chinese bayberry (Myrica rubra) populations and identification of sex-associated markers.
abstract: BACKGROUND
  Chinese bayberry (Myrica rubra Sieb. & Zucc.) is an important subtropical evergreen fruit tree in southern China. Generally dioecious, the female plants are cultivated for fruit and have been studied extensively, but male plants have received very little attention. Knowledge of males may have a major impact on conservation and genetic improvement as well as on breeding. Using 84 polymorphic SSRs, we genotyped 213 M. rubra individuals (99 male individuals, 113 female varieties and 1 monoecious) and compared the difference in genetic diversity between the female and the male populations.
  
  
  RESULTS
  Neighbour-joining cluster analysis separated M. rubra from three related species, and the male from female populations within M. rubra. By structure analysis, 178 M. rubra accessions were assigned to two subpopulations: Male dominated (98) and Female dominated (80). The well-known cultivars 'Biqi' and 'Dongkui', and the landraces 'Fenhong' are derived from three different gene pools. Female population had a slightly higher values of genetic diversity parameters (such as number of alleles and heterozygosity) than the male population, but not significantly different. The SSR loci ZJU062 and ZJU130 showed an empirical Fst value of 0.455 and 0.333, respectively, which are significantly above the 95 % confidence level, indicating that they are outlier loci related to sex separation.
  
  
  CONCLUSIONS
  The male and female populations of Chinese bayberry have similar genetic diversity in terms of average number of alleles and level of heterozygosity, but were clearly separated by genetic structure analysis due to two markers associated with sex type, ZJU062 and ZJU130. Zhejiang Province China could be the centre of diversity of M. rubra in China, with wide genetic diversity coverage; and the two representative cultivars 'Biqi' and 'Dongkui', and one landrace 'Fenhong' in three female subpopulations. This research provides genetic information on male and female Chinese bayberry and will act as a reference for breeding programs.
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. jiahuimin1988@163.com.
authors.forename: Hui-min
authors.initials: HM
authors.lastname: Jia
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. jydyx@163.com.
authors.forename: Yun
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: Fruit Research Institute, 315400, Yuyao, Ningbo, PR China. 517614074@qq.com.
authors.forename: Guo-yun
authors.initials: GY
authors.lastname: Wang
authors.affiliation: The National Key Facility for Crop Gene Resources and Genetic Improvement (NFCRI)/Key Lab of Germplasm Utilization (MOA), Chinese Academy of Agricultural Sciences, Institute of Crop Science, 100081, Beijing, China. liyinghui@caas.cn.
authors.forename: Ying-hui
authors.initials: YH
authors.lastname: Li
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. jiahuijuan@zju.edu.cn.
authors.forename: Hui-juan
authors.initials: HJ
authors.lastname: Jia
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. whx1106@163.com.
authors.forename: Hong-xia
authors.initials: HX
authors.lastname: Wu
authors.affiliation: Forestry Technology Extension Center, 315300, Cixi, Ningbo, China. cxccy@sina.com.
authors.forename: Chun-yan
authors.initials: CY
authors.lastname: Chai
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. justdx@126.com.
authors.forename: Xiao
authors.initials: X
authors.lastname: Dong
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. ypguo@nwsuaf.edu.cn.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. lpzhang8263@163.com.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Bio-Macromolecules Analysis Lab, Analysis Center of Agrobiology, Environmental Sciences of Zhejiang University, 310058, Hangzhou, China. qkgao@zju.edu.cn.
authors.forename: Qi-kang
authors.initials: QK
authors.lastname: Gao
authors.affiliation: Zhejiang Institute of Subtropical Crops, Wenzhou, 325005, China. carchen110@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Wenzhou Vocational and Technical College, 325035, Wenzhou, China. ljsong@163.com.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Song
authors.affiliation: Plant Breeding-Wageningen University and Research Centre, P.O. Box 16, 6700 AA, Wageningen, The Netherlands. eric.vandeweg@wur.nl.
authors.forename: Eric
authors.initials: E
authors.lastname: van de Weg
authors.affiliation: Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, 310058, Hangzhou, Zhejiang, China. gaozhongshan@zju.edu.cn.
authors.forename: Zhong-shan
authors.initials: ZS
authors.lastname: Gao
mesh_terms: D000483:Alleles; D001499:Bayes Theorem; D001947:Breeding; D002681:China; D016000:Cluster Analysis; D005638:Fruit / Q000235:genetics; D056426:Genetic Loci; D005819:Genetic Markers / Q000235:genetics*; D014644:Genetic Variation; D018745:Genome, Plant; D005838:Genotype; D006579:Heterozygote; D018895:Microsatellite Repeats / Q000235:genetics; D031641:Myrica / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic
chemical_list: D005819:Genetic Markers