Genetic diversity and population structure of teosinte - PubMed (original) (raw)

Genetic diversity and population structure of teosinte

Kenji Fukunaga et al. Genetics. 2005 Apr.

Abstract

The teosintes, the closest wild relatives of maize, are important resources for the study of maize genetics and evolution and for plant breeding. We genotyped 237 individual teosinte plants for 93 microsatellites. Phylogenetic relationships among species and subspecific taxa were largely consistent with prior analyses for other types of molecular markers. Plants of all species formed monophyletic clades, although relationships among species were not fully resolved. Phylogenetic analysis indicated that the Mexican annual teosintes divide into two clusters that largely correspond to the previously defined subspecies, Z. mays ssp. parviglumis and ssp. mexicana, although there are a few samples that represent either evolutionary intermediates or hybrids between these two subspecies. The Mexican annual teosintes show genetic substructuring along geographic lines. Hybridization or introgression between some teosintes and maize occurs at a low level and appears most common with Z. mays ssp. mexicana. Phylogeographic and phylogenetic analyses of the Mexican annual teosintes indicated that ssp. parviglumis diversified in the eastern part of its distribution and spread from east to west and that ssp. mexicana diversified in the Central Plateau of Mexico and spread along multiple paths to the north and east. We defined core sets of collections of Z. mays ssp. mexicana and ssp. parviglumis that attempt to capture the maximum number of microsatellite alleles for given sample sizes.

PubMed Disclaimer

Figures

F<sc>igure</sc> 1.—

Figure 1.—

Geographical distribution of the teosinte populations used in this study. Since many accessions come from geographically very close locations, their symbols overlap on the map.

F<sc>igure</sc> 2.—

Figure 2.—

Unrooted phylogeny of individual teosinte plants using the Fitch-Margoliash method and the log-transformed proportion of shared-allele distance among 93 microsatellite loci. The tree contains 237 individuals. A large H indicates plants identified as being of putative hybrid origin by population structure analysis. Z. mays ssp. parviglumis: (B) Central Balsas, (E) eastern Balsas, (J) Jalisco, (O) Oaxaca, (S) South Guerrero. Z. mays ssp. mexicana: (C) Central Plateau, (H) Chalco, (D) Durango, (N) Nobogame, (P) Puebla. (U) Z. mays ssp. huehuetenangensis, (Xg) Z. luxurians (Guatemala), (Xn) Z. luxurians (Nicaragua), (R) Z. diploperennis, (Z) Z. perennis.

F<sc>igure</sc> 3.—

Figure 3.—

Rooted phylogeny for 76 groups (OTUs) of individual plants using the Fitch-Margoliash method and the log-transformed proportion of shared-allele distance among 93 microsatellite loci. The numbers on the branches indicate the number of times a clade appeared in 1000 bootstrap samples and are shown for all clades with >50% bootstrap support. To locate the root for Zea, separate analyses including the outgroup, Tripsacum, but only 61 SSRs, were performed. The tree as drawn shows the placement of the root when null alleles in Tripsacum are coded as distinct (not identical by descent) from null alleles in Zea (see text). Bootstrap values from this analysis are underlined.

F<sc>igure</sc> 4.—

Figure 4.—

Dispersal models for 63 OTUs of Z. mays ssp. mexicana and ssp. parviglumis. Gray circles indicate nodes of the tree, which are labeled A–F. Model 1 shows the highest correlation with genetic distance.

F<sc>igure</sc> 5.—

Figure 5.—

Results of the population structure analysis for ssp. mexicana (squares) and ssp. parviglumis (circles). The symbols for plants of apparent mixed ancestry based on the arbitrary criterion of possessing <80% membership in their own subspecies are enlarged. For the enlarged symbols, the symbol is color coded proportionally to its degree of ancestry from ssp. mexicana (red), ssp. parviglumis (green), and ssp. mays (yellow).

Similar articles

Cited by

References

    1. Benz, B. F., L. R. Sánchez-Velásquez and F. J. Santana-Michel, 1990. Ecology and ethnobotany of Zea diploperennis: preliminary investigations. Maydica 35: 85–98.
    1. Brown, A. H. D., 1989. Core collections: a practical approach to genetic resource management. Genome 31: 818–824.
    1. Buckler, E. S., IV, 1999 Phylogeographer: A tool for developing and testing phylogeographic hypotheses. http://www.maizegenetics.net/bioinformatics/phyloindex.htm.
    1. Buckler, E. S., IV, and T. P. Holtsford, 1996. Zea systematics: ribosomal ITS evidence. Mol. Biol. Evol. 13: 612–622. - PubMed
    1. Dietz, E. J., 1983. Permutation tests for association between two distance matrices. Syst. Zool. 32: 21–26.

Publication types

MeSH terms

Substances

LinkOut - more resources