Analysis Of Genetic Relationships Between Maize And Its Wild Relatives And Identification Of Sampling Strategies Using Molecular Markers

Analyses of genetic relationsips between maize and its wild relatives and determination of sampling strategies of genetic diversity assessment is of great importance for studies on genetic variation, collection, preservation and utilization of genetic resources, and detection of gene flow and assessment of ecological effects of transgenic maize. The present study focused on the analysis of genetic relationships between maize and its wild relatives and sampling strategies of genetic diversity assessment of maize populations (including landraces and breeding populations), in order to provide the basis of collection, preservation and utilization of maize germplasm.The major results are as follows.1. AFLP marker technique was used to investigate the genetic relationships between maize and its wild relatives including teosintes, Tripsacum and Coix. Twenty-one AFLP primer combinations of PstlI/Msel were used in the study and 641 AFLP amplified bands were obtained, including 586 polymorphic bands with an average of 30.52 per primer combination. The polymorphism percentage was 91.4%. The cluster analysis using UPGMA method based on the data of AFLP showed that the 50 materials could be divided into three groups (Tripsacum, Zea and Coix), which agreed with the former taxonomical classification. But the groupings under Zea were not consistent with the taxonomy. The present study confirmed that maize had closer relationships with Tripsacum than with Coix, but did not find the evidence to support the closer relationships between maize and Zea mays ssp. parviglumis.2. AFLP and SSR markers were used to investigate the genetic structure of three maize populations (two landraces and one breeding population), and to identify the effects of genetic structure on sampling of maize populations. There were fewer differences among the bulks with different number of individuals or the same number of different individuals. The optimal sample size was 10-20 individuals per bulk for the groups with lower genetic diversity, and 30-40 for the higher. Using several bulks with fewer individuals is an appropriate strategy to assess genetic diversity or genetic variability.