The Construction Of Molecular Genetic Linkage Map For Coix-A Close Relative Genus Of Maize

Coix belongs to the tribe Maydeae Graminea., and is a close relative genus of maize. It has many advantages compared to staple crops, such as resistance to some disease, high food quality, long period of green maintainace etc, so coix is considered as a very good genetic resource and research material to improve maize genetic breeding and unravel the maize evolution. For the abundant resources and numeric type of wild and cultivated species of coix with widely geographic distribution, China has been accepted as one of the origins of coix. Rational exploitation of coix gene resource, more intensive research of the origin and evolution of the plant of tribe Maydeae and utilization of inter-genus gene transferring are significant for the maize and coix genetic improvement in our country, even in the world.1. A F2mapping population is constructed through the cross between BJ and WH coix accessions, with 131 individuals. Because of the strong capacity of tillering and perenniality , this population can be used permanently through vegetative regeneration.2. Most of the molecular markers , phenotypic markers and agronomic traits agree to normal distribution or expected segregation ratio, which indicate that this F2 population are suitable for genetic linkage mapping.3. Five major agronomic traits are investigated in the field, four of which agree to the normal distribution. The stem thickness agrees to skew distribution which maybe caused by two major effective loci. The silk color and husk hardness agree to 15:1 distribution, and the waxyness of the pollen starch to 1:2:1 distribution.4. AFLP markers are exploited in map construction. 140 ploymorphic bands are generated by 17 primer pairs in EcoRI/Msel and Pstl/Msel eynzem combinations., 15 of which showing distorted segregation indicated by chi-square test.5. Enlighted by the theory of comparative mapping we utilize RFLP probes fromrice, barly and maize for further map construction. Polymorphisms are screened for parents with 79 probes from different resources. 24 of which are polymorphic and 13 are tested in the F2 population. 14 loci are detected among which 5 showing distorted segregation.6. 100 maize SSR primer pairs are used for screening the two coix parents, but most of them are either with no polymorphism or low specificity. Only 3 primer pairs can amplify high quality DNA bands similar with maize SSR bands, implying that SSR can not be transferred among different species with high efficiency.7. The first coix genetic linkage map is constructed by mapmaker/Exp 3.0. The total length of the map is 1339.5cM, consisting of 80 AFLP markers and 10 RFLP markers with the interval of 14.88cM/Marker.8. The RFLP and AFLP experiment protocols are modified for getting high quality results in coix. Effectiveness of RFLP and AFLP markers for map construction is discussed and compared.