| Coix belongs to the Maydeae tribe of grass family, which has a close relative to maize. Of the generas in the Maydeae originating from Asia Coix is the only genus ever seriously considered as a possible ancester of maize. Coix tends to be a wild plant, which has many advantages, such as cold tolerance, disease resistance, and vigorous root systems etc. China that has been accepted as one of origin centers of Coix has abundant resources and numeric wild and cultivated types of Coix. But before now there is little systemic research on it. Developments of molecular markers provide elements for genetic linkage maps construction, important QTLs location and comparative genome research. Which will make great sense on exploiting Coix gene resources, maize genetic improvement and making clear of maize origin and evolution.The objectives of this study were: to develop an F2 segregation with BJ Coix and WH Coix used as parents, to endensify Coix genetic linkage map on the basis of AFLP, to locate some important agronomy traits (in two years one area) QTL, and to discuss comparative genome research by use of RFLP. The results were as follows:1. 184 RFLP probes were screened. Of which 39 RFLP probes could not get clear southern results. In the end, 29 RFLP probes were used to construct the map. The polymorphism ratio (deducting probes without clear southern results) was 20%. The polymorphism ratios of cDNA probes were higher than genome probes and rice probes were higher than maize probes. Of the 29 RFLP probes two were dominant, x2 test showed that at 0. 01 standard five showed distorted segregation (ratio: 17.2%) The total marker bands were counted to show that marker bands coming from two parents and their hybrids agreed to 1:2:1 distribution.2. 193 maize SSR primers were screened for polymorphisms, of which only four primer pairs could be amplified with high quality DNA bands similar with maize SSR bands. Three were co-dominant, and one was dominant. All agreed to their respect i ve ratio.3. The Coix genetic linkage map was constructed by mapmaker/Exp 3.0 when the LOD value was set at 3. 0. The total length of the map was 1275. 7cM, consisting of 11 linkage groups. There were only two RFLP markers in one group. 61 AFLP and 21 RFLP markers were mapped on it with an average interval of 15.6 cM. 21 RFLP markers distributed 10 linkage groups. The most of four RFLP markers werelaved in one linkage group.4. Five major agronomic traits (plant height, leaf length, leaf width, tassel length and stem diameter) were investigated in the same field in two years. Of which stem diameter diversified in notable standard, plant height, leaf length, leaf width and panicle length diversified in terribly notable standard between two years. In the first year stem diameter did not express normal distribution, and in the second year leaf length and leaf width did not express normal distribution. Leaf lenth, leaf width, plant height and tassel lenth in first year expressed normal distribution, and plant height, stem diameter and tassel lenth in second year expressed normal distribution. The five traits correlation coefficients in two years were 0. 785, 0. 820, 0. 700, 0. 313 and 0. 737.5. 31 QTL for five traits (plant height et al.) were determined by winQTLCart software by use of composite interval mapping, and the phenotypic variance explained by each QTL ranged from 12. 16% to 64. 39%. Three for plant height, seven for leaf length, seven for leaf width, six for tassel length and eight for stem diameter. There were 10 QTL determined in two years, which were one for plant height (the phenotypic variance explained in two years were 37.39%, 56.12 %); four for leaf length (the phenotypic variance explained ranged from 55. 7 %, 62. 62%) ; two for leaf width (the phenotypic variance explained in two years were 31.65%, 50.24% and 31.2%, 50.69%); and three for stem diameter (the phenotypic variance explained ranged from 21.15%, 32.51%).6. The location and copy number of RFLP markers were compared: 23. 33% probes of the 60 prob...
|
PDF Full Text Request