Southwest Mountainous And Hilly Ecological Zones Of Maize Inbred Lines Ssr Genetic Diversity And Heterosis

Simple sequence repeats ( SSRs) were used to detect genetic variation among 119 maize inbred lines . From 119 maize inbred lines , select 9 elite inbred lines used in field test. GCA of 9 elite inbred lines and SCA of 36 combinations were evaluated in a complete diallel crossing in 2001 on duoying farm of Sichuan Agriculture University . The main results of the study were summaried as follows :1 .Seventy-three SSR primers selected from all eighty-five primers gave stable profiles amplified in the sample of 119 inbred lines ,which could clearly resolve on 4.5% PAGE . Seventy-three primers produced 327 polymorphic amplified fragments .The average number of alleles per SSR locus was 4.3 with a range from 2 to 10 . The polymorphism information content ( PIC ) for the SSR loci varied from 0.14 to 0.84 with an average of 0.596 . Genetic distance amony the 119 lines ranged from 0 between the combination of 5147 and 5148 to 1.2458 between Mo 17 and 2725 .The cluster analysis showed that the inbred lines could be classifide into fourteen distinct clusters which corresponded to the heterotic groups determined by their pedigree analysis . Consequently SSR marker could be used for measuring genetic variation and assigning maize inbred lines to heterotic groups .2.Among the 9maize inbred lines , "48-2" "S37" "08-64" had higher general combining ability (GCA) and "5003" "dan340" "Mo 17" had lower . As to the specific combining ability ( SCA ) ,amony the 36 combinations , "48-2x5003" "Mol7xdan340" "08-64x5003" "48-2x478" "837x5003" "837x478" "Mol7xshenl25" showed high yield potential . The parents in high heterosis combinations , had the complementary yield factors , came from the different groups, and one parent had high GCA at least.3.The hybrid performane were revealed as FI grain yield ( F(Y ) and specific combining ability ( SCA ) .The correlation of genetic distance ( GD ) with F1Y was r=0.247 and the correlation GD with SCA was r=0.176 . The correlation were dispositive and it is too little to have a practical utility in predicting hybrid performance . The better correlation would be the pre-selection of specific markers linked to quantitative trait loci ( QTL ) correlated toheterosis.4. Given the yield as dependent variable y, and the mother's general combining ability (GCAM ) ,the father's general combining ability ( GCAF ) and the genetic distance ( GD ) as independent variable xi , X2 , X3 . By linear regression , gained equation : y=103.374+1.200xi+0.760x2+39.643x3 . Analysis show that the R between yield and GCAM , GCAF , GD was 0.866 and the R Square was 0.750 . All that indicated that the cooperation of perants'GCA and GD was the major factor in yield's transformation.