| In order to identify the marker linked with Fe-efficient gene and investigate on genetic background of Fe-efficient traits in Malus spp., 371 interspecific hybrid plants were obtained by controlled hand pollination of M.xiaojinesis (Fe-efficient genotype, 2n=4x=68)+M.baccata (Fe-inefficient genotype, 2n=2x=34). Since M.xiaojinesis is facultative apomictic, there exist sexual hybrids (triploid and pentaploid) and M.xiaojinesis seedling in the progeny of this combination. Through identified, the number of triploid plants was 34,the number of pentaploid plants was 9, and the rest was tetraploid plant (328). Then constructed analysis population using these sexual hybrids (41).The result of x 2 test showed that the segregation of chlorisis index in the analysis population fit the law of genetic segregation. This indicated that Fe-efficient trait was controlled by a major gene, but also influence by polygene.For detecting the genetic identity of Malus xiaojinesis from natural population. The AFLP fingerprinting of 20 seedlings of M.xiaojinesis with 8 EcoR I -Mse I primer combinations showed that M.xiaojinesis in natural population had a high degree of genetic identity, its genetic similar coefficient being 98.92%. Genetic difference also existed in this population, 0.93% fragments were different loci. The patterns analysis indicated that these different fragments were resulted from gene recombination of sexual hybridization.In order to study the segregation patterns of molecular marker in an interspecific Fl hybrid and to enhance our knowledge about the genetic background of M.xiaojinensis, genetic analysis of the Fl analysis population was performed through AFLP. The AFLP analysis led to the identification of 1126 AFLPs using 15 EcoR I -Mse I primer combinations, which were either M.xiaojinesis - (31.8%) or M. baccata-specific markers (12.5%) or markers present in both parent(54.5%). Segregation ratios of most of markers fit expected ratios. This result showed that most of the region of M.xiaojinesis's and M.baccata's genome segregated normally. In some cases the observed segregation ratios even allowed us to clearly determine that M.xiaojinesis is aautotetraploid plants, at least is a isosyndetic allotetraploid. These were the cases of 32 M.xiaojinesis-specific markers and 50 markers present in both parents, which fit 5:1 and 11:1 ratio respectively. Since these cases happened were owing to M.xiaojinesis's duplex loci.Among 42 EcoR I-Mse I primer combinations, fifty-one AFLP markers correlated to Fe-efficient trait were identified using BSA-AFLP technique. Through testing these AFLP markers on the hybrids that constructed Fe-efficient and Fe-inefficient bulk, 18 loci were found maybe linked with Fe-efficient trait and exhibited normal Mendelian segregation. Linkage relationships were established by the inheritance of the markers in the entire analysis population. These markers localized in the same linkage group. Analysis of the map confirms the presence of a major Fe-efficient gene lay between AFLP markers E-ACT-M-CTCb and E-ACG-M-CAC. Genetic distance are all 5.1cM.The existence of other efficient-associated loci was suggested by the continuous phenotypic distribution and the fact that some moderately inefficient hybrids possessed the efficiency-linked markers. The marker may be useful in the apple Fe-efficient genotype breeding program if it can be demonstrated that they are valid in other genetic backgrounds.After parents and F1 sexual hybrids were treated with 0mol.L-1 Fe, chlorophyll concentrations( u g/cm2) and the number of roots of M.xiaojinesis were higher than M.baccata's, chlorisis index and pH value was lower than M.baccata's. Distribution of four traits in Fl analysis population is between the value of two patents, but also there exist transgressive inheritance. Comparing with their controls respectively, chlorophyll concentrations (g/cm2) and pH value of each strain were lower and the number of roots of each strain was higher than their controls respectively. This implied that in...
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