The Affecting Factors Of Genetic Integrity Changes In Maize(Zea Mays L.) Germplasm Accessions During Regeneration

Application of safe conservation and scientific renovation to maintain the genetic integrity of germplasm resources in genebank is the most important issue for germplasm conservation. It is of great significance to study factors responsible for genetic integrity change of genetically-heterogeneous population in the renovation process. Seeds of six maize landraces ( Bendibaiyumi, Huangxiaoyumi, Xiaobaisu, Andonghuang , Tiaohuanuo and Jiahongzao) were analyzed morphologically and assayed with SSR markers in this work to study the effect of seed aging, renovated populations and the sampling model on the alteration of genetic integrity, so as to provide scientific and theoretical basis for making a criteria for regenerating germplasm resources. Main results found were as the followings.1 ,Genetic alteration of six maize landraces (Bendibaiyumi, Huangxiaoyumi, Xiaobaisu, Andonghuang, Tiaohuanuo and Jiahongzao) having different germination levels was analyzed by using agronomic traits. The seed aging had not any obviously inductive influences on the morphologica traits of plant height,ear height,ear length,ear diameter,row number per ear, leaf number of main culm,stem diameter,etc.2, Genetic alteration of seeds of maize landrace, Xiaobaisu, was analyzed using 51 SSR markers. There were three sources of seeds, one was conserved in the National Crop Genebank with high germination percentage and its filial generation after regeneration and the other one was the filial generation of seeds with low germination percentage from Shanxi Agricultural Sciences. It showed that the number of polymorphic loci and percentage of polymorphic loci of the filial generation after regeneration were same with the seeds before regeneration. The number of polymorphic loci and percentage of polymorphic loci were 45 and 88.24%. The filial generations of seeds conserved in the National Crop Genebank and from Shanxi Agricultural Sciences lost 8 and 11 alleles, respectively, and generated two novel alleles. The allele frequency and dendrogram comparison results indicated that the effect of seed aging on offspring'change of genetic integrity was less than the synthesized effect of size of regeneration population, seed aging and selective stresses in the field.3, Genetic alteration of seeds of 200, 100 and 50 plants of maize landrace, Tiaohuanuo, was analyzed using agronomic traits and 50 SSR markers. With the decrease of size of regeneration population, the kinds of seed color reduced, and the proportion of red blead sheath plants decreased while the white blead sheath plants increased. The numbers of alleles and polymorphic loci and the percentage of polymorphic loci of seeds decreased after regeneration. The regeneration populations of 200, 100 and 50 plants lost 2, 5 and 4 alleles, respectively. The population of 200 plants generated one novel allele. The allele frequency comparison, dendrogram and computer simulation...