Download or read book Genetic Analysis of Embryogeny in Maize written by John D. Sollinger and published by . This book was released on 1994 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize defective kernel (dek) mutants identify genes necessary for the successful passage of embryos through the embryogenic and maturation phases of embryo development. The goal of this thesis was to characterize the developmental potential of three dek mutants that appeared to be morphologically blocked prior to the maturation phase of embryogenesis. Descriptive and experimental studies of the mutants and their wild-type counterparts were used to compare their morphological and physiological progression through seed development. Parameters of growth, morphogenesis, maturation and germination were measured throughout their ontogeny. Two mutants, cp*-1311C and cp*-1399A, slowly progress to morphological stages 2 and 3, respectively. Growth and maturation processes remain in synchrony with morphology, as indicated by their size, germination behavior and level of storage reserve accumulation. Not every facet of development is retarded. Both dehydration of the seed and the accumulation of desiccation proteins, maize Lea group 3 (MLG3) and Lea group 2 dehydrin (DHN), are more globally regulated, since their accumulation is precocious with respect to embryo morphology. This suggests that some aspects of the embryonic program are mediated by maternal factors. Genetic and developmental characterization of a third mutant, dks8, indicates that it defines a pattern gene that functions to specify the initiation or maintenance of the embryonic shoot. The dks8 mutant is variable in phenotype; mutants with partial and abnormal shoot development are sometimes found on ears segregating for shootless dks8 embryos. dks8 is not allelic to other shootless dek mutants. The dks8 mutation was isolated from an active Mutator transposon stock. RFLP analyses for cosegregation of various Robertson's Mutator transposable elements with the dks8 allele demonstrate that a Mu8 element and dks8 are closely linked. The dks8 allele is under-represented on segregating ears, which may reflect either epigenetic suppression of the mutant phenotype or a bias against the mutant allele in the formation of the female gametophyte.