GENETIC DISSECTION OF SEED DEVELOPMENT IN MAIZE

One of the most interesting aspects, that is still poorly characterized from the genetic point of view, of the development of the higher plants is the formation of the seed. A better knowledge of the steps and of the genes involved in the development of the seed and the seedling is achieved with the isolation, in model species, of mutants impaired in the formation of the two compartments of the seed: the embryo and the endosperm. The choice of maize is due to the fact that it’s one of the model species most utilized to study the role of the genes in biosynthetic pathways and plant morphogenetics: thanks to its dimensions, the practices of dissection are easier, and thanks to the abundance of tissues in the embryo, leaves and ear, great quantities of material are available for biochemical and molecular analyses. Two features of maize plant helped largely genetic studies: the ear size and the development of separated male and female inflorescence. A normal plant can produce about 4-700 seeds. The plants that sprout from them can easily be crossed or selfed producing a wide progeny particularly useful in genetic studies. This progeny can be obtained in a relative short period, between 100 and 150 days from the sowing. Moreover the localization of male flowers in the tassel and female flowers in the ear allow to avoid pollutions with undesirable pollen, simply hooding the ear without emasculation. In this thesis several works are summarized regarding the study of several classes of mutants of different origin affecting either the seed or the plant development. Moreover the study of the interaction between two different insect pests and different maize genetic variants is presented: the results obtained will provide useful information for the selection of genotypes resistant to the attack from insect pests of stored products.