Approccio multidisciplinare per lo studio della regolazione epigenetica nello sviluppo del seme in Arabidopsis e mais

The changes in gene expression caused by mechanisms other than changes in the underlying DNA sequence are known as epigenetics, and include reversible processes as chromatin remodeling, histone post-translational modifications and DNA methylation. The plant life cycle involves developmental phase transitions that require the regulation and highly co-ordinated expression of many genes. The initial key points in plant development are gamete formation and embryogenesis. It has been recently suggested that epigenetics is essential in the regulation of these two processes. Thus, this multidisciplinary project will study some aspects of the epigenetic regulation of seed development in the model plants Arabidopsis thaliana and maize.



This research project will focus, on one hand, on the regulation of
SEEDSTICK
(
STK
), a homeotic gene that controls ovule identity in Arabidopsis. We will investigate whether
STK
expression is regulated by chromatin remodeling, as preliminary results from the Research Unit in Milan seem to indicate. The group identified that concrete transcription factors (BASIC PENTACYSTEINE (BPC) proteins) bind GA repeats in the
STK
promoter. It was also observed that BPC proteins bind putative chromatin remodeling factors, which make it possible that the regulatory role of BPC proteins is the recruitment of these factors for the modification of the histone code at target loci. This will be investigated in more detail and a genome wide assay for BPC1 binding sites will be performed in different tissues to understand which genes are regulated by these factors and the dynamics of this regulation.



On the other hand, maize (Zea
mays
L.) is a model organism for the study of seed growth. The importance of the auxin signaling in maize embryo and endosperm development has been recently highlighted by the Research Unit in Padova. The Research Units in Padova and Piacenza are studying the maize
defective endosperm-B18
(
de-18
) mutant, which shows reduced levels of IAA in the endosperm leading to a reduction in dry matter accumulation. In this project, the positional cloning and characterization of
de-18
mutant will be performed, including the study of the dynamic histone modification changes at the endosperm involved in the epigenetic control of the gene network of auxin distribution and dry matter accumulation during kernel development. This will led to the identification of potential interactions between various chromatin modifiers and other components in the auxin signaling cascade and reserve accumulation, throughout seed maturation.



Finally, we will compare the data obtained from ChIP-seq from Arabidopsis and maize, to identify conserved and divergent transcription factor sequences involved in seed development of these two model plants.