Diatoms carry out 1/5 of the photosynthesis on Earth and are essential to aquatic ecosystems. In addition to their fundamental role in carbon fixation, they play a key role in the biogeochemical cycle of nitrate and silica, have other complex metabolic abilities (urea cycle, fatty acid metabolism) and developed several strategies for the adaptation to different, sometimes extreme, environments. An improved knowledge of diatom biology is crucial for understanding the basis of their ecological success, for predicting their capability to adapt to a rapidly changing environment, including climatic changes due to greenhouse gasses, and for industrial exploitation of their biological properties.The scope of this project is to generate a collection of stable mutants for diatoms through random chemical mutagenesis. Specifically, we want to isolate mutants with altered production of fatty acids, oxylipins and domoic acid, both to characterise the molecular pathways involved and to obtain clones of potential interest to industry. So far genomics and functional data are available for less than 10 of the 200.000 known species, we want to generate a tool that will facilitate molecular studies in these organisms. We have selected the species Pseudo-nitzschia multistriata for our studies because of its ecological relevance in Mediterranean ecosystems and because of its controllable life cycle with known sexual stages. As a preliminary step to this study we plan to exploit new sequencing technologies to sequence the genome of the selected diatom, this will allow to undertake positional cloning once mutants have been isolated and will represent per se a valuable resource. We will contribute to establish a Pseudo-nitzschia multistriata as a model organism and to develop molecular biology and functional genomic resources for diatoms. Ultimately, we want to generate information that will allow a better comprehension of the data and observations that will come from the sea.