Abstract
This thesis approaches the study of the role of ethylene in different aspects of plant reproduction; flower development, pollination, fruit ripening and spoilage. These different aspects have been studied at physiological, biochemical and molecular level. Chapter I, general introduction is divided in three subchapters and an annex. Chapter I.1 reviews plant development in relation to the ethylene biosynthesis, mainly indicating how the use of transgenic plants and mutants enabled scientist to better understand ethylene functions. Chapter I.2 reviewes flower development and reproduction, describing both flower anatomy and the fertilisation mechanism. Chapter I.3 describes the Laser PhotoAcoustic system (LPA), since LPA is a very specific system that allows high sensitivity/high time resolution of trace gas analysis, including ethylene. Such system is not yet common to laboratory use, it is therefore advisable to browse that chapter for a better understanding of the studies where this method has been used (Chapt. II and III of this thesis). The ANNEX, describes different laser-based approaches used to address biological questions mainly in the field of plant biology and microbiology. In chapters II and III two aspects of cell-cell interactions related to ethylene release have been studied; fruit pathogenesis by the grey mould Botrytis cinerea (Chapt. II), and flower responses to pollination (Chapt. III). Chapters IV, V and VI describe flower development with special attention to ovule development and to the role of ethylene in megasporogenesis and subsequent fertilisation. This topic has been approached essentially by means of molecular biology and genetic engineering to characterise the pattern of expression of the gene encoding the ethylene-forming-enzyme ACC oxidase (ACO), and to produce transgenic plants in which ACO gene expression was greatly reduced. Chapter VII describes the cloning of flower-related EREBPs and the characterisation of their pattern of transcription in different plant tissues and in the pistil during flower development and pollination
