In recent years there has been a growing awareness of the need to conserve plant genetic resources both to maintain biodiversity and to support plant breeding programmes and the development of plant biotechnologies. This project aims to conserve germplasm from five economically important tomato varieties by cryopreservation (liquid nitrogen storage at -196°C) and subsequently assess the genetic stability of the conserved genotypes. Cryopreservation assumes the existence of stress factors acting on the plant material that are likely to induce changes in the regenerated plants after storage in liquid nitrogen. The sine qua non for successful cryopreservation is the maintenance of genetic stability in the regenerated plant material after freezing. A true-to-typeness assessment of the plants regenerated after cryopreservation in relation to the explant donor plants (caulary apices) is required. This will be analysed at the molecular level both by detecting possible genetic changes using AFLP markers and by sequencing the chloroplast lycopene beta-cyclase gene after cryopreservation. These studies will determine whether and how influential possible mutations in the structure of the gene involved are or to what extent they might affect the synthesis of lycopene beta-cyclase involved in the cyclisation of lycopene to beta-carotene.