Technology to validate the authenticity of varieties - a case study using apples of scientific principles and potential applications

The accurate description of apple cultivars is a challenge because many of the characters relate to subtle features of the fruit, and it has hitherto been unclear which is the minimum set of characters to provide an optimal description. An undergraduate project carried out this year at Reading, utilizing apple accessions from the National Fruit Collections at Brogdale, has made significant progress towards the objective of identifying a key morphological character set. Most interestingly, computer-aided shape analysis has indicated that apple shape appears to be a particularly powerful character when appropriately quantified. The project also showed that colour, previously used only qualitatively, can also be quantified using colourimetry and offers considerable potential as a character. Allied to description is identification. There is much interest, both amateur and commercial, in rapid and effective identification of apples. Examples range from the identification of 'that apple at the bottom of the garden', to the commercially significant problem of identifying apples (for sale on supermarket shelves) which are not what they claim to be. There are however, many thousands of apple cultivars in the world: the National Apple Register of the UK lists approx. 6,000 apple cultivars known to have been grown in the UK between 1853 and 1968; and there are over 2,000 cultivars of apple currently held in the National Fruit Collections at Brogdale. Objective identification is very difficult and only a few experts with many years experience can name cultivars by their appearance. DNA-based identification is expensive, slow and destructive. Computerised image analysis offers the potential to reduce thousands of possibilities down to a few tens of possibilities where manual identification is practical for those with less experience. In combination with a few other (easily-measured) characters the number of possibilities could be reduced still further until only cultivar differences relating, for example, to taste, or subtleties in colour patterning are likely to remain. Our PhD project would extend the preliminary analysis already carried out to include a much wider range of apple cultivars; it would develop the computer-aided analysis of shape and establish a definitive character set for identification. It would contrast the results obtained using a morphological approach with DNA marker methods (microsatellites and Diversity Array Technology, DArT). Alongside this scientific work, we would develop an image-analysis Web-based system with a view to providing an on-line identification service, requiring the input of a small number of key character measurements, including an appropriate photographic image of the unknown apples. The aim would be to provide a preliminary identification, associated probability of correctness, and possible alternatives. The student would also, in conjunction with Sainsbury's, explore the suitability of the approach for development of an identification system to allow automated identification of off-types in variety-specific lines of fruit. The potential wider applications of shape analysis to other fresh produce would also be explored.