Up until today, apple sport mutants proved to be indistinguishable from each other and their progenitors at the molecular level using random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) marker techniques. This is not surprising, since the genomes of these somatic mutants differ
... only in one or a few small regions that affect economically important characteristics, such as improved fruit colour, size, or flavour. In most cases, these genome differences are probably caused by retrotransposons which are able to convert their RNA transcripts to DNA with reverse transcriptase enzyme prior to reinsertion, but unable to leave the genome and infect other cells. Retrotransposon insertions can alter the expression of other genes and/or the structure of encoded proteins. The sequence-specific amplified polymorphism (S-SAP) technique is capable of revealing the genetic distribution of retrotransposable elements over the whole genome. The present study used this approach to try to characterize and distinguish 'Jonathan' somatic mutants via fingerprinting, which is an unsolved problem.
One of the most important parameter of apple cultivars is the scale and the intensity of the coloration of fruits. Nowadays among the bicolour cultivars those are the most saleable which have the highest and darkest fruit coloration. In our three years old study cultivars born with bud mutation and cross breading were examined, which have super
...ior coloration peculiarities than their parental cultivars. According to our results among the observed cultivars the cvs. ’Gala Decarli-Fendeca’, ’Galaval’, ’Wilton’s Red Jonaprince’, ’Early Red One’ and ’Red Cap Valtod’ reached favourable high fruit surface colour (80-100%) regardless the vintage effect. Concerning the colour intensity, that is the darkness of the red colour most of the cultivars (‘Gala Venus Fengal’, ‘Gala Fendeca-Fendeca’, ‘Galaval’, ‘Jeromine’, ‘Red Topaz’, ‘Early Red One’, ‘Crimson Crisp’, ‘Wilton’s Red Jonaprince’) showed excellent values (4,5-5,0). Based on the fruit surface colour and the fruit colour intensity a new index number, the fruit coloration index was created by us, which describes the coloration features in a complex way.