Articles
THE INHERITANCE OF ANTHOCYANIN IN APPLE FRUIT SKIN
More than 60 % of the parents used proved to be heterozygous for the Rf fundamental gene for production of anthocyanin in the skin.
Among the 120 progenies 90 /75 %/ could be clearly assigned to one of the five possible groups when combinig ‘red’ and ‘yellow’ apples in all combinations of the Rf gene.
In the remaining 30 progenies 20 showed a surplus of red-fruited seedlings, the other 10 a deficit.
When a modifier gene is combined with the Rf gene under the assumption that this gene is only expressed when the Rf gene is recessive and that the double recessives are red, it is possible to explain the occurence of a low percentage of red-fruited seedlings from selfing or intercrossing yellow-fruited parents.
Calculated ratios for the hypotheses: Rf gene /hyp. 1/, Rf gene + modifier /hyp. 2/, two complementary genes A and B/hyp. 3/ were compared with the actual results.
Segregation ratios of 3 red : 1 yellow /green/, 1 : 1, 1 : 0 or 0 : 1 could occur under all three hypotheses.
The combination yellow /green/ x yellow /green/ seems to be the critical one for verification of the hypotheses.
According to hypothesis 3 a considerably larger number of red-fruited seedlings would be expected than actually occuried.
It is therefore, postulated that one or possibly several modifier genes together with the Rf gene are a better approach towards understanding the inheritance of anthocyanin production in the apple fruit, than the most obvious alternative hypotheses.