Correlation between Anthocyanins and Tolerance to Crown Rot Disease in Five Different Half Sib Populations of Apple

Often, intense accumulation of anthocyanins surround restricted lesions where the damage to the tissue has been successfully contained. Anthocyanin accumulation occurred considerably after growth cease of the pathogen particularly in the cells affected by the fungal disease factor of croen rot. In a rootstock breeding program native dwarf cultivars of apple 'Azayesh', 'Zinati', 'Morabbaei' from 2 origins, Kamalabad-Karaj and Isfahan, and imported 'Northern Spy' were selected as maternal parents. The local crabs were elderly selected because of their dwarfing growth habit; high fruit set percent and tolerance to biotic and abiotic stresses. The half sib progenies, as the result of natural genetic variability, were used for obtaining tolerant progenies to Phytophthora cactorum, the causal agent of crown rot, in a screening program for new tolerant apple rootstocks. After artificial inoculation, damage severity was investigated on all half sib seedlings within 5 populations. During data collections from the damage symptoms in the single seedlings, we noted major accumulation of anthocyanin pigmentations where the young half sib plants presented less symptoms of the disease. We studied the existing correlations between anthocyanin appearance and tolerance to crown rot disease in the 5 genetically different populations. According to red pigmentation intensity and extension area measured by visual recognitions we classified 5 classes of susceptibilities. The data collections on single half sib seedlings were repeated in 4 monthly intervals. Simple linear regression by SAS software was used. Statistical analyzes confirmed the existence of correlation with significant differences between anthocyanins formation and tolerance to crown rot in all progenies as the components of 5 populations. We suggest use of anthocyanin emergence in screening for tolerant genotypes to fungal diseases as a marker for assisted selection of progeny after artificial inoculation of progenies.