Alternanztagung in Palermo: Von Chaostheorie, Flowering Locus T bis Klimawandel


The FSAB attracted ca. 100 participants from 26 countries and all continents. Topics included research on biennial-bearing-affected crops like pistachio, olive, almond, (Satsuma-)mandarin, litchi and mango and cultivars ‘Honeycrisp‘, ‘Kanzi‘, ‘Fuji‘ und ‘Elstar‘ in apple with the following results: (1) The 3-fold increase in leaf carbohydrates in off-years (low yielding) and carbohydrate shortage in ‘on years’ (high yielding) as an indicator of alternate bearing in fruit crops was commonly agreed. Once the tree has overcome its juvenile phase and its chilling is fulfilled, the flowering gene ‘flowering locus t’ is synthesized in the leaf veins in equal amounts in both on and off years and transported in the phloem to the bud meristem of the bourse shoot causing an apparent discrepancy in interpretation. Research on apple in Israel now showed that the heavy fruit load in high yielding ‘on years’ induced gene expression of the flowering inhibitor Terminal flower 2 (TFL 2) in the bud meristem, thereby preventing the function of the flowering gene flowering locus T (FT) after its import from the leaf veins to the meristem enabling an elegant explanation of the regulation of alternate bearing as a result of heavy fruit load in the previous year.