INCOMPATIBILITY ALLELES AND APPLE POLLINATION

Self-incompatibility in apple is determined by a S gene system which is expressed in 3 ways; intersterility, or 1 of 2 levels of compatibility, semi-compatibility or full compatibility.
Alleles of an isoenzyme gene Got-l, which is closely linked to the S locus, have been used as markers in recognition of the 11 S alleles so far recognized.

Following tissue analysis these markers provide a means of recognising compatible pollinators, together with analyses of S-RNase activity and DNA techniques.
Complete self- and cross-incompatibility is rare in the apple, its effects being modified according to temperature conditions at pollination time.
Stylar receptivity and pollen potency appear to be the dominant features which determine pollen tube growth and fruit set in apple.
Some apple cultivars can set economic crops after self-pollination.
In some situations, semi-compatible pollinators might be used to avoid overset and consequently biennial bearing.
Gaining information on the S allele status of apple cultivars is useful, but preference should be given to screening prospective main crop and pollinator cultivars for precocity, high stylar activity and pollen potency at low temperatures.

II Workshop on Pollination

F.H. Alston

Genetic markers, pollen potency, S-alleles, self-fertility, stylar receptivity

https://doi.org/10.17660/ActaHortic.1996.423.15