Utilization of the S-locus as a genetic marker in cherry to differentiate among different pollen donors

Abstract

Fruit set in sweet (Prunus avium L.) and sour cherry (P. cerasus L.) is frequently less than adequate for profitable production despite the availability of compatible pollen and abundant flowers. When fruit set consistently falls below acceptable levels, growers may attempt to increase fruit set by increasing the availability of compatible pollen. We describe the use of the self-incompatibility locus (S-locus) as a genetic marker to quantify the relative contributions of competing pollen sources in achieving fruit set in 'BalatonTM' sour cherry. Pollen race experiments were conducted to determine if nonself-pollen provided in a pollen mixture was more competitive than self-pollen in achieving fruit set in 'Balaton™'. We further investigated what pollen set the 'Balaton™' crop in two commercial 'Balaton™' orchards where multiple potential pollinators were planted in adjacent orchards. S-allele genotyping using DNA extracted from the seed was done to discriminate among the competing pollen sources. The results suggest that in certain environmental conditions, nonself-pollen may be more competitive in achieving fruit set in 'Balaton™' than self-pollen. These examples illustrate how seed genotyping can be used to further our understanding of the competitive abilities of different pollen sources in both controlled experiments and production orchards.