Molecular tools for improved productivity in Queensland plum orchards

Abstract

Most Japanese plum cultivars are self-infertile. In commercial orchards, cross-compatible pollinisers have to be interplanted to ensure fruit set. The self-incompatibility is controlled by S-loci in the pistil and pollen, which are tightly linked to each other. The Prunus S-RNase-specific PCR primers Pru-C2 and PCE-R were used to study candidate compatible pollinisers for the cultivar 'Queen Garnet', known for its high nutritional value. A total of 13 genotypes, including 'Queen Garnet', three other cultivars and nine DAFF breeding lines, were tested. 'Queen Garnet', which possesses gh S-haplotypes, shares none or only one S-haplotype with the other three cultivars and five of the DAFF breeding lines. Not only must an ideal polliniser be cross-compatible in terms of S-haplotype, but it must also overlap in flowering with the main cultivar and produce sufficient quantities of viable pollen. Based on these three criteria, lines ARF25, ARF86, ARF95 and ARF98 were identified for interplanting one row in five to ensure pollination each year and for ease of harvesting. Implementation of this pollination strategy coincided with a 50-fold increase in 'Queen Garnet' fruit yield between 2012-2013 and 2013-2014. While this increase may be partially due to tree maturity and environmental conditions, there is an expectation of up to another 13-fold increase in the following years as trees develop and mature within this improved pollination environment.