Cross-incompatibility in the cultivated almond (Prunus dulcis): Updating, revision and correction

Abstract

Most almond cultivars are self-incompatible, and so to obtain a yield they need to be pollinated with cross-compatible cultivars. For an efficient use of these cultivars in growing and breeding, over the years many have been S-genotyped. This information has been included in consecutive tables of cross-incompatibility groups, which are essentially an update of the previously proposed. However, the information of these tables has not always been reconciled and their inconsistencies have not been corrected. In this work the S-genotypes of 15 Spanish almond local cultivars, included in a research program for the preservation of almond biodiversity, were determined for the first time. For this, PCR with consensus primers for the Prunus S-RNases, PCR using S-RNase allele specific primers designed herein, and also cloning and sequencing were performed. As a result, a new S-RNase allele numbered as S53 could be identified, and a compilation table of almond cross-incompatibility groups is provided including the information from this and previous studies. In this novel Table, twelve new cross-incompatibility groups have been established, two former groups were omitted, and those cultivars with inconsistent genotypes have been removed. The information of this table will facilitate the use of a very high number of almond cultivars in research and breeding. Determination of the S-genotype might be considered as an important addition to a set of identity markers of almond genetic resources, what is of particular interest in the characterization of the agricultural biodiversity.