Self-(in)compatibility in 'AS-1', a local Spanish almond cultivar

Abstract

The finding of new self-compatible cultivars in local population is a breeder’s objective in order to increase the sources of self-compatibility for almond (Prunus amygdalus Batsch) breeding programmes. ‘AS-1’, a local Spanish selection, was considered to be self-compatible according to its self pollen tube growth and was incorporated in the almond breeding programme of Zaragoza as a source for this trait. However, both pollen tube growth and fruit set after self-pollination have shown that this selection is self-incompatible. The PCR analysis using specific and consensus primers revealed that its genotype is S8S12, where both alleles control self-incompatibility and do not confer self-compatibility in almond. The field crosses of ‘AS-1’ and ‘Marcona Flota’, of the same S genotype, were incompatible, confirming the S genotype of ‘AS-1’ determined by PCR analysis. The sequencing of the SFB S haplotype showed that 'AS-1' presents SFB8 and SFB12. Moreover, the absence of any notable deletion or insertion upstream from the HVa and HVb regions in the sequence of the SFB8 and SFB12 S-haplotypes confirm their identity. All these results, including pollination tests, PCR analysis, and cloning and sequencing of the S alleles of ‘AS-1’, indicate that this local selection is self-incompatible.