Molecular and phenotypic characterization of the S-locus and determination of flowering time in new ‘Marcona’ and ‘Desmayo Largueta’-type almond (Prunus dulcis) selections

Abstract

‘Marcona’ and ‘Desmayo Largueta’ are the most widely cultivated almonds in Spain, representing around 27% of the total production and 34% of the entire almond growing surface. The excellent quality of their kernels makes them highly appreciated and demanded worldwide. However, due to their self-incompatibility, they should be grown along with cross-compatible cultivars, whose lower kernel quality often reduces the economic benefits of the plantation. In addition, although they are cross-compatible, are not good candidates to share the orchard since ‘Desmayo Largueta’ usually flowers earlier than ‘Marcona’. Therefore, to optimize orchard yield, genotypes with overlapping flowering times, cross-compatible with these cultivars and of similar fruit and ripening characteristics are desirable. In order to find suitable pollinators of these cultivars, five ‘Marcona’ and four ‘Desmayo Largueta’-type selections from “Instituto Tecnico Agronomico Provincial (ITAP) de Albacete” (Spain) were characterized for flowering time and for self and cross-incompatibility. The results obtained showed that the nine ITAP selections were self-incompatible, and that three and one were promising candidates as pollinators of ‘Marcona’ and ‘Desmayo Largueta’, respectively. The S-haplotypes of two ITAP selections were characterized by cloning and sequencing their pistil S (S-RNase) and pollen S (SFB) genes. The results also showed that S f RNase does not have a mutated histidine in C2 region, and detected differences with other previously published sequences for S 23 RNase and SFB 23 allele. Moreover, the sequence for almond SFB 27 allele is reported here for the first time.