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Characterization of the region between S-RNases and SFB genes in almond selections with the Sf-haplotype but different incompatibility phenotype

Gómez, E.M., Dicenta, F., Ortega, E.
Acta horticulturae 2014 no.1028 pp. 91-94
almonds, cultivars, gametophytes, gene expression, genes, haplotypes, heterozygosity, homozygosity, intergenic DNA, loci, phenotype, pollen, proteins, transcription (genetics), Italy
The cultivated almond is predominantly self-incompatible, although some self-compatible cultivars originated in Apulia (Italy) have also been identified. Self-incompatibility (SI) is attributed to a gametophytic system controlled by a multiallelic locus (S-locus) that contains two linked genes expressed in the style (S-RNases) and in the pollen (SFB proteins). Self-compatibility has traditionally been associated with the Sf haplotype. However, recent studies have reported the existence of cultivars genotyped as Sf but with a self-incompatible phenotype. According to these studies Sf-RNase and SFBf genes from cultivars with different incompatibility phenotype have identical sequences, and so self-compatibility has been attributed to a low transcription level of the Sf-RNase in the style or to the action of other unknown factors involved in the functioning of the SI system (modifier factors). In the present study the sequence of the Sf-RNase gene from A2-198 (a homozygous self-compatible almond selection) and the intergenic region between the Sf-RNase and SFBf genes of A2-198 and ITAP-1 (a heterozygous self-incompatible almond selection) have been obtained. Alignment of both intergenic regions revealed differences among them.