ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds
MOLECULAR EVOLUTION AND DISTRIBUTION OF S-RNASE GENES AMONG ALMOND CULTIVARS |
| Authors: | R.-C. Ma, A.M. Sánchez, M.M. Oliveira |
| Keywords: | introns, Maloideae, Prunoideae, Prunus dulcis, Rosaceae, S-alleles, self-incompatibility. |
| Abstract:
Self-incompatibility (SI)-associated S-RNase genes represent an extreme example of allele polymorphism. We have cloned and analysed eight novel S-RNase cDNA sequences from almond (Prunus dulcis) cultivars of European origin. Insertions/deletions of 10 to 20 amino acid residues are present between RC4 and C5 domains in Amygdaloideae S-RNases. Synonymous and non-synonymous substitution analysis of the codon data identified positive selection regions. S-RNase genes of almond and sweet cherry and of apple and pear show little heterogeneity in substitution rates, however, significant difference was detected between the two subfamilies Amygdaloideae and Maloideae. Gene sequences of almond S-RNases were amplified by PCR with degenerate primers. The introns located between C2 and C3 are very different in sizes, ranging from 80 to 1100 bp. However, these introns display conserved features in primary sequences. S-allele specific PCR, coupled with RFLP analysis of the PCR products was performed to identify S-genotypes of almond cultivars mainly from Portugal. Up to now, twenty-four almond cultivars were identified genotypically. Some S-allele combinations were further confirmed by comparing the data of S-allele analysis with those of breeding tests. | |
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