Analysis of the expression of S alleles in "Rocha" pear

Analysis of the expression of S alleles in ‘Rocha’ pear. In this work, the expression of incompatibility genes (S-alleles) in ‘Rocha’ pear was investigated. The comparison of these alleles with the alleles of other cultivars may constitute a tool to help the technicians and farmers to choose pollinators when planning a new ‘Rocha’ orchard. We have used molecular techniques that include pistil RNA extraction from three clones of cultivar ‘Rocha’ (R1, R2 and R4C), fragment amplification by RT-PCR, cloning and sequencing. The flowers utilized to extract RNA were isolated before anthesis to guarantee the absence of pollen from other cultivars in their pistils, which could interfere with the rejection process of the auto-pollen. Analysing the genetic sequences obtained from the three clones, no differences between clones were detectable and the sequences corresponded to Sj and Sa alleles. ‘Rocha’ pear is semicompatible with cultivars which do not present Sj or Sa, totally incompatible with cultivars that carry Sj and Sa, and totally compatible with cultivars that do not carry Sj and Sa