S-RNase allele identification and incompatibility group assignment in apricot cultivars (Sara Herrera)
Apricot (Prunus armeniaca L.) is a temperate fruit species cultivated in more than 60 countries. In recent years, an important renewal of plant material is taking place worldwide. Traditionally, pollination requirements have not been considered important because most cultivars in Europe were self-compatible. However, the use of self-incompatible cultivars from North America as parental genotypes in several breeding programs, with the objective of incorporating a source of resistance to Plum pox virus (sharka), is resulting in the introduction of an increasing number of new self-incompatible cultivars, whose pollination requirements are unknown. In Rosaceae self(in)compatibility is determined genetically by a gametophytic system (GSI) that acts by the inhibition of the pollen tube growth in the style. This mechanism is controlled by a multiallelic locus S, which encodes two genes that determine the pistil and pollen genotype. In the pistil it is expressed as a ribonuclease, S-RNase, which determines the specificity of the style while the pollen determinant is a protein with an F-box, called SFB. When the S-allele in the pollen grain is the same as either of the two alleles expressed in the pistil, pollen tube growth is arrested in the style, preventing fertilization of the ovule. In this work, we perform the S-RNase allele identification in a group of 48 cultivars from different breeding programs, in order to establish the incompatibility relationships among cultivars. The two S-alleles of each cultivar were determined by PCR amplification of the S-RNase gene. The results enabled allocation of the cultivars into their corresponding incompatibility groups. To date, 33 different alleles have been identified in apricot, and one of them, identified as Sc, has been associated to the self-compatibility character. These results are valuable for the selection of parental genotypes in apricot breeding programs and for an appropriate distribution of pollenizer cultivars in commercial orchards.
Sara Herrera is currently pursuing her PhD under the direction of J. Rodrigo (CITA-IA2-Universidad de Zaragoza), J.I. Hormaza and J. Lora (IHSM-UMA-CSIC). She won an ISHS student award for the best poster at the I International Symposium on Flowering, Fruit Set and Alternate Bearing in Italy in June 2017.
Sara Herrera, Unidad de Hortofruticultura, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Instituto Agroalimentario de Aragón-IA2 (CITA-Universidad de Zaragoza), Avda. Montañana 930, 50059 Zaragoza, Spain, e-mail: email@example.com
The full article is available in Chronica Horticulturae