Fingerprinting and molecular characterisation of ARC's apricot and plum collection

Nyawo, Thembeka Amanda (2017-12)

Thesis (MSc)--Stellenbosch University, 2017.


ENGLISH ABSTRACT: In South Africa apricot (Prunus armeniaca) and plum (Prunus salicina) production forms part of the economically important stone fruit industry, which is mainly situated in the Western Cape, Northern Cape and the Eastern Cape. Cultivars of main importance to the industry are primarily supplied by the Cultivar Development Division of the Agricultural Research Council Infruitec-Nietvoorbij. The ARC produces new and improved apricots and plums through the breeding of cultivars and selections maintained in the stone fruit germplasms held at Bien Donne experimental farm in the Western Cape. Visual inspection of the gene banks has revealed mislabelling/mis-identification of cultivars and inefficient record keeping of the genetic information of the available cultivars. It is therefore essential to fingerprint and characterise the gene banks on a molecular level, in order to confirm trueness to type of the cultivars and to confirm parentages. A set of microsatellite primers designed from peach were used for fingerprinting 106 apricot and 95 plum accessions. Ten (in apricot) and eight (in plum) of the microsatellite primers were grouped into four multiplexes and were successfully used to determine the fingerprints. The obtained data was used as a starting point for comparing fingerprints of apricot and plum cultivars. In apricot, all reported parentages were confirmed to be true; however in plum one accession was found not to be related to the reported parents. Trueness to type was determined by evaluating the genetic relationship using UPGMA cluster analysis, where by four apricot cultivars were identified as false. The self-incompatibility genotypes of the apricot and plum collections were evaluated through the first and second intron amplification of the S-RNase gene using consensus primers. Furthermore, allele-specific SFB primers were used to distinguish self-compatible cultivars. In apricot, 14 PCR products were amplified corresponding to 14 previously published S-alleles. In plum, amplification of nine S-alleles was observed. Self-compatible apricots displaying the Sc allele were confirmed in 70 accessions. The self-compatibility S-allele (Se) in plum was identified in 39 accessions. Two cultivars were also observed that were self-compatible but which did not have the Se allele; indicating the possibility of another source of the self-compatibility phenotype. The findings of this study, which confirmed trueness to type as well as parentages of the cultivars, provides confidence for the breeders when planning crosses. The molecular fingerprints identified in this study also have the potential of being used as a database for cultivar comparison. In terms of the SI genotypes identified, the findings provide some level of certainty for the commercial farmers to expect good yield and provides information which assists in orchard planning, provided that they plant cultivars with different SI genotypes or self-compatible cultivars.

AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar

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