Application of amplified fragment length polymorphism (AFLPs) for detection of sex–specific markers in dioecious <i>Uapaca kirkiana Muell.</i> Årg.

Abstract

Uapaca kirkiana Muell. Årg is a dioecious fruit tree species for priority domestication in Southern Africa. It reaches reproductive maturity in eight to ten years with male plants making up 50% of breeding populations. Early identification of sex of seedlings is a prerequisite for selection and tree improvement. The amplified fragment length polymorphism (AFLP) technique was used to amplify DNA
segments of U. kirkiana male and female plants to identify sex-specific markers. A total of 84 selective primer combinations were screened using bulked segregant analysis (BSA) for males and females.
More than 110 polymorphic markers were obtained but each of the four primer pairs (E-ACT/M-CTG, EACA/ M-CAA, E41+A/M-CTA and E-AGG/M-CTC) showed one band that was linked to sex. When the four
primer pairs were tested in ten individuals from different populations only one primer pair (E-ACT/MCTG) amplified a 320 bp band in female plants only. It is possible that this marker is linked to a sexdetermining
locus. The results suggest that the gene that determines sex of U. kirkiana is autosomal in nature and this marker may be important during fruit domestication and tree improvement programmes. The marker has been sequenced and sequence characterised amplified region (SCAR) marker will be developed and used for precise and rapid identification of female plants.