Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/30/2002
Publication Date: 7/20/2002
Citation: v.106.p.107-111. 2002 Interpretive Summary: Plant breeding and horticulture can be improved if sex type of seedlings can be predicted in crops that have different sex types, for example female papayas are required for hybrid seed production and male ginkgo street trees do not produce foul-smelling fruit. This paper documents the development of DNA based markers that can be used to identify papaya sex types before the trees reach sexual maturity and flower, saving time and resources to grow plants to maturity.
Technical Abstract: Molecular markers tightly linked to Sex1, the gene that determines plant sex in papaya (Carica papaya L.), were developed. Three RAPD products have been cloned and a portion of their DNA sequenced. Based on these sequences SCAR primers were synthesized. SCAR T12 and SCAR W11 produce products in hermaphrodite and male plants and only rarely in females. SCAR T1 produces a product in all papayas regardless of plant sex. SCAR W11 showed no recombination in population of 137 F2 plants from a 'SunUp' by 'Kapoho' cross. SCAR T12 showed three recombination events in this same population giving a map distance of 1.1cM. Based on these results a PCR-based technique for rapidly and accurately determining the sex of papaya plants was developed using either W11 or T12 to detect the hermaphrodite or male allele and T1, which amplifies a product regardless of sex type, as a positive control. The sexing technique, using SCAR T12, and SCAR T1 as a positive control, was used to correctly predict hermaphrodite papaya plants in a population of seedlings with an overall accuracy of 99.2%.