Conversion of a male-specific RAPD marker into an STS marker in Asparagus officinalis L.

Garden asparagus (Asparagus officinalis L.) is an economically important plant. This species is dioecious, and male plants are considered to be more desirable than females due to their higher yields. To reduce the time required for asparagus breeding, molecular marker techniques have been employed to identify sex-linked DNA markers. In the present study, we converted the male-specific random amplified polymorphic DNA marker T35R54-1600 into a sequence tagged site marker. We cloned a male-specific DNA fragment amplified with the T35R54 primer and determined the sequence of the fragment. The size of T35R54-1600 is 1,586 bp, and this fragment is not homologous to known sex-linked BAC sequences, indicating that this fragment is a new sex-linked region. Within this fragment, we designed the primer pair 'MSSTS710' to amplify a 710 bp region. This marker could be used to identify the sex of eight cultivars of A. officinalis: 'Mary Washington 500W', 'UC157', 'Harumachi Green', 'Super Welcome', 'F4', 'Pacific 2000', 'F2' and 'Backlim'. We also analyzed the applicability of this marker to two dioecious Asparagus species, A. schoberioides and A. kiusianus, which are cross-compatible with A. officinalis. Although male-specific DNA fragments of two dioecious Asparagus species, A. schoberioides and A. kiusianus, were generated using the existing male-specific marker Asp1T7sp, no amplicon was obtained using the MSSTS710 marker. Since MSSTS710 can be employed for sex identification only in A. officinalis and not in closely related Asparagus species, the DNA region around the MSSTS710 marker must be variable among Asparagus species.