Exploitation of polyploids from open-pollinated triploid grapefruit progenies and their genetic identification by SSR molecular markers

【Objective】To exploit spontaneous polyploids as new germplasm from seedling progenies of open pollinated triploid grapefruit.【Method】Fruits of triploid grapefruit were harvested in autumn. Seeds were collected and cultured in vitro. Flow cytometry was applied to verify the seedlings' ploidy level,and simple sequence repeat(SSR) markers were used to characterize their genetic origin.【Results】172 Diploid,52 triploid,18 tetraploid,one pentaploid,one hexaploid and 18 putative aneuploid seedlings were identified from the recovered plants respectively. The genetic origin of these polyploids obtained by embryo rescue were determined by 13 SSR markers,and the results showed that diploid might be 1X gamete pollinated and fertilized by nearby 1X pollen grain from other citrus cultivars,or it might be a product of apomixes of recombinant 2X female gamete. Triploids were mostly derived from nucellar cells. Pentaploid and hexaploid have exactly the same banding pattern as the female parent.【Conclusion】These newly exploited polyploids hold great potential for citrus breeding.