Abstract: Seeds were extracted from mature fruits and undeveloped seeds were cultured in vitro and
mature seeds were sowed in field. Seedlings with 2–3 true leaves after germination were analyzed by
flow cytometry to screen polyploids，and simple sequence repeat （SSR） markers were used to characterize
the genetic origin of these polyploids. The results showed that a total of 44 tetraploid seedlings were obtained from all studied diploid genotypes，i.e. 6，1，3，12，3，6，2，1 and 10 seedlings from Early Gold
sweet orange，Cutter Valencia，Tarocco blood orange，Sunburst mandarin，Ortanique tangor，Murcott
tangor，Huanong Bendizao tangerine，Zhuhongju tangerine and Flame grapefruit respectively. A total of 8
triploid seedlings were obtained from all studied diploid genotypes，i.e. 1，1，2，4 seedlings from Early
Gold sweet orange，Tarocco blood orange，Itabori sweet orange and Ortanique tangor respectively. The
genetic origin of polyploids obtaining by embryo rescue were determined by 13 SSR markers，and the
results showed that the regenerated triploid plants of Early Gold and Itabori sweet oranges were
allotriploid and that of Tarocco blood orange and Ortanique tangor maybe were autotriploid. The
regenerated tetraploid plants of Early Gold sweet orange and Ortanique tangor maybe were autotetraploid
and those of Tarocco blood orange were allotetraploid. SSR analysis validated that the band profiles of
tetraploids derived from other eight diploid cultivars were identical to their diploid maternal line. These
exploited natural polyploids hold great value for both citrus seedless breeding and basic research.

Key words: Citrus, polyploidy, SSR（Simple Sequence Repeat）