Abstract:

The hybrid authenticity of 124 offsprings from the reciprocal cross between Shixia（a early-maturing and high-quality cultivar）and Xiangcui（a novel late-maturing and full aroma type）was detected using SSR markers，and the genetic diversity of top-grafting longan（Dimocarpus longan Lour.）seedlings were analyzed by phenotypic traits at age first-bloom and fruit flavor. The results showed that 9 pairs of primers that generated polymorphic bands in parental lines were selected from 20 pairs of longan genomic SSR and 50 pairs of litchi（Litchi chinensis Sonn.）EST-SSR，the percentage of polymorphicbands was 12.86%. One hundred and ten true hybrids were identified from 112 F1 offsprings of Shixia × Xiangcui by 6 pairs SSR primers，accounting for 98.21%. Eleven true hybrids was identified from 12 offsprings of Xiangcui × Shixia by 4 pairs SSR primers，accounting for 91.67%. The UPGMA based dendrograms indicated that the genetic variation of 121 reciprocal hybrids was significant and these offsprings could be classified into 3 groups and 5 subgroups. The rate of short first-bloom age（2.5 years old） between direct and reciprocal cross were 31.58% and 28.57%，medium first-bloom age（3.5–4.5 years old）were 68.42% and 57.14%，long first-bloom age（≥ 5.5 years old）were 0 and 14.29%. The fruit flavor traits varied widely and showed three types as‘absent’，‘weak’and‘strong’.

Key words: longan, reciprocal crosses, SSR, hybrid identification, genetic diversity