Abstract:

Genetic relationship amongst the 6 cultivars of cut chrysanthemum and their 38 F₁ hybrids derived from a 2 × 4 incomplete diallel cross was unraveled by SRAP markers. The SRAP genotyping suggested that of the 229 fragments produced by 17 SRAP primer combinations 127 were polymorphic，with an average of 7.5 polymorphic fragments per primer combination，thus indicative of a moderate molecular diversity present in the entries. The Nei’s genetic distances were estimated between 0.11–0.25 and averaged at 0.19，denoting a close genetic relationship among the parental cultivars. The SRAP-based genetic similarity was calculated at 0.42–0.72 and 0.40–0.85，respectively，for the parental cultivars  and the F₁ hybrids，and the median of genetic similarity（0.61）for the hybrids were higher than that（0.55）for parental cultivars. This suggests a narrowing genetic base or homogenization during hybridization in chrysanthemum，despite the occurrence of some variant lines. Based on genetic similarity matrix，the UPGMA clustering classified the investigated entries into two major groups well congruent with female parents and cross combinations，reinforcing the reliability of SRAP markers in distinguishing F₁ hybrids resulted from different combinations in chrysanthemum.

Key words: chrysanthemum, hybrid progeny, incomplete diallel cross, genetic similarity, molecular identification, SRAP marker