| Chrysanthemum morifolium,native to China,is one of the ten famous flowers in China and a leading cut flower in the world,with high cultural and economic value.Chrysanthemums are generally considered to be self-incompatible plants,but the reproductive obstacles between chrysanthemums are not complete.Recent investigations announced that some cultivars（especially potted or small-flowered cultivars）showed a relatively high selfed seed-set rate,but inbreeding depression were observed in most of the inbred lines.Thus far the self-compatible cultivars have been being so limited that the inbred depression are not detailed,which affects the development of advanced inbred population in chrysanthemum.In this study were set out to investigate the selfed seed setting,phenotypic variation,and genetic performance for cut flower chrysanthemum Q1-80 and its inbred progenies,and to screen out some self-compatible lines for future development of advanced inbred populations in chrysanthemum.The main findings are as follows:（1）Selfed seed setting,emergence rate and flowering traits were investigated for two-generation inbred populations of cut flower chrysanthemum cultivar Q1-80.The results showed that the S1（82）,S1（88）,and S1（13）lines had relatively high seed setting rates of 10.97,37.5,and 19.8 seeds per inflorescence,and the seed emergence rate was 17.78%,28.62%,28.95%,respectively;in S2 population the selfed seed setting rate was 4.1-12.7 seeds per inflorescence,and seed emergence rate was 33.08%～43.9%.It was observed that rosetted plants with non-flowering or withered flower buds during flowering often occurred as typical inbreeding depression in the S2 populations.The proportion of 25.5%,20%and 17%for rosette was observed in the S2（82）,S2（88）,and S2（13）populations,respectively.The post-flower lethal situation,i.e.,withered flower buds during flowering mainly occurred in the S2（13）population,the post-flower lethal rate reached 12.5%,and the post-flower lethal rates in the other two S2 populations,S2（82）and S2（88）,was 0.015%,0%,respectively.（2）The inflorescence morphology and a total of 11 horticultural triats,i.e.,plant height,leaf length,leaf width,petiole length,flower diameter,ray floret number,ray floret length and width,tubular floret number,and tubular floret length and width were investigated for Q1-80 and its inbred S1 and S2 progenies.The results showed that typical inbreeding depression was present in all three S2 progenies,with abnormal flower or florets（flower deformity）,decreased ray floret length and width,and decreased number of ray and tubular florets.The investigated traits in inbred population were all significantly lower than that of the parental genotype Q1-80,and it was observed that the variation coefficient of the S2 generation is significantly greater than that of the S1 generation for most investigated traits except tubular flower length and width.A comparative analysis between the three S2 populations revealed that most significant variation in the S2（13）population for tubular floret number,in the S2（82）population for ray floret number,and in the S2（88）population for tubular floret width.（3）SRAP molecular markers were used to analyze the genetic diversity cut flower chrysanthemum Q1-80 and some inbred progenies.The results showed that 13 pairs of SRAP primers amplified 92 bands,57 of which were polymorphic bands,with an average polymorphism rate of 63%and an average polymorphism information content of 0.53.The average number of effective alleles,gene diversity index and Shannon index were 1.67,0.39 and 0.57,respectively.The genetic similarity coefficient of 43 genotypes ranged between 0.44 and 0.86.UPGMA cluster analysis divided the 43 genotypes into 8 subgroups at 0.65,whereas the clustering based on morphological traits seperated the 43 genotypes into 4 groups.In which,the results of morphological clustering rather than the marker analysis was in accordance with the phenotypic performance of the inbred progenies. |
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