| Zinnia elegan Jacq.is an annual herbaceous flower of Zinnia of Compositae,which is an excellent flower in summer and autumn.It has a lot of advantages such as long flowering period,large amount of flowers,strong flower doubleness and bright colors.Therefore,it has been widely used in landscaping at home and abroad.However,As lacking of dwarfed male sterile two-type lines,the selection of dwarf varieties is largely limited.In addition,the use of molecular marker-assisted breeding techniques can shorten the breeding cycle,and the breeding would be higher efficiency and lower cost,which contribute to change the status of the lag in breeding work to a certain extent of Zinnia.This study,on the one hand,carried out breeding of parental male sterile two-type lines in flower color and dwarfing,and carried out 7×7complete diallel crosses to investigate the combining ability,heritability and genetic regularity of important ornamental traits of Zinnia elegan.On the other,the bulked segregant RNA-Seq used to study on the male fertility of Zinnia,differentially expressed Unigenes between fertile bulk and sterile bulk were compared,CAPS marker primers which associated with male fertility gene(s)were designed for screening.The main results are as follows:1.Breeding of parental male sterile two-type lines in flower color and dwarfing(1)The results of breeding of male sterile two-type lines in pink flower color showed that,through crossbreeding and selective breeding for three generations,we obtained the male sterile two-type lines(FMah001AB)which all fertile plants with pink flower color,plant height were dwarfed basically stable(only one plant is over 30 cm among 37 plants),and the fertility separation is 1:1 steadily.(2)The results of dwarfing and flower color selecting of crimson male sterile two-type lines in middle plant height showed that,through crossbreeding and selective breeding for one generation,we obtained the male sterile two-type lines(AMS5001AB)which plant height of 76.9% plants are less than 30 cm,52.9% fertile plants with crimson flower color,and the fertility separation is 1:1 steadily.2.Analysis of 7×7 complete diallel crosses(1)Analysis of the heterosis,among impotant ornamental traits,number of flowers,number of branches,and number of whorls of ray florets across capitulum showed strong positive heterosis,moreover,plant heigh did not show over-high-parent heterosis,it can be seen that Zinnia has the potential to cultivate varieties with abound of flowers and branches,flower doubleness strongly and plant height dwarfed.(2)Analysis of the combining ability,the general combining ability and the special combining ability are independent of each other of Zinnia,whereas both of them have a certain correlation with the performance of hybrids.In addition,there was a significant positive correlation between the special combining ability with the over-high-parent heterosis and the mid-parent heterosis.(3)Analysis of the heritability,comprehensive analysis of genetic parameters of impotant ornamental traits showed that the inheritance of plant height,diameter of inflorescence,pedicel length,and number of whorls of ray florets across capitulum are mainly controlled by gene additive effects.Hence,there is strong capability in genetic transmission of those ornamental traits,suitable for early generation selection.On the contrary,the inheritance of number of flowers,number of branches,and crown size are mainly controlled by non-additive effects.Thus,phenotypes of those ornamental traits are easily affected by the environment and cannot be inherited stably to hybrids,breeding improved varieties can be used heterosis.(4)Evaluation the application value of parents and combinations,the results showed that,in parental materials,J18 is suitable for breeding potted flowers varieties,A5 F is suitable for breeding cut flower varieties.In combinations,J18×A5M(Plant height 30 cm,Diameter of inflorescence 10.5cm)is an excellent potted flower with bigger diameter of inflorescence,A5F×Mah001B(Plant height 28.7cm,Number of flowers in full-bloom stage 11-12)is an excellent potted flower with multi-flower,A1GH×J18(Plant height 75.1cm,Diameter of inflorescence 11.1cm)is an excellent cut flower with bigger diameter of inflorescence,and S5×A1GH(Plant height 79.7cm,Number of flowers in full-bloom stage 11-13)is an excellent cut flower with multi-flower.3.Analysis of genetic regularity of discrete traits(1)The genetic regularity of flower color,it followed the genetic regularity of qualitative characters,pink is dominant inheritance for orange,and rose is dominant inheritance for orange,pink,and red.In addition,pink with orange hybrids and crimson with orange hybrids was followed the genetic regularity of quantitative characters.Moreover,pink with red or orange hybrids and rose with orange,pink or red hybrids show additive effects between genes.(2)The genetic regularity of fertility,male sterile is controlled by a pair of recessive nuclear genes,fertile(Msms): sterile(msms)is 1:1.(3)The genetic regularity of petal type,silk type dominant inheritance for flat type and tube type,and flat type dominant inheritance for tube type.4.Analysis of the male fertility genes of Zinnia Analysis of the data from the bulked segregant RNA-Seq showed that there were 283 differentially expressed Unigenes between fertile bulk and sterile bulk.Among them,48(16.96%)Unigenes were significantly enriched in GO,and enrichment results indicated that they were mainly involved in secondary metabolites,phenylpropanoid metabolites and biological processes of pollen wall assembly.In addition,according to the frequency difference of SNPs between the two bulks,there were 40 pairs of CAPS marker primers were designed randomly,and 4 pairs of them showed polymorphisms between the two bulks. |
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