Selection Of Aromatic Petunia And Establishment Of Regeneration System

Petunia hybrida belongs to the genus Petunia of Solanaceae.It is a perennial herb,native to the temperate region of South America,and mainly planted in China,Japan,Europe and America.P.hybrida has many varieties,colorful flowers,large corolla and unique fragrance,which make it one of the common model plants in the field of floral and flower color research.However,there are many varieties of P.hybrida.Due to the different breeding objectives,the floral characteristics of P.hybrida varieties are quite different.Under the help of the current concept of "health raising",the aromatic P.hybrida varieties are more and more favored by people.In this study,12 P.hybrida varieties of 8 series were used as materials,and the degree of fragrance was classified by olfaction.Meanwhile,headspace volatile components of different P.hybrida varieties were identified and quantitatively analyzed by headspace solid phase microextraction(HS-SPME)and gas chromatography-mass spectrometry(GC-MS).On this basis,principal component analysis and cluster analysis were carried out.Combined with the analysis results,a regeneration system was established for the aromatic variety ‘Carpet Blue’,which provided technical support for the cultivation of P.hybrida,the conservation of aromatic variety resources and the promotion of aromatic varieties.There are many kinds of volatile components in P.hybrida,and there are significant differences in corolla traits and volatile components among different varieties.According to the intensity of P.hybrida flower fragrance,12 varieties were divided into three types: aromatic type,delicate fragrant type and light fragrant type.A total of 66 kinds of volatiles were detected in 12 P.hybrida varieties,mainly including 10 categories such as ethers,alcohols,lipids,terpene,alkene,alkane and other 10 categories.A total of 66 volatiles were detected in 12 P.hybrida varieties,but there were significant differences in the volatiles among different P.hybrida varieties.The main volatiles of ’Carpet’ series are lipids(Methyl benzoate);the key volatiles of the ‘Miracle’ series are ethers(Dimethyl ether,Hexyl ether),alcohols(Ethanol)and alkenes((S)-(-)-limonene);the key volatiles of the ‘Light Wave’ series are terpenes and alkenes(Tricyclene,β-Pinene)and lipids(Methyl 2-methylbutyrate,Methyl benzoate);the key volatile constituents of the remaining 4 species are Tricyclene,β-Pinene,Methyl 2-methylbutyrate,Methyl benzoate,etc.Cluster analysis shows that the genetic relationships of varieties with similar volatile components are closer.Among the 12 P.hybrida varieties tested,the aromatic variety ‘Carpet blue’ contains the most volatile components,up to 18 kinds,including alcohols,lipids,terpenes,alkenes,aldehydes,aromatic hydrocarbons and alkanes.Among them,the relative content of Methyl benzoate in ‘Carpet blue’ of aromatic P.hybrida varieties was 97.49%,which was the highest among all varieties.In addition,‘Carpet blue’ this variety can also specific volatile phenyl acetate(plum blossom characteristic aroma component),the relative volatile amount is 0.65%.This discovery can provide a basis for the study of the synthesis,transport and release mechanism of the volatiles of plum flowers,and also provide a theoretical basis for P.hybrida flower breeding.Therefore,the young leaves of a romatic P.hybrida ‘Carpet blue’ were selected as explants in this paper to establish its regeneration system.Regeneration system study showed that the best surface disinfection effect was obtained by rinsing with 75% alcohol(C2H5OH)for 30 seconds,and then disinfected with 5% Na Cl O for 8 minutes.The rate of sterile explants was 93.75%;The optimum medium for callus induction and adventitious bud differentiation was MS+1.5 mg·L-1 6-benzyladenine(6-BA)+0.3 mg·L-1 NAA,the induction rate could reach 100%,and strong adventitious buds could be differentiated;The optimal medium for adventitious bud proliferation was MS+0.5 mg·L-1 6-BA + 0.4 mg·L-1 NAA,the proliferation coefficient was 14.67 times;The optimal rooting medium was 1/2MS+0.4 mg·L-1 NAA,the rooting rate was 100%,the average number of roots was 37.67,the average root length was 2.61 cm,the highest rooting index was 9.82,and the longest single adventitious root was 5.22 cm.The survival rate was 92.50% after transplanting.