Analysis Of Morphological And Genetic Characteristics Of The Offspring Of Cymbidium Golden Elf × Cymbidium Faberi During Vegetative Growth Stage

Cymbidium is an important genus in Orchidaceae family.It has many excellent germplasms with higher ornamental value.Up to now,there have been many reports on the breeding of new cultivars of Cymbidium by interspecific hybridization at home and abroad.However,there are few reports on the early stage screening and identification of the offspring of Cymbidium hybrids.In this study,the Cymbidium hybrid ‘Golden Elf’(Cymbidium ensifolium × Cymbidium Enid Haupt)and Cymbidium faberi were used as the crossing parents,and the F1 population was obtained by aseptic sowing of their offspring seeds.By using the crossing parents and hybrid progeny lines as materials,the morphological and genetic characteristics were further analyzed.The objective of this study is to elucidate the genetic characteristics of main growth traits during vegetative growth stage between parents and their hybrids.The results will be helpful for further selecting fine Cymbidium hybrid lines with stronger fragrance and plant types in this population.The main results are as follows:1.15 phenotypic morphological characteristics of crossing parents ‘Golden Elf’(seed parent)and Cymbidium faberi(pollen parent)and their offspring lines were investigated,and the genetic characteristics of the hybrid offspring lines were analyzed using morphological markers.The results showed that there were differences in the range of variation of morphological characteristics of different progeny lines.In terms of leaf color,the lines fcf-2 and fcf-6 were the same as the seed parent,and the lines fcf-11,fcf-16 and fcf-17 were the same as the pollen parent.On the leaf margin,the lines fcf-2,fcf-6,fcf-13 and fcf-17 were the same as the seed parent,and fcf-11 and fcf-16 were the same as the pollen parent.On the leaf position,the lines fcf-2,fcf-6,fcf-13 and fcf-15 were the same as the seed parent,and the lines fcf-10,fcf-11,fcf-16 and fcf-17 were the same as the pollen parent.On the leaf veins,the lines fcf-2,fcf-13 and fcf-17 were the same as the seed parent,and fcf-11 and fcf-16 were the same as the pollen parent.In terms of plant type,the lines fcf-2,fcf-6,fcf-13 and fcf-15 were the same as the seed parent,and the lines fcf-10,fcf-11,fcf-16 and fcf-17 were the same as the pollen parent.Through the cluster analysis of leaf length,leaf width and aspect ratio,all the lines could be divided into two groups.All the offspring lines and the pollen parent were grouped together,indicating that the offspring lines were closely related to the pollen parent.The seed parent was a single category,which means that all the offspring lines were relatively distant from the seed parent.This indicated that the phenomenon of gene recombination occurred in the hybrid progeny lines,which resulted in abundant variation among the offspring.2.Three physiological indicators of the seed parent ‘Golden Elf’,the pollen parent Cymbidium faberi and their offspring lines were measured and analyzed.The results showed that the contents of chlorophyll,soluble sugar and soluble protein in the leaves of the seed parent were lower than those of the pollen parent.The chlorophyll content of the offspring lines was higher than that of the parents,fcf-10 and fcf-16,and the lines close to the pollen parent were fcf-2,fcf-6,fcf-11,fcf-15 and fcf-17.The soluble sugar content of the progeny lines was higher than that of the parent,fcf-13,and the lines close to the pollen parent were fcf-2,fcf-11,fcf-16 and fcf-17.The soluble protein content in the progeny lines was lower than the pollen parent,and the lines similar to the seed parent were fcf-2,fcf-6,fcf-10,fcf-13 and fcf-15.3.The number and morphological characteristics of the chromosomes of the crossing parent ’Golden Elf’,Cymbidium faberi and their offspring lines were analyzed.The results showed that the karyotype of the seed parent ‘Golden Elf’ was 2n = 2x = 32 m + 8sm,which was type 2B;The karyotype of the pollen parent Cymbidium faberi was 2n = 2x = 34 m +6sm,which belongs to type 2B;There were many types of karyotype formulas of hybrid offspring lines: 32 m + 8sm,34 m + 6sm,2M + 38 m,34m + 6sm,32 m + 8sm,30 m + 10 sm,32m + 8sm,38 m + 2sm,etc.Among them,type 2B accounted for 87.5% and type 1B accounted for 12.5%.4.Using ISSR molecular markers to analyze the genetic characteristics of crossing parents and progeny lines.The PCR amplification program,different primers,primer dosage,template dosage and annealing temperature conditions were optimized,and the parental and hybrid progeny lines were further amplified.The results showed that the optimal reaction procedure for ISSR-PCR was 94 ℃ pre-denaturation for 5 min,94 ℃denaturation for 30 s,annealing temperature(depending on different primers)30 s,72 ℃extension for 1 min,36 cycles,72 ℃ final extension for 5 min.A total of 15 ISSR primers were screened to amplify the hybrid combination.15 ISSR primers were used to amplify this hybridization combination,and a total of 57 DNA bands were obtained,of which 45 were polymorphic DNA bands,and the polymorphism rate was 78.9%.According to the UPGMA clustering results,the ‘Golden Elf’ and Cymbidium faberi and their hybrid progeny lines can be divided into two groups when the similarity coefficient was 0.42.Among them,the lines fcf-10,fcf-11,fcf-16 and fcf-17 were grouped with the pollen parent,and the lines fcf-2,fcf-6,fcf-13 and fcf-15 were grouped with the seed parent.The identification results of morphological characteristics were consistent with ISSR markers analysis.