2019 ASHS Annual Conference
Development and Characterization of EST-SSR Markers from Balsam Fir (Abies balsamea, L.) Transcriptome and Genetic Conformity Studies in Somatic Embryogenic Lines
Development and Characterization of EST-SSR Markers from Balsam Fir (Abies balsamea, L.) Transcriptome and Genetic Conformity Studies in Somatic Embryogenic Lines
Wednesday, July 24, 2019
Cohiba 5-11 (Tropicana Las Vegas)
Balsam fir (Abies balsamea L.) the principal Christmas tree species, shapes eastern Canada’s Christmas tree and greenery industries due to its unique qualities such as fragrance, color and tree architecture. Improving postharvest needle retention has been an economically important attribute in this species. However, revealing the genetic basis of needle retention and high throughput genotyping of balsam fir lines having valuable economic traits have been hindered by limited genomic resources. A balsam fir transcriptome was constructed from six lines with variability in needle retention and was used to generate simple sequence repeat (SSR) markers. Transcriptome was generated via paired-end Illumina HiSeq 2000 platform and resulted in 30,647 unigenes. A SSR search of the transcriptome identified 2144 SSRs, including 2081 perfect (di- 122; tri- 930; tetra- 217; penta- 90 and hexa- 852) and 63 compound SSRs. The transcriptome dataset provides a valuable resource for future genetic and genomic studies in balsam fir.
A growing demand for high needle retaining balsam fir clones with industrial interest reinforces the need to establish clonal propagation via somatic embryogenesis and preservation of high value genotypes that retain traits of interest. Towards this end, a successful protocol of somatic embryogenesis (SE) and cryopreservation of embryogenic tissue has been established for high quality balsam fir hybrids. However, prolonged maintenance of tissues in cultures reduces its embryogenic potential and increases the chances of genetic instability. In the present study, genetic stability of balsam fir embryogenic cell lines (ECLs) was evaluated with the aid of SSR markers developed from transcriptome data. Sixty-five primer pairs were randomly selected and screened for identifying their utility in differentiating somaclones. Out of the 65 SSR primers analysed, 7 shown polymorphic banding pattern between the selected parental clones. A total of 53 ECLs developed from immature zygotic embryos of balsam fir collected from 8 full-sib families were subjected to genetic conformity studies using microsatellite marker assay. The analysis was performed on proliferating callus, mature somatic embryos and regenerated seedlings and compared with that of parental genotypes. In addition, the effect of overall SE process was also assessed through the analysis of genetic stability in somatic embryos regenerated from cryopreserved calluses. The results of the study demonstrated that clonal propagation of elite balsam fir lines using SE can be carried out with a low risk of genetic instability and the use of SSR marker system to successfully assess genetic variations within balsam fir lines.
A growing demand for high needle retaining balsam fir clones with industrial interest reinforces the need to establish clonal propagation via somatic embryogenesis and preservation of high value genotypes that retain traits of interest. Towards this end, a successful protocol of somatic embryogenesis (SE) and cryopreservation of embryogenic tissue has been established for high quality balsam fir hybrids. However, prolonged maintenance of tissues in cultures reduces its embryogenic potential and increases the chances of genetic instability. In the present study, genetic stability of balsam fir embryogenic cell lines (ECLs) was evaluated with the aid of SSR markers developed from transcriptome data. Sixty-five primer pairs were randomly selected and screened for identifying their utility in differentiating somaclones. Out of the 65 SSR primers analysed, 7 shown polymorphic banding pattern between the selected parental clones. A total of 53 ECLs developed from immature zygotic embryos of balsam fir collected from 8 full-sib families were subjected to genetic conformity studies using microsatellite marker assay. The analysis was performed on proliferating callus, mature somatic embryos and regenerated seedlings and compared with that of parental genotypes. In addition, the effect of overall SE process was also assessed through the analysis of genetic stability in somatic embryos regenerated from cryopreserved calluses. The results of the study demonstrated that clonal propagation of elite balsam fir lines using SE can be carried out with a low risk of genetic instability and the use of SSR marker system to successfully assess genetic variations within balsam fir lines.
Keywords: Abies balsamea, Christmas tree, transcriptomics, SSR, somatic embryogenesis, clonal fidelity