Effects of Desiccation on Anatomical Structure of Somatic Embryo and Expression of Cell Wall Remodelin g Gene of Picea asperata
[Objective]To explore the effects of desiccation on the anatomical structure of somatic embryo of Picea asperata,identify the key genes that lead to the changes in anatomical structure,and preliminar-ily explore the reasons why desiccation promotes somatic embryo germination.[Method]The high em-bryonic cell line of Picea asperata was used to induce somatic embryogenesis.The phenotypic observa-tion and germination rate of somatic embryos were determined after desiccation treatment for different time.Ultra depth of field microscope,scanning electron microscope and transmission electron microscope were used to observe the differences of tissue and cell structure and morphology between desiccated so-matic embryos and non-desiccated somatic embryos,and transcriptome sequencing was combined to analyze the changes of gene expression between desiccated and non-desiccated somatic embryos.[Results]The somatic embryo morphology of spruce was significantly changed after desiccation.The rad-icle turned red and the cotyledon turned green after desiccation.Microscopic observation showed that the cells of the desiccated somatic embryo were shrunken and irregularly distributed.At high magnification,the cell wall was no longer rigid,showing a relaxed and twisted state.Transcriptome analysis found that several transcripts of XTHs,EXPAs and PMEs involved in cell wall remodeling and affecting the mechanic-al properties of cell walls were significantly differentially expressed between desiccated and non-desic-cated somatic embryos,and their expressions were mostly up-regulated,which was consistent with the results of microscopic observation on the morphological changes of desiccated somatic embryos.These genes may synergically regulate the process of desiccation and affect the germination of somatic embryos.[Conclusion]The differential expression of cell wall remodeling genes during desiccation leads to the relaxa-tion of somatic embryo cell wall,the disappearance of rigid structure,and the release of cell differentiation and growth restrictions,which is a potential reason for desiccation to promote somatic embryo germination.
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万方数据
维普
