Cytological and physiological characteristics of somatic embryogenesis in Lycoris
[Objective]This study,with an exploration of the changes of cytology and physiological and biochemical indexes during somatic embryogenesis of Lycoris chinensis×radiate'Astro Girl',which can improve the coefficient and quality of tissue culture and rapid propagation of'Astro Girl',is aimed to provide technical support for the factory production of new Lycoris varieties.[Method]Paraffin section,enzyme-linked immunosorbent assay and ultra high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)were used to determine the changes of somatic embryo morphology,histology and corresponding physiological and biochemical indexes such as content of soluble starch and total protein,antioxidant enzyme activity and polyamine content during somatic embryo culture(0-40 d)of'Astro Girl'.[Result](1)During the process of somatic embryogenesis,the globular embryo lasted for about 20 days from initiation to transient expansion,before it was further differentiated into heart-shaped embryo,rod-shaped embryo and cotyledon embryo with vascular bundles formed at the base of the enlarged globular embryo or heart-shaped embryo.(2)During somatic embryogenesis,significant changes occurred in the content of total protein and starch and the activity of antioxidant enzymes.The change of starch content was positively correlated with the formation of globular embryo and negatively correlated with somatic embryo morphogenesis and somatic embryo maturation,whereas the changes of total protein(TP)content,peroxidase(POD)activity and catalase(CAT)activity were positively correlated with cotyledon embryo formation but negatively correlated with cotyledon embryo maturation.The activity of superoxide dismutase(SOD)was negatively correlated with globular embryo and cotyledon embryo,but positively correlated with heart-shaped embryo and rod-shaped embryo.Such results showed that starch,protein and antioxidant enzymes which are closely related to plant physiology play an important role in somatic embryogenesis.(3)The activity of polyamine oxidase(PAO)and the content of polyamine(PAs)changed significantly during somatic embryogenesis,and the contents of putrescine(Put),spermine(Spm)and spermidine(Spd)determined the change trend of polyamine content.Polyamine content and polyamine oxidase activity mainly accumulated in the early stage of somatic embryo differentiation,which was positively correlated with globular embryo differentiation,and the changes of spermine and spermidine content were positively correlated during cotyledon embryo formation.In the mature stage of cotyledon embryo,putrescine,spermine and spermidine decreased at first and then increased,while spermine and spermidine increased at first and then decreased.[Conclusion]During the 0-40 days of somatic embryogenesis of'Astro Girl',the main morphology of somatic embryo developed from proembryo,globular embryo,heart-shaped embryo and rod-shaped embryo to cotyledon embryo,among which,the physiological characteristics changed significantly,and the accumulation or consumption of starch content may be an important factor affecting the formation of globular embryo and the subsequent morphological development and maturation of somatic embryo.During the formation and maturation of cotyledon embryo,the changes of total protein content,peroxidase activity and polyamine content may play a closely joint role.The active accumulation of polyamine oxidase activity and polyamine content may be beneficial to the early development of somatic embryos.[Ch,4 fig.32 ref.]
Lycoriscallussomatic embryophysiology and biochemistry
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