| As an important commercial timber and afforestation tree species,the demand for Cunninghamia lanceolata is increasing.It is of great significance to establish and optimize efficient Cunninghamia lanceolata somatic embryogenesis system for breeding,seedling production and production.In this paper,the mature zygotic embryos,immature zygotic embryos and three specific maternal genotypes of Cunninghamia lanceolata were used as explants to study the effects of zygotic embryo maturity,basic medium type,maternal genotype,exogenous additives Thidiazuron(TDZ)and Methyl jasmonate(MeJA)on the induction of embryogenic callus of Cunninghamia lanceolata.Three embryogenic callus cell lines(2#,6#,10#)which were preserved in the laboratory and three newly induced embryogenic callus cell lines(Z2#,Z17#,Z22#)as materials,the effects of Abscisic acid(ABA),Gibberellic acid(GA3),Polyethylene glycol(PEG)and redox conditions on mature culture of Cunninghamia lanceolata were studied.This study provides theoretical basis and technical support for optimizing and breaking through the difficulties of somatic embryo induction and low somatic embryo maturity in the existing somatic embryogenesis system of Cunninghamia lanceolata.The results of this study are as follows:(1)The immature zygotic embryo of Cunninghamia lanceolata,which was in the multi-embryonic stage and collected in early July as explants,DCR as the basic medium,adding sucrose 30 g/L,activated carbon 1 g/L,phytagel 5 g/L and adding plant growth regulator 2,4-Dichlorophenoxyacetic acid(2,4-D)1.5 mg/L under the conditions of Kinetin(KT)0.4 mg/L,MeJA 1.2 μmol/L and TDZ 0.004 mg/L,the induction rate of embryogenic callus of Cunninghamia lanceolata was the highest,reaching 19.83%(2)The induction rate of embryogenic callus of Zhongshan 039,Zhongshan 042 and Zhongshan 047 was over 16%,which were 18.13%,16.83%and 17.22%,respectively.The induction rate of embryogenic callus reached a high level in the induction of embryogenic callus of Cunninghamia lanceolata,and the donor plants of the three genotypes could be used for future experimental selection.(3)During the induction process of embryogenic callus of Cunninghamia lanceolata,the proembryogenic masses experienced three stages of PEM I,PEM II and PEM III.Embryogenic callus and non-embryogenic callus appear in the process of induction.The difference between the two is obvious.The embryogenic callus has a bright luster and some protruding structures on the surface and most of the proembryogenic masses are in the PEM III period;Non-embryogenic callus is characterized by liquefaction,loose texture and poor adhesion,irregular shape,and the cells of the cell cluster are mostly round or elliptical,loose or have no polar structure.(4)The newly induced embryogenic callus cell line was used as the material,DCR was used as the basic medium,and sucrose 30 g/L,phytagel 5 g/L,activated carbon 1 g/L,AgNO3 10 mg/Lwere added.Adding plant growth regulator ABA 50μmol/L+GA3 0.8 mg/L+PEG8000 180 g/L,the highest maturity rate was 87.50%,and the number of early somatic embryos was 185.33/g.(5)The change of redox conditions has significant effect on the mature culture of Cunninghamia lanceolata embryo.In the early stage of mature embryo culture of Cunninghamia lanceolata,the exogenous addition of 0.25 mmol/L of Glutathione(GSH)has a good effect on promoting mature culture. |
