Studies On Embryo Culture Of Pinus Armandii Franch. In Vitro

Pinus armandii Franch. is one of the most important fast-growing conifers in China with highly value of general utilization . There are great theoretical and practical importances on developing the genetic improvement and biology engineering to explore the generation technology in vitro and establish the rapid propagation system of Pinus armandii Franch. The innovations of this paper lied in that we have established the direct organogensis and plantlet regeneration system through mature embryos , and explored the influencing elements of somatic embryogenesis of Pinus armandii Franch., while no relevant reports about that in domestic and overseas studies. The main results are as following:1 Studies of direct organogensisSeeds of Pinus armandii Franch. were soaked in 70% alcohol for 30s, then being sterilized into 0.1% HgCl₂ for 10 min. The mature embryos were inoculated vertically in the DCR medium for induction. The contents of medium inducing the adventitious buds are : DCR+BA3.0⁵.0mg/L+sucrose30g/L,with the highest frequency of 67.57%; while the differentiation medium were: DCR+IBA 0.1mg/L+AC2 g/L;and the rooting medium were :1/2DCR+IBA 4.0⁵.0 mg/L,on which the stubbed adventitious roots can be induced from the calli, but the seedlings are difficult to survive after transplanted .2 Somatic embryogenesis by mature embryosThe contents of medium inducing the calli from mature embryos of Pinus armandii Franch.were: DCR+2,4-D10mg/L+BA4mg/ L +CH,Myoinositol 1000mg/L individually +Gln 500mg/L,with the highest frequency of similar embryonic calli of 21.58%. After 2 weeks calli were transferred to the medium whose contents were similar as induction medium but hormones reduced to 10 times, but the subculture substances were browned and dead.3 Somatic embryogenesis by immature embryosThe contents of medium were as following: DCR+2,4-D 10mg/L +BA,KT 4mg/L individually+CH,Myoinositol 1000mg/L individually+Gln500mg/L;1/2LM+2,4-D 2mg/L+BA 1mg/L+CH,Myoinositol 1000mg/Lindividually+Gln500mg/L. The immature embryos of Pinus armandii Franch.inoculated in the DCR medium can induce calli only, with the frequency of similar embryonic calli of 47.62%. While the highest frequency of similar embryonic calli can reach 52.71% when the precotyledonary embryos were inoculated in 1/2LM medium. But all the calli induced by immature embryos did not differentiate the embryoids through solid and liquid subculture. The whole plantlets with root and stem can be formed through precocious germination when the cotyledonary embryos of Pinus armandii Franch. were inoculated in 1/2LM medium with the induction frequency of 92%.In a word, the rooting induction from cultured seedlings of Pinus armandii Franch. is not easy, so we should strengthen the rooting studies from inside and outside of the culture containers. The somatic embryogenesis system establishment through immature embryos and mature embryos is very difficult, which needs further research about how to keep and propagate the embryonic calli efficiently, and induce the embryoids differentiation and somatic embryos germination.