Study On Plant Regeneration From Embryo Of Peony In Vitro And The Problenm Of Callus Browning

Peony as a Chinese traditional ornamental plant is famous on the world. It originates in China and has long cultural history. Peony is widely used in garden. The characteristic of peony epicotyl's dormancy makes the conventional crossbreeding had longer cycle, so the peony breeding has been restriction. Secondary metabolism of peony is vigorous, so there are more polyphones generated, which can lead to browning in the process of tissue culture. It is difficult to improve the peony verities through genetic engineering, because there is no good regeneration system.This paper studied on plant regeneration from embryo of peony in virto and the problem of callus browning. The main results were as follows:1. Tissue culture embryos in vitro needs higher air humidity, but doesn't need high osmotic pressure. When the sucrose concentration arrives to 3%, the osmotic pressure can meet the embryos in vitro growth. VC is not suitable for in vitro embryo culture. 150 mg/L VC will make vitro embryo death. 1g/L PVP can be used to prevent the callus browning. 400mg/L CH make embryo grew well. The seeds have higher vitality when they were store in a short time. They grow quicker than the stored in 4℃environment for a long time. So it is suitable for culture the cotyledon. Stored in 4℃environment for two month can help to break down the peony epicotyl's dormancy. 0.5mg/L 6-BA, 1.0mg/L GA3 can also help to break down the peony epicotyl's dormancy.Two ways can get peony plant. One is to use 6-BA on the hypocotyls break dormancy, germination cotyledons, leaves grow, and then root induction. 2.0mg/L IBA can make root induction rate higher, at 80.5%. The other is to make embryo grown on the MS medium first, and then broke down the hypocotyls dormancy by adding 6-BA or GA3. When the 6-BA or GA3 added to the medium, the cotyledon can grow up and the leaves can grow up too. MS+6-BA 1.0mg/L+GA3 1.0mg/L+AC0.5% and MS+6-BA 0.5mg/L+GA3 1.0mg/L+PVP 0.1% are the right medium for subculture.2. WPM+6-BA 1.0mg/L+NAA 1.0mg/L+2,4-D 1.0mg/L+PVP 0.1% is a suitable medium for the callus induction. The cotyledon is better explants than the hypocotyls. The callus'quality came from the cotyledon is better than that came from the hypocotyls. The color of the callus came from the cotyledon is light green and has glossy. The suitable medium for bud differentiation is WPM+2,4-D 1.0mg/L+6-BA 2.0mg/L+NAA 0.5mg/L+KT 0.1mg/L+PVP 0.1%.The rate of the bud differentiation is very low, only 24.6%. 1/2MS+IBA 2.0mg/L is beneficial to induce root formation, and the rooting rate is 8.9%.In the process of bud differentiation generated more fronds and roots, therefore inferred that the organ direct approach may be more suitable for the proliferation cotyledon explants cultured in vitro.3. There was significant difference in different species and in different explants of a species. So the species and the explants of the lower browning rate could be choosing to tissue culture. Jinyang, Jinge and Saixuetai are the suitable species for the tissue culture. The cotyledon is the best explants for tissue culture for it is lowest browning rate.There was significant correlation between polyphone content and browning rate in petiole. There was negative correlation between POD activity and browning rate in petiole. In leaf, there was significant correlation between MDA content and browning rate.VC,AC and PVP can prevent the brown occurrence, but 1.0 g/L PVP has the best effect. Five days of dark treatment can also lighten the browning.