Browning is one of the key factors that influenced the callus subculture of tree peony (Paeonia suffruticosa Andr.). Effects of medium composition and exogenous hormones: macro elements of Murashige and Skoog (MS salts) and iron salt (Fe2+), pH, agar and 6-benzylaminopurine (6-BA), 1-naphthaleneacetic acid (NAA) and kinetin (KT) on the callus browning of P. suffruticosa ‘Shan Hu Tai’ in vitro were studied in this paper. Results showed that the browning of P. suffruticosa callus were more sensitive to KT than 6-BA in different concentrations of 6-BA and KT separately with different concentrations of NAA, and reduced to the lowest (13.3%) under 0.5 mg·L-1 NAA plus 0.3 mg·L-1 KT. 1/4 × MS plus 1/4 × Fe2+ was the best basic medium in which the browning rate was only 18.2%. The browning rate of the callus was the lowest of 4.0% under pH 6.5 and the callus grew better in 7.0 g·L-1 agar than others. This study indicated that the best medium preventing P. suffruticosa callus in vitro from browning was: 1/4 × MS medium supplemented with 6.95 mg·L-1Fe2+, 0.3 mg·L-1 KT, 0.5 mg·L-1 NAA, 6.0 g·L-1 agar and 30 g·L-1 sucrose in pH 6.5.
In the present study, the plantlets in vitro of Paeonia suffruticosa ‘Wu Long Peng Sheng’ were used as laboratory materials. The proteome during adventitious root induction process was investigated to sift the related proteins by two-dimensional electrophoresis and mass spectrometry. The results indicated that the protein spots were concentrated in the acidity gel region (pH 4 - 7) and the spots number had a dynamic change ranged from 373 to 462 at the process of root induction (0 – 7 d). 8 spots significantly changed were analyzed with a mass spectrometer and identified using associated software and databases. The peptide information of the 8 spots was similar to the ATP synthase β-subunit of P. suffruticosa (Spots 1 - 4 and 8), P. tenuifolia (Spots 5), P. californica (Spot 6) and P. brownie ( Spots 7) r espectiv ely. T he expression levels of protein spots 1, 4, 5, 6 and 7 was dramatically downregulated, and that of protein spots 2 and 3 had a slightly opposite tendency on the 3rd day. The obviously decreased period is particularly interesting as it was consistent with the induction period of adventitious root primordial of tree peony plantlet in vitro. The ATP synthase β-subunit could be consumed for assembling the ATP synthase in order to supply energy to the rooting process. Therefore, we speculated that the ATP synthase β-subunit was involved in adventitious root initiation of tree peony plantlets in vitro and we expect that further studies should be carried out in order to export its action mechanism.
The section Moutan DC., tree peony is woody species in the genus Paeonia L. (Paeoniaceae). This taxon as an ornamental and medicinal plant is a traditional floricultural and popuJar flower in China from old times. The cultural history of tree peony in China is more than 2,00) years and in the present tree peony of over 800 cultivars is growing in China. In China, many researches about tree peony were accomplished in many fields: origin, distribution, breeding, taxonomy, physiology, reproduction and molecular biology, etc. Tree peony resource of China is the most abundant in the world and also it has the wide distribution range in China. Characteristics for culture and ornament of each cultivar group are very superior. Therefore to improve the genetic resource of 01ina tree peony using modem biotechnology and to enlarge its cultivation range is very important for development of newly improved varieties of tree peony.