Optimization Of High-Efficiency Tissue Culture And Regeneration Systmes Of Castor (Ricinus Communis L.)

As a kind of biological diesel oil, castor oil is widely used in chemical industry. China is the third largest country cultivating castor with a plenty of cultivars. However, with the rapid development of industry, demand of castor oil increases every year. Nowadays, China still needs to import castor oil from abroad on a large scale. As a result breeding and cultivation technology of castor is played a great value of and good quality and high yield castor varieties are in urgent need.This study picked 7 varieties from 31 domestic conventional castor hybrids for tissue culture test, result of which showed that Zhe Bi 3, Jia Xiang 2 and Tong Bi 6 are the gene types more suitable for tissue culture. A highly efficient protocol for castor in vitro propagation from upper hypocotyls was established by testing disinfectant, sterilization time, plant growth regulators (PGRs) and culture time for pre-culture, inoculation method, bud induction PGRs and training time, bud elongation PGRs and root induction factors, and so forth.In this research, the best sterilization system was established which was made up by 70% ethyl alcohol 10 s, 1%NaClO 30 min. As a result, both the pollutation rate and the rate of survival were all acceptable. Among upper hypocotyl, lower hypocotyl, epicotyl, cotyledon and cotyledonary node, the best suitable explant was screened out that is upper hypocotyl which performed very well in the shoot buds induction period on MS medium supplemented with 6-BA with a shoot induction rate of 26.82%. In this reseach, efficient protocols for shoot buds induction as well as shoot buds elongation were established, which contained an efficient shoot buds induction system, an efficient shoot elongation system and an efficient shoot buds induction and elongation system, respectively. The efficient shoot buds induction system is:MS+ 6-BA 1.5 mg/L (pre-culture), and MS+ TDZ 0.14 mg/L(shoot induction culture), which gave the highest shoot induction rate (84.67%). The efficient shoot buds elongation system is:MS+ 6-BA 0.3 mg/L (pre-culture), and MS+ 6-BA 0.2 mg/L and then 6-BA 0.5 mg/L (shoot induction culture), which gave the best average length for buds (1.9 cm). The efficient shoot buds induction and elongation system is:MS+ 6-BA 1.5 mg/Lfor pre-culture period, and the combination of TDZ 0.1 mg/L and 6-BA 0.15 mgL for shoot induction period, which resulted in a farily high rage of shoot buds induction (76.64%) and a good acceptable average length for shoot buds as 1.40 cm. Thoug the length was not as ideal as the one of the second system, considering both of the two factors, this system ranked top. The best root induction protocol was also established through screening best plant growth regulators of IBA and NAA. The protocol is: 1/2MS+IBA 0.3 mg/L+1%AC (activated charcoal), which gave the best root induction rate (90.55%) and the mean numbers of roots as 3.2 per explant.Morphological research of induced shoot buds was studied through paraffin section. The results showed that the adventitious shoot buds originated from endodermis and the cells of buds were closely spaced and well developed which was very beneficial for buds formation.