Abstract:

Mass culture of pulp callus can provide material basis for the establishment of suspension cell system，the isolation and culture of protoplasts，the establishment of genetic transformation system and the study of secondary metabolites. In this study，10 media were selected to study callus induction of jujube pulp from 77 jujube cultivars at five developmental stages. The results showed that the genotypes，fruit development stages，medium type and the proportion of growth regulators had significant effects on the callus induction. At the initial cultivating stage，one to six kinds of medium were screened which were suitable for callus induction for 42 cultivars. There were eight kinds of media that can successfully induce callus，among which G1（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 0.5 mg · L^-1 6-BA + 2.5 mg · L^-1 2,4-D）and G7（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 0.8 mg · L^-1 6-BA + 1.5 mg · L^-1 2,4-D）medium had the highest applicability，up to 60%，followed by G5（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 1.0 mg · L^-1 6-BA + 2.0 mg · L^-1 2,4-D），up to 45%. Young fruits were the most suitable for pulp callus induction and cultivation，and the successful rate of cultivars reached 88%. In addition，the closer the fruit was to maturity，the more difficult the pulp callus cultivation was. Among them，only‘Yuanling Xiaozao’pulp at the whole red stage could be successfully induced callus. At the sub-cultivation stage，22 cultivars pulp callus were achieved subcultivition，and the appropriate medium was G1（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 0.5 mg · L^-1 6-BA + 2.5 mg · L^-1 2,4-D），G3（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 1.0 mg · L^-1 6-BA + 1.0 mg · L^-1 2,4-D），G5（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 1.0 mg · L^-1 6-BA + 2.0 mg · L^-1 2,4-D），G6（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 3.0 mg · L^-1 TDZ + 0.5 mg · L^-1 NAA），G7（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 0.8 mg · L^-1 6-BA + 1.5 mg · L^-1 2,4-D），G9（4.41 g · L^-1 MS + 6 g · L^-1 agar + 20 g · L^-1 sucrose + 0.5 mg · L^-1 NAA + 1.0 mg · L^-16-BA），G10（4.41 g · L^-1 MS + 6 g · L^-1 agar + 25 g · L^-1 sucrose + 0.4 mg · L^-1 6-BA + 1.5 mg · L^-1 2,4-D）. The changes of hormone ratio could significantly improve the callus sub-cultivation effect at the following cultivating stage. In addition，at the initial cultivating，a very small number of cultivars such as‘Wuhe 72’and‘Linyi Lizao’could directly induce bud germination.

Key words: Chinese jujube, callus, pulp cultivation, plant growth regulator