Optimization of Callus Induction Conditions from Immature Embryos of Maizeunder Stress

The embryos of maize (ZeamaysL.) inbred lines GS02, GS07, GS08, GS11 and GS15 were used as receptor mate-rials to optimize the receptor system from the aspects of genotype, medium components and stress (PEG6000,mannitol, salt and low phosphorus). The results showed that GS07 had the highest induction rate (95.2%). Ortho-gonal test analysis showed that the best combination of medium components in induction was A2B3C1D3(2),namely, the concentration of 2, 4-dichlorophenoxy acetic acid (2,4-D) was 4 mgmiddotmL-1, the concentration of L-Pro-line (L-Pro) was 0.8 mgmiddotmL-1, and the concentration of silver nitrate (AgNO3) was 10 mgmiddotmL-1(or 5 mgmiddotmL).Interestingly, we found that the optimal medium supplemented with 30 gmiddotL-1PEG6000or80gmiddotL-1mannitolwas suitable for antioxidant enzyme activity and malondialdehyde (MDA) content in GS07 callus. Exogenous10 mmolmiddotL-1Ca2+in the medium components with 100 mmolmiddotL-1sodium chloride (NaCl) could improve theactivity of antioxidant enzymes in GS07 callus. Callus of GS07 could divide normally and grow well in mediumcomponents with 27 mgmiddotL-1KH2PO4. This study enhanced the adaptability of maize callus to stress and optimizedthe culture conditions.