[Objective] The aim was to explore the conditions of high frequency induction of embryonic callus and plant regeneration of maize. [Method] Immature embryos of maize inbred lines were used as explants to study the effect of different 2,4-D concentrations on the induction of callus,the effect of different 6-BA concentrations on the differentiation of test-tube plantlet,as well as the effect of different IBA concentrations on the rooting of test-tube plantlet. [Result] 2,4-D showed obvious effect on the induction of inducement rate of maize,and the optimum induction medium was：N6 ＋ 2 mg/L of 2,4-D ＋ 500 mg/L of CH ＋ 500 mg/L of Pro ＋10 mg/L of AgNO3; the optimum differentiation medium was：N6 ＋ 0.5 mg/L of BA ＋ 500 mg/L of Pro; the optimum for the rooting of test-tube plantlet was 1/2 MS ＋ 0.5 mg/L of IBA. [Conclusion] The study had provided basis for the genetic transformation of maize.
[Objective] This study aimed to explore the conditions of transformation of maize by microprojectile bombardment. [Method] Immature embryo-derived callus of maize inbred line 7239 was used as explants to study the effects of shoot distance, helium pressure, vacuum and bombardment frequency on the transformation efficien- cy in the particle bombardment system of maize. [Result] Considering the transfor- mation efficiency, particle bombardment with 100 μg/P of golden particles, at a shoot distance of 9 cm from the target cells, under helium pressure of 1 350 psi and vac- uum 25 inHg, and bombarding twice could achieve relatively ideal results. After se- lection on media supplemented with different concentration of hygromycin, some re- generated plants were obtained. The results of PCR and Southern blotting analysis demonstrated that the NPR1 gene had been integrated into the genome of trans- genic maize plants, with an average transformation efficiency of 1.76%. [Conclusion] The study laid the foundation for the cultivation and breeding of excellent resistant varieties of maize.
