Evaluation Of Shoots Regeneration Ability In Different Maize Inbred Lines

Maize is an important food crop and genetic transformation is an important technical means for basic research and genetic improvement of maize.The shoots regeneration ability of explants directly affects the genetic transformation efficiency of maize.The regeneration ability of maize shoots is usually affected by some factors,for example,the genotype and the medium.The inbred lines A188 and B104 are usually used for maize genetic transformation,but they have some shortcomings such as poor agronomic characters and slow growth.Therefore,it is necessary to screen some new inbred lines with good regeneration ability for the establishment of high efficient genetic transformation system.In this study,nine medium combinations were constructed among N6 callus induction medium(N6-CIM),N6 shoot induction medium(N6-SIM),MS1-CIM,MS1-SIM,MS2-CIM,MS2-SIM.By comparing the callus induction rate,callus type,seedling emergence rate and seedling emergence time of the experimental materials in different culture systems,a medium combination system(MS1-CIM/MS2-SIM),which can maximize the material regeneration potential and is suitable for most inbred lines,was selected for further study.The most of callus induced by this system are type II callus,which are in good condition and suitable for long-term subculture.They can not only maximize the shoots regeneration ability of immature embryos of maize inbred lines,but also shorten the time of seedling emergence,and the morphology of regenerated seedlings induced by this system is more normal.This provides a new medium system with universal adaptability and good tissue culture effect for maize genetic transformation system.In this study,the shoots regeneration ability of the immature embryos of 92 maize inbred lines was evaluated and the inbred lines A188 and B104 were used as control.The regeneration ability of the selected materials was evaluated by comparing the primary callus induction rate,embryonic callus induction rate,green shoots differentiation rate,seedling regeneration rate of per callus,seedling regeneration rate and other five tissue culture traits.Finally,16 maize inbred lines with seedling emergence rate than or similar to that of B104 were selected,among which 6 inbred lines had higher seedling emergence rate than A188.The seedling emergence rate of the material with the highest shoots regeneration ability was246.67%.It provides more excellent receptor materials for the improvement of maize genetic transformation system.And correlation analysis was conducted for the primary callus induction rate,embryonic callus induction rate,type II callus induction rate,green shoots differentiation rate,seedling regeneration rate,seedling regeneration rate of per callus.It found that the green shoots differentiation rate,seedling regeneration rate of per callus were significantly correlated with total seedling regeneration rate,correlation coefficient were0.675 and 0.635,the reference for the evaluation in the future.