Studies On Screening Of Salt-tolerant Variant Cell Lines And Identifing Index Of Apple Rootstocks

The research was carried out with calli and suspension cells of apple rootstocks.The screening techniques for salt-tolerant variants of apple rootstock cells were studied. The main results were as follows:1 Different species of apple rootstocks have different tolerance on EMS.The relative growth of calli were decreased with the increasing of mutagen concentrations and the prolongation of treatment time. In the experiment, about 60% lethal dose of the mutagens was used as the selection indexes of optimal mutagen concentrations and treatment time. The best combination of treatment was as the follows:EMS solution treatment calli:0.2%+l .5hAdding EMS to medium treatment suspention cells:0.02%+2d2 Nine variant cell lines were achieved after selection. Among these 7 lines were achieved after Hyp selection and 2 lines were achieved after NaCl selection. From diffferent select system, one step active selection resulted in 4 lines; cominuons multi-step selection system resulted in 3 lines and interval multi-step selection system resulted in 2 lines.Contrasting the salt tolerance of variant cell lines after identifing indexs appraisal,the results were as follows:The salt tolerance of Hyp variant cell lines were higher than NaCl variant cell lines.The variant cell lines after 60Co- and EMS induction treatment had higher salt tolerance than EMS treatment variants.Among the Hyp variant cell lines, the lines derived from multi-step selection system have higher salt tolerance than those derived from one step selection system.3 Through 7 index identifing, higher salt tolerance existed in variant cell lines with higher relative growth, SOD activity, POD activity and free Pro content; lower cell membrane permeability, MDA content and Cl- content than control.It was recommended that relative growth, relative pemeability of cell membrane, MDA content and Cl- content could be used as the evaluation indexes of salt tolerance;Pro content and POD activity could be used as the reference indexes of salt tolerance and SOD activity could not be used as the evaluation index of salt tolerance.4 The variant cell lines still have high ability of accumulating free proline after cultivation on normal medium,which indicated the variant cell lines have steady salt tolerance.The optimal regermination medium of 78-48 was MS+3.5% sucrose+0.6% agar+ TDZ 0.5 mg'L-1+BA 0.5 mg'L-1+CA 0.02mmol L-1'+KT 0.15 mg'L-1.The Hyp-resistant variant cell lines still have high ability of regerminating which was 4X to the NaCl-resistant variant cell lines. The regenerative plant of 78-48 variant cell lines have better growth than control on 0.8% NaCl medium.