Establishment of Genetic Transformation System for'Populus leucopyramidalis 1'and Transformation of Insect Resistance Gene
'Populus leucopyramidalis 1'is an excellent poplar clone with narrow crown and saline-alkali tolerance.Due to the lack of its genetic transformation system,genetic improvement could not be achieved through genetic engineering methods.In this study,an Agrobacterium mediated genetic transformation system of'P.leucopyramidalis 1'was established and the high genetic transformation efficiency was achieved.Firstly,the tissue culture seedlings were subcultured at different time periods(35,45,55,65 d),and three types of tissues(leaves,petioles,and stem segments)were taken to compare the differentiation ability,and it was determined that the leaves sub-cultured after 45 d had the strongest differentiation ability,with a proliferation ratio of 8.77.Then,leaves sub-cultured after 45 d were used for genetic transformation,and the effects of different infection conditions on the transformation rate were examined.Orthogonal experiments were established with three gradients of bacterial concentration,infection time,and co-culture time to screen the best levels of these three factors,and the transgenic strains were identified through PCR detection and GUS staining.The results showed that the optimal combination for the genetic transformation system of'P.leucopyramidalis 1'was bacterial concentration OD600=0.4,infection-time 15 min,and co-cultivation time 2 d could reach the highest transformation rate 54.23%.Finally,the'P.leucopyramidalis 1'transgenic strain of BtCry3Aa insect resistant gene using this genetic transformation system was obtained,and the results proved that this system could be an effective method for genetic improvement of'P.leucopyramidalis 1'.