The Optimization Of Oriental Pear Expanding Propagation System And The Foundation Of Leaf Effective Regeneration System

China is one of the most important botanical origins of the Pyrus L,also pear variety and cultivation area are in the first place in the world.As the development of plant tissue culture technology and plant in vitro tissue regeneration technology,the genetic transformation technology were as a kind of effective way in pear genetic engineering breeding,which greatly accelerated the process of pear germplasm innovation and breeding the new varieties.But compared with other species,Pear's genetic transformation research progress has been slow and lack of the efficiency.The main reason is that:(1)The explants of woody plant growth is slow and have a long growth cycle,so it is prone to be polluted in the process of growing.(2)There are many difficulties in pear's regeneration,with a low regeneration rates and the regeneration rates is considerably different between different varieties.It is hardly regenerate adventitious bud,especially after infection,co-culture,darkness and a series of operations.The fast and high quality proliferation and efficient regeneration system is necessary for pears gene transfer technique successful.Taking adventitious shoots of'Yali','Cuiguan','Jingbaili' and 'Xuehuali' as materials,the optimal medium for propagation of pear were selected by adjusting the 6-BA and IB A ratio and calculating the bud proliferation rate and plant height.Taking 'Xuehuali' and'jingbaili' leaves as materials,a high-efficiency system for leaf regeneration was constructed by comparing the effects of basal medium types,leaf inoculation ways,hormone types and concentration ratios,and dark incubation time on leaf regeneration rate,callus incidence,average regeneration-bud number per leaf and browning rate.This research is useful in achieving a high-efficiency propagation system and leaf regeneration system,laying an effectively theoretical and practical basis for rapid propagation,detoxification and genetic transformation of 'Xuehuali' and providing a reference to solve the problem of browning inr leaf regeneration of pear.The main research results are as follows:1.The optimal medium for propagation of 'Yali' was MS medium containing 1.5 mg·L-1 6-BA and 0.4 mg·L-1 IBA with 4.33 of bud proliferation rate and 2.27 cm of plant height.The optimal medium for propagation of 'Cuiguanli' was MS medium containing 1.0 mg·L-1 6-BA and 0.3 mg·L-1 IBA with 5.67 of bud proliferation rate and 2.3 cm of plant height.The optimal medium for propagation of 'Jingbaili' was MS medium containing 1.5 mg·L-1 6-BA and 0.3 mg·L-1 IBA with 6.33 of bud proliferation rate and 1.8 cm of plant height.the optimal medium for propagation of 'Xuehuali' was MS medium containing 1.0 mg·L-1 6-BA and 0.3 mg·L-1 IBA with 5.33 of bud proliferation rate and 2.73 cm of plant height.2.The optimal medium for leaf regeneration of 'Xuehuali' was NN69 medium containing 1.5 mg·L-1 TDZ and 0.2 mg·L-1 IBA with 70.83%of leaf regeneration rate,2.06 of average regeneration-bud number per leaf,100%of callus incidence and zero of browning rate.The leaf regeneration rate increased when the abaxial side of leaf touched the medium,and the highest regeneration value under the treatment of 21 days dark incubation.The browning could be effectively prevented with the method of shortening the dark incubation time and increasing the content of cytokinin and auxin.The optimal medium for the primary culture of regeneration-bud was MS containing 0.2 mg·L-1 IBA and lmg·L-1 6-BA.The optimal medium for leaf regeneration of 'jingbaili' was NN69 medium containing 1.0 mg·L-1 TDZ and 0.5 mg·L-1 IBA with 66%of leaf regeneration rate,2.10 of average regeneration-bud number per leaf,100%of callus incidence and 28%of browning rate.The leaf regeneration rate increased when the abaxial side of leaf touched the medium,and the highest regeneration value under the treatment of 21 days dark incubation.The browning could be effectively prevented with the method of shortening the dark incubation time and increasing the content of cytokinin and auxin.The optimal medium for the primary culture of regeneration-bud was MS containing 0.2 mg·L-1 IBA and 1 mg·L-1 6-BA.