Agrobacterium-mediated transformation of LJAMP2 gene into 'Red Sun' kiwifruit and its molecular identification / 生物工程学报

Bacterial canker caused by Pseudomonas syringae pv. Actinidiae is one of the most important diseases of kiwifruit (Actinidia chinensis) and leads to considerable yield losses. In order to obtain transgenic plants with resistance for 'Red Sun' kiwifruit to canker disease, a non-specific lipid transfer protein-like antimicrobial protein gene (LJAMP2) from motherwort (Leonurus japonicus) was introduced into 'Red Sun' kiwifruit through Agrobacterium-mediated transformation. After two days of co-cultivation with A. tumefaciens strain LBA4404 harboring 35S:LJAMP2, the transformed explants were transferred to the selection medium containing 25 mg/L kanamycin+3.0 mg/L BA+1.0 mg/L NAA. The regeneration efficiency of kanamycin-resistant shoots reached to 85%. All (100%) of kanamycin-resistant shoots rooted on half-strength MS medium supplemented with 0.8 mg/L IBA and a total of 40 regenerated plantlets were obtained. PCR and histochemical GUS activity analysis show that 23 of 40 lines (57.50%) were positive, suggesting that the LJAMP2 gene was integrated into the genome of 'Red Sun' kiwifruit. Taken together, we established an efficient genetic transformation method for 'Red Sun' kiwifruit using A. tumefaciens and the transformation frequency reached 5.11%. This protocol will be useful for the genetic breeding of 'Red Sun' kiwifruit for improvement of disease resistance.

Establishment of high frequency regeneration via leaf explants of 'Red Sun' kiwifruit (Actinidia chinensis) / 生物工程学报

A high efficient in vitro regeneration protocol was developed from leaf explants of the female 'Red Sun' kiwifruit (Actinidia chinensis) and the multiplication coefficient and rooting rate of adventitious buds were also optimized. This method does not require formation of callus tissues which leads to somaclonal variations. The results show that the adventitious buds developing directly from explants tissue were noticed after 30 d of culture. The maximum regeneration frequency of adventitious buds is 100% and 18.67 shoots was observed in each leaf explants when MS medium was supplemented with 3.0 mg/L BA+1.0 mg/L NAA. The optimal culture medium for bud multiplication is MS+2.0 mg/L BA+1.0 mg/L NAA+0.1 mg/L GA3 and the multiplication coefficient reached 8.63. On the rooting medium with 1/2 MS+0.8 mg/L IBA for 15 d, the adventitious plantlets were transferred into matrix perlite supplied with 1/2 MS liquid medium for 15 d and the rooting rate reached 100%. 95 out of 98 plantlets (96.94%) survived acclimatization, producing healthy plants in the greenhouse. Taken together, a highly efficient regeneration method via leaf explants of 'Red Sun' kiwifruit was successfully established. This protocol may be useful for micropropagation and genetic transformation studies of 'Red Sun' kiwifruit.