DEVELOPMENT OF A METHOD FOR IN VITRO GERMINATION OF ACTINIDIA SEEDLINGS TO ENABLE PSA BIOASSAYS AND PLOIDY MANIPULATION
Kiwifruit industries throughout the world are threatened by the bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa). Vines of the yellow-fleshed and red-fleshed cultivars seem very susceptible and can die shortly after infection. Even green-fleshed cultivars can be seriously affected. The best solution is to breed Psa-resistant or tolerant cultivars. Using conventional methods, this would not only take a long time and require a large planting area for screening of response to field infection and selection of resistant plants, but could also pose a danger by supplying inoculum which would spread the disease. Screening of young plantlets could provide a solution saving time and keeping infected plant material in controlled environments. We report the development of a protocol for germinating kiwifruit seedlings on agar medium. The usual methods of germinating Actinidia seed involve a short cold treatment with a suitable degree of moisture, and then stratification. This approach cannot be used for seed to be germinated on agar medium because of the enhanced risk of contamination. Several different pre-treatments (warm water or cold storage) and application of gibberellic acid (GA3) were trialled. Germination rates varied widely with species, genotype, and pre-treatment. The protocol has enabled in vitro kiwifruit seedlings to be used to develop bioassays to identify Psa-tolerant offspring in our kiwifruit breeding programme. Following the procedures we have previously described for in vitro chromosome doubling by treatment with colchicine, we are using the in vitro seedlings to create a polyploid population for the next generation of novel kiwifruit cultivar selection.
Wu , J.H. and Datson, P.M. (2015). DEVELOPMENT OF A METHOD FOR IN VITRO GERMINATION OF ACTINIDIA SEEDLINGS TO ENABLE PSA BIOASSAYS AND PLOIDY MANIPULATION. Acta Hortic. 1096, 383-388
colchicine, cross breeding, flow cytometry, kiwifruit, novel breeding, ploidy manipulation