Efficiency of transformation of Polish cultivars of pea (Pisum sativum L.) with various regeneration capacity by using hypervirulent Agrobacterium tumefaciens strains.

An Agrobacterium-mediated transformation method of pea has been developed for several edible and fodder cultivars of pea (Pisum sativum L.), characterized previously in their potential for regeneration via organogenesis. The most appropriate explant, which was susceptible to Agrobacterium infection and capable of regenerating transgenic plants, turned out to be a slice of an immature embryo, including the embryo axis and the basal part of a cotyledon. Three hypervirulent strains of A. tumefaciens were tested: AgL0, AgL1 and EHA105. Each carried the binary vector pP35SGIB containing the uid gene, with an intron under control of the 35S promoter, and the bar gene conferring resistance to phosphinotricin. Strain AgL0 was found to be efficient for the majority of cultivars, followed by AgL1 and EHA105. Transformation efficiency varied from 0.7 to 4.1%, depending on cultivar and Agrobacterium strain. The transformation efficiency of particular pea cultivars did not clearly correspond to their regeneration capacity, which--although indispensable--was not a critical parameter of successful transformation. The presence of integrated genes in pea genomic DNA was detected by the PCR. T-DNA was stably transmitted to the progeny, as it was confirmed by Southern hybridization. The activity of introduced genes was analysed by the histochemical GUS assay and by painting leaves or by spraying transgenic plants with the herbicide Basta.