Segregation of genes transferred to one plant cell from two separate Agrobacterium strains

Abstract

Agrobacterium tumefaciens and Agrobacterium rhizogenes are soil bacteria which transfer DNA (T-DNA) to plant cells. Two Agrobacterium strains, each with a different T-DNA, can infect plants and give rise to transformed tissue which has markers from both T-DNAs. Although marker genes from both T-DNAs are in the tissue, definitive proof that the tissue is a cellular clone and that both T-DNAs are in a single cell is necessary to demonstrate cotransformation. We have transferred two distinguishable T-DNAs, carried on binary vectors in separate Agrobacterium rhizogenes strains, into tomato cells and have recovered hairy roots which received both T-DNAs. Continued expression of marker genes from each T-DNA in hairy roots propagated from individual root tips indicated that both T-DNAs were present in a single meristem. Also, we have transferred the two different T-DNAs, carried on identical binary vector plasmids in separate Agrobacterium tumefaciens strains, into tobacco cells and recovered plants which received both T-DNAs. Transformed plants with marker genes from each T-DNA were outcrossed to wild-type tobacco plants. Distribution of the markers in the F1 generation from three cotransformed plants of independent origin showed that both T-DNAs in the plants must have been present in the same cell and that the T-DNAs were genetically unlinked. Cotransformation of plant cells with T-DNAs from two bacterial strains and subsequent segregation of the transferred genes should be useful for altering the genetic content of higher plants.

Vectors carrying two separate T‐DNAs for co‐transformation of higher plants mediated by Agrobacterium tumefaciens and segregation of transformants free from selection markers

“…Multiple T-DNAs were delivered to plant cells either from a mixture of strains ('mixture methods') or from a single strain ('single-strain methods'). Segregation of one T-DNA from others was observed on various occasions (De Block and Debrouwer, 1991;De Framond et al, 1986;McKnight et al, 1987). These studies indicated that the Agrobacterium system is potentially useful for production of marker-free transformants.…”

“…Thus, A. tumefaciens is a naturally occurring co-transformation vector for higher plants. Co-transformation mediated by Agrobacterium has been examined in several laboratories (De Block and Debrouwer, 1991;De Framond et al, 1986;Depicker et al, 1985;McKnight et aL, 1987;Simpson et aL, 1986). Multiple T-DNAs were delivered to plant cells either from a mixture of strains ('mixture methods') or from a single strain ('single-strain methods').…”

Agrobacterium -Mediated Plant Transformation: the Biology behind the “Gene-Jockeying” Tool

“…The use of two Agrobacterium strains to deliver different T-DNAs to the same plant cells was studied by a number of groups (65,66,67,76,217). Although cotransfer of T-DNAs to genetically unlinked sites was reported, some authors also reported close linkage of the two different T-DNAs in many instances.…”

Hairy root induction and plant regeneration of medicinal plant Dracocephalum kotschyi

“…Hairy root-derived plants are usually real transgenic (Maknight et al 1987). Putative transgenic regenerated plants from hairy roots could be formed directly or indirectly (via callus).…”