Grapevine stem segments were cocultivated with three different Agrobacterium tumefaciens and three different A. vitis strains. A. tumefaciens strains induced tumors at variable frequencies, while A. vtös-infected stem segments never formed crown galls. The tumorous nature of tissues grown on hormone free medium was confirmed by opine assays. Bioinformatic and PCR analysis of the virulence regions of various A. tumefaciens and A. vitis Ti plasmids showed that virH2 and virK genes are common in A. tumefaciens but they are lacking from A. vitis. Thus vir H2 and virK genes may be essential for grapevine stem segment transformation, but expression of certain T-DNA genes of A. vitis may also prevent the growth of transformed cells. Our data indicate that the tumorigenic ability of A. vitis is different on intact plant and on their expiants, and that the specific host association of A. vitis on grapevine is probably determined by physiological and biochemical factors (e. g., better colonizing ability) rather than by its increased tumorigenic ability. Therefore it is not reasonable to develop "helper" plasmids for grapevine transformation from A. vitis pTis, unless their avirulence on in vitro expiants is determined by T-DNA gene(s). Due to the inability of A. vitis to induce tumors on grapevine stem segments, the use of in vitro expiant assays cannot be reliably used to select A. vitis resistant grapevine genotypes or transgenic lines.
|Number of pages||8|
|Journal||Vitis - Journal of Grapevine Research|
|Publication status||Published - 2014|
- Crown gall
- Ti plasmids
ASJC Scopus subject areas