Agrobacterium-Mediated Transformation in the Evolution of Plants

Abstract

In most cases, the genetic engineering of plants uses Agrobacterium-mediated transformation to introduce novel genes. In nature, insertion of T-DNA into the plant genome and its subsequent transfer via sexual reproduction have been shown for several species in the genera Nicotiana, Ipomoea , and Linaria . A sequence homologous to T-DNA of the Ri plasmid of Agrobacterium rhizogenes was found in the genome of wild-type Nicotiana glauca (section Noctiflorae) more than 30 years ago and was named "cellular T-DNA" (cT-DNA). It comprises an imperfect inverted repeat and contains homologs of several T-DNA oncogenes (NgrolB, NgrolC, Ngorf13, Ngorf14) and an opine synthesis gene (Ngmis). Multiple cT-DNAs have also been found in species of the sections Tomentosae and Nicotiana of the genus Nicotiana. These ancient cT-DNA genes are still expressed, indicating that they may play a role in the evolution of these plants. In 2012-2013, cT-DNA was detected and characterized in Linaria vulgaris and L. genistifolia ssp. dalmatica. Their cT-DNA is present in two copies and organized as an imperfect direct tandem repeat, containing LvORF2, LvORF3, LvORF8, LvrolA, LvrolB, LvrolC, LvORF13, LvORF14, and the Lvmis genes. In 2015, cT-DNA was found in Ipomoea. Two types of T-DNA-like sequences were described within this genera, and their distribution varied among cultured hexaploid, tetraploid, and wild diploid forms. Thus, several independent T-DNA integration events occurred in the genomes of these three plant genera. We propose that the events of T-DNA insertion in the plant genome might have affected their evolution, resulting in the creation of new plant species. In this chapter, we focus on the structure and functions of cT-DNA in Linaria, Nicotiana, and Ipomoea and discuss their possible evolutionary role.

Plant Cellular and Molecular Biotechnology: Following Mariotti’s Steps

“…Indeed, overexpression studies in plants suggest that “ plast ” genes have growth-modifying properties similar to their A. rhizogenes equivalents [54,55]. It was hypothesized that the effect of T-DNA on the regenerative capacity and the interaction with microorganism communities might have affected the evolution of natural transformant plants [56]. However, loss-of-function studies of expressed cT-DNA genes should be performed to assess their possible adaptive roles in plants.…”

Agrobacterium-mediated transformation of <i>Nicotiana glauca</i> and <i>Nicotiana sylvestris</i>

“…These sequences, homologous to the agrobacterial T-DNA, are called cellular T-DNA (cT-DNA) (White et al, 1983). Plants that carry cT-DNA are considered natural transgenic species or natural genetically modified organisms (nGMOs) (Matveeva, 2018). To date, the list of nGMOs includes more than 40 genera of angiosperms (Ma tveeva, 2021).…”

Transcriptome Profiling of Barley Cultivar Hua 30 MDEC in Response to Agrobacterium Infection

“…Agrobacterium tumefaciens possesses the ability to integrate self T-DNA into plant genomic [1]. The Agrobacterium tumefaciens-mediated genetic transformation system has been widely used in both basic research and breeding in plants, based on the low copy number of large segments of DNA into host genome DNA and low cost.…”