Editorial: “Agrobacterium biology and its application to transgenic plant production”

(2015) Editorial: " Agrobacterium biology and its application to transgenic plant production. " Front. Plant Sci. 6:265. The extraordinary Agrobacterium research story started from the search for the causative agent of crown gall disease more than 100 years ago. Agrobacterium tumefaciens was first isolated from grapevine galls in 1897 and later isolated from Paris daisy in 1907 (Cavara, 1897a,b; Smith and Townsend, 1907). The Agrobacterium infection mechanism involves processing and transfer of a specific DNA fragment (the transferred-DNA, T-DNA) from a bacterial tumor-inducing (Ti) plas-mid. Transfer to the plant occurs via a type IV secretion system (T4SS), after which T-DNA is integrated into the plant host genome (Gelvin, 2010; Lacroix and Citovsky, 2013). This interking-dom DNA transfer leads to overproduction of the plant hormones auxin and cytokinin, resulting in tumors. The interkingdom DNA transfer ability of Agrobacterium and the possibility to replace the oncogenes in the T-DNA with genes of interest has made Agrobacterium-mediated transformation the most popular technique to generate transgenic plants. This Research Topic provides a collection of reviews and original research articles on Agrobac-terium genes involved in bacterial physiology/virulence and plant genes involved in transformation and defense against Agrobacterium. A review by Kado (2014) provides a historical overview of how A. tumefaciens was first established as the cause of crown gall disease. In this review, Kado highlights key early plant pathology and milestone molecular biology studies leading to the conclusion that the expression of oncogenes in native T-DNA is the cause of tumor growth in plants. With the solid foundation of these pioneering discoveries, A. tumefaciens evolved from a phytopathogen to a powerful genetic transformation tool for plant biology and biotechnology research. The first complete genome sequence of an Agrobacterium species (A. tumefaciens C58) was completed in 2001 (Goodner et al., 2001; Wood et al., 2001). The 5.67-megabase genome of this strain carries one circular chromosome, one linear chromosome, and two megaplasmids: the Ti plasmid pTiC58 and a second plasmid, pAtC58. In the review by Platt et al. (2014), the properties, ecology, evolution, and complex interactions of these two A. tumefaciens megaplasmids are discussed. The costs and benefits to A. tumefaciens strains carrying the Ti plasmid and/or the pAtC58 plasmid are discussed and presented from an ecological and evolutionary perspective. Modeling predictions are presented for the relative cost and benefits to A. tumefaciens strains harboring the Ti and/or the pAtC58 plasmids determined by environmental resources. Conjugation and …