title: Enhanced Agrobacterium-mediated transformation efficiencies in monocot cells is associated with attenuated defense responses.
abstract: Plant defense responses can lead to altered metabolism and even cell death at the sites of Agrobacterium infection, and thus lower transformation frequencies. In this report, we demonstrate that the utilization of culture conditions associated with an attenuation of defense responses in monocot plant cells led to highly improved Agrobacterium-mediated transformation efficiencies in perennial ryegrass (Lolium perenne L.). The removal of myo-inositol from the callus culture media in combination with a cold shock pretreatment and the addition of L-Gln prior to and during Agrobacterium-infection resulted in about 84 % of the treated calluses being stably transformed. The omission of myo-inositol from the callus culture media was associated with the failure of certain pathogenesis related genes to be induced after Agrobacterium infection. The addition of a cold shock and supplemental Gln appeared to have synergistic effects on infection and transformation efficiencies. Nearly 60 % of the stably transformed calluses regenerated into green plantlets. Calluses cultured on media lacking myo-inositol also displayed profound physiological and biochemical changes compared to ones cultured on standard growth media, such as reduced lignin within the cell walls, increased starch and inositol hexaphosphate accumulation, enhanced Agrobacterium binding to the cell surface, and less H(2)O(2) production after Agrobacterium infection. Furthermore, the cold treatment greatly reduced callus browning after infection. The simple modifications described in this report may have broad application for improving genetic transformation of recalcitrant monocot species.
authors.affiliation: Department of Grassland Science, China Agricultural University, Beijing 100193, China. wjzhang@cau.edu.cn
authors.forename: Wan-Jun
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Dewey
authors.forename: Wendy
authors.initials: W
authors.lastname: Boss
authors.forename: Brian Q
authors.initials: BQ
authors.lastname: Phillippy
authors.forename: Rongda
authors.initials: R
authors.lastname: Qu
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000502:physiology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism; D003080:Cold Temperature; D003470:Culture Media; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D005973:Glutamine / Q000494:pharmacology*; D049452:Green Fluorescent Proteins; D006861:Hydrogen Peroxide / Q000378:metabolism; D007294:Inositol / Q000494:pharmacology*; D008031:Lignin / Q000378:metabolism; D008129:Lolium / Q000187:drug effects / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D010833:Phytic Acid / Q000378:metabolism; D057865:Plant Immunity; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000502:physiology; D030821:Plants, Genetically Modified; D012038:Regeneration; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000276:immunology / Q000502:physiology; D013213:Starch / Q000378:metabolism; D046509:Tissue Culture Techniques; D014170:Transformation, Genetic
chemical_list: D003470:Culture Media; D005973:Glutamine; D049452:Green Fluorescent Proteins; D007294:Inositol; D010833:Phytic Acid; D013213:Starch; D008031:Lignin; D006861:Hydrogen Peroxide