Agrobacterium-Mediated Transformation of Tomato Using a Cotyledonary Explant System

Abstract

Tomato was among the first crops to be transformed through Agrobacterium tumefaciens, and the use of cotyledon explants, cut from young sterile seedlings and induced to form shoots on selective medium, remains one of the commonest routes to a transgenic plant. This narrative review describes how that system works and what the published literature says about its weak points. It covers the biology of T-DNA transfer, the choice of strain and binary vector, the preparation and wounding of explants, co-cultivation, selection and regeneration, and the molecular checks used to confirm that a regenerated plant is transgenic. Reported efficiency depends on genotype, explant age and position, and on how a laboratory handles the interval between infection and selection, so figures from different papers are rarely comparable. Regeneration from cotyledons can also yield plants with altered ploidy, and some regenerants escape selection. The review sets out what a well-reported protocol would state, and notes that evidence on several variables rests on single laboratories. It reports no new experimental data and does not validate any protocol.