Pea transformation: History, current status and challenges

This review recapitulates the history, important milestones, the current status, and the perspectives of the pea (Pisum sativum L.) transformation as a tool for pea crop breeding. It summarises the developments of the pea transformation from the first methodological experiments to achieving the complete transformation and regeneration of genetically modified (GM) plants, transformation with the first genes of interest (GOI), to recent techniques of targeted genome editing. We show how recent biotechnological methods and genetic engineering may contribute to pea breeding in order to speed up the breeding process and for the creation of new pea cultivars. The focus is laid on genetic engineering which represents an excellent technology to enhance the pea gene pool with genes of interest which are not naturally present in the pea genome. Different methods of pea transformation are mentioned, as well as various GOI that have been used for pea transformation to date, all aimed at improving transgenic pea traits. Tolerance to herbicides or resistance to viruses, fungal pathogens, and insect pests belong, among others, to the pea traits that have already been modulated by methods of genetic engineering. The production of phytopharmaceuticals is also an important chapter in the use of genetically modified peas. We compare different methods of introducing transgenes to peas and also the usage of different selective and reporter genes. The transformation of other major legumes (soybeans, beans) is marginally mentioned. The effect of genetically modified (GM) peas on animal health (feeding tests, allergenicity) is summarised, the potential risks and benefits of pea modification are evaluated and also the prime expectations of GM peas and the real current state of this technology are compared. Unfortunately, this technology or, more precisely, the products created by this technology are under strict (albeit not scientifically-based) legislative control in the European Union.