The ability to transfer genes into agronomically important crops offers the potential to improve traits such as yield, nutritional quality, and resistance to pathogens, pests, and ecological stresses. Plant transformation technology has been the subject of intense efforts over the past two decades. As a result several complementary approaches have been developed:
(1) Agrobacterium tumefaciens mediated transformation, based on regeneration of plants from protoplasts, cells, leaf-discs, or other tissues.
(2) Direct DNA delivery, employing electroporation of protoplasts or embryogenic tissues, microparticle bombardment of cell culture or tissues having regenerative potential.
These methods were proven to be very efficient in transformation of many dicot crops. However, for the majority of monocots, especially cereals (Graminae), A. tumefaciens- mediated gene transfer is very limited. Significant difficulties remain also in employing methods of direct DNA delivery, due to high dependence of regeneration ability on the genotype. As a consequence, in the known examples of successful transformation of maize the experimental material was based on the line A188 which is easily regenerated. Noteworthy, in all of the methods based on multicellular target (embryos, leaf-discs or calli) the resulting transformed tissue is mosaic, demanding further steps to obtain non-mosaic progeny. The above methods face also the problems such as low fertility of regenerated plants, genetic instability, or unidirectional inheritance of the transferred gene. Most of these difficulties are due to the use of long-term tissue culturing.
A new and breakthrough genotype-independent method of plant genetic transformation has been developed employing the pollination pathway. The basic strategy is as follows: Recipient plants are pollinated by pollen grains carrying the transforming DNA. High efficiency and reproducibility of transformation are achieved with the pollen grains pre-treated by silicon carbide fibers and the transforming DNA. Other protocols of pollen treatment are also possible. The technology is protected by an issued patent. The uniqueness of the proposed method is in combining the pollination pathway and the delivering of the transforming DNA into pollen grains, e.g., by using silicon carbide fibers. The method takes advantages of the natural reproduction system resulting in transformed zygotes. The advantages of the developed strategy are as follows:
The proposed technology could be employed for transformation of any plant species with sexual reproduction. The platform aims to be focused on:
1. Monocotyledon plants, especially cereal crops (maize, wheat, barley) where conventional methods encounter difficulties.
2. Any flowering plant species with high number of seed per fruit (sunflower, cotton, pepper, egg plant, etc.)
3. Gymnosperm plants (e.g., pines)
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