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| Authors: | W. Dillen, M. Zambre, J. De Clercq, A. Goossens, J. Kapila, E. Vranová, M. Van Montagu, G. Angenon |
| Keywords: | in vitro regeneration, Phaseolus acutifolius, Agrobacterium, common bean, genetic transformation, Phaseolus vulgaris, tepary bean |
Abstract:
Dry Phaseolus beans are an important staple food and immature bean pods are popular as a vegetable. Phaseolus seeds are deficient in the sulfur-containing amino acids and the most important Phaseolus species, the common bean (P. vulgaris) is susceptible to many pests and diseases.
Genetic modification of the crop could contribute to solving some of these problems.
However, the recalcitrance of Phaseolus towards in vitro regeneration is a major bottleneck in transgenic plant production.
It has been reported that, in an attempt to avoid the use of in vitro regeneration, transgenic plants have been produced through particle bombardment of seedling meristems of P. vulgaris. This approach relies on screening rather than selection for transformed tissues and is therefore inefficient.
We anticipate that a regeneration procedure that involves a callus phase is more suitable for obtaining transgenic plants because selection for transformed cells can be more readily achieved in callus than in organized meristems.
Regeneration from callus in P. vulgaris is hard to attain but it has been reported for two genotypes that were constructed from a P. vulgaris x P. acutifolius (tepary bean) hybrid.
We found that the same mode of regeneration can be obtained in a wide range of P. acutifolius genotypes.
The regeneration system enabled us to produce transgenic plants of a wild genotype of P. acutifolius with Agrobacterium. P. acutifolius can now be used as a ‘bridge species’ to introgress transgenes into the common bean.
Optimized cocultivation and regeneration procedures are now applied to cultivated tepary and common bean genotypes in order to obtain transgenic plants with Agrobacterium.
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