Progeny rescue of amino acid auxotroph plants derived from haploid protoplasts of Nicotiana plumbaginifolia

Attempts have been made to study the genetics of histidine (his-) and methionine (met-) requiring plants to understand how the biosynthesis of these amino acids is controlled. In the first phase, transmission to the progeny of a recessive auxotrophic trait by selfing has only been observed in met- plants, but no (or only a few) recessive types segregated in the F2 generation after backcrossing. To overcome this problem, different treatments were considered: First, supplementation by spraying an amino acid solution on to homozygous plants cultured in the greenhouse and, second, transfer of freshly pollinated flowers to amino acid supplemented culture media and subsequent transfer of young embryos to amino acid supplemented media for further development. The first approach has provided successful results in that all the original regenerants produced seeds upon selfing. The second approach proved to be effective for the met- and his- types. When these two supplementations were applied, a synergistic effect was observed. (author). 10 refs, 1 fig., 1 tab