Progeny tests of barley, wheat, and potato regenerated from cell cultures after in vitro selection for disease resistance.

Because plant cells cultured in vitro express genetic variability and since they can be regenerated into functional plants, procedures have been designed to use this system for the production of plants with new important agronomic characteristics, particularly for disease resistance. For barley, wheat, and potato somaclones have been found that were less susceptible to a toxin of Helminthosporium, fusaric acid, Fusarium coeruleum, F. sulphureum, or Phytophthora infestans, when screened in the first in-vitro-derived generation. Here the progeny of such somaclones is evaluated after natural and artificial infection, using greenhouse-grown or field material. The progenies of the same somaclones did not express detectable differences, which indicated that no heterozygous mutations occurred. Most lines and clones differed in their level of susceptibility to the pathogen compared to the level of the starting material, but these data were in no instance significant. It is discussed here whether this lack of significance is due to a lack of genetic differences or whether the test procedures are in adequate for detecting and securing the slight, probably quantitative, alterations.