This mutation, which was induced with X-rays, shows an interesting collection of co-segregating traits. It was selected for tolerance to salt (NaCl) and gametophytes carrying the mutation show a high level of tolerance to this agent. Sporophytes also show NaCl tolerance, but at a lower level and in a semi-dominant fashion. In addition, stl2 confers tolerance to magnesium salts, but sensitivity to moderate levels of potassium in the medium. Sensitivity of the wild type to sodium salts is associated with the level of calcium in the medium. That is, in the presence of 150 mM NaCl, the calcium level in C-Fern Basic Medium (CFBM) results in very poor growth and necrosis of the wild type with little apparent effect on the mutant. At higher calcium levels commonly found in other plant nutrient formulations, the wild type and stl2 show similar responses at 150 mM NaCl. This mutation can be used to show a simple salt tolerance response and also can be used to demonstrate the complexities of mineral and nutrient interactions in the environment.

Vogelien, D L.., L. G. Hickok and T.R. Warne. 1996. Differential effects of Na+, Mg2+, K+, Ca2+ and osmotic stress on the wild type and NaCl-tolerant mutant, stl2, of Ceratopteris richardii. Plant, Cell and Environment 19:17-23.

Warne, T. R., L. G. Hickok, T. B. Kinraide and D. L. Vogelien. 1996. High salinity tolerance of the stl2 mutation of Ceratopteris richardii is associated with enhanced K+ influx and loss. Plant Cell and Environment 19:24-32.