Designing an appropriate selection procedure is important for successfully identifying mutants

Figure 1. A successful selection using media supplemented with FuDR (5-flurodeoxy uridine). There are about 12,000 spore on this dish and all except one are severly inhibited or killed by this concentration of FuDR. The single individual to the right of center exhibits tolerance to FuDR and has nearly normal growth and development.

The identification of an appropriate selection condition typically requires careful dose response curves to determine the correct concentration of a toxin (for example, selections using herbicides, FuDR, etc.) that results in lethality or sufficient and distinctive inhibition of gametophyte growth or development. Several factors may need to be considered when choosing the appropriate selection regime, for example:

  • The nature of the toxic response, e.g. whether abrupt or gradual.
  • The pattern of gametophytic growth and development over time, e.g. whether gametophytes exhibit differential response dependent upon age.
  • Identification of phenotypes other than growth that may identify mutants.
  • Also for identification of putative morphological mutants (for example clumped chloroplast or callus-like growth habit) careful observation of gametophytes at a sufficiently young stage is important.

The standard selection procedure is outlined in this illustration.(Figure not yet available!)

A number of confirmed and putative mutants have been obtained using both X-ray and EMS mutagenesis. Protocols for X-ray or EMS mutagenesis are given in the C-Fern Web Manual.

Mutant Selections of Ceratopteris and References
Selection Agent / Criteria Strain / Mutant Codes Reference
paraquat HaPQn, pq2, pq45, pqa

Hickok and Schwarz 1986a
Hickok and Schwarz 1986b
Hickok and Schwarz 1989
Carrol et al. 1988

acifluorfen HaBn / blt1 Hickok et al. 1987
Hickok, unpublished
glyphosate HaGn / glt1, glt2 Tai Chun and Hickok 1992
NaCl HaNn / stl1, stl2 Hickok et al. 1987
Warne and Hickok 1987
Hickok et al. 1991
Vogelien et al. 1993
Warne et al. 1995
hydroxy-L-proline HaYn Singh, 1990
azetidine-2-carboxylate HaAZn Hickok et al. 1987
5-flurodeoxy uridine HaFn Hickok et al. 1987
2-aminoethyl-L-cysteine HaCYn Hickok et al. 1987
Al2(SO4)3 at pH 4.4 HaAT37,29 Wright et al. 1990
antheridiogen (ACe) HaCn / her#

Warne et al. 1988
Banks et al. 1993
Banks 1994

abscisic acid HaAn/ abr48, abr104 Hickok 1985a
Banks 1994
germination: darkness HaDn / dkg1 Scott and Hickok 1991
Cooke et al. 1987
Cooke et al. 1993
germination: altered red / blue responses GERM1,2,3,4

Cooke et al. 1995

irregular meristem HaTUBE1 Hickok et al. 1995
clumped chloroplasts HaCPn /cp1 Vaughn et al. 1990
self sterility: 230X (C.thalictroides)
spermatozoid / flagella development
  Duckett et al. 1979

(1) All listed selections, with the exception of 230X, were derived from the Hn-n strain. Strain designations ending with 'n' indicate that a number of independent selections are available, all of which have not been fully characterized genetically.

Complete information on references can be found in the Bibliography