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Thomas R. Warne and
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Mutant Selection


  wild type and 'polka dot'  C-Fern gametophytes
Protocols for either X-ray or EMS mutagenesis are given in the C-Fern Web Manual

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 a sufficient 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!)

An example of a successful selection using media supplemented with FuDR is illustrated below. 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 (right, central region of dish) exhibits tolerance to FuDR and has nearly normal growth and development.

A number of confirmed and putative mutants have been obtained using both X-ray and EMS mutagenesis.

Examples of mutant selections of Ceratopteris

paraquat HaPQn, pq2, pq45, pqa6

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


acifluorfen HaBn / blt1

Hickok et al. 1987 and unpublished


glyphosate HaGn / glt1, glt2

Tai Chun and Hickok 1992


NaCl HaNn / stl1, stl2

Hickok et al. 1987; Warne and Hickok1987; 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, 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 Ceratopteris Bibliography