INHERITANCE OF 2 MUTATIONS CONFERRING GLYPHOSATE TOLERANCE IN THE FERN CERATOPTERIS-RICHARDII

Two mutant strains (G492, G343) of the fern Ceratopteris richardii, selected following X-irradiation, showed enhanced tolerance to the herbicide glyphosate in both the haploid gametophyte and diploid sporophyte generations. Segregation analysis indicated that each strain carried a different nuclear mutation that was responsible for tolerance. The two mutations were unlinked. The glt1 mutation (strain G492) showed incomplete dominance and conferred higher tolerance than the recessive glt2 mutation (strain G343). Gametophyte segregants carrying both mutations did not show enhanced tolerance relative to gametophytes carrying only glt1. For both mutants, tolerance to glyphosate did not result in reduced fitness in the absence of the herbicide.