Publication Date

1989

Description

A reliable seedling genetic marker would • improve the efficiency of a recurrent selection scheme used in the tropical forage legume Stylosanthes guianensis (Miles, 1985; Cameron and Irwin, 1986). However, seedling markers are rare in S. guianensis. Only presence vs. absence of stem pubescence is reported (Cameron and Irwin, 1986), and this is an unreliable marker in many crosses (Miles, unpublished data). We initiated a project to induce a seedling mutant with gamma radiation. Non-nodulating mutants have been found in other legume species (e.g. Davis et al., 1985) so our project was deliberately designed to identify these if they occurred. An M2 screening and M3 progeny test identified four lines which appeared to be deficient in N-fixation. The purpose of the present report is to describe three studies aimed at characterizing these mutants.

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An Induced Non-Nitrogen-Fixing Mutant in Stylosanthes guianensis

A reliable seedling genetic marker would • improve the efficiency of a recurrent selection scheme used in the tropical forage legume Stylosanthes guianensis (Miles, 1985; Cameron and Irwin, 1986). However, seedling markers are rare in S. guianensis. Only presence vs. absence of stem pubescence is reported (Cameron and Irwin, 1986), and this is an unreliable marker in many crosses (Miles, unpublished data). We initiated a project to induce a seedling mutant with gamma radiation. Non-nodulating mutants have been found in other legume species (e.g. Davis et al., 1985) so our project was deliberately designed to identify these if they occurred. An M2 screening and M3 progeny test identified four lines which appeared to be deficient in N-fixation. The purpose of the present report is to describe three studies aimed at characterizing these mutants.