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PNL Volume 21 1989 RESEARCH REPORTS |
31 |
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MUTANTS DEFECTIVE IN SYMBIOTIC NITROGEN
FIXATION
Kneen, B.E., T.A. LaRue
Boyce Thompson Institute, Ithaca
NY 14853-1801, USA and N.F.
Weeden
N.Y.S.
Agricultural Experiment Station
Geneva, NY 14456, USA
Induced symbiosis mutants provide
new tools to study the host plant contribution to symbiotic nitrogen
fixation. We have described the induction of non-nodulated mutants of the
pea cultivar 'Sparkle', and have designated some of the sym genes
(1,2,3). Analysis of four mutants, not allelic with those previously
described, indicates four additional loci.
Line E135N (sym-14) is
non-nodulating, and was discovered as a segregant from the nodulating,
non-fixing line E135 (sym-13) (2). A very close linkage to
Fum locates sym-14 to chromosome 2.
Line E1 51 (sym-15) has few
or no nodules, and lateral roots are shorter than those of 'Sparkle' (1 ).
Sym-1 5 also maps to chromosome 2, near Amy-1.
R50 (sym-16) similarly has
short laterals and few or no nodules (1). It has shortened internodes and
pale leaflets. R50 was mapped to chromosome 5 near a previously mapped
stubby root mutant coh. Crosses between R50 and a line homozygous
for coh gave F1 plants with normal root morphology,
indicating the two mutants are probably not allelic.
R82 (sym-17) is a dwarf and
has thick stubby roots with few or no nodules. R82 displayed linkage to
Prx-2, an isozyme locus as yet unmapped. |
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1. Kneen, B.E. and T.A. LaRue. 1986.
PNL 18:33.
2. Kneen, B.E. and T.A. LaRue. 1987.
PNL 19:17.
3. Kneen, B.E. and T.A. LaRue. 1988. Plant
Science 58:177-182. |
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