SELECTION OF NODULATION AND MYCORRHIZAL MUTANTS IN THE MODEL-PLANT MEDICAGO-TRUNCATULA (GAERTN) AFTER GAMMA-RAY MUTAGENESIS

Seeds of Medicago truncatula cv. Jemalong line J5 were treated by gamm a-rays to create mutations affecting Rhizobium symbiosis. Putative mut ants were selected in M(2) and true mutant phenotypes were confirmed i n M(3), M(4), M(5) and M(6) generations. Fixed nodulation mutant lines were then screened for their endomycorrhizal characters. Eighteen mut ant lines are now available. They consist of 2 non-nodulating and non- mycorrhizal (Nod(-), Myc(-)), 4 low-nodulating and mycorrhizal (Nod(+/ -), Myc(+)), 9 nodulating, non-fixing and mycorrhizal (Nod(+)Fix(-), M yc(+)) and 3 supernodulating, nitrate tolerant nodulation and mycorrhi zal (Nod(++)Nts, Myc(+)) mutant lines.